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  • 1.
    Al-Obaidi, Mudhar A.
    et al.
    Technical Institute of Baquba, Middle Technical University, Baquba 32001, Iraq;Technical Instructor Training Institute, Middle Technical University, Baghdad 10074, Iraq.
    Rashid, Farhan Lafta
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Kadhom, Mohammed
    Department of Environmental Science, College of Energy and Environmental Science, Al-Karkh University of Science, Baghdad 10081, Iraq.
    Mujtaba, Iqbal M.
    Department of Chemical Engineering, Faculty of Engineering and Informatics, University of Bradford, Bradford BD7 1DP, UK.
    Optimizing Reverse Osmosis Feed Spacer Design for Enhanced Dimethylphenol Removal from Wastewater: A Study of Hydrodynamics and Performance Indicators2024Ingår i: Water, E-ISSN 2073-4441, Vol. 16, nr 6, artikel-id 895Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Due to its high pollutant rejection and low energy usage, the spiral wound module of reverse osmosis (RO) process is the most commonly used technology utilised in wastewater treatment. For a spiral wound module, the presence of a feed spacer is important as a key solution to mitigate the concentration polarisation phenomenon, due to disorderly fluid flow, and to improve the mass transfer coefficient. Undoubtedly, improvements in the spiral wound module design, mainly in the symmetrical shape of the feed spacer, can have a significant impact on the cost and probable use of these modules. Despite the wide interest in appraising the impact of feed spacer geometry and orientation on the performance of a spiral wound module for RO process-based water desalination, the hydrodynamics of feed spacers (pressure drop and mass transfer coefficient) and the associated influences of feed spacer design (the height of the feed spacer, the angle of the filaments, and the porosity) on the removal of pollutants from wastewater have not yet been addressed. The current investigation aims to fill this gap by studying the hydrodynamics and design parameters of the selected parallelogram feed spacer type ultrafiltration (UF−3) for the removal of dimethylphenol from wastewater. Using model-based simulation, the impacts of UF−3 feed spacer design parameters, including the height, angle between the filaments (orientation), and porosity on the pressure drop, friction factor, axial flow fluid velocity, mass transfer coefficient, water flux, dimethylphenol rejection, recovery rate, and specific energy consumption are detailed in this study. The study intends to demonstrate the optimum design features of UF−3 feed spacer that should be considered to assure the highest elimination of dimethylphenol from wastewater in addition to the lowest specific energy consumption.

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  • 2.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Experimental and numerical study of corner impinging jet ventilation for an office environment2024Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Ett effektivt ventilationssystem är en viktig komponent i en byggnads serviceinfrastruktur. Den tjänar det dubbla syftet att skapa en bekväm och hälsosam inomhusmiljö för de boende, därigenom förbättrande deras välbefinnande och produktivitet. Dock är ventilationssystemet också en del av byggnaden som använder en hög andel energi.

    Den huvudsakliga målsättningen med denna studie är att utvärdera en ny implementering av impinging jet ventilationssystem genom att placera inloppen i hörnen av rummet, i stället för den traditionella mellanväggsektionen. Fokus för denna studie är att testa och utvärdera corner impinging jet ventilation (CIJV) i en medelstor kontorsmiljö i en byggnad som kräver måttlig uppvärmning och kylning.

    I den första delen av denna studie utvärderas systemet i en experimentell miljö, där det jämförs med andra system såsom deplacerade ventilation och omblandad ventilation för sommar fall. De utvärderade parametrarna indikerar att CIJV presterar bättre än omblandad ventilation men visar liknande resultat som deplacerad ventilationssystem när det gäller luftväxlingseffektivitet. Denna experimentella uppställning testades också under vinterförhållanden och resultaten visade att systemet var mest effektivt under sommartiden jämfört med vintertiden. Under vintertiden var resultaten för luftväxlingseffektiviteten liknande de för omblandande ventilationssystem.

    I den andra delen användes numeriska simuleringar för att fördjupa förståelsen av CIJVs beteende nära golvytan. En numerisk modell skapades och validerades mot experimentella mätningar. I den här delen granskades spridningen av luftstrålen över golvet och dess relation till olika parametrar som tilluftshastighet, ventilationsdonet geometri och ventilationsdonets höjd över golvytan. Resultaten indikerade att ventilationsdonet geometri har en marginell inverkan på hastighetsutvecklingen längs golvvägens mittlinje, maximal hastighetsminskning och strålens spridningshastighet. Resultaten visade också en hög grad av flexibilitet när det gäller rumsstorlek, mellan 25–100m2 för vilka resultaten var tillämpliga. Resultaten konstaterade också att det fanns en märkbar restriktionseffekt närvarande och att strålen kunde färdas långt in i rummet.

    I den tredje delen användes numeriska simuleringar i en kontorsmiljö med två arbetsstationer. Kontorsrummet utvärderades både när det gällde den lokaltermisk komforten och luftkvalitén inomhus. Resultaten visade att CIJV presterade bättre än ett konventionellt omblandande system, särskilt när man utvärderade luftkvalitén med avseende på luftens medelålder. Utvärderingen beaktade också både utomhusförhållanden på sommaren och vintern samt olika flödeshastigheter. Olika platser för arbetsstationerna utvärderades också med goda resultat, förutom att när arbetsstationerna placerades nära inloppen.

    På grund av systemets effektivitet när det gäller att förse frisk luft till kontorsarbetarna gjordes en ytterligare analys för att försöka minska luftflödet men behålla samma nivå av luftkvalitén som ett motsvarande omblandande system. Genom att använda denna metod kunde studien visa på en minskning i energiförbrukningen genom att minska luftflödet för tilluften med 7-9 % för utomhustemperaturer som sträckte sig från -15 °C till 25 °C.

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  • 3.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    El Tayara, Khaled
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Energy Performance Evaluation of Historical Building2022Ingår i: Buildings, E-ISSN 2075-5309, Vol. 12, nr 10, artikel-id 1667Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Retrofitting measures in old buildings aimed at reducing energy usage have become important procedures meant to counteract the effects of climate change and greenhouse gas emissions. The aim of this study is to evaluate energy usage, thermal comfort, and CO2 emissions of an old building by changing parameters such as building orientation, shading systems, location, low energy film application, and alternative energy supply in the form of a geothermal heat pump. When evaluating the buildings in terms of geographical location with or without applying the low energy film, the results show that the city of Gävle in Sweden requires the most heating energy, 150.3 kWh/m2∙year (B0) compared to Jakarta (L0), which requires 23.8 kWh/m2∙year. When examining the thermal comfort, cases B4 and L4 demonstrate the best results in their respective categories (B0–B4 are cases without low energy film and L0–L4 are cases with applied low energy film). The results for the CO2 emissions levels for B0–B4 and L0–L4 indicate that B4 has the highest value, 400 kg CO2 eq/year higher than B0, and L1 has the lowest value, 731 kg CO2 eq/year lower than B0. The economic feasibility study illustrates that the installation of a geothermal heat pump with at least a coefficient of performance of 4.0 leads to a shorter payback period than solely applying LEF.

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  • 4.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Elousa Ansa, Ibai
    Assessment of Thermal Comfort and Indoor Air Quality in Library Group Study Rooms2023Ingår i: Buildings, E-ISSN 2075-5309, Vol. 13, nr 5, artikel-id 1145Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Human performance and health are among the most relevant topics in the modern society, especially at young ages, when academic performance is indispensable. Thus, as humans spend most of their lifetime inside a building, thermal comfort and indoor air quality are an essential aspect of a room. The aim of the current study is to numerically evaluate the main thermal comfort parameters such as PMV and PPD as well as indoor air quality, i.e., CO2 concentration, in library group study rooms at the University of Gävle in Sweden. Rotroninc Measurement Solutions CL11 sensors were utilized for temperature measurements. Simulation models were created and validated based of building data as well as temperature measurements. Several simulations were conducted throughout a year, covering different periods. The results show that even though the ventilation system, with only temperature control, works as intended for maintaining the thermal comfort, the CO2 concentration rises above 1000 ppm when more than one student occupy the rooms, which is not recommended by different thermal comfort ruling institutions. Consequently, a modification to the ventilation system control is recommended, changing it from temperature control to CO2 and temperature control.

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  • 5.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Reducing energy usage in multi-family housing2019Ingår i: 2019 9th International Conference on Future Environment and Energy 9–11 January 2019, Osaka, Japan, Institute of Physics Publishing (IOPP), 2019, Vol. 257, artikel-id 012030Konferensbidrag (Refereegranskat)
    Abstract [en]

    The energy usage in residential sector have been around 22% of the total energy use in the world and increasing due to the population growth and higher living standards. The energy sources for this are made up primarily of non-renewable energy resources which generates a large amount of global greenhouse gases. A lot of countries have implemented various regulations and rules to reduce the energy usage in buildings and promoting the use of renewable energy technologies. This paper presents a parametric study of a typical multi-family building in its pre-design stage. The climate location used is Sweden (Gothenburg) and Japan (Osaka). The aim of the study is to compare various configurations and to examine how they affect the energy use. The most interesting configurations are the use of heat pump and solar cells. Other configurations that are examined are infiltration levels, pressure coefficients, wind impact, ventilation with heat recovery, ventilation scheduling, building orientation and finally changing U-values in the building material. Results of this study show that the energy saving, by utilizing a heat pump and solar panels, can reduce the total energy use by 34.9% for Gothenburg and 32% for Osaka. The results also show that the difference in total energy use between the two cities reduce substantially (3% difference) when utilizing a heat pump in combination with solar panels.

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  • 6.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Numerical investigation of indoor thermal comfort and air quality for an office equipped with corner impinging jet ventilation2023Ingår i: Advances in Building Energy Research, ISSN 1751-2549, E-ISSN 1756-2201, Vol. 17, nr 5, s. 578-604Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigates the feasibility of using only corner impinging jet ventilation (CIJV) for heating and cooling a medium-sized office space with two occupants while maintaining adequate indoor thermal comfort and air quality compared to traditional mixing ventilation systems. This study examines what impact various outdoor temperatures, ranging from −15°C to 25°C, have on an office environment in terms of indoor thermal comfort and air quality. Three different workspace positions were evaluated. The results show that the CIJV system meets the ASHRAE thermal comfort standards for all three positions. In terms of indoor air quality, CIJV performs better than traditional mixing systems, with improved mean age of air and ACE values. This study concludes that CIJV can be used both close and far away from the supply inlets and still provide adequate indoor thermal comfort and air quality during both cooling and heating season.

