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  • 1.
    Abellán Guallarte, Alejandro
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Energy analysis between traditional hot water circulation system and an innovative pipe-in-pipe system2022Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    We are at a time when energy efficiency and the reduction in the use of non-renewable energy is an important objective in all aspects and will continue to be so, therefore it is necessary to try to reduce energy and heat losses in the systems used in homes and, in particular, in the domestic hot water (DHW) system. This study aims to find out the advantages and disadvantages of an innovative pipe-in-pipe (PIP) system for DHW circulation with respect to the conventional system of two separate pipes. Previous studies have shown that DHW circulation is indeed an important point of energy losses in the home and that it is possible to reduce these losses by using the innovative system under study. The properties and coefficients defining the heat transfer system have been obtained for both the traditional and innovative systems by using empirical equations and iterative processes, indicating a 32% reduction in heat losses in favour of the pipe-in-pipe system. However, this result has been obtained in a kind of case study, using some simplifying assumptions, needed to accomplish to work within limited time. So the result could vary if a somewhat different system is studied, which is why it is necessary to carry out further studies and research on this subject in order optimize DHW systems in buildings.

    Fulltekst (pdf)
    fulltext
  • 2.
    Abeywardana, Asela Janaka
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Solar - Biomass hybrid system for process heat supply in medium scale hotels in Sri Lanka2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This study aimed at evaluating and demonstrating the feasibility of using Concentrated Solar Thermal technology combined with biomass energy technology as a hybrid renewable energy system to supply the process heat requirements in small scale industries in Sri Lanka. Particularly, the focus was to apply the concept to the expanding hotel industry, for covering the thermal energy demand of a medium scale hotel.

    Solar modules utilize the rooftop area of the building to a valuable application. Linear Fresnel type of solar concentrator is selected considering the requirement of the application and the simplicity of fabrication and installation compared to other technologies. Subsequently, a wood-fired boiler is deployed as the steam generator as well as the balancing power source to recover the effects due to the seasonal variations in solar energy. Bioenergy, so far being the largest primary energy supply in the country, has a good potential for further growth in industrial applications like small hotels. 

    When a hotel with about 200-guests capacity and annual average occupancy of 65% is considered, the total annual CO2 saving is accounted as 207 tons compared with an entirely fossil fuel (diesel) fired boiler system. The annual operational cost saving is around $ 40,000 and the simple payback period is within 3-4 years. The proposed hybrid system can generate additional 26 employment opportunities in the proximity of the site location area.  

    This solar-biomass hybrid concept mitigates the weaknesses associated with these renewable technologies when employed separately. The system has been designed in such a way that the total heat demand of hot water and process steam supply is managed by renewable energy alone. It is thus a self-sustainable, non-conventional, renewable energy system. This concept can be stretched to other critical medium temperature applications like for example absorption refrigeration. The system is applicable to many other industries in the country where space requirement is available, solar irradiance is rich and a solid biomass supply is assured.    

    Fulltekst (pdf)
    SEE_KTH_HIG_AJA1
  • 3.
    Abolghasemi Moghaddam, Saman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap.
    The effects of low-emissivity window films on thermal comfort and energy performance of a historic stone building in cold climate: computer simulations with "IDA ICE"2019Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Low-emissivity (low-E) window films are designed to improve the energy performance of windows and prevent indoor overheating by solar radiation. These films can be applied to different types of glazing units without the need for changing the whole window. This characteristic offers the possibility to improve the energy performance of the window of old and historic buildings for which preservation regulations say windows should remain more or less unchanged. This research aims to figure out to what extent a low-E window film can improve thermal comfort and energy performance of an old three-storey historic stone building in the cold climate of Mid-Sweden. In this research, first, with help of the simulation software “IDA ICE”, the entire building was modelled without window films in a one-year simulation. Second step was to add the low-E window films (3M Thinsulate Climate Control 75 (CC75)) to all the windows and repeat the simulation. Comparison between the results of the two cases revealed an improvement in energy use reduction as well as the thermal comfort when applying the films. For the application of the window films, a cost analysis using payback method was carried out which showed a long- time payback period. Although an investment with a long-time payback period is considered as a disadvantage, for historic buildings with very strict retrofit regulations specially when it comes to the building’s facades, application of the low-emissivity window films for better energy performance and thermal comfort is among the recommendable measures, but not necessarily the best.

    Fulltekst (pdf)
    fulltext
  • 4.
    Aguirre Sánchez, Mikel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Air flow disturbance by moving objects at local exhaust ventilation2015Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The present thesis aims to study the effect of human movements on local exhaust ventilation.

    In its simplest terms, local exhaust ventilation is a system which has the function of extracting contaminated air situated close to the contaminant source, protecting a working person from exposure to hazardous substances by containing or capturing them locally, at the emission point. As an important security measure referred to terms of health, it is crucial for the healthiness of workers to control and prevent them from the exposure to vapour, mist, dust or other airborne contaminants. Additionally, to a lesser degree of significance, it can be stressed an expected increase in worker performance due to an improvement of the working conditions.

    There is an existing necessity for well-defined and appropriate methods to test the performance of local exhaust devices in order to reach standard efficiency values. The lack of an international standardization led to the realization of this study, which, ultimately, has the purpose of obtaining relevant results that can be utilized for future normalized test procedures.

    The study entails full scale experimental measurements that include air velocity measurements in 3 dimensions, a local exhaust ventilation device with circular hood and a flat flanged plate and a controlled generation of air turbulence through physical movements of a human-sized cylinder, simulating a walking person.

    The present study extends previous similar studies at the University of Gävle, where the controlled air turbulence was generated by a moving plate. After meaningful results obtained in that study, one of the considerations was to better simulate a walking person, by replacing the plate for a movable cylinder. The present study points at a larger similarity occurring with a cylinder than with a plate, as regards the air flow pattern produced by a real walking person.

    As in the previous study, the Percentage of Negative Velocities, PNV, has been used as the main measure of turbulence induced risk of contaminant spread. The PNV represents the fraction of the time when the flow is directed opposite to the suction air stream in front of the local exhaust hood. The obtained results conclude that the use of the cylinder as a moving object has been an improvement to simulate the effect of the movement of a human being on a relaxed walking pace.

    The present study was carried out in parallel with the thesis work by Leyre Catalán Ros, which complements this study by analyzing the effect of an added heated dummy, simulating a person seated in front of the local exhaust device.

    Fulltekst (pdf)
    fulltext
  • 5.
    Ahlund, Viktor
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energikartläggning av förskolan Smultronstället2015Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Detta är ett examenarbete på grundnivå, 15 högskolepoäng. Examensarbetet är en energikartläggning med rekommenderade energieffektiviseringsåtgärder. Energikartläggningen är baserad på ett verkligt objekt vilket är en förskola i norra Gävle. Denna skola förvaltas av Gavlefastigheter.I Sverige går cirka 40 % av energianvändningen till bostäder och service. Därför finns det stora mängder energi att spara inom denna sektor. Ett bra sätt att utreda på vart energin går i en byggnad är att göra en energikartläggning.Energikartläggningen är utförd utifrån ritningar, verkliga mätningar, schablonvärden, antaganden och litteratur.Skolan har en beräknad energianvändning på 1239 MWh per år, detta är uppdelat på ventilation, transmissionsförluster och tappvarmvatten. Efter 3 beräknade effektiviseringsåtgärder blir energibesparingen sammanlagt 612 MWh detta är 49,4 %. De åtgärder som är beräknade är tilläggsisolering, byte av ventilation och byte av fönster. Att enbart byta till FTX-ventilation sparar 522 MWh detta är en besparing på 42,1 % av den totala energianvändningen och den rekommenderade åtgärden.

    Fulltekst (pdf)
    fulltext
  • 6.
    Ahmed, Basem
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Investigation of energy retrofits of a multi-family building by using IDA Simulation Software2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Energy simulation in building sector was an important issue which can eliminate energy use and improve energy efficiency. The building, which is located at Ringvägen 18 in Ljusdal community in Sweden, was chosen to be the main mission of this research and it was one of eleven objects which were involved in EKG project. First step was to create the model and simulate it to reach heating value of 117 MWh which was reached by EKG project. After getting validation value, many renovations were implemented and the heating value was reduced by 58.7% and the heating demand by 55.2%. Improving of energy use through prefabrication gave reduction of heating value of 70.4% and heating demand of 65.8%

    The LCC part was important issue because it gave clear vision and judgment about the economic and investment issue. The acceptability of the investment decision was decided by 198 answers which were responsible to judge if the investments were good or not. There were 22 types of different renovation and every type included 9 cases which depended on interesting rate and energy price factors. The result was 198 answers which were divided to 100 answers as “YES” for good investment and 98 answers as “NO” for good investment.

