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  • 251.
    Forslund, John
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Optimering och dimensionering av ett solcellssystem till ett flerbostadshus i Mellansverige: En beräknings- och simuleringsstudie2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Solar power is estimated to be able to cover the whole earths energy demand many times without releasing greenhouse gases or other pollutants while they operate and is therefore considered a renewable energy source. Solar power is therefore a suitable replacement to today’s fossil based energy systems.

    The cost for solar cells have decreased a lot in recent years. At the same time Sweden and the European Union have goals set for reducing the amount of carbon dioxide released so a tax reduction is given to those who sells overproduced electricity from solar power to the grid. This means it could eventual be profitable even in Sweden for installing solar power even though the sun doesn’t shine as much that close to the poles. It is suitable to install solar panels at buildings since it is the building and service sector that uses the most electricity in Sweden.

    It must be profitable for private investors before they make the choice to invest in solar panels. Environmental benefits are not as attractive for private investors. Should the solar arrays be optimized in such way that the profit is maximized the investment is more likely to occur.

    This paper examines how an optimal solar cell system should look like from a profitable perspective for a building with 25 apartments in the middle of Sweden under different economic conditions. Most focus is directed towards how the tilt angle affects the results. The electricity production of different configurations of solar panels was simulated. These results were then compared to the electricity demand for the building so the amount used for self-consumption and how much is sold to the grid could be calculated and from that calculate how profitable that system is.

    Most electricity is produced at the tilt angle of 40°, but marginally more than 30° which the roof is tilted. The difference between tilt angles are just a few percent at most. The difference is most noticeable when the system is just big enough to cover the base electricity demand. The best tilt angle for those systems are 45°. It is hard to advocate for more expensive mounting for bigger systems since the roof already is close to the optimal tilt angle. The value for saved and sold electricity is very close to each other if tax reduction is given. It’s however uncertain for how long tax reduction will last. It is much safer to size a solar array to cover the building’s electricity demand. It could be very costly to size a solar array which relies upon selling electricity with today’s economic condition. However, solar power is questionable in Sweden in an environmental perspective.

  • 252.
    Francisco Contero, Jose
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Zaragoza.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Gustafsson, Mattias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Karlsson, Björn O.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    The impact of shading in the performance of three different solar PV systems2017In: PROCEEDINGS OF THE 11TH ISES EUROSUN 2016 CONFERENCE, INTL SOLAR ENERGY SOC , 2017, p. 1168-1179Conference paper (Refereed)
    Abstract [en]

    Partial shading decreases the performance of PV modules due to the series connection between the solar cells. In the recent years, several new technologies have emerged within the photovoltaics field to mitigate the effect of shading in the performance of the PV modules. For an accurate assessment of the performance of these devices, it is required to evaluate them comparatively in different circumstances. Three systems with six series-connected PV modules (each containing 60 cells) have been installed at the University of Gavle. System One comprises a string inverter system with 6 PV modules; System Two features a DC-DC optimizer per panel and a string inverter; System Three incorporates three micro inverters for six modules. A major conclusion of this study was that under partial shading of one (or more) modules both System Two (DC-DC optimizers) and System Three (micro inverters) perform considerably better than System One (string inverter), as long as the Impp of the shadowed module is lower than the Impp of the unshaded string It is also important that the Vmpp in the shaded module is higher than the lowest allowed voltage of the DC-DC optimizer or module inverter. The economic implications of the usage of these devices were also analyzed.

  • 253.
    Fredriksson, Anton
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Fors Edman, Christoffer
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    En ekonomisk analys av att använda en Quartzenebaserad puts vid energieffektivisering av äldre q-märkta byggnader.2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Older q-labeled buildings may not be changed according to the corruptions banning, resulting in difficulties in energy efficiency of q-marked buildings, as traditional energy efficiency methods cannot be used without altering the building's properties. This report examines the profitability to energy-efficient a q-labeled building with a heat insulating plaster based on Z1 quartzene and lime cement render. By only changing the render properties of the plot, the building does not change characteristic or cultural historical value.

    The report sets out a general framework describing the maximum additional cost of a heat insulation plaster in comparison to a traditional plaster at four different thermal conversion coefficients; 0.2, 0.4, 0.6 and 0.8 W/m2 ×K. The framework can be used as a template that shows what a heat insulation plaster at varying thermal conductivities maximally may cost for the product to be economically viable compared to lime cement plaster. 