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  • 7.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Experimental Investigation of Ventilation Performance of Different Air Distribution Systems in an Office Environment: Heating Mode2019Ingår i: Energies, E-ISSN 1996-1073, Vol. 12, nr 10, artikel-id 1835Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A vital requirement for all-air ventilation systems are their functionality to operate both in cooling and heating mode. This article experimentally investigates two newly designed air distribution systems, corner impinging jet (CIJV) and hybrid displacement ventilation (HDV) in comparison against a mixing type air distribution system. These three different systems are examined and compared to one another to evaluate their performance based on local thermal comfort and ventilation effectiveness when operating in heating mode. The evaluated test room is an office environment with two workstations. One of the office walls, which has three windows, faces a cold climate chamber. The results show that CIJV and HDV perform similar to a mixing ventilation in terms of ventilation effectiveness close to the workstations. As for local thermal comfort evaluation, the results show a small advantage for CIJV in the occupied zone. Comparing C2-CIJV to C2-CMV the average draught rate (DR) in the occupied zone is 0.3% for C2-CIJV and 5.3% for C2-CMV with the highest difference reaching as high as 10% at the height of 1.7 m. The results indicate that these systems can perform as well as mixing ventilation when used in offices that require moderate heating. The results also show that downdraught from the windows greatly impacts on the overall airflow and temperature pattern in the room.

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  • 8.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Experimental investigation of ventilation performance of different air distribution systems in an office environment – cooling mode2019Ingår i: Energies, E-ISSN 1996-1073, Vol. 12, nr 7, artikel-id 1354Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The performance of a newly designed corner impinging jet air distribution method with an equilateral triangle cross section was evaluated experimentally and compared to that of two more traditional methods (mixing and displacement ventilation). At nine evenly chosen positions with four standard vertical points, air velocity, turbulence intensity, temperature, and tracer gas decay measurements were conducted for all systems. The results show that the new method behaves as a displacement ventilation system, with high air change effectiveness and stratified flow pattern and temperature field. Both local air change effectiveness and air exchange effectiveness of the corner impinging jet showed high quality and promising results, which is a good indicator of ventilation effectiveness. The results also indicate that there is a possibility to slightly lower the airflow rates for the new air distribution system, while still meeting the requirements for thermal comfort and indoor air quality, thereby reducing fan energy usage. The draught rate was also lower for corner impinging jet compared to the other tested air distribution methods. The findings of this research show that the corner impinging jet method can be used for office ventilation.

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  • 9.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Yamasawa, Haruna
    Kyushu University, Fukuoka, Japan.
    Kobayashi, Tomohiro
    Osaka University, Osaka, Japan.
    Numerical investigation of the flow behavior of an isothermal corner impinging jet for building ventilation2022Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 223, artikel-id 109486Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The corner impinging jet concept has been proposed as a new air distribution system for use in office environments. The present paper reports the mean flow field behavior of an isothermal corner-based turbulent impinging jet in a room. A detailed experimental study is carried out to validate the numerical simulations, and the predictions are performed using three turbulence models. RNG k−ε model was chosen for this study. This study investigates the influence different configuration parameters such as jet discharge height, diffuser geometry (shape and size) and supply airflow rate have on the flow field. The results show that the diffuser geometries used in this study had in general a minor effect on the velocity developments along the centerline of the floor, maximum velocity decay and jet spreading rate except for some specific cases. When evaluating the triangle geometry cases, the results show that all the cases with volume flow <20 L/s are able to meet Boverket's building regulations velocity requirement both for summer and winter. The applicability evaluation show that the results can be considered for room sizes between ≈25 and 100 m2. In addition, the wall confinement effect (90° vs. 180°) is having a significant impact on the maximum velocity decay for corner impinging jet ventilation. In the regression analysis the results shows that the distance along the diagonal centerline of the room has the most impact on the evaluation of maximum velocity decay and jet spreading rate.

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  • 10.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Yamasawa, Haruna
    Osaka University, Japan..
    Kobayashi, Tomohiro
    Osaka University, Japan..
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Energy saving, indoor thermal comfort and indoor air quality evaluation of an office environment using corner impinging jet ventilation2023Ingår i: Developments in the Built Environment, ISSN 2666-1659, Vol. 15, artikel-id 100179Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The performance of a corner based impinging jet ventilation system (CIJV) in an office environment was evaluated numerically. The evaluation was done both in terms of the local thermal comfort and the local indoor air quality. Three different inlet configurations were tested for a range of outdoor temperatures that included both winter and summer conditions. In terms of indoor air quality, the results showed that CIJV performed better than a traditional mixing system. The study also revealed that CIJV creates a stronger temperature stratification in summertime compared to wintertime. When evaluating the energy saving potential the results showed a possible reduction of 7% for the ventilation flowrate when the outdoor temperatures were between -15 °C and -5 °C, 8 % when the outdoor temperatures were between 0 °C and 10 °C and 9 % when the outdoor temperatures were between 15 °C and 25 °C.

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  • 11.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Choonya, Gasper
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Experimental Evaluation of the Ventilation Effectiveness of Corner Stratum Ventilation in an Office Environment2019Ingår i: Buildings, E-ISSN 2075-5309, Vol. 9, nr 7, artikel-id 169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An experimental study was conducted in a room resembling an office in a laboratory environment. The study involved investigating the ability of corner-placed stratum ventilation in order to evaluate the ventilation’s effectiveness and local thermal comfort. At fixed positions, the air temperature, air velocity, turbulence intensity, and tracer gas decay measurements were carried out. The results show that corner-placed stratum ventilation behaves very similar to a mixing ventilation system when considering air change effectiveness. The performance of the system was better at lower supply air flow rates for heat removal effectiveness. For the heating cases, the draught rates were all very low, with the maximum measured value of 12%. However, for the cooling cases, the maximum draught rate was 20% and occurred at ankle level in the middle of the room.

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  • 12.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Mattsson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Boström, Hanna
    Lindelöw, Hanna
    Assessment of Thermal Comfort and Air Quality in Office Rooms of a Historic Building: A Case Study in Springtime in Continental Climate2023Ingår i: Buildings, E-ISSN 2075-5309, Vol. 13, nr 1, artikel-id 156Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the most important aspects of working in an office environment is ensuring that the space has optimal thermal comfort and an indoor environment. The aim of this research is to investigate the thermal comfort and indoor climate in three office rooms located at one of the campus buildings at the University of Gävle, Sweden. The evaluated period is in the month of April during springtime. During this period, parameters such as temperature, relative humidity, CO2, supply air flow rate, and room air velocities are measured on site. The results of the measurement show that the indoor temperature is on average lower in the rooms facing north, at 21–23.5 °C, compared to the rooms facing south, which reach high temperatures during sunny days, up to 26 °C. The results also show that the ventilation air supply rate is lower than the requirement for offices in two of the office rooms. The ACH rate is also low, at ≈ 1 h−1 for all the rooms, compared to the required levels of 2–4 h−1. The CO2 levels are within the recommended values; on average, the highest is in one of the south-facing rooms, with 768 ppm, and the maximum measured value is also in the same room, with 1273 ppm for a short period of time.

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  • 13.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Yamasawa, Haruna
    Kyushu University, Fukuoka, Japan..
    Kobayashi, Tomohiro
    Osaka University, Osaka, Japan..
    Numerical Evaluation of the Flow Field of An Isothermal Dual-Corner Impinging Jet for Building Ventilation2022Ingår i: Buildings, E-ISSN 2075-5309, Vol. 12, nr 10, artikel-id 1767Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The corner impinging jet ventilation is a new air distribution system for use in office environments. This study reports the mean flow field behavior of dual isothermal corner-placed inlets based on an impinging jet in a square-shaped room with the size of 7.2 m × 7.2 m. A detailed numerical study is carried out to evaluate the influence the different configuration parameters, such as the inlet placement, same side or opposite side, and supply airflow rate, have on the flow field. The results show that the highest velocity peak for all cases is obtained at x = 0.5 m and the lowest at x = 3.5 m. The velocity profiles development remains similar when increasing the flow rate. For the zone evaluation, the results show that Case 1 and 2 (V = 20 L/s) meet the requirement of not exceeding 0.15 m/s during the heating season in the occupied zone according the BBR standard both for same-side and opposite-side configurations. For Case 4, the optimal placement of the inlets is opposite to each other when V = 30 L/s for the BBR requirements. Case 1, 2, 3, 4, 5, and 7 all meet the requirement of not exceeding 0.25 m/s during the cooling season both for the same-side and opposite-side configurations. For Case 8, the optimal placement of the inlets is opposite to each other when V = 50 L/s.

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  • 14.
    Bahrami, Alireza
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Halvarsson, Mattias
    Aho, Mikael
    Potential Electricity Production of Roof-Mounted Solar PV Systems in a Row House Area in Sweden2023Ingår i: Sustainable Technology for Society 5.0: Case Studies, Examples, and Advanced Research Findings / [ed] Tilottama Singh, Richa Goel, Jan Alexa Sotto, CRC Press, 2023, s. 167-182Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Sweden's energy policy goal is to have completely renewable electricity production by the year 2040; thus, alternatives such as wind and solar energies are being investigated for electricity supply, where mainly solar energy has the potential for small and medium-sized systems for houses of private individuals and companies. As a part of this development, the tenant-owner's association, Stenbär, in the city of Gävle in Sweden has considered installing solar PV systems, which has become the basis for this research. The aim of this chapter is to investigate the potential areas for a solar cell plant, and how much electricity this could produce per year. The simulations are performed by using the computer software IDA ICE 5.0 beta. It is demonstrated that there is a good potential to produce a large amount of solar energy in the area. As the system produces a surplus during the summer half of the year, there is also the possibility of selling the electricity.

  • 15.
    Bahrami, Alireza
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Nkweto, Henry
    Energy Audit of Two Multifamily Buildings and Economic Evaluation of Possible Improvements2023Ingår i: Urban Transition: Perspectives on Urban Systems and Environments / [ed] Marita Wallhagen and Mathias Cehlin, IntechOpen , 2023Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    AbstractThe energy use of buildings is gradually increasing, which is due to economic growth and an increase in population. Several studies have indicated that the implementation of energy-saving measures (ESMs) such as thermal insulation results in more energy saving; however, most ESMs are not economically viable. This chapter outlines ESMs using the IDA ICE computer software. The evaluation of the energy performance of two multifamily buildings is conducted, and possible ESMs are suggested such as thermal insulation, changing windows, installing a new air handling unit, installing a heat exchanger in showers, improving thermal bridges, replacing lighting bulbs, increasing external insulation plus temperature reduction, and changing schedules for air discharge control. The economic feasibility of these suggestions is assessed using the life cycle cost analysis to determine their economic viability. This involves the determination of the life cycle cost and life cycle cost saving to decide the best option. The most important factor in determining life cycle cost saving is the modified uniform present value. The addition of the attic insulation, installing a heat exchanger in showers, replacing lighting bulbs, and changing schedules meet the economic requirement within a feasible time frame.