    Fulltekst (pdf)
    fulltext med korrigerad TOC
  • 7.
    Akander, Jan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Department of Management and Engineering, Division of Energy Systems, Linköping University.
    Assessing the Myths on Energy Efficiency When Retrofitting Multifamily Buildings in a Northern Region2017Inngår i: Sustainable High Rise Buildings in Urban Zones: Advantages, Challenges, and Global Case Studies / [ed] Ali Sayigh, Cham: Springer Publishing Company, 2017, 1, s. 139-161Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    In the light of EU’s requirements to achieve a major cut in energy use by 2050, Sweden has the same target. The built environment must by 2020 reduce energy use by 20 and 50 % by 2050. The size of the future building stock will naturally increase and regardless of how energy efficient future buildings will be, the energy performance of the old stock must be improved in order to reach those goals. In major renovation projects involving multifamily buildings in large residential areas in the cities, 50 % reduction can be achieved. This is cost-effective and profitable even if the rent is increased.

    Gävleborg is a sparse region in the North, with few cities. Multifamily buildings are generally much smaller than in large cities and owners are reluctant to impose changes that increase rents due to the housing situation in the region. In consequence, the Regional Council and the University of Gävle set out to assess the potential and feasibility of reducing energy use and carbon dioxide emissions in this region’s multifamily buildings. Eleven real buildings were investigated, each having various ownership forms, different technical attributes and heating sources. Energy audits and measurements were conducted to assess the condition of each building. Performances of the buildings and proposed improvements were simulated with building energy simulation programs, whilst life cycle cost analyses were conducted to study viability. Carbon dioxide emission (CO2) reductions were estimated for each improvement.

    Based on the results, a concluding discussion is made on whether or not some myths on energy use and retrofitting are true. The following is concluded: It is possible to reach a 50 % reduction, but it is not economical with the costs involved and with today’s energy prices and moderate price increase over time.

    Retrofitting or improvements made in the building’s services systems (HVAC) are more economical than actions taken to improve performance of building by constructions. HVAC improvements give about 20 % reduction in energy use. However, mechanical ventilation systems with heat recuperation are not economical, though these may or may not substantially reduce use of thermal energy.

    Solar energy is, despite the latitude of the region, economically viable—especially PV solar energy. Photovoltaic panels (PVs) are becoming viable—the combination of PVs and district heating is beneficial since saving electricity is more important than thermal energy in district-heated areas.

  • 8.
    Al hamdany, Yarub
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Simulering och energieffektivisering för en kontorsbyggnad iForsmark2018Independent thesis Basic level (university diploma), 180 hpOppgave
    Abstract [en]

    The society changes rapidly and is heavily dependent on energy. The Energy usage in buildings account for about 40% of total Sweden's energy usage, where energy is used by buildings for electricity, cooling and heating. Therefore, energy is an important issue in today's society from an energy use approach to stop the global warming. In this work, a survey was carried out by an office building in Forsmark Kraftgrupp AB to find out about energy use and create a basis for energy-saving measures. The IDA ICE 4.7.1 program was used to simulate the building's energy use by creating a base model of the building. After that, the base model has been compared with different energy efficiency measures to check where the biggest and least energy saving potentials occur. The result shows that the total energy use in the office building is 198 125 kWh / year. The simulations show that energy efficiency measures could reduce energy use in the building by 81 962 kWh / year, which corresponds to 41.4% of the total energy use. Time control of ventilation systems gives the largest energy savings of 51, 2 kWh / m2, year.

    Fulltekst (pdf)
    examensarbete-11
  • 9.
    Alcheikh, Ahmad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Advantages and Challenges of Hemp Biodiesel Production: A comparison of Hemp vs. Other Crops Commonly used for biodiesel production2015Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Reducing reliance on a fossil fuel is a major challenge to many advanced and developing economies. This is due to the fact that fossil fuel, a finite resource, is depleting at a rapid rate with increasing demand. Additionally, the burning of fossil fuel is responsible for the current climate change, as a result of produced greenhouse gas emissions. Lastly, developing alternative renewable fuels improves energy security and decreases vulnerability of fuel supply. This thesis work explores the advantages and challenges of hemp biodiesel production. The aim of this research is to present a comprehenive evaluation of these advantages and disadvantages in the way of large-scale production of biodiesel produced from hemp oil. The thesis work relies on relavent research paper in the field and reports from the industry. Industrial hemp, a variant of the Cannabis Sativa plant (Cannabis Sativa Linn), is an important industrial and nutritional crop. Hemp seed oil can be used to produce biodiesel though the process of transesterification. Oil from hemp seeds presents a viable feedstock option for biodiesel production. Hemp provides a competitively high yield compared to similar crops. Biodiesel from hemp seed oil exhibits superior fuel quality with the exception of the kinetic viscosity and oxidation stability parameters, which can be improved with the introduction of chemical additives. Hemp remains a “niche” crop in the food supply chain, which makes it prohibitively expensive a primary feedstock in biodiesel production. Legal and perception challenges remain a major challenge in the way of wide-scale hemp biodiesel production. 

    Download (pdf)
    Master Thesis
  • 10.
    Alcoverro Colom, Pau
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    A new energy model for the Lakshadweep islands: Change from a diesel-based model to a hybrid model with renewable energy systems considering the ecological fragility of the islands2019Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    A new energy model for the Lakshadweep islands
  • 11.
    Ali, Sabir
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Building Information Modelling for Energy Analysis and Environmental Assessment: The comparison of LEED and Miljöbyggnad for two school buildings in Gävle, Sweden2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The building sector is one of the largest energy consumers and there are global efforts toward sustainable and energy-efficient new buildings and existing buildings retrofit. The application of Building Information Modelling (BIM) in environmental assessment was practiced and studied following the increasing number of projects adopting the BIM workflows and pursuing green building certifications. The interest of this thesis is to study the use of different Building Information Modelling tools used globally for energy and environmental assessment to examine their practical benefits and challenges. Case studies of two primary school buildings that achieved the Swedish Miljöbyggnad system were used to compare what could have been achieved with Leadership in Energy and Environmental Design (LEED) categories of energy and atmosphere and indoor environmental quality to what has been achieved in similar Miljöbyggnad areas. A review and summary of energy and atmosphere and indoor environmental categories in the LEED version 4 user’s guide is presented to evaluate the case study potential score in them.

    The early adoption of modeling in the evaluation from the conceptual design is the best approach to achieve better performance. It will improve the way of working and result in a more efficient and sustainable building.

    The Building Information Modelling software can be used directly in assessment using the integrated modules within the popular authoring tools such as Revit’s lighting and Insight the cloud base service or by transferring the model data to a stand-alone tool like IDA-ICE. The energy plug-ins of the authoring tools such as Revit are still lacking full control over the analytical model and the limited input options.

    The identified and discussed advantages of Building Information Modelling implementation are collaboration, accuracy, time, and cost saving. Data exchange issues, knowledge, and the differences in assessment tools were discussed as implementation barriers.

    Although the full comparison of certification systems is difficult, the comparison between the potential LEED score and achieved Miljöbyggnad rating showed some differences and similarities in the rating systems. The comparison requires rearranging the rating system indicators into unified categories. The framework that compares the scope, structure, content, and aggregation, would give a meaningful comparison. The way that the LEED and Miljöbyggnad are rewarding the indicators and the aggregation of aspects towards the final rating is totally different.

    Fulltekst (pdf)
    fulltext
  • 12.
    Alonso Lozano, Alvaro
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Coal gasification in entrained flow gasifiers simulation & comparison2012Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    Coal gasification
  • 13.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energianalys och energieffektivisering av en förskola: Söderskolan (Slottets förskola) i Gävle, simulering utförd genom IDA ICE 4.612014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Bostad- och servicesektorn står för 38 % av Sveriges totala energianvändning. Av det här står bostäder och lokaler för 90 % av energianvändningen och nästan 60 % av det går till att värma upp byggnaderna och till varmvatten. Därför är det viktig att börja titta på den här sektorn och se om det finns möjlighet att spara på energianvändningen. I den här studien har en kartläggning gjorts av en gammal skolbyggnad för att kunna skapa ett underlag för energieffektiviseringsåtgärder. Genom att använda simuleringsprogrammet IDA ICE 4.61 har man skapat en basmodell av byggnaden som då används som simuleringsbas. Basmodellen har jämförts med fjärrvärmekostnader för att kunna verifieras. Därefter har man lagt in energieffektiviserar och tittat på vilka besparingar man har kommit fram till. Resultatet av den här studien visade att i den här byggnaden så är den mest effektiva åtgärden isolering av taket till vinden.