    A life cycle cost analysis is used in a case study to assess if it is profitable to energy-efficient a qlabeled building in Gävle, with a heat insulating plaster based on Z1 and lime cement pits. Five theoretical mixtures with different proportions of Z1 and lime cement plaster was analyzed to assess profitability at different thermal conductivity. The result of the case study shows that all heat-insulating plasters is economically profitable, where the most profitable mixing is the one with the highest proportion of Z1 (80%). That the most profitable mixture is the one with the highest proportion of Z1 can be explained by the fact that energy saving is increasing at a faster rate than the additional cost of the heat insulating plaster

    The estimated additional cost of the case study is tested in the cost ceiling to identify the profitability at different heat transfer coefficient. The results shows that walls with an high heat transfer coefficient has the largest profitability, while the walls with a lower heat transfer coefficient (a better heat transfer coefficient) is the least profitable. This is because of the walls with a higher heat transfer coefficient has a greater energy saving potential then walls whit a lower heat transfer coefficient

  • 254.
    Fredriksson, Jane
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Weissmann, Angelica
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Effektivisering vid bedömningsprocessen av  indikatorn Dagsljus för miljöcertifieringsmetoden Miljöbyggnad: Ett förprojekteringsverktyg2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Daylight in buildings is important for both physical and mental health. Daylighting in buildings is transferred through windows, but the windows are also the building component that causes the greatest energy loss in a building. Therefore, there is a problem in creating a good balance between design, energy efficiency and thermal comfort while maintaining a sufficient daylight to be applied in buildings where people are staying.

    This thesis comprising 15 hp aims to efficiency and simplify the assessment of satisfying daylight, to achieve the requirements of the environmental certification method Miljöbyggnad, where neighboring factors such as energy and the thermal environment is studied. The goal was to establish a pre-planning tool for the indicator Daylight that can be used in the future by consultants and similar when a building is assessed by environmental certification according to the method Miljöbyggnad. The tool is based on computer models of experimental room with different conditions where the daylight factor, DF, was controlled. The computer programs Velux, ParaSol and Thermal Comfort Calculator where applied during the study.

    Parametric studies were performed to illustrate the connection between daylight factor, window area and the shape and size of the room, resulting in the establishment of two charts. To check that the parameter results of the study can be applied to real-world objects and rooms a case study was performed on the building Ängsbacken in Sandviken. This case study validated that the diagrams drawn can appreciate a daylight factor, DF, for a room that can then obtain a preliminary rating for the indicator Daylight in Miljöbyggnad.

    The diagrams can be used as a rough pre-planning tool that can be applied when the consultant, architect or similar knows the room depth and facadewall area (width and height of the room) but want to know how big window needed to achieve BRONZE or SILVER for indicator Daylight in Miljöbyggnad. In the future it might be interesting to study if there is also a correlation between the three indicators Daylight, Solar Thermal Load and Thermal environment and the impact of windows, sun screens etc. which can affect the daylight factor.

    For all test room modeled and applied in the study, grade GOLD were obtained for the Solarheating. For the Thermal environment all the test room obtained the grade SILVER. These indicators seem unaffected by the geometry just as much as the daylight factor, which takes more into account both the room and the window size and design. Therefore the assessment according to Miljöbyggnad paramount lie on meeting a satisfying daylight by checking that the daylight factor is fulfilled in the room, which can easily be performed with the help of this studies pre-planning tool.

    The effective pre-planning tool can be used to simplify and speed up the evaluation process and appreciate a score for indicator Daylight in Miljöbyggnad. By making use of the tool in an early planning stage, where the use of time-consuming computer programs is avoided, both the cost and time can be minimized.

  • 255.
    Freudenthal, Jesper
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Förlustanalys av ett industriellt ångsystem: En studie vid Bomhus Energi AB2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This paper investigates the losses within steam distribution systems with additional research in two of the potential losses at Bomhus Energi AB, Gävle Sweden. Bomhus Energi is a steam producing company mainly for the pulp and paper plant nearby but also a heat producer for the city’s district heat. Electricity is also produced from a steam turbine connected to the boiler. Minimising losses is a way to achieve a more efficient system, this is of great interest due to the European Union´s climate goals but also because it can increase income and in the long run improve the company’s competitiveness on the market. EU:s climate goals involve lowering the energy consumption and increasing the amount of renewable energy production. Increasing the steam distribution efficiency will be one small part of achieving the goals. To motivate and ease the efficiency improvement measures at Bomhus Energi a list of potential losses within steam distribution together with deeper analyses within two of the losses have been composed. The deeper analyses were made on steam traps and steam pressure reducing valves. This was done with the help from relevant literature and discussion with experienced employees and other people within the industry. The losses that occur when steam is distributed are steam leakage, heat losses through pipes, condensate losses and flash losses. The deeper analyses were made as a basis for detecting, measure and evaluate losses. To make the analyses production data was obtained from Bomhus Energi and component data from suppliers. Calculation and models were made in cooperation with employees. The loss from the steam traps lead to decreased electric production and decreased energy delivery to the users. The loss from the steam pressure reducing valves lead only to decreased electric production due to the energy in the steam stays in the system. To achieve the climate goals and at the same time minimise the energy and economical losses, monitoring and maintenance of the steam distribution system should be carried out continuously. Losses occur within distribution and not only within production and consumption. Through knowledge about the possible losses within the steam system and its consequences, understanding and the winnings about minimising losses can be achieved. An energy system based on biofuel and by-products should always aim towards increased efficiency because it leads to decreased environmental impact and increased income and in the end a greater competitiveness on the market.