  • 16.
    Cehlin, Mathias
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Claesson, Leif
    Wigö, Hans
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Lin, Yuanyuan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Urban Morphology and City Ventilation2020Konferensbidrag (Refereegranskat)
    Abstract [en]

    The purpose of the paper is to examine the relation between urban morphology, wind direction and air flow rates. In the study a highly idealized city model was used consisting of a circular block divided into two or four equally large sectors. Wind tunnel experiments and CFD predictions have been conducted. The interaction between the atmospheric boundary layer and a city is considered to be both a function of the overall shape and the internal resistance to the flow caused by the friction when the wind flows over the urban surfaces. Flow along the streets is generated by pressure differences. In the wind tunnel, velocity measurements have been recorded in the streets at several points and pressure on the ground was registered in 400 points. The wind tunnel measurements were used to validate the CFD model. The CFD predictions provided complete flow and pressure fields for different configurations and wind directions. The flow balance is presented considering both the horizontal air flow and the vertical air flow (subsidence and updraft). Special attention was on the pressure distribution at ground level (pressure footprint), which is believed to provide valuable information that can be used for qualitative city ventilation analyses. 

  • 17.
    Cehlin, Mathias
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Comparing thermal comfort and air quality performance of two active chilled beam systems in an open-plan office2019Ingår i: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 22, s. 56-65Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The traditional air distribution and supply devices in ventilated rooms are not always able to effectively remove excess heat from the space. Therefore, chilled beams, especially the active systems, are used to achieve the desired cooling demand. The focus of this paper was the potential benefit of a newly designed active chilled beam (ACB) system, to improve heat removal effectiveness local thermal condition and indoor air quality in the occupants’ breathing zone. The system based on 1-way flow design (1W-ACB) was installed in an open-plan office and its performance was studied by analysing the temperatures, velocities and tracer gas concentrations in predetermined risky zones. The system was compared against a traditional 4-way flow design (4W-ACB).

    The obtained results showed that heat removal effectiveness was slightly higher for the 1W-ACB system compared to the 4W-ACB system. The local thermal condition was very good close to the workstations when using 1W-ACB. The benefits of the new system were also shown in the occupied zone by analysing the mean age of air and air-change effectiveness (ACE) in the breathing level at the workstation locations. The 1W-ACB system provided air with lower mean age (fresher air), and therefore higher ACE, near the breathing zone at the workstations compared to the 4W-ACB. On the other hand, the 4W-ACB system had the advantage of providing high thermal and mean age of air uniformity throughout the room.

  • 18.
    Dulaimi, Anmar
    et al.
    University of Warith Al-Anbiyaa, Iraq; Liverpool John Moores University, UK; University of Kerbala, Iraq.
    Al Busaltan, Shakir
    University of Kerbala, Iraq.
    Mydin, Md Azree Othuman
    Universiti Sains Malaysia, Malaysia.
    Lu, Dong
    Harbin Institute of Technology, China.
    Özkılıç, Yasin Onuralp
    Necmettin Erbakan University, Turkey; Lebanese American University, Lebanon.
    Jaya, Ramadhansyah Putra
    Universiti Malaysia Pahang Al-Sultan Abdullah, Malaysia.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Innovative geopolymer-based cold asphalt emulsion mixture as eco-friendly material2023Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 13, artikel-id 17380Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In recent years, there has been a growing interest in cold asphalt emulsion mixture (CAEM) due to its numerous advantages, including reduced CO2 emissions, energy savings, and improved safety during construction and application. However, CAEM has often been considered inferior to hot mix asphalt (HMA) in terms of performance. To address this issue and achieve desirable performance characteristics, researchers have been exploring the modification of CAEM using high-cost additives like ordinary Portland cement. In this study, the focus was on investigating the effects of utilizing waste alkaline Ca(OH)2 solution, ground granulated blast-furnace slag (GGBFS), and calcium carbide residue (CCR) as modifiers to enhance the properties of CAEM. The aim was to develop an innovative geopolymer geopolymer-based cold asphalt emulsion mixture (GCAE). The results of the study revealed that the use of waste alkaline Ca(OH)2 solution led to an increase in early hydration, which was confirmed through scanning electron microscopy. Furthermore, the experimental findings demonstrated that waste alkaline Ca(OH)2 solution significantly contributed to the rapid development of early-age strength in GCAE. As a result, GCAE showed great potential for utilization in pavement applications, particularly for roads subjected to harsh service conditions involving moisture and temperature. By exploring these alternative modifiers, the study highlights a promising avenue for enhancing the performance of CAEM and potentially reducing the reliance on expensive additives like ordinary Portland cement. The development of GCAE has the potential to offer improved performance and durability in pavement applications, thus contributing to sustainable and efficient road infrastructure.

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  • 19.
    Jwaida, Zahraa
    et al.
    Industrial Preparatory School of Vocational Education Department, Educational Directorate Babylon, Ministry of Education, Babylon 51001, Iraq.
    Dulaimi, Anmar
    College of Engineering, University of Kerbala, Karbala 56001, Iraq;College of Engineering, University of Warith Al-Anbiyaa, Karbala 56001, Iraq.
    Mydin, Md Azree Othuman
    School of Housing, Building and Planning, Universiti Sains Malaysia, Penang 11800, Malaysia.
    Özkılıç, Yasin Onuralp
    Department of Civil Engineering, Faculty of Engineering, Necmettin Erbakan University, Konya 42000, Turkey;Department of Civil Engineering, Lebanese American University, Byblos 1102-2801, Lebanon.
    Jaya, Ramadhansyah Putra
    Faculty of Civil Engineering Technology, Universiti Malaysia Pahang Al-Sultan Abdullah, Kuantan 26300, Malaysia.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    The Use of Waste Polymers in Asphalt Mixtures: Bibliometric Analysis and Systematic Review2023Ingår i: Journal of Composites Science, E-ISSN 2504-477X, Vol. 7, nr 10, artikel-id 415Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Asphalt is widely employed in road construction due to its durability and ability to withstand heavy traffic. However, the disposal of waste polymers has emerged as a significant environmental concern. Recently, researchers have used polymer waste to modify asphalt pavements as a new approach. This approach aims to improve pavement performance and address the environmental concerns of polymer waste. Researchers have demonstrated that incorporating polymeric waste into asphalt mixtures can lead to performance improvements in asphalt pavements, particularly in mitigating common distresses including permanent deformation and thermal and fatigue cracking. The current comprehensive review aims to summarize the recent knowledge on the usage of waste polymers in asphalt mixtures, encompassing their impact on performance properties and mixture design. The review also addresses different types of waste polymers, their potential benefits, challenges, and future research directions. By analyzing various studies, this review offers insights into the feasibility, effectiveness, and limitations of incorporating waste polymers into asphalt mixtures. Ultimately, this contributes to the advancement of sustainable and environmentally friendly road construction practices.

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  • 20.
    Kabanshi, Alan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Hayati, Abolfazl
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Yang, Bin
    Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden.
    Cooling energy simulation and analysis of an intermittent ventilation strategy under different climates2018Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 156, s. 84-94Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Energy use on heating, ventilation and air conditioning (HVAC) accounts for about 50% of building energy use. To have a sustainable built environment, energy efficient ventilation systems that deliver good indoor environmental quality are needed. This study evaluates the cooling energy saving potential of a newly proposed ventilation system called Intermittent Air Jet Strategy (IAJS) and compares its performance against a mixing ventilation (MV) system in a classroom located in three cities with different climates, Singapore with ‘hot and humid’, Ahvaz with ‘hot and dry’ and Lisbon with “moderate” climate. The results show a significant reduction of cooling energy need and flexibility in control strategies with IAJS as a primary system in hot and humid climates like Singapore. Hot and dry climate with short cool periods like Ahvaz show possible application and considerable energy savings with IAJS as a primary system under optimized variable setpoints, but moderate climates have an increased risk of occupant discomfort likely due to increased draft especially during the cool season.  Thus, IAJS as a secondary system that operates only during cooling season may be conducive for moderate climates like Lisbon. Additionally, the results show that supply fan energy savings can also be realized if well implemented. 

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  • 21.
    Kabanshi, Alan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Yang, Bin
    Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden.
    Wigö, Hans
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Energy simulation and analysis of an intermittent ventilation system under two climates2017Ingår i: 10th International Conference on Sustainable Energy and Environmental Protection: Energy Efficiency / [ed] Krope J., Olabi, A.G., Goričanec D. & Božičnik S., Maribor: University of Maribor Press , 2017, s. 1-10Konferensbidrag (Refereegranskat)
    Abstract [en]

    Energy use on heating, ventilation and air conditioning (HVAC) accounts for about 50% of total energy use in buildings.  Energy efficient HVAC systems that do not compromise the indoor environmental quality and at the same time meet the energy reduction directives/policies are necessary and needed. The study herein, evaluates the energy saving potential of a newly proposed ventilation system in spaces with high occupancy density, called Intermittent Air Jet Strategy (IAJS). The aim of the study was to evaluate through simulations the potential energy savings due to IAJS as compared to a mixing ventilation (MV) system in a classroom located in a ‘hot and humid’ climate (Singapore), and in a ‘hot and dry’ climate (Kuwait). The analysis is based on IDA Indoor Climate Energy simulation software. The results herein demonstrate significant reduction of cooling energy use of up 54.5% for Singapore and up to 32.2% for Kuwait with IAJS as compared to MV. Additionally, supply fan energy savings can also be realized if well implemented.