    Fulltekst (pdf)
    Examensarbete_Arman
  • 14.
    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 Rooms2023Inngår i: Buildings, E-ISSN 2075-5309, Vol. 13, nr 5, artikkel-id 1145Artikkel i tidsskrift (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
  • 15.
    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 ventilation2023Inngår i: Advances in Building Energy Research, ISSN 1751-2549, E-ISSN 1756-2201, Vol. 17, nr 5, s. 578-604Artikkel i tidsskrift (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
  • 16.
    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 Mode2019Inngår i: Energies, E-ISSN 1996-1073, Vol. 12, nr 10, artikkel-id 1835Artikkel i tidsskrift (Fagfellevurdert)
    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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  • 17.
    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 ventilation2023Inngår i: Developments in the Built Environment, ISSN 2666-1659, Vol. 15, artikkel-id 100179Artikkel i tidsskrift (Fagfellevurdert)
    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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  • 18.
    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 Environment2019Inngår i: Buildings, E-ISSN 2075-5309, Vol. 9, nr 7, artikkel-id 169Artikkel i tidsskrift (Fagfellevurdert)
    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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  • 19.
    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 Climate2023Inngår i: Buildings, E-ISSN 2075-5309, Vol. 13, nr 1, artikkel-id 156Artikkel i tidsskrift (Fagfellevurdert)
    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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  • 20.
    Amiri, Shahnaz
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Economic and Environmental Benefits of CHP-based District Heating Systems in Sweden2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Future energy systems and thus the climate are affected by many factors, such as energy resources, energy demand, energy policy and the choice of energy technologies. Energy systems of the future are facing three main challenges; the steady growth of global energy demand, the energy resource depletion, as well as the increasing emissions of carbon dioxide (CO2) and other greenhouse gases and their impact on climate change. To meet the mentioned challenges with sustainability in mind, actions that increase energy efficiency and choosing an energy-efficient energy system which is cost efficient will be essential. Combined heat and power (CHP) plants and district heating and cooling could contribute greatly to increased system efficiency by using energy otherwise wasted.

    The aim of this study is to increase the understanding of how CHP-based district heating and cooling systems using different primary energy sources can contribute to more cost-efficient energy systems, which reduce global CO2 emissions, and to highlight the impact of some important parameters and measures on Swedish municipal district heating systems. An important assumption in this study is the estimation of CO2 emissions from electricity production, which is based on marginal electricity perspectives. In the short term, the marginal electricity is assumed to come from coal-fired condensing power plants while in the long term it consists of electricity produced by natural gas-fired combined cycle condensing power plants. This means that the local electricity production will replace the marginal electricity production. The underlying assumption is an ideal fully deregulated European electricity market where trade barriers are removed and there are no restrictions on transfer capacity.

    The results show that electricity generation in CHP plants, particularly in higher efficiency combined steam and gas turbine heat and power plants using natural gas, can reduce the global environmental impact of energy usage to a great extent. The results confirm, through the scenarios presented in this study, that waste as a fuel in CHP-based district heating systems is fully utilised since it has the lowest operational costs. The results also show how implementation of a biogas-based CHP plant in a biogas system contributes to an efficient system, as well as lowering both CO2 emissions and system costs. The results show that replacing electricity-driven (e.g. compression) cooling by heat-driven cooling using district heating (e.g. absorption chillers) in a CHP system is a cost-effective and climate friendly technology as electricity consumption is reduced while at the same time the electricity generation will be increased. The results of the study also show that there is potential to expand district heating systems to areas with lower heat density, with both environmental and economic benefits for the district heating companies.

    The results reveal that the operation of a studied CHP-based district heating system with an imposed emission limit is very sensitive to the way CO2 emissions are accounted, i.e., local CO2 emissions or emissions from marginal electricity production. The results show how the electricity production increases in the marginal case compared with the local one in order to reduce global CO2 emissions. The results also revealed that not only electricity and fuel prices but also policy instruments are important factors in promoting CHP-based district heating and cooling systems. The use of electricity certificates has a large influence for the introduction of biogas-based cogeneration. Another conclusion from the modelling is that present Swedish policy instruments are strong incentives for cogeneration with similar impact as applying external costs.

  • 21.
    Amiri, Shahnaz
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik. Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Henning, Dag
    Optensys Energianalys, Linköping, Sweden .
    Karlsson, Björn G.
    Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden .
    Simulation and introduction of a CHP plant in a Swedish biogas system2013Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 49, s. 242-249Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objectives of this study are to present a model for biogas production systems to help achieve a more cost-effective system, and to analyse the conditions for connecting combined heat and power (CHP) plants to the biogas system. The European electricity market is assumed to be fully deregulated. The relation between connection of CHP. increased electricity and heat production, electricity prices, and electricity certificate trading is investigated. A cost-minimising linear programming model (MODEST) is used. MODEST has been applied to many energy systems, but this is the first time the model has been used for biogas production. The new model, which is the main result of this work, can be used for operational optimisation and evaluating economic consequences of future changes in the biogas system. The results from the case study and sensitivity analysis show that the model is reliable and can be used for strategic planning. The results show that implementation of a biogas-based CHP plant result in an electricity power production of approximately 39 GW h annually. Reduced system costs provide a profitability of 46 MSEK/year if electricity and heat prices increase by 100% and electricity certificate prices increase by 50%. CO2 emission reductions up to 32,000 ton/year can be achieved if generated electricity displaces coal-fired condensing power.

  • 22.
    Amiri, Shahnaz
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Weinberger, Gottfried
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Increased cogeneration of renewable electricity through energy cooperation in a Swedish district heating system - A case study2018Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 116, s. 866-877Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present study of the district heating (DH) system in the city of Kisa, Sweden, shows how, through energy cooperation with a nearby sawmill and paper mill, a local energy company contributes to energy-efficient DH and cost-effective utilization of a new biofuel combined heat and power (CHP) plant. Cases of stand-alone and integrated energy systems are optimized with the linear program MODEST. The European power market is assumed to be fully deregulated. The results show clear advantages for the energy company to cooperate with these industries to produce heat for DH and process steam for industry. The cooperating industries gain advantages from heat and/or biofuel by-product supply as well. The opening to use a biofuel CHP plant for combined heat supply results in cogenerated electricity of almost 29 GWh/a with an increased biofuel use of 13 GWh/a, zero fuel oil use and CO2 emission reductions of 25,800 tons CO2/a with coal-condensing power plant on the margin and biofuel as limited resource. The total system cost decreases by −2.18 MEUR/a through extended cooperation and renewable electricity sales. The sensitivity analysis shows that the profitability of investing in a biofuel CHP plant increases with higher electricity and electricity certificate prices.

  • 23.
    Andersson, David
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Olsson, Philip
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Hur kan en skola med högre energianvändning än det svenska genomsnittet energieffektiviseras?: Energikartläggning2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Europeiska unionen som helhet är en av de största energianvändarna och har en av världens största utsläpp av växthusgaser. För att minska globala uppvärmningen har mål sats upp för att medeltemperaturen på jorden inte ska öka mer än 2 grader sen förindustrielltid. Närmare 40 % av Sveriges totala energianvändning kommer från bostads- och servicesektorn detta i samband med att 2020-målen närmar sig bidrar till att energieffektiviseringar i byggnader blir allt mer essentiellt. Energikartläggningar är ett verktyg för att bestämma vad som har stört energibesparingspotential innan effektiviseringsåtgärder sker.

    Examensarbetet inkluderar en energikartläggning av Trödje skola som förvaltas av Gavlefastigheter. Arbetet är utfört med simuleringsverktyget IDA Indoor Climate and Energy. IDA ICE användes för att modulera den befintliga byggnaden där all data för skolan inkluderades. Rapportens vision är att undersöka hur mycket energi som är möjlig att spara genom energibesparingsåtgärder samt vilken åtgärd som är effektivast.

    Energibesparingspotentialen i skolan är hög, skolan använder 42,6 kWh/m2år mer än genomsnittet för Gavlefastigheters skolor vilket motsvarar 21 %. Resultaten visar att skolans komplexitet samt att påbyggnationen även kallad paviljongen är en stor faktor till att energianvändningen är hög. Skolans energianvändning har en potential att minska med 17 % vilket inte motsvarade det uppsatta 25 % - målet med arbetet. Arbetet visar att störst besparingspotential finns via byte av fönster och värmeväxlare i ventilationssystemet men även att de åtgärder som antas ge störst besparing inte alltid är effektivast.

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  • 24.
    Andersson, Harald
    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.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik. Linköpings universitet.
    A numerical and experimental investigation of a confluent jets ventilation supply device in a conference room2022Inngår i: Energies, E-ISSN 1996-1073, Vol. 15, nr 5, artikkel-id 1630Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, confluent jets ventilation (CJV) supply devices with three different nozzle arrays (1 × 19, 2 × 19, 3 × 19) were investigated both numerically and experimentally at two different airflow and supply air temperature set-ups. The performance of the CJV supply devices was investigated concerning thermal comfort, indoor air quality (IAQ), and heat removal effectiveness in a conference room environment. A comparison between the experimental and numerical results showed that the v2−f model had the best agreement out of the investigated turbulence models. The numerical results showed that the size of the array had a great impact both on near-field development and on the conditions in the occupied zone. A larger array with multiple rows and a lower momentum conserved the inlet temperature and the mean age of the air better than a single-row array with a higher momentum. A larger array with multiple rows had a higher IAQ and a greater heat removal effectiveness in the occupied zone because the larger array conserved the mean age of air better and the buoyancy driven flow was slightly better at removing the heat. Because of the lower inlet velocities, they also had lower velocities at ankle level, which decreased the risk of draft and thermal discomfort.