  • 256.
    Friberg, Linnéa
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Lärorika leksaker och lek på samma villkor2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 257.
    Frisk, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Simulering av solavskärmning och nattkyla för att minimera kylbehovet för en kontorsbyggnad i Forsmark2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Society today depend on energy for it to work. The energy needed for heating buildings in the cold or cool buildings when it is warm. Energy is used for power lighting, appliances and transportation needs. Residential and commercial buildings account for 40% of total final energy consumption and half the energy residential buildings use goes to heating. To reduce energy consumption and stop global warming, it is important that new buildings are energy efficient. The targets that control the reduced energy consumption is EU 20/20 /20- goals. These goals should be reached by 2020 and will reduce greenhouse gas emissions by 20%, reduce energy consumption by 20%, increase the share of renewable energy to 20% and raise the share of biofuels in transport to 10%. For Sweden to achieve its environmental objectives Boverket have developed energy requirements for real estate buildings with the goal of reducing energy consumption in the residential sector. The requirements apply to new buildings and limiting the energy use for buildings heating, hot water and cooling. The thesis is about to perform a simulation of the night cooling and window shading of an office building. Simulations will be performed for the building's energy-, thermal power- and cooling demand. The program that has been used for the simulation is IDA ICE v4.7. The simulations showed that the solar shading reduced the effect of the cooling power by 4,8kW, a 13% reduction compared to a building without shading. Both the sun shading and night cooling was found to be effective to reduce cooling demand for building. Total cooling load can be reduced by 84% for the building at the given conditions. Energy simulation showed that the building meets the specific energy requirements of both the installed heating power and energy.

  • 258.
    Frisk, Carolina
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering. Gästrike Vatten.
    Multikriterieanalys för avsättningsmöjligheter för slam från avloppsreningsverket Duvbacken i Gävle2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of the study is to provide and evaluate possible disposal alternatives for sludge from the wastewater treatment plant Duvbacken in Gävle by using a multicriteria analysis with respect to technical availability, environmental sustainability, economic perspective and health & hygiene. Three methods have been used in the study; literature study, personal contact and a multicriteria analysis. The sewage sludge quality today at Duvbacken does not meet national requirements to be used in agricultural purposes nor within less sensitive land use. Thus, other options should be investigated. Three deposal options have been suggested in this study by considering the legal basis and sludge quality, these are; combustion in combined heat and power plant, fertilizer to forest and fertilizer to willow (salix) cultivation, the latter is only possible if an exemption from the provincial government can be obtained. Those three alternatives, together with current landfill deposition, were evaluated in a multicriteria analysis, according to the weighting group`s priorities. The average value of the group´s priorities shows for example that important criteria seem to be flexibility, resource utilization, demand and work environment. The final results was relatively even among the options, willow got the highest rating, then forestry, then landfill cover, combustion received the lowest score. All options have pros and cons and the spreading of unwanted substances cannot be completely avoided as long as they exist in the incoming flows into the wastewater treatment plant, therefore the best investment might be upstream investigation, e.g. preventing these substances at their sources. Conclusion from this study is that willow cultivation seems to be the best disposal option for sludge from Duvbacken according to the multicriteria analysis. However, in a sustainable holistic perspective, upstream investigation would probably be the best investment.