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  • 22.
    Kabanshi, Alan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Choonya, Gasper
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Window size optimization and shading with photovoltaic panels: Simulation of cooling energy demand in the tropics in the southern hemisphere2021Ingår i: 13th International Conference on Sustainable Energy and Environmental Protection: Solar Energy. September 13-16, 2021, Vienna, Austria. / [ed] Christoph Pfeifer, Rafat Al Afif & Abdul Ghani Olabi, 2021Konferensbidrag (Refereegranskat)
    Abstract [en]

     Window size and orientation of holding façade influences the quantity of solar insolation into buildings and consequently the heating/cooling demand and occupant thermal comfort. In cold climates, window optimization (size and the orientation) can reduce the heating requirements if well integrated into the building envelope. However, in hot climates window sizing and orientation poses challenges as it only adds to the cooling energy demand. In addition to design strategies like window size and orientation, passive strategies like blinds or shades are recommended to reduce and control the solar insolation. The current study, through IDA-ICE building simulations, explores optimization of window size, orientation and shading configurations (internal blinds and PV as external shades) and its influence on the cooling energy demand in Harare, Zimbabwe, located in the tropic of Capricorn in the Southern Hemisphere. The results shows that cooling demand and occupant thermal comfort was sensitive to the North facing facades, and slightly on the west, but not on the South and west oriented windows. Shading reduced the cooling demand and use of PV panels proved equally effective although only a slight improvement in thermal comfort level was obtained compared to using internal blinds. However, PV panels produced electricity that could help offset the cooling demand by powering a heat pump or reduce the imported power for other building services. Implications of the results on building design and operation are discussed.

  • 23.
    Kabanshi, Alan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Choonya, Gasper
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Liu, Wei
    KTH Royal Institute of Technology.
    Mulenga, Enock
    Luleå University of Technology.
    Windows of Opportunities: Orientation, Sizing and PV-Shading of the Glazed Area to Reduce Cooling Energy Demand in Sub-Sahara Africa2023Ingår i: Energies, E-ISSN 1996-1073, Vol. 16, nr 9, artikel-id 3834Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In hot climates, such as sub-Sahara Africa, window sizing and orientation pose challenges as they add, through solar insolation, to the building cooling energy demand and thus the cause of indoor overheating risk. This risk can be reduced through passive building-design-integrated measures, e.g., optimizing the window size, orientation and solar shading strategies. Through an IDA-ICE building performance simulation tool, the current study explores the impact of window size, optimization and building-integrated PV panels as shading strategies on cooling energy demands in three cities (Niamey, Nairobi and Harare) in sub-Sahara Africa. Results show that thermal comfort and cooling energy demand are sensitive to a window-to-wall ratio (WWR) > 70%, while the need for artificial lighting is negligible for a WWR > 50%, particularly in the north for cities in the Southern hemisphere and the south in the Northern hemisphere. A WWR > 70% in the east and west should be avoided unless shading devices are incorporated. Internal blinds perform better in improving occupant thermal comfort but increase artificial lighting while integrating PV panels, as external shading overhangs reduce cooling energy but also produce energy that can be utilized for building services, such as air conditioning. In this study, the results and implications of the optimization of window size, orientation and building-integrated shading and operation are discussed.

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  • 24.
    Khalaf, Abbas Fadhil
    et al.
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala, Iraq.
    Rashid, Farhan Lafta
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala, Iraq.
    Al-Obaidi, Mudhar A.
    Technical Institute of Baquba, Middle Technical University, Baquba, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Mohammed, Hayder I.
    Department of Cooling and Air Conditioning Engineering, Imam Ja’afar Al-Sadiq University, Baghdad, Iraq.
    Numerical investigation of the effect of an air layer on the melting process of phase change materials2024Ingår i: Materials for Renewable and Sustainable Energy, ISSN 2194-1459, E-ISSN 2194-1467Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Designing more effective thermal energy storage devices can result from understanding how air layers impact the melting process. The total efficiency of these systems can be improved by optimizing the melting process of the phase change materials (PCMs), which are utilised to store and release thermal energy. The current study utilises an analysis to evaluate how an air layer would affect melting of the PCM. The enthalpy-porosity combination based ANSYS/FLUENT 16 software is specifically used to accomplish this study, considering the paraffin wax (RT42) as the PCM. The study reveal that the presence of an air layer would impact the dissolution process. This result is assured an increase of melting time of PCM by 125% as a result to having an air layer of 5 cm thickness compared to a cell without an air layer. Furthermore, an increase of the layer thickness beyond 5 cm has a progressive effect on the melting time of PCM. One important component that affects the melting process is the existence of an air layer above the cell. Greater heat transfer resistance from thicker air layers prolongs the time needed to finish melting. The efficient heat transmission of PCM is shown to be reduced when there is an air layer above the cell. The melting process gradually slows down as the air layer thickness rises, which reflects the decreased heat transmission. These results highlight how crucial it is to take the environment into account while creating PCM-filled energy storage cells.

  • 25.
    Khalaf, Abbas Fadhil
    et al.
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Rashid, Farhan Lafta
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Letif, Shaimaa Abdel
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Mohammed, Hayder I.
    Department of Cooling and Air Conditioning Engineering, Imam Ja’afar Al-Sadiq University, Baghdad 10011, Iraq.
    A Numerical Study of the Effect of Water Speed on the Melting Process of Phase Change Materials Inside a Vertical Cylindrical Container2024Ingår i: Applied Sciences, E-ISSN 2076-3417, Vol. 14, nr 8, artikel-id 3212Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present work offers a thorough analysis of the impact of water velocity on phase change material (PCM) melting in a vertical cylindrical container. A detailed quantitative analysis uses sophisticated numerical techniques, namely the ANSYS/FLUENT 16 program, to clarify the complex relationship between enthalpy and porosity during the melting process. The experimental focus is on phase transition materials based on paraffin wax, particularly Rubitherm RT42. This study’s primary goal is to evaluate the effects of different water velocities (that is, at velocities of 0.01 m/s, 0.1 m/s, and 1 m/s) on the PCM’s melting behavior at a constant temperature of 333 K. This work intends to make a substantial contribution to the development of thermal energy storage systems by investigating new perspectives on PCM behavior under various flow circumstances. The study’s key findings highlight the possible ramifications for improving PCM-based thermal energy storage devices by revealing significant differences in melting rates and behavior that correlate to changes in water velocities. Future research is recommended to explore the impact of temperature variations, container geometries, and experimental validation to improve the accuracy and practicality of the results and to advance the creation of sustainable and effective energy storage solutions.

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  • 26.
    Mattsson, Magnus
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karlsson, Björn O.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Fältstudie av två metoder för energieffektivisering av äldre fönster – fönsterfilmer testade med hotbox-teknik2020Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Föreliggande studie har undersökt två typer av fönsterfilmer som avser förbättra fönster avseende energi- och komfortaspekter. Filmerna utgörs av tunn självhäftande plast med högteknologisk strålningsreflekterande beläggning. Framför allt har en ny typ av värmeisolerande film (här kallad ”Energifilm”) testats, vilken främst syftar till att minska värmeförlusten genom fönstret mot ett kallare uteklimat. Energifilmen har i detta projekt provats i fält med den s.k. hotbox-metoden, varvid ett 2-glasfönsters värmeförlust kunnat mätas på plats i en verklig, kulturhistorisk byggnad – Rådhuset i Gävle. Hotbox-metoden används normalt i laboratoriemiljö och ett viktigt syfte med projektet har varit att utvärdera metoden i fält. Förutom energifilmen provades även solreflekterande film (”Solfilm”), vilken främst avser minska transmission av strålningsvärme från direkt solljus. Studien innefattar även antikvariska och estetiska aspekter på applicering av fönsterfilmer, där byggnadsantikvarier anlitats för subjektiv bedömning.  

    Resultaten pekar på att hotbox-metoden är användbar i fält, om än ganska mödosam att få på plats rent praktiskt. Mätresultaten indikerar att montage av Energifilm minskar värmetransporten (U-värdet) genom fönstrets glasade del med ca 31 % om filmen placeras på någon av glasytorna i spalten mellan glasen, medan minskningen blir ca 19 % vid placering på insidan av innerglaset. Placering i spalten tycks därmed effektivast när så är möjligt; det minskar också risken för kondens och kallras längs fönstrets insida. Rent ekonomiskt tycks det emellertid svårt att räkna hem någon vinst genom investering i vare sig Energifilm eller Solfilm. Montage av Solfilm tenderar tvärtom att öka energikostnaderna. Termisk buffring i den tunga rådhusbyggnaden bidrar till att hålla nere den värmeökning som kan ske vid mycket solinstrålning och internvärme; Solfilm torde komma bättre till pass i lättare byggnader. Rådhusbyggnaden var även försedd med mekanisk behovsstyrd ventilation, med möjlighet till ganska höga ventilationsflöden för kylning; i byggnader utan sådant system kommer Solfilm till bättre nytta. Både energi- och Solfilm förbättrar dock den termiska komforten, både avseende kyla och värme, särskilt för personer som befinner sig i närheten av fönstren. Så, snarare än minskade kostnader torde det vara komfort- och/eller miljöskäl som kan motivera investering i fönsterfilmerna. 

    Fönsterfilmerna medförde minskad ljustransmittans (-16 % för Energifilm; -22 % för Solfilm) och viss (måttlig) färgförändring vid vissa ljusförhållanden och betraktelsevinklar. Överlag fick de studerade fönsterfilmerna emellertid tämligen hög acceptans av byggnadsantikvarierna, men man noterade att noggrannhet vid montaget är mycket viktigt. Montage av filmerna demonstrerades också gå förhållandevis snabbt och medföra liten störning på verksamheten i lokalerna under installation. Filmerna kan också klippas till att passa t.ex. krökta bågar, och de medför inte någon ökad belastning (tyngd) för fönstret, i jämförelse med andra metoder som innebär komplettering med ett extra glas på bågen. Test av borttagning av 3 år gammal Energifilm visade att detta kunde göras utan att skada fönster-glasen, men det synes tveksamt att montera filmerna på riktigt tunna, ömtåliga glas, då sådana riskerar gå sönder vid borttagning av filmen, som ändå noterades sitta tämligen hårt fast.

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    Slutrapport Fönsterfilmer testade i hotbox
  • 27.
    Moghaddam, Saman Abolghasemi
    et al.
    University of Coimbra, Portugal.
    Mattsson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Gameiro Da Silva, Manuel
    University of Coimbra, Portugal.
    Simoes, Nuno
    University of Coimbra, Portugal.
    Low‐Emissivity Window Films as an Energy Retrofit Option for a Historical Stone Building in Cold Climate2021Ingår i: Energies, E-ISSN 1996-1073, Vol. 14, nr 22, artikel-id 7584Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Low‐emissivity (low‐E) window films are designed to improve the thermal comfort andenergy performance of buildings. These films can be applied to different glazing systems withouthaving to change the whole window. This makes it possible to apply films to windows in old andhistorical buildings for which preservation regulations often require that windows should remainunchanged. This research aims to investigate the impacts of low‐E window films on the energyperformance and thermal comfort of a three‐story historical stone building in the cold climate ofSweden using the simulation software “IDA ICE”. On‐site measurements were taken to acquirethermal and optical properties of the windows. This research shows that the application of the lowemissivitywindow film on the outward‐facing surface of the inner pane of the double‐glazedwindows helped to reduce heat loss through the windows in winter and unwanted heat gains insummer by almost 36% and 35%, respectively. This resulted in a 6% reduction in the building’sannual energy consumption for heating purposes and a reduction in the percentage of totaloccupant hours with thermal dissatisfaction from 14% (without the film) to 11% (with the film).However, the relatively high price of the films and low price of district heating results in a ratherlong payback period of around 30 years. Thus, the films seem scarcely attractive from a purelyeconomic viewpoint, but may be warranted for energy/environmental and thermal comfort reasons.