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  • 25.
    Andersson, Harald
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Energy-Saving Measures in a Classroom Using Low Pressure Drop Ceiling Supply Device: A Field Study2016Inngår i: 2016 ASHRAE Winter Conference Papers, ASHRAE, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Between 1990 and 2006 the energy use by ventilation systems in Swedish schools doubled. This is explained by high airflows in schools because of the high occupant density. Studies show that 87% of Swedish schools use constant air volume (CAV), and it is estimated that a change to variable air volume (VAV) could save 0.12-0.33 TWh (4.1*10(12) - 1.1*10(13) Btu) per year. Therefore the aim of this study is to investigate whether it is possible to replace displacement ventilation (DV) with mixing ventilation (MV) to create a comfortable indoor climate in a typical classroom and at the same time decrease the energy use by using VAV and Low Pressure Drop Ceiling Supply Device (LPDCSD). The study used two LPDCSDs which consist of circular channels with 190/228 round jets placed in an interlocking pattern, with a horizontal one/two-way-direction. The field study was carried out in a school which is intended to be extensively renovated. The school currently has DV and CAV. The study was carried out by installing MV with LPDCSD in one of the typical classrooms. Several different air-flow rates were investigated using tracer-gas technology to measure the local mean age of the air in the occupied zone. Simultaneously, thermal comfort and vertical temperature gradients were measured in the room. The results show nearly uniform distribution of the local mean age of air in the occupied zone, even in the cases of relatively low air-flow rates. Since the mixing of air is more or less the same in the entire occupied zone VAV can be used to reduce air-flow rate based on the desired CO2-level. Because of the number of students in each classroom and the fact that changes in air-flow rates have no significant effect on the degree of mixing, it is possible to reduce the air-flow rates for extended periods of time. Finally, since the LPDCSD has a lower pressure-drop than the currently used supply devices and it is possible to use VAV to lower the airflows in cases with reduced heat loads, it is possible to significantly reduce the energy usage in the school while maintaining the IAQ, increasing the thermal comfort and the available floor area of the occupied zone.

  • 26.
    Andersson, Martin
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Berge, Nils
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Energi- och miljökonsekvenser vid energieffektivisering av belysning och installation av solceller på Nacka Forum i Stockholm2016Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Energianvändningen ökar världen över och på grund av hotet om en global uppvärmning diskuteras det alltmer hur användandet skall minskas samtidigt som fler hållbara energikällor efterfrågas. Bostad- och service sektorn står för ca 40 % den totala energianvändningen i världen där energin främst kommer från fossila källor.För att minska miljöpåverkan har EU satt upp klimatmål som bland annat innebär att energianvändandet ska minskas med 20 % till 2020 räknat från år 2008. En viktig del för att uppnå detta mål är genom energieffektiviseringar.Syftet med denna fallstudie var att finna lösningar för vilket Nacka Forums elkostnader kunde sänkas. Arbetet begränsade sig till de utrymmen som Unibail-Rodamco själva ansvarar över såsom servicegångar och allmänna utrymmen i gallerian. Genom en litteraturstudie erhölls idéer om tänkbara energieffektiviseringsåtgärder som lämpar sig för denna typ av byggnad. Där framgick också att köpcentrum använder över lag mycket energi och framförallt elenergi där belysning är en av de större lasterna.Ett allt mer förekommande inslag hos fastigheter idag är solceller som både bidrar till minskade elkostnader samtidigt som efterfrågan på fossilenergi minskar. Då gallerian tillsynes verkade ha goda förutsättningar undersöktes möjligheterna till om detta var något att rekommendera. En anläggning på 100 kWp med en takyta på 921 m2 beräknades ge en energibesparing på 93 534 kWh/år och författarna konstaterar att detta vore en bra lösning samt att en än större toppeffekt bör undersökas.Delar av byggnaden upplevdes vara överbelyst och mätningar av belysstyrkan utförde i dessa områden. Resultatet visade vid de flesta mätpunkterna att så var fallet och det föreslogs att reglera belysningen efter dagsljuset.Vid inventering av den befintliga belysningen togs förslag på en energieffektivare lösning fram där LED-belysning ansågs som det bästa alternativet. Byte av endast ljuskällorna skulle i teorin göra en bra besparing men då de befintliga armaturerna ansågs vara i slutet av sin tekniska livslängd skulle ett byte av dessa även behöva göras inom de kommande åren. Därför förslås här ett byte av både armaturer och ljuskällor vilket skulle ge en energibesparing på 544,4 MWh/år och en återbetalningstid på 3,3 år. Denna energibesparing minskar även potentiellt de globala koldioxidutsläppen med 218 ton/år. Oavsett förslag så minskas både energianvändningen och miljöpåverkan med minst 50 %.Belysningen i en butik undersöktes och det konstaterades att de effektkrav på belysning som i nuläget ställs på butikerna är för låga. Trots att butiken hade stora problem med den termiska komforten till följd av just detta underskreds de satta 50 W/m2 med marginal. Det för lågt satta kravet hämmar här energieffektiviseringar och bidrar även med onödigt värmetillskott.

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  • 27.
    Antón, Raúl
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för energi- och maskinteknik. Royal Institute of Technology, Stockholm, Sweden; TECHUN, University of Navarra, San Sebastián, Spain.
    Jonsson, Hans
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för energi- och maskinteknik. Royal Institute of Technology, Stockholm, Sweden.
    Moshfegh, Bahram
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för energi- och maskinteknik.
    Detailed CFD modelling of EMC screen for radio base stations: A conjugate heat transfer problem2007Inngår i: International Journal of Heat Exchangers, ISSN 1524-5608, Vol. 8, nr 1, s. 95-116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this paper is to perform an experimental as well as CFD investigations of the conjugate heat transfer problem in a sub-rack slot model. A steady-state three-dimensional detailed model, which serves as the most accurate representation of the model, was used in order to evaluate the details of the airflow paths and temperature field. A general model that covers a considerable range of velocities, screen porosities and heat fluxes was validated experimentally by wind tunnel measurements. The result shows that the RNG k-ε model used with correct y+ and mesh strategy accurately predicts the temperature field. The average temperature deviation at several locations is less than 4% compared to experimental data. The influence of the velocity, screen porosity, heat flux and presence of the EMC screen on the PCB temperature field is commented. © 2007 R.T. Edwards, Inc.

  • 28.
    Arana, Eneko
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Energy improvement options for a small-scale brewery: a literature study2022Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    In the age of technology and development in which we live nowadays, it is inevitable to realise that this so-called progress is translated into pollution, damage to the environment and abuse of energy and fossil fuels. The companies and factories that produce the goods we need, use a lot of energy and pollute in massive ways, posing dilemmas such as how to make these companies more energetically and environmentally efficient, with the aim of decreasing the emissions and energy use. This literature review proposes a compilation and update of suggestions made to microbreweries after undergoing an energy audit, in an attempt to make these companies more energy-efficient, competitive, economical and sustainable. The information has been obtained by searching peer-reviewed articles in different databases and re-arranged in this article into sections on energy efficiency measures, waste treatment options and environmental impact. Several studies have been carried out on improving efficiency and trying to decrease the environmental impact of beer production processes. The main issues found during the process are energy efficiency and the generated wastewater. Both problems could be solved either by using an internal boiler that would generate less waste, applying renewable energies or by treating the residues in bioreactors, a field that needs further study. The choice of packaging material will be influenced by customer preferences and material recycling, being glass bottles and aluminium cans the most popular choices. 

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  • 29.
    Aranaga Decori, Pierre Ander
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap.
    Implementation of energy recovery and storage systems in cranes in the Port of Gävle2020Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Container traffic in seaports around the world in constantly increasing, with energy costs being a significant part of the total costs. The container terminal (CT) of the Port of Gävle, the largest in the east coast of Sweden, is not an exception to this. With traffic growing annually, a new terminal will be opened in the following years, adding three more ship-to-shore (STS) cranes to the two existing ones, and six electric rubber tyred gantry (eRTG) cranes. Therefore, it is highly important to strengthen energy efficiency measures, reducing the energy consumption and the costs associated with it. This is why the aim of this report is to analyse whether implementing energy storage systems in the cranes of the container terminal Port of Gävle can contribute to reduce electricity costs by recovering energy when braking lowering containers, and by shaving power peaks. After a literature review of current energy recovery and storage options, this work presents three solutions: two alternatives for the current situation with two ship-to-shore (STS) cranes, and a third solution to be implemented in the three future STS cranes to be installed, which can also be beneficial for any other crane in the terminal. According to the made calculations, the three alternatives can reduce considerable energy consumption, and they are highly profitable. However, those solutions are a preliminary study and more work needs to be done to determine the exact profitability and technical system details. This work has been done in collaboration with the Port of Gävle and Yilport, the company operating the container terminal.