  • 259.
    Färnström, Dennis
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Energibalans av två glödgningsugnar inom ett integrerat stålverk2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The steel industry occupies the whole 7 % of the global carbon dioxide emissions caused by human factors and 5 % of the global energy usage. The steel industry is an energy intense industry and it’s therefore important to analyze its energy use for its future sustainability. Furnaces are driven on non-renewable fuels and are one of the devoting components to the high energy consumption, so studies of this are of high relevance.  Regarding modern techniques of furnaces in today’s mode are much concentrated on the combustion, which means the combustion of the fuel that supplies the furnaces with heat.  Oxy-fuel technology means that the fuel is combusted with pure oxygen instead of air, and its purpose is to increase the combustion efficiency. A second modern technology is the usage of burners that are able to recycle flue gases as an increase of energy efficiency.  Outokumpu is a world leading company in the manufacture of stainless steel and the plant in Avesta is an integrated steel mill, which means the steel production cover the entire process from scrap and raw material to finished product. The plant consists of three main works called the steel mill, hot rolling mill and KBR L76 which is the department for these annealing furnaces.  The main objective of this report is to present an energy balance of two annealing furnaces at the Outokumpu plant in Avesta. The boundary of the study is clear, the energy balance will take part from the inlet of the first furnace to the outlet of the second one. It’s the thermal energy efficiency that has been studied, that is to say how much energy you get from the fuel that is added. Information has been collected using historical data on the operation of the furnaces during a three month period of time, also manual temperature measurements has been carried out.  By calculations an efficiency has been developed for each furnace and the furnaces together. This has been carried out by weighing the proportion of the amount of heat that all material have accumulated, with the amount of oil used during the same time.  The results of this study mainly indicate that the furnaces are effective in heating the steel, and its heat losses from the surrounding areas are small. On the other hand, there is potential for recycling more heat regarding the use of flue gases in the exhaust-boiler.

  • 260.
    Galarraga, Maider
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Heat balance of a historical church- transmission losses2014Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The structure of old monumental churches differs a lot from contemporary buildings. The structural materials were wood, brick and stone. In order to construct high buildings with huge spans, thick massive walls and many massive columns were needed. Originally these buildings had no heating and for centuries the outdoor temperature determined the indoor climate. As churches are considered historical heritage buildings their renovation should be thoroughly studied.

     

                In this thesis the transmission losses of Hamrånge church will be analysed. Hence, the transmission trough walls and windows as well as the heat buffering of materials will be examined. In addition, the effect of possible reformation measurements will be concluded.

     

                Finally, this project belongs to a complete study of the church, were not only transmission losses are considered but also air infiltration losses and solar heat gain. That way, a comparison between them will be carried out in order to contribute to attain the objective of the project: possible restoration for church heating system with respect to preservation, energy requirements, thermal comfort and aesthetics.

  • 261.
    Gallardo Saavedra, Sara
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Analysis and simulation of shading effects on photovoltaic cells2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The usage of conventional energy applications generates disproportionate emissions of greenhouse gases and the consumption of part of the energy resources available in the world. It has become an important problem which has serious effects on the climatic change. Therefore, it is crucial to reduce these emissions as much as possible. To be able to achieve this, renewable energy technologies must be used instead of conventional energy applications. Solar Photovoltaic (PV) technologies do not release greenhouse gas emissions directly and can save more than 30 million tonnes of carbon per exajoule of electricity generated relative to a natural gas turbine running at 45% efficiency.

    Shadowing is one of the most important aspects that affects the performance of PV systems. Consequently, many investigations through this topic are being done in order to develop new technologies which mitigate the impact of shadowing during PV production. In order to minimise the impact of shadowing it is desired to be able to predict the performance of a system with PV-modules during shadowing.

    In this thesis a simulation program for calculating the IV-curve for series connected PV-modules during partial shadowing has been developed and experimentally validated. PV systems modelling and simulation in LTspice environment has been presented and validated by means of a comparative analysis with the experimental results obtained in a set of tests performed in the laboratory of Gävle University. Experimental measurements were carried out in two groups. The first group corresponds with the experiments done in the string of six modules with bypass diodes while the measurements of the second group have been performed on a single PV module at HIG University.

    The simulation results of both groups demonstrated a remarkable agreement with the experimental data, which means that the model designed at LTspice supposes a very useful tool that can be used to study the performance of PV systems. This tool contributes to the investigations in this topic and it aims to benefit future installations providing a better knowledge of the shading problem.

    The master’s thesis shows an in-depth description of the required method to design a PV cell, a PV module and a PV array using LTspice IV and the input parameters as well as the needed tests to adjust the models.

    Moreover, it has been carried out a pedagogical study describing the effect that different shadow configurations have in the performance of solar cells. This study facilitates the understanding of the performance of PV modules under different shadowing effects.