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  • 28.
    Pekdogan, Tugce
    et al.
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Udriștioiu, Mihaela Tinca
    University of Craiova, Craiova, Romania.
    Yildizhan, Hasan
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    From Local Issues to Global Impacts: Evidence of Air Pollution for Romania and Turkey2024Ingår i: Sensors, E-ISSN 1424-8220, Vol. 24, nr 4, artikel-id 1320Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Air pollution significantly threatens human health and natural ecosystems and requires urgent attention from decision makers. The fight against air pollution begins with the rigorous monitoring of its levels, followed by intelligent statistical analysis and the application of advanced machine learning algorithms. To effectively reduce air pollution, decision makers must focus on reducing primary sources such as industrial plants and obsolete vehicles, as well as policies that encourage the adoption of clean energy sources. In this study, data analysis was performed for the first time to evaluate air pollution based on the SPSS program. Correlation coefficients between meteorological parameters and particulate matter concentrations (PM1, PM2.5, PM10) were calculated in two urban regions of Romania (Craiova and Drobeta-Turnu Severin) and Turkey (Adana). This study establishes strong relationships between PM concentrations and meteorological parameters with correlation coefficients ranging from −0.617 (between temperature and relative humidity) to 0.998 (between PMs). It shows negative correlations between temperature and particulate matter (−0.241 in Romania and −0.173 in Turkey) and the effects of humidity ranging from moderately positive correlations with PMs (up to 0.360 in Turkey), highlighting the valuable insights offered by independent PM sensor networks in assessing and improving air quality.

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  • 29.
    Pekdogan, Tugce
    et al.
    Department of Architecture, Faculty of Architecture and Design, Adana Alparslan Türkeş Science and Technology University, 46278 Adana, Turkey.
    Yildizhan, Hasan
    Department of Energy Systems Engineering, Adana Alparslan Türkeş Science and Technology University, 46278 Adana, Turkey.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Unveiling the Air Quality Impacts of Municipal Solid Waste Disposal: An Integrative Study of On-Site Measurements and Community Perceptions2024Ingår i: Atmosphere, E-ISSN 2073-4433, Vol. 15, nr 4, artikel-id 410Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    AbstractThis study examines air quality conditions in and around a classroom located in the Sarıçam/Adana region of Türkiye, near the campus of Adana Alparslan Türkeş Science and Technology University and the Sofulu municipal solid waste (MSW) facility. This academic setting was strategically chosen due to its proximity to the waste facility. The study aims to provide a comprehensive view of the environmental and social impacts of solid waste management through a methodological approach that combines quantitative on-site measurements and qualitative survey studies. Findings from measurements and surveys underline the significant and measurable impacts of MSW facilities on the ambient air quality of university residents. The analysis revealed a marked increase in concentrations of key pollutants, including carbon monoxide (CO), hydrogen sulfide (H2S), dust, and methane (CH4). At sampling point N1, H2S levels rose from 0 ppm in July to 13 ppm in November. Methane increased from 0.2% to 2.5% of the Lower Explosive Limit (LEL) at the same point, although it remained within safety limits. Additionally, CO levels showed a 40% increase, and dust concentration levels rose from 0.21 mg/m3 to 2.36 mg/m3 from summer to winter, indicating a seasonal variation likely influenced by the landfill’s operational dynamics, as well as changes in temperature and relative humidity. In particular, the results indicate high concentrations of CO, H2S and dust, which are directly related to air quality degradation. The study also sheds light on the impacts of these waste disposal facilities on the general well-being and health of the university community, particularly on students and staff. In addition to these findings, the study highlights a general lack of awareness in the university community about the impacts of MSW facilities on air quality. This highlights the need for increased education and information dissemination. The results support the development of comprehensive and effective strategies, including technical solutions and public awareness initiatives, to mitigate the impacts of these facilities on residential areas. In conclusion, the impacts of MSW facilities on air quality should be seen as a multidimensional issue that requires a holistic approach addressing environmental, health, social, and educational dimensions.

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  • 30.
    Rashid, Farhan Lafta
    et al.
    University of Kerbala, Iraq.
    Al-Gaheeshi, Asseel M. Rasheed
    University of Kerbala, Iraq.
    Mohammed, Hayder I.
    Imam Ja’afar Al-Sadiq University, Baghdad, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Heat Convection in a Channel-Opened Cavity with Two Heated Sources and Baffle2024Ingår i: Energies, E-ISSN 1996-1073, Vol. 17, nr 5, artikel-id 1209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study employs COMSOL software v 5.6 to investigate a novel approach to heat transfer via mixed convection in an open hollow structure with an unheated 90° baffle elbow. Two 20 W heat sources are strategically positioned on the cavity’s bottom and right-angled wall for this research. Notably, the orientation of the baffle perpendicular to the airflow is used to direct external, unrestricted flow into the square cavity. The research investigates a range of air velocities (0.1, 0.5, 1.0, and 1.5 m/s) and the intricate interaction between input air velocity, dual heated sources, and the presence of a right-angle baffle on critical thermodynamic variables, such as temperature distribution, isotherms, pressure variation, velocity profile, air density, and both local and mean Nusselt numbers. Validation of the applicable computational method is achieved by comparing it to two previous studies. Significant findings from numerical simulations indicate that the highest velocity profile is in the centre of the channel (2.3–2.68 m/s at an inflow velocity of 1.5 m/s), while the lowest profile is observed along the channel wall, with a notable disruption near the inlet caused by increased shear forces. The cavity neck temperature ranges from 380 to 640 K, with inflow air velocities varying from 0.1 to 1.5 m/s (Re is 812 to 12,182), respectively. In addition, the pressure fluctuates at the channel-cavity junction, decreasing steadily along the channel length and reaching a maximum at the intake, where the cavity neck pressure varies from 0.01 to 2.5 Pa with inflow air velocities changing from 0.1 to 1.5 m/s, respectively. The mean Nusselt number exhibits an upward trend as air velocity upon entry increases. The mean Nusselt number reaches up to 1500 when the entry air velocity reaches 1.5 m/s. Due to recirculation patterns, the presence of the 90° unheated baffle produces a remarkable cooling effect. The study establishes a direct correlation between input air velocity and internal temperature distribution, indicating that as air velocity increases, heat dissipation improves. This research advances our understanding of convective heat transfer phenomena in complex geometries and provides insights for optimising thermal management strategies for a variety of engineering applications.

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  • 31.
    Rashid, Farhan Lafta
    et al.
    University of Kerbala, Iraq.
    Aljibori, Hakim S.
    University of Warith Al-Anbiyaa, Karbala, Iraq.
    Mohammed, Hayder I.
    Imam Ja’afar Al-Sadiq University, Baghdad, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ahmad, Shabbir
    China University of Geosciences, Wuhan, China; Muhammad Nawaz Sharif University of Engineering and Technology, Multan, Pakistan.
    Ben Hamida, Mohamed Bechir
    Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia; University of Monastir, Monastir City, Tunisia; University of Sousse, Sousse City, Tunisia.
    Al-Rubaye, Ameer H.
    Al-Kitab University Altun Kupri, Iraq.
    Recent advances and developments of the application of hybrid nanofluids in parabolic solar collector energy systems and guidelines for future prospects2024Ingår i: Journal of Engineering Research, ISSN 2307-1877Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study addresses challenges in enhancing the thermal efficiency of parabolic solar collector energy systems using hybrid nanofluids, focusing on issues like nanoparticle clumping and decreased effectiveness. The objective is to optimize design parameters for improved energy absorption and efficiency by evaluating the thermal performance of hybrid nanofluids through theoretical and experimental analyses, aiming to enhance the overall efficiency of solar collector systems. The thermal performance of solar collector systems was evaluated by conducting numerical simulations and experimental analyses to investigate the effects of various nanoparticle compositions and concentrations. The findings suggest that hybrid nanofluids, specifically Au-Cu/EO and Cu-Al2O3, demonstrate enhanced heat transfer properties in comparison to conventional fluids, resulting in efficiency enhancements ranging from 22.44% to 35.01%. Compared to water, Al2O3/water (0.04%), and MWCNT/water (0.04%), the solar collector's thermal efficiency improves by 197.1%, 69.2%, and 6.1%, respectively. Furthermore, the research emphasizes the potential advantages of integrating precise nanoparticle concentrations to improve thermal efficiency while reducing the adverse effects of friction factors. The results emphasize the significance of tackling primary obstacles such as the clumping together of nanoparticles, heightened energy demands for pumping, and elevated expenses in the manufacture of hybrid nanofluids. The study enhances the advancement of cost-effective and efficient solar collector systems by identifying limits and suggesting alternative solutions. The research highlights the necessity for additional investigation into innovative combinations of nanomaterials, fine-tuning of fluid characteristics, and thorough evaluations of long-term stability in order to forward the practical use of hybrid nanofluids in solar energy systems.

  • 32.
    Rashid, Farhan Lafta
    et al.
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Al-Obaidi, Mudhar A.
    Technical Institute of Baquba, Middle Technical University, Baquba 32001, Iraq;Technical Instructor Training Institute, Middle Technical University, Baghdad 10074, Iraq.
    Mahdi, Ali Jafer
    Electrical and Electronic Engineering Department, University of Kerbala, Karbala 56001, Iraq;Department of Scientific Affairs, Al-Zahraa University for Women, Karbala 56001, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Advancements in Fresnel Lens Technology across Diverse Solar Energy Applications: A Comprehensive Review2024Ingår i: Energies, E-ISSN 1996-1073, Vol. 17, nr 3, artikel-id 569Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Concentration of solar energy may be obtained by reflection, refraction, or a combination of the two. The collectors of a reflection system are designed to concentrate the sun’s rays onto a photovoltaic cell or steam tube. Refractive lenses concentrate light by having it travel through the lens. The sun’s rays are partially reflected and then refracted via a hybrid technique. Hybrid focus techniques have the potential to maximize power output. Fresnel lenses are an efficient tool for concentrating solar energy, which may then be used in a variety of applications. Development of both imaging and non-imaging devices is occurring at this time. Larger acceptance angles, better concentration ratios with less volume and shorter focal length, greater optical efficiency, etc., are only some of the advantages of non-imaging systems over imaging ones. This study encompasses numerical, experimental, and numerical and experimental studies on the use of Fresnel lenses in various solar energy systems to present a comprehensive picture of current scientific achievements in this field. The framework, design criteria, progress, and difficulties are all dissected in detail. Accordingly, some recommendations for further studies are suggested.