    Fulltekst (pdf)
    Implementation of energy recovery and storage systems in cranes in the Port of Gävle
  • 30.
    Archakis, Viktor
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    The Design of a Passive House2018Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    About 25 % of the total buildings in the European Union have been categorized as ”old buildings”. Followed the recent strickt rules for carbon emissions reduction, each house has to approximetely cut 20 % of CO2 by 2020. Countries like England, have taken the issue very seriously and planning to reduce the carbon emissions by 30 % until the end of 2020 and by an extra 80 % by 2050 (Francis Moran, 2014). The aim of the report is to present how a traditional house can be retroffited into a passive house and also to identify the key points that every passive house should have. For the purpose of the project an avtual house, based in Gävle, was provided and all the simulations are based on actual data. The initial design of the house which was used for the simulation and the 3D design, was provided by the house owner. The building was built in 1953, information regarding the current insulation of the house was provided by the owner as well. For the simulations and the 3D design a software know as IDA ICE was used, license and access to the software were given by the University of Gävle. The report simulates the current house and compares the results with two possible scenarios that are reducing the energy demand of the house. Furthermore, the possible ways and tools that could be used to reduce the energy demand of the house and cost estimation for the retrofitting is available in the paper.The first simulations were occured on the actual house, the first retrofitting package introduces new simulations based on new insulation materials, like wood and cement, that are placed mainly on the roof and on the outer walls. Also, the thickness have changed, thus the new insulations are thicker.Moreover, the second and final retrofitting package, introduces an HVAC system, which is a standard system. The aim is to achieve further energy demand reductions and prove that simple and basic changes can improve the quality of living and reduce CO2 emissions.After the completition of the first analysis, a reduction equal to 60 % and after the addition of the HVAC a further 20 % reduction achieved.

    Fulltekst (pdf)
    fulltext
  • 31.
    Arcos Usero, Lucía
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Analysis and improvements of outdoor hot benches in Gävle2017Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Five exterior hot benches have been installed in Gävle, in Kyrkogatan street by the company Gävle Energi with the aim of achieving the wellnes of people that sit on them. This system uses the residual heat from the district heating, representing consequently a non-polluting system. However, the temperature desired on the surface, 35°C is not always achieved before different exterior conditions. For this reason, Gävle Energi is interested in carrying out a study about enhancements that could be made in the system in order to take them into account for future projects of this kind of technology.

     

    The aim of this project is analysing if it would be possible to achieve the requirements established by Gävle Energi, changing with this objective all the necessary system parameters of the current system such as diameter of the pipes, materials, number of turns... These requirements consist of working with a supply temperature of 40, 45 and 50°C when the exterior conditions are 0, -5 and -10°C respectively, accomplishing always 35°C on the surface. Moreover, in case that it was not possible, providing the company with the characteristics of the system that would make the system as efficient as possible, specifying for different exterior temperatures the mass flow, pressure drop, velocity and needed power.

     

    The study has been developed by different simulations with the software COMSOL, whose use requires a high knowledge on heat transfer. After several simulations, it has been checked that it is not possible to accomplish the requirements established by the company. However, a new more efficient design has been designed because the supply temperatures of the system to accomplish an average temperature of around 35°C on the surface have been minimised. For that, several changes have been carried out. The number of pipes turns have been increased from 12 to 17, their total diameter from 20mm to 30mm and the distance between the centres of the pipes from 5.5cm to 4cm. The 2mm of outer plastic thickness of the pipes has been replaced by copper and the height of the pipes has been moved 2cm upwards.

     

    With all these changes, the final length of the pipes inner the stones has a value of 40.6m and the supply temperatures reach 46, 47 and 49°C for the 0,-5 and -10°C exterior conditions respectively. Apart from the supply temperatures for the study cases, the ones necessary to accomplish always the temperature desired on the surface for other exterior temperatures have been provided together with the amount of power necessary, velocity flow, volumetric flow and pressure drop for all the different cases. These values would allow the company to work always at the optimum point as well as to design the heat pump for the system.

    Fulltekst (pdf)
    Thesis project Lucía Arcos
  • 32.
    Arfan, Muhammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    Utilization of local bioresources for transport fuels - System analysis for decision support2023Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents a comprehensive system analysis of the utilization of biowaste and forest industry residues to produce transportation fuels. It explores various aspects such as the constraints to the production system’s value chain development, the utilization of the geographical proximity of biofuel technology innovation system components, environmental impacts, and economic costs. The primary goal is to establish a knowledge base that can aid regional policymakers and decision-makers in formulating informed policies for the efficient management of local bioresources for transport fuel production. By addressing these aspects, the study seeks to contribute to the wider discourse on efficient local bioresource management and transition to a low-carbon economy. The focused bioresources in this thesis are municipal biowaste and forest industry residues (i.e., sawdust, black liquor, crude tall oil, and fiber waste of the pulp and paper industry). The study focuses on three systems: i) biowaste to biogas for transport, ii) biowaste and sawdust to hydrogen, and iii) forest industry residues to liquid biofuels for transport.

    The biofuel policy instruments in Sweden have proven to be effective in introducing alternative transport fuels, particularly in big cities or urban areas. The results of the biowaste to biogas value chain analysis show that development in the Gävleborg region is stagnated throughout the value chain compared to the national average. This stagnation is mainly attributed to local geodemographic factors. The identified obstacles to development include a lack of regional political agreement regarding the use of biogas as a viable transport fuel, insufficient connectivity and communication among the various regional actors and stakeholders, and a limited understanding among stakeholders of the potential and socio-economic impacts of biogas. 

    The environmental and economic assessment of hydrogen production from biowaste and sawdust is performed from a life cycle perspective, using SimaPro LCA software and CML-IA, 2001 impact assessment method. Economic analysis includes capital and operational expenditures and monetization cost of life cycle environmental impacts. The results show that hydrogen production from biowaste has a higher global warming, photochemical oxidant, and freshwater eutrophication potential than sawdust. Biowaste conversion to hydrogen performs far better in ozone depletion, terrestrial ecotoxicity, abiotic depletion-fossil, abiotic depletion, human toxicity, and freshwater ecotoxicity potential. The fossil energy inputs in biogas and pyrolysis oil reforming, emissions from the digestate treatment, storage, and utilization as bio-fertilizer are the main contributing processes to the overall environmental impacts of biowaste and sawdust conversion to hydrogen. 

    The sensitivity analysis of the LCA results indicates that feedstock to biogas/pyrolysis oil yield ratio and the type of energy source for the reforming process can significantly influence the results, particularly climate change, abiotic depletion, and human toxicity. 

    The life cycle cost (LCC) analysis reveals that the production of hydrogen from biowaste exhibits a lower cost compared to sawdust. This significant cost reduction in the biowaste case can be attributed to lower variable operating expenses (OPEX), primarily due to the price of the biowaste itself. Whereas, in the sawdust case, the feedstock contributes the highest percentage (54%) to the system's OPEX, indicating that variable OPEX is highly sensitive to sawdust prices. Additionally, the capital investment required for the biowaste case was 50% lower, which further contributes to the lower overall LCC compared to the sawdust case.

    The results of forest industry residues to liquid biofuel technology development and the utilization of system components in geographical proximity indicate that geographical proximity can significantly influence the system’s structural growth, trajectory, and development pace. An adapted version of the technological innovation system (TIS) framework was operationalized with the lens of geographical proximity utilization of the system components to the technology development and diffusion. The method of data acquisition involved document analysis and interviews with subsystem actors. The study found that the development of the system is hampered by competition between technologies and low utilization of geographical proximity of the system components, which was partly attributed to a lack of network among subsystem actors and with the national TIS structure. 

    Bioresources in Gävleborg are present in substantial amounts, particularly biowaste from agriculture, the food industry, and households, as well as biomass from the forest industry, which have the potential to be utilized for transport fuel production. However, the evolution of their utilization to power transportation in Gävleborg has been delayed in comparison to several other regions in Sweden. In the case of the technology development of forest industry residue-based transport fuels, the utilization of geographical proximity of artefacts and institutions has played a crucial role. Significant strides have been accomplished in diverse technology domains. However, these advancements have faced obstacles, partially due to the rivalry among system actors aiming to secure a competitive edge in acquiring both knowledge and capital resources and the underutilization of the geographical proximity of actors and industry networks. 