    Lastly, it has also been discussed the benefits of installing some newer technologies, like DC-DC optimizers or module inverters, to mitigate the shadowing effects. The main conclusion about this topic has been that although most of the times the output power will be increased with the use of optimizers sometimes the optimizer does not present any benefits.

  • 262.
    Gallardo-Saavedra, Sara
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Universidad de Valladolid (UVa), School of Forestry, Agronomic and Bioenergy Industry Engineering (EIFAB), Department of Agricultural and Forestry Engineering, Campus Duques de Soria, Soria, Spain.
    Karlsson, Björn O.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Simulation, validation and analysis of shading effects on a PV system2018In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 170, p. 828-839Article in journal (Refereed)
    Abstract [en]

    A simulation program for calculating the IV-curve for series connected PV-modules during partial shadowing has been developed and experimentally validated. The software used for modelling the modules is LTspice IV. The validation has been done by means of a comparative analysis using the experimental results obtained in a set of tests performed on the mono-crystalline modules of the Gävle University's laboratory in Sweden. Experimental measurements were carried out in two groups. The first group is a string of six modules with bypass diodes while the second one corresponds to a single PV module. The simulation results of both groups demonstrated a remarkable agreement with the experimental data, which means that the designed model can be used for simulating the influence of shading on the power of a string. The model has been used for analysing the performance of strings of PV modules with shadows and the benefits of installing DC-DC optimizers or module inverters, that minimise the impact of shading, have been investigated.

  • 263.
    Gamage, Amila
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    CO2 Emission of Hotel Sector in Sri Lanka: A Case study & Scenario Analysis2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This research focused the CO2 emission and energy consumption pattern of Sri Lanka’s Hotel sector in both present and 2020 scenarios. It was proven from the literature survey that there was no study carried out to assess the current and future CO2 emission in Sri Lankan Hotel sector which is the government main focused area to develop within next 10 years of time. Also there is a long conversation in tourism sector from last few years and understood the importance of Sustainability of tourism business and identified the Green concept, Low carbon emission and less environmental impact are the key attributes to concern for the business sustainability.

    It was identified the CO2 emission in 2020 is 404,234 tonnes against the 121,458 tonnes of 2010 which is a huge impact to the environment because of expected growth of tourism sector. Also it was identified the CO2 emission per room in 2020 is 61.26 kg against the same 61.85 kg in 2010. This was slight change compared to the emission per room in 2010 but it will not considerably reduce the impact to the expected environmental pollution. The main energy consumption is from 5-star hotel category, which was contributed to 47% of total energy consumption even though this sector has contributed only 24% of total room capacity of the country in the present scenario of 2010, which was forecasted and identified the contribution to the total CO2 emission is 49.2% in 2020. This analyzing and modeling was done by using LEAP (Long Range Energy Alternative Planning System).

  • 264.
    Garcia Valladolid, Pablo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    EXPANDED IMPINGNING JET AIR SUPPLY METHOD, AIR TERMINAL DEVICE ANALYSIS AND OPTIMIZATION.2012Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
  • 265.
    Gattzén, Viktor
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Industrial design.
    Upplevd säkerhet i en digital låslösning: Att designa säkerhet2017Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Det första mekaniska låset dateras till ungefär 4000 år sedan. Sedan dess har lås kommit att bli en allt mer central part av våra dagliga liv. Vad som i början skapades för att säkra skatter och hem utvecklades till att säkra mobiltelefoner, datasystem och kreditkort. Tillsammans med den digitala revolutionen kom ny teknologi och nya möjligheter. En av de möjligheterna är Internet of Things, vilket erbjuder användare att numera låsa up en dörr via sin mobiltelefon.

    Detta examensarbetet studerar användarupplevelsen och mänsklig respons av modaliteter i samband med en digital låslösning och hur design kan användas för att få användarna att känna sig säkra och trygga. Precis som intentionen var för 4000 år sedan. Resultatet blev en designutveckling av gränssnittet i en digital låslösning, som en adderad funktion till den befintliga produkten.

    Arbetet resulterade i en utveckling av deras produkt med en multimodal lösning som fokuserade på att öka den upplevda säkerheten. 

  • 266.
    Gavilán del Amo, Asier
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Alonso Lopez, Ana
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Drain water heat recovery in a residential building2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Numerous of energy saving measures have been carried out in the Swedishhousing stock since the energy crisis in the 70’s. Additionally, there have been manylow-energy housing projects. However, so far few of these have been followed up aftersome years in operation concerning the energy use. That the energy use stays on a lowlevel is important from a sustainable perspective.