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  • 33.
    Rashid, Farhan Lafta
    et al.
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Dulaimi, Anmar
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq;School of Civil Engineering and Built Environment, Liverpool John Moores University, Liverpool L3 2ET, UK;College of Engineering, University of Warith Al-Anbiyaa, Karbala 56001, Iraq.
    Hatem, Wadhah Amer
    Technical Institute of Baquba, Middle Technical University, Baquba 32001, Iraq.
    Al-Obaidi, Mudhar A.
    Technical Institute of Baquba, Middle Technical University, Baquba 32001, Iraq;Technical Instructor Training Institute, Middle Technical University, Baghdad 10074, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Eleiwi, Muhammad Asmail
    Electromechanical Engineering Department, College of Engineering, University of Samarra, Samarra 34010, Iraq.
    Jawad, Sarah Abbas
    Department of Energy Engineering, College of Engineering-Al-Musayab, University of Babylon, Babylon 51002, Iraq.
    Bernardo, Luís Filipe Almeida
    Department of Civil Engineering and Architecture, University of Beira Interior, GeoBioTec-UBI, 6201-001 Covilhã, Portugal.
    Hu, Jong Wan
    Department of Civil and Environmental Engineering, Incheon National University, Incheon 22022, Republic of Korea;Incheon Disaster Prevention Research Center, Incheon National University, Incheon 22022, Republic of Korea.
    Recent Advances and Developments in Phase Change Materials in High-Temperature Building Envelopes: A Review of Solutions and Challenges2024Ingår i: Buildings, E-ISSN 2075-5309, Vol. 14, nr 6, s. 1582-1582Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of phase change materials (PCMs) has become an increasingly common way to reduce a building’s energy usage when added to the building envelope. This developing technology has demonstrated improvements in thermal comfort and energy efficiency, making it a viable building energy solution. The current study intends to provide a comprehensive review of the published studies on the utilization of PCMs in various constructions of energy-efficient roofs, walls, and ceilings. The research question holds massive potential to unlock pioneering solutions for maximizing the usefulness of PCMs in reducing cooling demands, especially in challenging high-temperature environments. Several issues with PCMs have been revealed, the most significant of which is their reduced effectiveness during the day due to high summer temperatures, preventing them from crystallizing at night. However, this review investigates how PCMs can delay the peak temperature time, reducing the number of hours during which the indoor temperature exceeds the thermal comfort range. Additionally, the utilization of PCMs can improve the building’s energy efficiency by mitigating the need for cooling systems during peak hours. Thus, selecting the right PCM for high temperatures is both critical and challenging. Insulation density, specific heat, and thermal conductivity all play a role in heat transfer under extreme conditions. This study introduces several quantification techniques and paves the way for future advancements to accommodate practical and technical solutions related to PCM usage in building materials.

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  • 34.
    Rashid, Farhan Lafta
    et al.
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Eleiwi, Muhammad Asmail
    Mechanical Engineering Department, College of Engineering, Tikrit University, Tikrit 34001, Iraq;Electromechanical Engineering Department, College of Engineering, University of Samarra, Samarra 34010, Iraq.
    Mohammed, Hayder I.
    Department of Physics, College of Education, University of Garmian, Kurdistan, Kalar 46021, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ahmad, Shabbir
    Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China;Department of Basic Sciences and Humanities, Muhammad Nawaz Sharif University of Engineering and Technology, Multan 60000, Pakistan.
    A Review of Using Solar Energy for Cooling Systems: Applications, Challenges, and Effects2023Ingår i: Energies, E-ISSN 1996-1073, Vol. 16, nr 24, artikel-id 8075Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Energy security refers to a country’s capacity to provide the energy resources essential to its wellbeing, including a reliable supply at an affordable costs. Economic growth and development cannot occur without access to reliable energy sources. Energy availability is a proxy for a country’s standard of living and a key factor in its economic development and technical progress. Solar power is the most reliable and cost-effective option when it comes to meeting the world’s energy needs. Solar-powered cooling systems are one example of how solar energy may be used in the real world. Solar-powered air conditioners have become more popular in recent years. The problems caused by our reliance on fossil fuels may be surmounted with the help of solar cooling systems that use solar collectors. Solar cooling systems may utilize low-grade solar energy, making them popular in the construction industry. Solar cooling systems powered by photovoltaic–thermal (PVT) collectors have been the subject of much research to improve the thermodynamic and economic performance of solar cooling systems. This research focuses on exploring the potential of solar-generated heat for use in cooling systems. This study will also examine the current challenges involved with using solar energy in cooling applications, as well as the possible benefits that may help pave the way for more research and greater employment of heat gain from the solar system in various cooling applications.

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  • 35.
    Rashid, Farhan Lafta
    et al.
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Hashim, Ahmed
    Department of Physics, College of Education for Pure Sciences, University of Babylon, Babylon 51002, Iraq.
    Dulaimi, Anmar
    College of Engineering, University of Warith Al-Anbiyaa, Karbala 56001, Iraq;School of Civil Engineering and Built Environment, Liverpool John Moores University, Liverpool L3 2ET, UK.
    Hadi, Aseel
    Department of Ceramic and Building Materials, College of Materials Engineering, University of Babylon, Babylon 51002, Iraq.
    Ibrahim, Hamed
    Department of Scientific Affairs, Al-Zahraa University for Women, Karbala 56001, Iraq.
    Al-Obaidi, Mudhar A.
    Technical Institute of Baquba, Middle Technical University, Baquba 32001, Iraq;Technical Instructor Training Institute, Middle Technical University, Baghdad 10074, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Enhancement of Polyacrylic Acid/Silicon Carbide Nanocomposites’ Optical Properties for Potential Application in Renewable Energy2024Ingår i: Journal of Composites Science, E-ISSN 2504-477X, Vol. 8, nr 4, artikel-id 123Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Composites made from polymers and nanoparticles have promise to be effective solar collectors and thermal energy storage devices due to benefits including improved thermal characteristics and increased structural stability. This study intends to fabricate polyacrylic acid/silicon carbide (PAA−SiC) nanocomposites and examine the optical properties for use in solar collectors and thermal energy storage (TES) fields. The optical properties of PAA−SiC nanocomposites are investigated within the wavelength between 340 and 840 nm. The findings indicate that an increase in SiC concentration in the PAA aqueous solution to 50 g/L at a wavelength of λ = 400 nm causes an increase in the absorption by 50.2% besides a reduction in transmission by 6%. Furthermore, the energy band gaps were reduced from 3.25 eV to 2.95 eV to allow for the transition, and subsequently reduced from 3.15 eV to 2.9 eV to allow for forbidden transition as a result of the increasing SiC concentration from 12.5 g/L to 50 g/L. The optical factors of energy absorption and optical conductivity were also enhanced with a rising SiC concentration from 12.5 to 50 g/L. Specifically, an improvement of 61% in the melting time of PAA−SiC−H2O nanofluids is concluded. Accordingly, it can be said that the PAA−SiC−H2O nanofluids are suitable for renewable energy and TES systems.

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  • 36.
    Rashid, Farhan Lafta
    et al.
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Khalaf, Abbas Fadhil
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Al-Obaidi, Mudhar A.
    Technical Institute of Baquba, Middle Technical University, Baquba 32001, Iraq;Technical Instructor Training Institute, Middle Technical University, Baghdad 10074, Iraq.
    Dulaimi, Anmar
    Department of Civil Engineering, College of Engineering, University of Kerbala, Karbala 56001, Iraq;College of Engineering, University of Warith Al-Anbiyaa, Karbala 56001, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Investigating the Impact of Cell Inclination on Phase Change Material Melting in Square Cells: A Numerical Study2024Ingår i: Materials, E-ISSN 1996-1944, Vol. 17, nr 3, artikel-id 633Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to determine the ideal degree of inclination that should be employed for constructing effective thermal energy storage systems, it is important to examine the impact of inclination angle on the melting behavior of phase change materials (PCMs) such as paraffin wax within a square cell. In consequence, this would guarantee the greatest capacity for energy release and storage. Additionally, analyzing this influence aids engineers in creating systems that enhance heat flow from external sources to the PCM and vice versa. To find out how the cell’s inclination angle affects the melting of PCM of paraffin wax (RT42) inside a square cell, a numerical analysis is carried out using the ANSYS/FLUENT 16 software. Specifically, the temperature and velocity distributions, together with the evolution of the melting process, will be shown for various inclination angles, and a thorough comparison will be made to assess the influence of inclination angle on the PCM melting process and its completion. The findings demonstrated that when the cell’s inclination angle increased from 0° to 15° and from 0° to 30° and 45°, respectively, the amount of time required to finish the melting process increased by 15%, 42%, and 71%, respectively. Additionally, after 210 min of operation, the PCM’s maximum temperature is 351.5 K with a 0° angle of inclination (horizontal) against 332.5 K with an angle of inclination of 45°.

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  • 37.
    Rashid, Farhan Lafta
    et al.
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Khalaf, Abbas Fadhil
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Al-Obaidi, Mudhar A.
    Technical Institute of Baquba, Middle Technical University, Baquba 32001, Iraq;Technical Instructor Training Institute, Middle Technical University, Baghdad 10074, Iraq.
    Investigation of Thermo-Hydraulics in a Lid-Driven Square Cavity with a Heated Hemispherical Obstacle at the Bottom2024Ingår i: Entropy, E-ISSN 1099-4300, Vol. 26, nr 5, artikel-id 408Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lid-driven cavity (LDC) flow is a significant area of study in fluid mechanics due to its common occurrence in engineering challenges. However, using numerical simulations (ANSYS Fluent) to accurately predict fluid flow and mixed convective heat transfer features, incorporating both a moving top wall and a heated hemispherical obstruction at the bottom, has not yet been attempted. This study aims to numerically demonstrate forced convection in a lid-driven square cavity (LDSC) with a moving top wall and a heated hemispherical obstacle at the bottom. The cavity is filled with a Newtonian fluid and subjected to a specific set of velocities (5, 10, 15, and 20 m/s) at the moving wall. The finite volume method is used to solve the governing equations using the Boussinesq approximation and the parallel flow assumption. The impact of various cavity geometries, as well as the influence of the moving top wall on fluid flow and heat transfer within the cavity, are evaluated. The results of this study indicate that the movement of the wall significantly disrupts the flow field inside the cavity, promoting excellent mixing between the flow field below the moving wall and within the cavity. The static pressure exhibits fluctuations, with the highest value observed at the top of the cavity of 1 m width (adjacent to the moving wall) and the lowest at 0.6 m. Furthermore, dynamic pressure experiences a linear increase until reaching its peak at 0.7 m, followed by a steady decrease toward the moving wall. The velocity of the internal surface fluctuates unpredictably along its length while other parameters remain relatively stable.