    Based on these research findings, recommendations are provided to support policy and strategy aiming to enhance the utilization of local bioresources for transportation fuels sustainably and cost-effectively with increased local benefits. For example, the study recommends addressing the identified local political, communication, and networking issues, along with integrating regional geodemographic conditions into national biofuel policies and measures. By addressing identified challenges, the Gävleborg region can overcome the stagnation in bioresource to transportation fuel technological systems development and leverage its significant potential.

    This thesis adds valuable insights to the sustainability transition literature about the environment, economy, and the geography of innovation processes. The findings highlight the need for policy interventions to foster collaboration, coordination, and knowledge sharing among stakeholders, as well as support for the development and commercialization of emerging technologies, including forest-based transport fuel technologies. The analysis of cost and environmental impacts of bioresource utilization for hydrogen production provides insights into the potential trade-offs and benefits of different feedstocks and impact categories. The study provides important input for policy and strategy development towards a more sustainable and cost-effective use of local bioresources for transport fuel production in Gävleborg. This study can also serve as a valuable reference for researchers, policymakers, and stakeholders interested in the sustainable utilization of renewable resources for biofuel production, contributing to the advancement of knowledge in this critical area.

    Fulltekst (pdf)
    fulltext
  • 33.
    Arfan, Muhammad
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    Eriksson, Ola
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    Wang, Zhao
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    Soam, Shveta
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    Life cycle assessment and life cycle costing of hydrogen production from biowaste and biomass in Sweden2023Inngår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 291, artikkel-id 117262Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, an environmental and economic assessment of hydrogen production from biowaste and biomass is performed from a life cycle perspective, with a high degree of primary life cycle inventory data on materials, energy, and investment flows. Using SimaPro LCA software and CML-IA, 2001 impact assessment method, ten environmental impact categories are analyzed for environmental analysis. Economic analysis includes capital and operational expenditures and monetization cost of life cycle environmental impacts. The hydrogen production from biowaste has a high climate impact, photochemical oxidant, and freshwater eutrophication than biomass while it performs far better in ozone depletion, terrestrial ecotoxicity, abiotic depletion-fossil, abiotic depletion, human toxicity, and freshwater ecotoxicity. The sensitivity analysis of LCA results indicates that feedstock to biogas/pyrolysis-oil yields ratio and the type of energy source for the reforming process can significantly influence the results, particularly climate change, abiotic depletion, and human toxicity. The life cycle cost (LCC) of 1 kg hydrogen production has been accounted as 0.45–2.76 € with biowaste and 0.54–3.31 € with biomass over the plant's lifetime of 20 years. From the environmental impacts of climate change, photochemical oxidant, and freshwater eutrophication hydrogen production from biomass is a better option than biowaste while from other included impact categories and LCC perspectives it’s biowaste. This research contributes to bioresources to hydrogen literature with some new findings that can be generalized in Europe and even globally as it is in line with and endorse existing theoretical and simulation software-based studies.

    Fulltekst (pdf)
    fulltext
  • 34.
    Arfan, Muhammad
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    Hillman, Karl
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    The geography of technological innovation systems - The case of forest-based biofuels in a Swedish region2024Inngår i: Innovation and Green Development, E-ISSN 2949-7531, Vol. 3, nr 2, artikkel-id 100122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Geographical proximity exerts a substantial influence on structural evolution, developmental trajectory, and pace of sociotechnical system growth. This study explores this aspect within the context of the development of forest biomass-based biofuel technology, employing a Technological Innovation System (TIS) framework with the lens of geographical proximity utilization of system components. The research employed a combination of document analysis and interviews with key system stakeholders as data collection methods. The analysis reveals that the close geographical proximity of the system components and technologies, encompassing both technical aspects and sectors, did not result in synergetic effects, in contrast to prior TIS research findings. Rather than fostering collaboration, it has engendered a competitive dynamic, partially driven by actors vying for knowledge leads and funding from both regional and national agencies. Consequently, the potential benefits of geographical proximity of system components remain largely untapped. In light of these results, this study offers practical recommendations for exploiting untapped opportunities, advocating for more strategic use of geographical proximity to foster system technology development and enhance its role in national TIS development. This case study enriches sustainability transition literature by providing valuable insights into the role of geographical proximity in innovation processes.

    Fulltekst (pdf)
    fulltext
  • 35.
    Arnaiz Remiro, Lierni
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Modelling and assessment of energy performance with IDA ICE for a 1960's Mid-Sweden multi-family apartment block house2017Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The present thesis has been carried out during the spring of 2017 on behalf of Gavlegårdarna AB. This is a public housing company in Gävle (Sweden) which is a large energy consumer, over 200 million SEK per year, and has the ambitious goal of reduce its energy consumption by 20 % between 2009 and 2020. Many multi-family apartment blocks were built during the "million programme" in the 60’s and 70’s when thermal comfort was the priority and not the energy saving. Nevertheless, this perspective has changed and old buildings from that time have been retrofitted lately, but there are many left still. In fact, one of these buildings will be retrofitted in the near future so a valid model is needed to study the energy saving measures to be taken. The aim of this thesis is to get through a calibration process to obtain a reliable and valid model in the building simulation program IDA ICE 4.7.1. Once this has been achieved it will be possible to carry out the building’s energy performance assessment. IDA ICE has shown some limitations in terms of thermal bridges which has accounted for almost 15 % of total transmission heat losses. For this reason, it is important to make a detailed evaluation of certain joints between elements for which heat losses are abundant. COMSOL Multiphysics® finite element software has been used to calculate these transmittances and then use them as input to IDA ICE to carry out the simulation.

    Through an evidence-based methodology, although with some sources of uncertainty, such as, occupants’ behaviour and air infiltration, a valid model has been obtained getting almost the same energy use for space heating than actual consumption with an error of 4% (Once the standard value of 4 kWh/m2 for the estimation of energy use in apartments' airing has been added). The following two values have been introduced to IDA ICE: household electricity and the energy required for heating the measured volume of tap water from 5 °C to 55 °C. Assuming a 16 % of heat losses in the domestic hot water circuit, which means that part of the heat coming from hot water heats up the building. This results in a lower energy supply for heating than the demanded value from IDA ICE. Main heat losses have been through transmission and infiltration or openings. Windows account 11.4 % of the building's envelope, thus the losses through the windows has supposed more than 50 % of the total transmission losses. Regarding thermal comfort, the simulation shows an average Predicted Percentage of Dissatisfied (PPD) of 12 % in the worst apartment. However, the actual value could be considerably lower since the act of airing the apartments has not been taken into account in the simulation as well as the strong sun's irradiation in summer which can be avoided by windows shading. So, it could be considered an acceptable level of discomfort. To meet the National Board of Housing Building and Planning, (Boverket) requirements for new or rehabilitated buildings, several measures should be taken to improve the average thermal transmittance and reduce the specific energy use. Among the energy saving measures it might be interesting replace the windows to 3 pane glazing, improve the ventilation system to heat recovery unit, seal the joints and intersections where thermal bridges might be or add more insulation in the building’s envelope.

    Fulltekst (pdf)
    fulltext
  • 36.
    Arnal Estelles, Paloma
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Hand drying in public places: Paper towel vs warm air blower, which is best from an energy and environmental point of view.2023Independent thesis Advanced level (degree of Master (Two Years)), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    fulltext
  • 37.
    Arrese Foruria, Ander
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Analysis of a Low Energy Building with District Heating and Higher Energy Use than Expected2016Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this thesis project, a building in Vegagatan 12, Gävle has been analysed. The main objective has been to find why it consumes more energy than it was expected and to solve theoretically the problems.This building is a low energy building certified by Miljöbyggnad which should use less than 55kWh/m2 year and nowadays it is using 62.23 kWh/m2. In order to find why the building is using more energy than the expected several different things has been measured and analyzed.First of all, the heat exchanger of the ventilation unit has been theoretically examined to see if it works as it should and it does. This has been done using the definition of the heat exchangers.Secondly, the heating system has been analysed by measuring the internal temperature of the building and high temperatures have been found (around 22°C) in the apartments and in the corridors. This leads to 5-10% more use of energy per degree.Thirdly, the position and the necessity of all the heaters have been checked. One of the heaters may not make sense, at least in the way the building has been constructed. This leads to bigger heating needs than the expected.Fourthly, the taps and shower heads have been checked to see if they were efficient. Efficient taps and shower heads, reduce the hot water use up to 40%. The result of this analysis has been that all taps and shower heads are efficient.Fifthly, the hot water system has been studied and some heat losses have been found because the lack of insulation of several pipes. Because of this fact 8.37kWh/m2 are lost per year. This analysis has been carried out with the help of an infra red camera and a TA SCOPE.Sixthly, the theoretical and real U values of the different walls have been obtained and compared (concrete and brick walls). As a conclusion, the concrete wall has been well constructed but, the brick wall has not been well constructed. Because of this fact 1 kWh/m2 of heat are lost every year. Apart from that, windows and thermal bridges have also been checked.