    The objectives of this study are find a system capable of reduce energy demandand minimize the environmental impact, make the minimum investment with themaximum results and maintain the actual infrastructure of the building.

    This report looks into the potential for saving energy and money with greywastewater. This potential depends on both the quantity available and whether thequality fits the requirement of the heating load. To recover heat from waste water inresidential buildings is hard to achieve in quality because of its low temperature range.Nevertheless, efforts to recycle this waste energy could result in significant energysavings.

    To implement this system the method used is to gather all the information aboutthis system, compare all the options available and calculate how much energy can besaved and how much time is the payback.

    The building studied is on Maskinisten Brynäs in Gävle with 23 apartments onfive different floors and a total living area of 400 m2 in each floor.

    In the case building used in this report the 60% of the total water used is hotwater. Installing a heat recovery system can be saved up to 23% of the energy used forheating water. This energy can be used for the preheating of the hot water.

    In this report is given two different solutions to save energy with this systems,the first one is to use a heat exchanger only in the drain of the showers saving up to7.045 MWh or using a centralized heat exchanger saving up to 23.16 MWh.

    After analysing the results the best option is to use the centralized heatexchanger system, it can be saved more energy and the total investment is lower thanusing a heat exchanger in each shower.

  • 267.
    Gellerstedt, Jennifer
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Westman, Simon
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Sambandet mellan radarsignaler och fukthalt i en lättbetongkonstruktion2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Moisture in buildings is common and can lead to damage. The moisture can cause moldand rot, which is not good for human health. The moisture can also affect different properties of the building materials such as strength, thermal insulation and dimensional changes. Because high moisture levels can have a major impact on the materials, it is important to detect and fix the problem at an early stage. The purpose and aim of this report is to see if there is a correlation between radar and moisture content and determine whether radar technology is a useful method of measuring moisture contentin a building element.

    In this work, literature studies, measurements and analyzes have been made. The material used is lightweight concrete that is built up to four walls in two different thicknesses, two large and two small walls. The large test-walls were used for radar measurements and the small ones as sample-walls for the gravimetric method. The walls were built in a tent where relative humidity (RF) and temperature could be controlled. At the beginning of the experiment, the RF in the tent was set to 98-99 % and the temperature of 22 °C, which was then regulated to dry out the walls. Measurements have been made with radar and the gravimetric method in parallel, where the latter was made by weighing the sample-walls light concrete blocks at the same time as the radar measurements. The blocks of the sample walls were then dried in an oven at 105 °C to determine drydensity. The collected data from the radar measurements have been processed by the Radarbolaget’s personnel. The results for the different methods have then been analyzed and compared to see if there is a relationship.

    The results from the study show that there is a connection between moisture content and the signals from the radar measurements. The moisture content can be determined on a light concrete wall with a margin of error of ± 4 kgH20/m3material, which corresponds to about 4 %. It is possible to get a good result with radar measurement. However, the method is complicated, but there may be value for further studies on multilayered structures to determine whether the technology can be useful for existing building constructions.

  • 268.
    Gentil, Emmanuel C.
    et al.
    Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark.
    Damgaard, Anders
    Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark.
    Hauschild, Michael
    DTU Management, Innovation and Sustainability Group, Technical University of Denmark, Kongens Lyngby, Denmark.
    Finnveden, Göran
    Environmental Strategies Research - fms, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Eriksson, Ola
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Thorneloe, Susan
    US EPA, Office of Research and Development, National Risk Management Research Laboratory, United States.
    Kaplan, Pervin Ozge
    US EPA, Office of Research and Development, National Risk Management Research Laboratory, United States.
    Barlaz, Morton
    Department of Civil, Construction and Environmental Engineering, NC State University, Raleigh, United States.
    Muller, Olivier
    PricewaterhouseCoopers, Neuilly-sur-Seine, France.
    Matsui, Yasuhiro
    Graduate School of Environmental Science, Okayama University, Okayama, Japan.
    Ii, Ryota
    Pacific Consultants Co. Ltd., Tokyo, Japan.
    Christensen, Thomas H.
    Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark.
    Models for waste life cycle assessment: Review of technical assumptions2010In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 30, no 12, p. 2636-2648Article, review/survey (Refereed)
    Abstract [en]