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  • 38.
    Rashid, Farhan Lafta
    et al.
    University of Kerbala, Iraq.
    Mohammed, Hayder I.
    University of Garmian, Iraq.
    Dulaimi, Anmar
    University of Warith Al-Anbiyaa, Iraq; Liverpool John Moores University, UK.
    Al-Obaidi, Mudhar A.
    Middle Technical University, Iraq.
    Talebizadehsardari, Pouyan
    China University of Geosciences, Wuhan, China.
    Ahmad, Shabbir
    Muhammad Nawaz Sharif University of Engineering and Technology, Pakistan.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Analysis of heat transfer in various cavity geometries with and without nano-enhanced phase change material: A review2023Ingår i: Energy Reports, E-ISSN 2352-4847, Vol. 10, s. 3757-3779Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Numerous heating and cooling design methods, including energy storage, geothermal resources, heaters, solar collectors, underground water movement, lakes, and nuclear reactors, require the study of flow regimes in a cavity and their impact on thermal efficiency in heat transportation. Despite the existence of several review studies in the open literature, there is no specific review of heat transfer investigations that consider different cavity designs, such as spheres, squares, trapezoids, and triangles. Therefore, this work aims to conduct a comprehensive review of previous research published between 2016 and 2023 on heat transfer analysis in these cavity designs. The intention is to clarify how various cavity shapes perform in terms of flow and heat transfer, both with and without the addition of nano-enhanced phase change materials (NePCMs), which may include fins, obstacles, cylinders, and baffles. The study also explores the influence of factors like thermophoresis, buoyancy, magnetic forces, and others on heat transport in cavities. Additionally, it investigates the role of air, water, nanofluids, and hybrid nanofluids within cavities. According to the reviewed research, nanoparticles in the base fluid speed up the cooling process and reduce the required discharging time. Thermophoresis, where nanoparticles move from the heated wall to the cold nanofluid flow, becomes more pronounced with increasing Reynolds numbers. Increasing the heated area of the lower flat fin enhances the heat transfer rate, while increasing both the Rayleigh number and the solid volume percentage of nanoparticles reduces it. Radiation blockage alters the path of hot particles and affects the anticipated radiative amount. Optical thickness plays a role in rapidly cooling a medium, and partition thickness has the most significant effect on heat transport when the thermal conductivity ratio is low. Heat transmission is most improved when the Rayleigh number is high and the Richardson number is low.

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  • 39.
    Saribulut, Lutfu
    et al.
    Adana Alparslan Turkes Science and Technology University, Adana, Turkey.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Student Project-Based Space Vector Modulation Technique for Power Electronics Laboratory2023Ingår i: Electronics, E-ISSN 2079-9292, Vol. 12, nr 12, artikel-id 2714Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two-level DC/AC inverter topologies are widely used for low voltage and high voltageapplications in power systems and industrial areas. Space Vector Modulation (SVM) is a popularPulse-Width Modulation technique used for controlling the inverters and providing the efficientenergy conversion from DC sources. However, applications of SVM-based studies are limited in thePower Electronics Laboratory (PEL) due to the vital risks associated with high voltage applications,and it is not easily learned through mathematical analysis and visual learning without implementation by undergraduate students. A simulation and experimental setup of an SVM-controlled twolevel, three-phase inverter was presented in this study for undergraduate students to learn its basicsin the PEL. Several programs were used to simulate the inverter in the classroom environment andto design a power circuit and microcontroller-based printed circuit board of the inverter for PELexperiments. The two case studies were given. In the case results, the output voltage waveforms ofsimulation and experimental inverters were compared to show the validation of simulation results.With this study, the students’ experience is enhanced in electronic circuit design, programming,coordination with hardware and software development activities, self-learning, and teamwork. Additionally, practical applications increase undergraduate students’ interest in Power ElectronicsCourses and reinforce their knowledge from lecture and laboratory studies. 

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  • 40.
    Saribulut, Lutfu
    et al.
    Department of Electrical-Electronics Engineering, Adana Alparslan Turkes Science and Technology University, Adana 01250, Turkey.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Voltage Sag Detection and Compensation Signal Extraction for Power Quality Mitigation Devices2023Ingår i: Energies, E-ISSN 1996-1073, Vol. 16, nr 16, artikel-id 5999Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The importance of voltage quality is continuously increasing in electrical networks due to the rising manufacturing costs resulting from system faults and disturbances in utility dynamics. Researchers generally prefer reference-frame transformation-based methods to detect and mitigate these disturbances. However, these methods are adversely affected during unbalanced loading and disturbances due to their direct dependence on system dynamics (currents and voltages). In this study, a new and simple method based on Clarke transformation is proposed to detect disturbances and generate compensation signals for Power Quality Mitigation Devices. The aim is to address the deficiencies of existing approaches. Firstly, the Clarke transformation is introduced through the vector presentation. Then, the mathematical derivation of the proposed method is provided to enhance readers’ understanding. The voltage sag detection and compensation signal extraction of its control algorithm for a Dynamic Voltage Restorer is illustrated graphically. Subsequently, a simple power system is created using a simulation program. Balanced and unbalanced voltage disturbances are applied to the test system to demonstrate the validation of the proposed method under distorted system conditions. The results of voltage sag detection and compensation signal extraction for both the proposed and existing methods are compared at the end of the case studies.

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  • 41.
    Saribulut, Lutfu
    et al.
    Adana Alparslan Turkes Science and Technology University, Turkey.
    Ok, Gorkem
    Adana Alparslan Turkes Science and Technology University, Turkey.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    A Case Study on National Electricity Blackout of Turkey2023Ingår i: Energies, E-ISSN 1996-1073, Vol. 16, nr 11, artikel-id 4419Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The necessary precautions should be taken in order to prevent service interruption during the maintenance and repairing of electricity networks. Among these measures, emergencies that may occur in the network should be foreseen, hazard scenarios should be created, and solutions should be developed. If these are not done, a blackout, which first follows the local regions and eventually results in the collapse of the national electrical network, may take place. In this study, the national blackout of Turkey that occurred on 31 March 2015 is examined. The information about Turkey’s electrical infrastructure and its energy policies was provided, as well as the reliability assessment criteria for power systems and examples of significant blackouts that occurred worldwide. The direct relation between line voltage and system frequency was provided with mathematical derivation by using real data taken from a local industrial zone. Then, a case study is presented to demonstrate this direct relation. The causes, development process, and consequences of the blackout are discussed in detail, and some recommendations are offered to increase the security of the electrical infrastructure and to prevent future occurrences while ensuring the sustainability of the system.

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  • 42.
    Uçal, Esmanur
    et al.
    Adana Alparslan Turkes Science and Technology University, Turkey.
    Yildizhan, Hasan
    Adana Alparslan Turkes Science and Technology University, Turkey.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Erbay, Zafer
    Adana Alparslan Turkes Science and Technology University, Turkey.
    Assessment of Whole Milk Powder Production by a Cumulative Exergy Consumption Approach2023Ingår i: Sustainability, E-ISSN 2071-1050, Vol. 15, nr 4, artikel-id 3475Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The production of food is a sector that consumes a significant amount of energy and encompasses both agricultural and industrial processes. In this study, the energy consumption of whole milk powder production, which is known to be particularly energy-intensive, was examined. The study used a cumulative exergy consumption approach to evaluate the overall production process of whole milk powder, including the dairy farm (raw milk production) and dairy factory (powder production) stages. The results showed that raw milk production dominated energy and exergy consumption and carbon dioxide emissions. An amount of 68.3% of the total net cumulative exergy consumption in the system was calculated for raw milk production. In the dairy factory process, the highest energy/exergy consumption occurred during spray drying, followed by evaporation and pasteurization. In these three processes, 98.3% of the total energy consumption, 94.6% of the total exergy consumption, and 95.7% of the total carbon dioxide emissions in powder production were realized. To investigate the improvement potentials in the system, replacing fossil fuels with renewable energy sources and using pasture feeding in animal husbandry were evaluated. While using alternative energy sources highly influenced powder production, pasture feeding had a high impact on consumption in raw milk production. By using renewable energy and pasture feeding, the exergy efficiency, cumulative degree of perfection, renewability index, and exergetic sustainability index values for the overall process increased from 40.5%, 0.282, −0.22, and 0.68 to 68.9%, 0.433, 0.65, and 2.21, respectively.

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  • 43.
    Yamasawa, Haruna
    et al.
    Kyushu University, Kasuga, Japan.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Kobayashi, Tomohiro
    Osaka University, Suita, Japan.
    Kuga, Kazuki
    Kyushu University, Kasuga, Japan.
    Ito, Kazuhide
    Kyushu University, Kasuga, Japan.
    Influence of Exhaust Opening Height on Indoor Environment in Impinging Jet Ventilated Room2023Konferensbidrag (Refereegranskat)
    Abstract [en]

    The impinging jet ventilation system (IJV) is one of the ventilation systems with high ventilation effectiveness systems, which creates temperature and contaminant stratification. The influence of exhaust opening locations on temperature and ventilation effectiveness in a room with IJV was studied using computational fluid dynamics (CFD). The height of the exhaust outlet location was changed as a parameter. As a result, it is shown that although the values of temperature and contaminant concentration at the occupied zone do not differ depending on the height, however, the height has a large impact on those at the higher level and residence time period of air.