    Fulltekst (pdf)
    fulltext
  • 38.
    Ayoub, Ali
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    The role of nuclear energy2023Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The societies in Europe have developed enormously in recent decades, and this in turn has led to a greater need for electricity. Large parts of society are electrified and are now one of the most essential parts of the system. Electrification has resulted in more energy sources, which in turn has resulted in even greater emissions that harm the environment. Recently, the world has experienced various climate changes because of the industrialization of society.

    Therefore, it is essential today to phase out the energy sources that have a large negative impact on the environment to replace them with environmentally friendly ones. Greenhouse gas emissions are the main cause of climate change and will lead to increased extreme weather, such as droughts, floods, heat waves, and storms. This in turn will negatively affect societies, economies, and ecosystems. The rising global temperature leads to melting glaciers and results in rising sea levels. Climate change is affecting ecosystems all over the world and is also threatening biodiversity. Nuclear power has long been a debatable topic because of a couple of accidents in history, which have had devastating consequences on climate and society. In contrast, nuclear power plants are one of the energy sources that have no contribution to emissions during their operation. This work is a literature study which is based on a case study where the results are built on a comparison of nuclear power plants, coal power plants, and wind power plants based on carbon dioxide emissions, air pollution, land use, and waste management. The aim is to answer the question of whether nuclear power plants are an environmentally friendly alternative based on the results reported in the study.

    The result shows that nuclear power has a significant role in the Swedish and European electricity grid, as it is a foundation for a stable electricity grid. The result also shows that nuclear power plants are an environmentally friendly alternative. The study also shows that future research is essential and has significance. The most common argument against nuclear power plants is the risks in the event of an accident and what consequences they can have.

    Future research may mean safer operation of nuclear power plants and a reduction in the risk of accidents. The study shows that the survival of nuclear power plants has a significant role and is vital in sustainable work.

    Fulltekst (pdf)
    fulltext
  • 39.
    Back, Nina
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Optimering av underhållsstrategier i åldrande kärnkraftsanläggningar: En litteratur- och intervjustudie med kompletterade fallstudie kring kabel- och rörgenomföringar2020Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Rapporten baseras på en litteratur- och intervjustudie kring underhållsstrategier och komponentutbyten i kärnkraftverk, med fokus på komponenter som tenderar till att påverkas av åldring i en högre grad. Exemplifiering sker genom en kompletterande fallstudie kring kabel- och rörgenomföringar av typen Brattbergare som har packbitar bestående av ett polymert material.

    Erhållet resultat av litteratur- och intervjustudien belyser vilka säkerhetsföreskrifter som råder för all kärnteknisk verksamhet i Sverige. Utöver det erhålls information om hur åldring påverkar ett materials egenskaper över tid och att detta ligger till grund för fastställandet av ett system eller en komponents kvalificerade livslängd. I takt med att majoriteten av världens kärnkraftverk närmar sig sin ursprungligt tilltänkta livslängd och planeras underhållas för fortsatt långtidsdrift finns det ett ökat intresse för effektiva underhållsstrategier. Åldershanteringen har en avgörande roll för anläggningens lönsamhet och driftsäkerhet.

    Fallstudien föreslår två olika underhållsstrategier som stöds av resultatet av litteratur- och intervjustudien. Deras ekologiska påverkan och ekonomiska omfattning beaktas för att utse den metod som har störst potential att öka resurseffektiviteten och minska kostnaderna för underhållsåtgärder. Vald metod går ut på att praktiska tillståndsmätningar tillämpas för att undersöka hårdheten av packbitar till Brattbergare. Hårdhetsmätningarna syftar till att ge indikationer på i vilken grad packbitarna harpåverkats av degraderande åldringsmekanismer under olika förutsättningar.

    Resultatet av fallstudien överensstämmer med de resultat som noterades i litteratur- och intervjustudien. Packbitarna hårdnar när de åldras. Två miljöbetingelser som tenderar till att påskynda åldringsprocessen är förhöjda temperaturer och stråldoser. Vald metod för fallstudien är praktiskt realiserbar trots vissa begränsningar i befintliga kärnkraftsanläggningar vid Forsmark. Presenterad strategi bör kunna bistå med en ekologisk och ekonomisk optimering av underhållsarbetet för kabel- och rörgenomföringar.

    Fulltekst (pdf)
    Examensarbete2020NinaB
  • 40.
    Baena Juan, Cristian
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Comparison of the performance of silicon and thin film solar cells at the laboratory of the University of Gävle2016Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The huge environmental awareness emerging last years by reason of global warming and greenhouse effect, on one hand, and the need of finding other sources of energy production and conversion due to the declining of fossil resources and the increasing cost of this kind of energy resource, on the other hand, both have led position renewable energies as a powerful alternative on the energy production and conversion.

    PV-systems have emerged at an exponential rate in recent year as the main candidate and a satisfactory possibility with respect to environmental and economic sustainability.

    Nowadays, the large volume on photovoltaic market is currently dominated by four types of solar cells, divided by the semiconductor material used to absorb light and convert the energy into electricity: (1) crystalline silicon (monocrystalline and polycrystalline), (2) amorphous silicon, (3) CIGS and (4) cadmium telluride; and among them, monocrystalline silicon and CIGS technologies are installed on the building 45 of the University of Gävle, at the south face of the laboratory.

    In this context and with the motivation to contribute knowledge on PV field, a comparison between single crystal solar technology and thin film CIGS technology has carried out through f ratio and performance ratio procedures in order to perform an assessment of the energy conversion of each one under field conditions.

    A logger monitors the power conversion from the PV modules since June 2014 while two pyranometers monitor global and diffuse solar radiation since March 2016. It must take into account that only clear sunny days have been considered during a period from 8:00 to 14:00 in order to avoid shadows effect on the PV systems.

    The results come to conclude that single crystal silicon modules present a better behavior with respect to energy conversion under no shadows effect conditions by two reason: (1) f ratio, relationship of PV conversion per kW (PV yield) between CIGS and single crystal silicon, is about 87.25% with some variations along a day due to ambient temperature, cell temperature and incidence angle; (2) PV module's performance ratio of monocrystalline silicon modules is higher than thin film CIGS ones during a sunny day about 87.56% and 76.38%, respectively; and they are consistent with usual performance ratio values between 80% and 90% since 2010 onwards.

    In light of the outcome and in order to confirm these conclusions, it intends to launch a project with the objective of evaluating the data collected and compare the performance of the module after a year of measurements outdoors by the PV module's performance ratio procedure.

    Along the same lines, the next step of the University of Gävle will be to launch a project with the objective of evaluating the potential to be self-sufficient.

    Fulltekst (pdf)
    fulltext
  • 41.
    Bahilo Rodríguez, Edgar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Power Plant Operation Optimisation: Unit commitment of gas turbines using Machine Learning and MILP programming2018Independent thesis Advanced level (degree of Master (Two Years)), 30 poäng / 45 hpOppgave
  • 42.
    Bahilo Rodríguez, Edgar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Swedish and Spanish electricity market: Comparison, improvements, price forecasting and a global future perspective2017Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    This report aims to make a comparison between the Swedish and Spanish electricity market, the design of new improvements that could achieve a better operation for both markets as well as the price forecasting for both spot markets. These enhancements are oriented to decrease electricity prices, energy use and the system CO2 emissions.

    Also, the main organizations of the market and their roles has been characterized, clarifying the functions of the Market Operator and the System Operator. In addition, the different markets, the trading products and the price formation have been explained and the picture of the market structure has been achieved with enough depth.

    Moreover, some of the most used methods in Time Series Analysis has been enumerated to understand which techniques are needed for forecast the electricity prices and the methodology used (Box-Jenkins Method) has been explained in detail. Later, all these methods have been implemented in an own code developed in Python 3.6 (TSAFTools .py) with the help of different statistics libraries mentioned during the method chapter.

    On the other hand, the description of the market situation has been carried out for both countries. Power installed capacity, electricity generation, average prices, main renewable technologies and policies to increase the renewable energy share has been analysed and corresponding described.

    Then, to estimate the market’s future spot electricity prices, ARIMA models have been selected to analyse the evolution of the day-ahead price using the TSAFTools.py. The final models show a proper performance in the two markets, especially in the Nordpool, achieving an RMSE: 37.68 and MAPE: 7.75 for the year in 2017 in Nordpool and a RMSE: 270.08 and MAPE: 20.24 in OMIE for 2017. Nordpool spot prices from 2015 to 2016 has been analysed too but obtaining a result not as good as the year 2017 with an RMSE: 49.01 and MAPE: 21.42.

    After this analysis, the strengths and weaknesses of both markets are presented and the main problems of the Spanish electricity system (power overcapacity, fuel dependency, non-cost-efficient renewable energies policies, lack of interconnexion capacity etc.) and the Swedish electricity system (dependency for nuclear power, uncertainty for solar electricity Generation) are presented.