    A number of waste life cycle assessment (LCA) models have been gradually developed since the early 1990s, in a number of countries, usually independently from each other. Large discrepancies in results have been observed among different waste LCA models, although it has also been shown that results from different LCA studies can be consistent. This paper is an attempt to identify, review and analyse methodologies and technical assumptions used in various parts of selected waste LCA models. Several criteria were identified, which could have significant impacts on the results, such as the functional unit, system boundaries, waste composition and energy modelling. The modelling assumptions of waste management processes, ranging from collection, transportation, intermediate facilities, recycling, thermal treatment, biological treatment, and landfilling, are obviously critical when comparing waste LCA models. This review infers that some of the differences in waste LCA models are inherent to the time they were developed. It is expected that models developed later, benefit from past modelling assumptions and knowledge and issues. Models developed in different countries furthermore rely on geographic specificities that have an impact on the results of waste LCA models. The review concludes that more effort should be employed to harmonise and validate non-geographic assumptions to strengthen waste LCA modelling.

  • 269. Ghadimi, M.
    et al.
    Ghadamian, H.
    Hamidi, A. A.
    Shakouri, M.
    Ghahremanian, Shahriar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy engineering. Division of Energy Systems, Department of Management and Engineering, Linköping University, Sweden.
    Numerical analysis and parametric study of the thermal behavior in multiple-skin facades2013In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 67, p. 44-55Article in journal (Refereed)
    Abstract [en]

    The general aim of this research is contributed to the energy performance assessment of single storey multiple-skin facade. To cover this aim; multiple skin facade are studied by means of experiments and numerical simulation. In this research a numerical model for multiple-skin facades with mechanical and natural ventilation has been developed. The numerical model is two-dimensional and based on a cell centered volume method (CVM). As an improvement, radiation and convection are treated separately and by this means an innovative method is applied to calculate the view factors and heat transfer coefficients between surfaces and each cavity. Then the developed numerical model is validated using measurements from the vliet test building. However, there is no multiple-skin facade application in Tehran. Thus the model is used to assess the influence of different multiple-skin facade parameters in Tehran's climate conditions to show its effect on heat losses if this technology would be applied. As a consequence of the diversity of results, designer should be aware that multiple-skin facades do not necessarily improve the energy efficiency of their designs. (C) 2013 Elsevier B.V. All rights reserved.

  • 270.
    Ghahremanian, Shahriar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Near-Field Study of Multiple Interacting Jets: Confluent Jets2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with the near-field of confluent jets, which can be of interest in many engineering applications such as design of a ventilation supply device. The physical effect of interaction between multiple closely spaced jets is studied using experimental and numerical methods. The primary aim of this study is to explore a better understanding of flow and turbulence behavior of multiple interacting jets. The main goal is to gain an insight into the confluence of jets occurring in the near-field of multiple interacting jets.

    The array of multiple interacting jets is studied when they are placed on a flat and a curved surface. To obtain the boundary conditions at the nozzle exits of the confluent jets on a curved surface, the results of numerical prediction of a cylindrical air supply device using two turbulence models (realizable  and Reynolds stress model) are validated with hot-wire anemometry (HWA) near different nozzles discharge in the array. A single round jet is then studied to find the appropriate turbulence models for the prediction of the three-dimensional flow field and to gain an understanding of the effect of the boundary conditions predicted at the nozzle inlet. In comparison with HWA measurements, the turbulence models with low Reynolds correction ( −  and shear stress transport [SST]  − ) give reasonable flow predictions for the single round jet with the prescribed inlet boundary conditions, while the transition models ( −  and transition SST ) are unable to predict the flow in the turbulent region. The results of numerical prediction (low Reynolds SST model) using the prescribed inlet boundary conditions agree well with the HWA measurement in the nearfield of confluent jets on a curved surface, except in the merging region.

    Instantaneous velocity measurements are performed by laser Doppler anemometry (LDA) and particle image velocimetry (PIV) in two different configurations, a single row of parallel coplanar jets and an inline array of jets on a flat surface. The results of LDA and PIV are compared, which exhibit good agreement except near the nozzle exits.

    The streamwise velocity profile of the jets in the initial region shows a saddle back shape with attenuated turbulence in the core region and two off-centered narrow peaks. When confluent jets issue from an array of closely spaced nozzles, they may converge, merge, and combine after a certain distance downstream of the nozzle edge. The deflection plays a salient role for the multiple interacting jets (except in the single row configuration), where all the jets are converged towards the center of the array. The jet position, such as central, side and corner jets, significantly influences the development features of the jets, such as velocity decay and lateral displacement. The flow field of confluent jets exhibits asymmetrical distributions of Reynolds stresses around the axis of the jets and highly anisotropic turbulence. The velocity decays slower in the combined regio  of confluent jets than a single jet. Using the response surface methodology, the correlations between characteristic points (merging and combined points) and the statistically significant terms of the three design factors (inlet velocity, spacing between the nozzles and diameter of the nozzles) are determined for the single row of coplanar parallel jets. The computational parametric study of the single row configuration shows that spacing has the greatest impact on the near-field characteristics.