  • 44.
    Yamasawa, Haruna
    et al.
    Osaka University.
    Kobayashi, Tomohiro
    Osaka University.
    Yamanaka, Toshio
    Osaka University.
    Choi, Narae
    Osaka University.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Applicability of Displacement Ventilation and Impinging Jet Ventilation System to Heating Operation2021Ingår i: Japan Architectural Review, ISSN 2475-8876, Vol. 4, nr 2, s. 403-416Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study aims to acquire an understanding of the fundamental feature of IJV and DV under heating operation. Full‐scale experiments were conducted under these two different systems and supply air conditions along with temperature distribution and ventilation effectiveness. A wall surface of the test room was cooled as a heating load, and heating elements simulating occupants were located as internal heat load and contaminant emission source. Three cases of supply temperature were tested and the flow rate was also varied correspondingly. The position of the supply terminal was also changed to see its effect on heating performance, that is, mounted on the interior/exterior wall. For DV, the temperature/contaminant distribution differed significantly depending on the supply conditions, while that of IJV remained almost the same as a perfect mixing condition. Generally, IJV can achieve better temperature distribution compared to DV; however, the ventilation effectiveness of DV was superior to that of IJV with large supply flow rate. The correlation between the Archimedes number based on supply conditions and indices expressing local temperature and ventilation effectiveness is obtained. For IJV, the position of the terminal was found to have a larger impact on air distribution than the supply flow rate, while the opposite feature was obtained for DV.

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  • 45.
    Yamasawa, Haruna
    et al.
    Osaka University, Japan.
    Kobayashi, Tomohiro
    Osaka University, Japan.
    Yamanaka, Toshio
    Osaka University, Japan.
    Choi, Narae
    Osaka University, Japan.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Effect of supply velocity and heat generation density on cooling and ventilation effectiveness in room with impinging jet ventilation system2021Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 205, artikel-id 108299Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study aims to understand the effect of supply momentum and heat generation density on the cooling and ventilation effectiveness in a room with an impinging jet ventilation system (IJV). A parametric study was conducted by CFD analysis, and the number of supply terminals and occupants were varied as parameters. CFD validation was conducted before the parametric study by comparing the experimental and analytical results. RNG k-ε and SST k-ω model showed almost the same accuracy for simulating, and SST k-ω model was chosen to be used for the parametric study. It is shown that the larger number of terminals and/or occupants leads to the air distribution to be displacement flow, whereas the smaller number leads to that of mixed condition. The ventilation effectiveness and cooling effectiveness within the room could be kept higher by locating the supply terminal at the centre of the walls than at the corner of the room. When the supply velocity was smaller than 0.833 m/s, the draught rate (DR) at ankle level in the central cross-section could keep lower than: 20% in the region farther than 0.5 m horizontally away from the terminals, and 15% in the region farther than 1.0 m away from the terminals. Finally, the cooling and ventilation effectiveness is expressed as the function of Archimedes number (the balance between supply momentum and buoyancy) in the specific studied cases. The asymptotic values for both large and small Archimedes numbers are obtained for each index expressing cooling and ventilation effectiveness.

  • 46.
    Yamasawa, Haruna
    et al.
    Kyushu University, Japan..
    Kobayashi, Tomohiro
    Osaka University, Japan..
    Yamanaka, Toshio
    Osaka University, Japan..
    Choi, Narae
    Osaka University, Japan..
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Prediction of Temperature and Contaminant Concentration Profiles in a Room with Impinging Jet Ventilation System by Zonal Model2022Konferensbidrag (Refereegranskat)
    Abstract [en]

    The impinging jet ventilation (IJV) system has been proposed as a new air distribution strategy and is expected to overcome the disadvantages of the mixing ventilation system (MV), which is the most widely used system, and displacement ventilation, which provides better air quality than MV.The present study aims to predict the temperature and contaminant distribution by a simple calculation model that is applicable for IJV with multiple heating elements inside the room. The present calculation model is based on the zonal model and turbulence jet theory. The concept and theory of the calculation model are introduced, and the calculation results are compared to that of CFD analysis.The correlation between the thickness of the jet along the floor and the radial coordinate is obtained by the results of CFD analysis under isothermal conditions and adapted to the model as the height of the first zone from the floor. The turbulent diffusion coefficient of heat in the vertical direction is identified by the CFD results of the vertical temperature profile, whereas the turbulent diffusion coefficient of heat in the horizontal direction is obtained by the function of the number of heating elements in the present paper. It has to be noted that the turbulent diffusion coefficient of heat and contaminant is treated to be equal, due to the assumption in the present paper that the turbulent Prandtl number and the turbulent Schmidt number are the same.Finally, the turbulent diffusion coefficient of vertical direction is expressed as the function of the Archimedes number (balance between buoyancy and inertial force of supply flow) defined in the present paper. The correlation was expressed by the equation from the previous study and also by the newly developed equation. It was shown that although some limitations exist, the calculation model developed in the present paper can predict the temperature and contaminant gradient in the room.The calculation results of temperature gradient fitted that of CFD well except for the cases with large supply velocity. However, those cases are not practically applicable, thus, the accuracy of the model is more important in the cases with supply velocity lower than those cases. Although the calculation results of contaminant concentration fitted that of CFD analysis well in some cases, the prediction accuracy of contaminant concentration is generally lower than that of temperature. It is assumed to be because of the assumption in the present calculation model that the thermal and material turbulent diffusion coefficients are equal. Moreover, it is assumed that the modelling of the flow along the wall and the thermal plume from heating elements also need to be improved to increase the accuracy of the calculation model.

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  • 47.
    Yamasawa, Haruna
    et al.
    Osaka University, Japan.
    Kobayashi, Tomohiro
    Osaka University, Japan.
    Yamanaka, Toshio
    Osaka University, Japan.
    Choi, Narae
    Osaka University, Japan.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Prediction of thermal and contaminant environment in a room with impinging jet ventilation system by zonal model2022Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 221, artikel-id 109298Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The impinging jet ventilation (IJV) system has been proposed as a new air distribution strategy and is expected to overcome the disadvantages of the mixing ventilation (MV) system, which is the most widely used system, and displacement ventilation (DV), which provides better air quality than MV. This study aims to predict the vertical profile of temperature and contaminant in a room with impinging jet ventilation system (IJV) by a calculation model based on the zonal model and turbulence jet theory. The correlation between the thickness of the jet along the floor and radial coordinate is obtained by the results of CFD analysis under isothermal conditions and adapted to the model as the height of the first zone from the floor. The concept and theory of the calculation model are introduced, and the calculation results are compared to that of CFD analysis. The turbulent diffusion coefficient in the vertical direction is identified by the CFD results, whereas the turbulent diffusion coefficient in the horizontal direction is obtained by the function of the occupant density in the present paper. Finally, the turbulent diffusion coefficient of vertical direction is expressed as the function of the Archimedes number (balance between buoyancy and inertial force of supply flow) defined in the present paper. It was shown that although some limitations exist, the calculation model developed in the present paper can predict the temperature and contaminant gradient in the room. In addition, the draught risk around the floor is also predicted.

  • 48.
    Yamasawa, Haruna
    et al.
    Kyushu University, Fukuoka, Japan.
    Kobayashi, Tomohiro
    Osaka University, Osaka, Japan.
    Yamanaka, Toshio
    Osaka University, Osaka, Japan.
    Choi, Narae
    Osaka University, Osaka, Japan.
    Koshida, Moe
    Osaka University, Osaka, Japan.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Experimental Investigation on the velocity profile of supply flow in impinging jet ventilation system2023Ingår i: E3S Web of Conferences / [ed] Ooka R., EDP Sciences , 2023, Vol. 396, artikel-id 02014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Using the impinging jet ventilation system (IJV), it is possible to accomplish high ventilation effectiveness by creating temperature and contaminant stratification within the room. Since the air is supplied toward the floor and directly spreads into the occupied zone at the lower level, it is important to understand the flow feature of supplied jet around the floor. To understand this, the velocity profile of the jet around the floor at the central cross-section was measured using hotwire anemometer under isothermal conditions, and particle image velocimetry (PIV) under isothermal, cooling, and heating conditions. As a result, the obtained velocity profiles at the central cross-section by the hotwire anemometer and PIV are almost the same in the region more than 0.5 m horizontally away from the supply duct. The velocity in the region close to the supply duct was underestimated when using PIV, due to the insufficient entrainment of the surrounding air. However, its measurement accuracy is assumed to be sufficient for the flow that goes into the occupied zone. In addition, it was also shown that at the central-cross section, the velocity profiles under isothermal and cooling conditions are almost the same.

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  • 49.
    Yildizhan, Hasan
    et al.
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Yıldırım, Cihan
    Ağrı İbrahim Çeçen University, Ağrı, Turkey.
    Gorjian, Shiva
    Tarbiat Modares University (TMU), Tehran, Iran.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    How May New Energy Investments Change the Sustainability of the Turkish Industrial Sector?2023Ingår i: Sustainability, E-ISSN 2071-1050, Vol. 15, nr 2, artikel-id 1734Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Utilization of renewable energy in the Turkish industrial sector is becoming more important nowadays. The tendency toward renewable energy can be clearly seen with newly planned energy investments. The energy appearance of the Turkish industrial sector for past two decades and ongoing energy projects are discussed in this study with the help of sustainability indicators. The sustainability index is based on advanced exergy analysis and shows the environmental impact of production processes and measures the transformation of energy resources in the Turkish industrial sector. This index was approximately 2.03 in 2000 and it improved to 2.25 in 2008, and then remained constant with minor fluctuations until 2019. Depending on the fulfillment of the continuing fossil, nuclear, and recommended renewable energy investment scenarios, the sustainability index may change to between 1.96 and 2.17 by 2023. None of the ongoing investments will make a major improvement in the sustainability of the industrial sector; therefore, a major shift toward the use of more renewable energy is urgently needed. Establishing solar or wind energy microgrids plants may improve the sustainability indicators drastically, therefore, encouragement of their investments is very important.

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  • 50.
    Çelik, Onur
    et al.
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Yilmaz, S. Ece
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Yildizhan, Hasan
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Consumer purchasing behavior and its organizational evaluation toward solar water heating system2023Ingår i: Energy Reports, E-ISSN 2352-4847, Vol. 10, s. 1589-1601Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Renewable energy sources are fundamental to a country’s economic growth. Solar energy is one of these resources that has a favorable effect on economic growth. Turkey’s solar energy industry is still in its early stages. Due to its location and degree of sunshine each year, the country has a great solar potential. Despite the huge potential, solar energy awareness and utilization are not widespread in all parts of Turkey. In order to identify the factors that affect consumers’ decisions to utilize water heating systems, which is a sort of solar energy system, the purpose of this research is to examine these systems. In this study, all factors influencing consumers’ decisions to acquire solar water heating systems were evaluated holistically for the first time. A questionnaire was used in the study, which is a quantitative research technique. The study identifies the variables that influence consumers’ attitudes toward solar collector purchases and assesses the consequences from an organizational point of view. The study’s results act as a guide for decision-makers.

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