    Finally, due to the quick development of the energy sector in the last years and the concern of the European Committee to reach a new design for the electricity market, different kinds of recommendations for the future have been considered.

    Fulltekst (pdf)
    Swedish and Spanish electricity market: Comparison, improvements, price forecasting and a global future perspective
  • 43.
    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 Improvements2023Inngår i: Urban Transition: Perspectives on Urban Systems and Environments / [ed] Marita Wallhagen and Mathias Cehlin, IntechOpen , 2023Kapittel i bok, del av antologi (Fagfellevurdert)
    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.

  • 44.
    BAIGORRI GARCIA, ISRAEL
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    DESIGN AND VIABILITY OF A THERMAL POWER-PLANT IN SPAIN2020Independent thesis Advanced level (degree of Master (One Year)), 40 poäng / 60 hpOppgave
  • 45.
    Bakhtiari, Hossein
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Evaluation of Thermal Comfort and Night Ventilation in a Historic Office Building in Nordic Climate2020Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Envelopes with low thermal performance are common characteristics in European historic buildings resulting in insufficient thermal comfort and higher energy use compared to modern buildings. There are different types of applications for the European historic buildings such as historic churches, historic museums, historic theatres, etc. In historic buildings refurbished to offices, it is vital to improve thermal comfort for the staff. Improving thermal comfort should not increase, preferably reduce, energy use in the building.

    The overall aim in this research is to explore how to improve thermal comfort in historic buildings without increasing, preferably reducing, energy use with the application of non-intrusive methods. This is done in form of a case study in Sweden. Thermal comfort issues in the case study building are determined through a field study. The methods include field measurements with thermal comfort equipment, data logging on BMS, and evaluating the occupant’s perception of a summer and a winter period indoor environment using a standardized questionnaire. According to questionnaire and thermal comfort measurements results, it is revealed that the summer period has the most dissatisfied occupants, while winter thermal comfort is satisfactory – but not exceptionally good.

    Accordingly, natural heat sinks could be used in form of NV, as a non/intrusive method, in order to improve thermal comfort in the building. For the historic building equipped with mechanical ventilation, NV strategy has the potential to both improve thermal comfort and reduce the total electricity use for cooling (i.e. electricity use in the cooling machine + the electricity use in the ventilation unit’s fans). It could decrease the percentage of exceedance hours in offices by up to 33% and reduce the total electricity use for cooling by up to 40%. The optimal (maximum) NV rate (i.e. the potential of NV strategy) is dependent on the thermal mass capacity of the building, the available NV cooling potential (dependent on the ambient air temperature), COP value of the cooling machine, the SFP model of the fans (low SFP value for high NV rate is optimal), and the offices’ door scheme (open or closed doors).

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  • 46.
    Balciunas, Dominykas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Thermoeconomic analysis of LNG physical exergy use for electricity production in small-scale satellite regasification stations2019Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Liquefied natural gas (LNG) cold utilization in small scale regasification stations is a novel topic in the industry, while such systems have been proven feasible in large scale LNG facilities. Cold recovery and utilization in LNG regasification facilities would increase the thermodynamic efficiency and reduce cold pollution. The aim of the study is to analyze the possibility to apply industry-proven thermodynamic cycles in small scale satellite regasification stations for electricity production, taking the characteristics of a real-world regasification station project in Druskininkai, Lithuania for which useful cold utilization is not currently planned.

    Direct Expansion (DE) and Rankine (ORC) Cycles are analyzed together with cascading using Aspen Hysys software to find the optimal solution considering thermal and exergy efficiency as well as the payback period.

    Thermoeconomically feasible retrofit solutions of approximately 13% thermal efficiency and approximately 17% exergy efficiency showing payback periods of 5 to 10 years and 3.3 to 6 thousand euro additional capital expenditure (CAPEX) per net kW of power production are found.

    Increase in complexity of thermodynamic cycles is directly proportional to both increased thermodynamic efficiencies and capital costs and the study proves that there is a limit at which increase in thermodynamic efficiency of a cycle by cascading becomes economically infeasible. Future work is suggested to improve the accuracy of the results by rigorous design to evaluate pressure drops as well as improvements in economic analysis by utilizing the discounted cash flow methodology. Sensitivity analysis of LNG physical and chemical conditions as well as ambient air could be performed whereas changes in working fluid and better engineering of the part related to intial heat exchange could improve thermodynamic efficiencies. Alternative solutions with a higher temperature heat source are also suggested.

    Fulltekst (pdf)
    fulltext
  • 47.
    Barguilla Jiménez, Núria
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    The effect of a thin foil on the heat losses behind a radiator2013Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

     

    This thesis work is the study of the effect of an aluminium foil on the losses that produced by a radiator, situated under a window, through the wall behind it. The reason behind this topic is due to the energy problem and the different goals that governments have set up to try to reduce the use of energy. For example, more specifically a Swedish national goal is to decrease the energy use of the built stock with 50% by 2050.

     

    For this purpose, an experimental set-up was built in the University of Gävle, Sweden. The arrangement was composed by a radiator and a window facing a climate chamber. A total of twenty-one temperatures and two heat fluxes in the exterior wall were measured in the set-up. Ten different measurement scenarios with different radiator temperature, 40°C, 50°C and 60°C; two different distance between the radiator and the wall, 5 and 9 centimetres and with and without the aluminium foil, were performed.

     

    With the experimental results, a CFD model was validated. Two different models were done, first a 2D model and afterwards a 3D model. For the turbulence, the chosen model was standard k-ε model. There were 54 cases simulated with the 2D model and the 3D model was used just for validation. The cases had different variables such as radiator temperature, outdoor temperature and wall insulation. With these cases, analysis of the effectiveness of the presence of an aluminium foil behind the radiator is performed to evaluate if there is a significant reduction of the losses.

     

    The results showed with both methods that the aluminium foil reduces the losses of the wall behind the radiator. The savings varied depending on the boundary conditions of the case and it were obtained a maximum of 4% and a minimum of 1,3%.

    Fulltekst (pdf)
    fulltext
  • 48.
    Barquín del Rosario, Susana
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    The future of geothermal energy in Europe2022Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this paper it is investigated the role that geothermal energy could play in theenergy mix, to meet new system requirements.

    As any other source, geothermal energy harnessing implies a number of risksmainly related to induced seismicity and landslides, together with the releaseof as greenhouse gases and metal salts. Moreover, important barriers to itsimplementation still exist, mainly concerning financial aspects and drillingoperations. As well, administrative status is uncertain and related investmentin R&D negligible.

    However, geothermal energy presents important advantages in relation toother energy sources, as its reliability and large capacity factor, comparable tonuclear and natural gas plants. It could help to reduce both the globalwarming, whose potential is up to 5 times lower than in the case of fossilfuels, and the landuse, the lowest of any power plant. Additionally, in spite ofthe high and risky initial investment, energy produced by geothermal means is amongst the cheapest.

    The geothermal potential is large enough to substantially contribute to theenergy mix, through locally available resources. Economic potential in Europeby 2050 is estimated in 100 – 4 000 TWheand 880–1 050 TWhth. Nevertheless, currently available technology strongly limits the access togeothermal resources. In addition, predictions about geothermal utilizationare modest and have hardly been achieved to date. The key for the future isthe development of the Engineered Geothermal Systems.

    Fulltekst (pdf)
    The future of geothermal energy in Europe
  • 49.
    Barroeta, Ander
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Design of a ventilation system for carbon dioxide reduction in two gym rooms2013Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    This project is mainly focused on the improving and design of the ventilation system of two rooms at different levels of a gym (Friskis and Svettis in Gävle, Sweden) to reduce the  concentration to never be higher than 1000 ppm.

    For this purpose, several field measurements were performed in different locations and situations. Two main measurements were necessary. On one hand, the  level in different parts of the rooms during different activities. On the other hand, the air flow through the inlet and outlet ducts of the ventilation system. It was also important to take into account the indoor temperature and humidity. These measurements were enough to analyze the failures of the system and to recognize the worst points of each room.

    Comparing both rooms, the necessity of changing the ventilation system in one of these rooms was much higher, due to there were measured  values up to 3000 ppm during a typical day in the gym.

    With this information the consequences of high CO2 levels in human people were analyzed. Among various ventilation systems, displacement ventilation system was proposed as the new design. Theoretical calculations were made to reach to the value of 31.8  in the air change rate (ACH), which was the necessary value for the new design to keep the carbon dioxide level under 1000 ppm.

    Fulltekst (pdf)
    Ander Barroeta Master Thesis
  • 50.
    Batista, Rúben
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik. University of gävle.
    The impact of shadowing in photovoltaic systems and how to minimize it: An analysis with the PVsyst Software2018Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    fulltext
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