  • 271.
    Ghahremanian, Shahriar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Department of Management and Engineering, Linköping University.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Department of Management and Engineering, Linköping University.
    A study on proximal region of low reynolds confluent jets: Part 1: Evaluation of turbulence models in prediction of inlet boundary conditions2014In: ASHRAE Transactions, 2014, no PART 1, p. 256-270Conference paper (Refereed)
    Abstract [en]

    Conventional ventilation systems (mixing and displacement) produce low air quality in industrial premises. A new air supply system (confluent jets system) may improve the ventilation efficiency and the energy efficiency. When round jets issue from co-planar nozzles with enough spacing, they converge, merge, and combine at certain downstream distances, which are called confluent jets. In order to numerically predict confluent jets, it is crucial to provide inlet boundary conditions for these jets at the nozzles' exit. Numerical prediction of inlet boundary conditions of confluent jets was chosen due to two reasons: the difficulty of measurement at the nozzles' exit, and lack of information about the shape of the employed nozzles to make artificial inlet profiles. Numerical predictions by two turbulence models (Realizable k - ε and RSM) of the supply device producing the confluent jets was verified by hot-wire measurements at 0.26 d0 downstream of the nozzles' exit in both lateral and vertical direction. The verification was carried out for different nozzles in an array by measuring axial velocity and its turbulence intensity. The axial velocity profile at the nozzles exit has a saddle-back shape with two distinct off-centered overshoots. The convergence of the velocity profile shows the existence of Vena contracta phenomena. Low turbulence intensity at the central part of nozzles was found with narrow shear layer upstream of confluent jet flow. Differences of velocity components, turbulent kinetic energy (TKE), and turbulent dissipation rate (TDR) of the studied contraction nozzle were examined with a flow issuing from a typical long pipe. Reynolds number dependency in the studied range has been carried out and Re effects were observed on TKE but not on TDR. 

  • 272.
    Ghahremanian, Shahriar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    A study on proximal region of low reynolds confluent jets: Part 2: Numerical prediction of the flow field2014In: ASHRAE Transactions, 2014, no PART 1, p. 271-285Conference paper (Refereed)
    Abstract [en]

    Conventional ventilation systems (mixing and displacement) produce low air quality in industrial premises. A new air supply system (confluent jet system) may improve both ventilation and energy efficiency. When round jets are issued from coplanar nozzles with enough spacing, they converge, merge, and combine at a certain downstream distance, which are called "confluent jets." In this study, the velocity field of the proximal region of confluent jets was recorded by traversing a hot-wire probe across the jets in one column at selected distances from the nozzles' exit in order to examine the performance of SST k - ω turbulence model. The experimental and numerical results from this work are summarized in a set of mapping fields of mean velocity for the confluent jet zones, which are presented in a generalized non-dimensional form. The existence of an initial, a converging, a merging, and a combined region in the confluent jets has been found for three low Reynolds numbers. Three different confluent jets can be seen in the array of jets studied placed six by six symmetrically on the long side of a cylindrical supply device. The streamwise velocity of the geometrical centerline of side jets and corner jets decays faster than that for the fully confluent jets, due to deflection towards their adjacent neighboring jets. Side jets and corner jets deflect to their adjacent jets and finally merge and combine with them, while fully confluent jets normally spread and amalgamate with each other. Low local pressure is responsible for the amalgamation of confluent jets, but the static pressure reaches a minimum value between side jets and their neighboring jets, which results in the deflection of the side jets.

  • 273.
    Ghahremanian, Shahriar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Department of Management and Engineering, Linköping University.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Department of Management and Engineering, Linköping University.
    Evaluation of RANS models in predicting low reynolds, free, turbulent round jet2014In: Journal of Fluids Engineering - Trancactions of The ASME, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 136, no 1, article id 011201Article in journal (Refereed)
    Abstract [en]

    In order to study the flow behavior of multiple jets, numerical prediction of the three-dimensional domain of round jets from the nozzle edge up to the turbulent region is essential. The previous numerical studies on the round jet are limited to either two-dimensional investigation with Reynolds-averaged Navier-Stokes (RANS) models or three-dimensional prediction with higher turbulence models such as large eddy simulation (LES) or direct numerical simulation (DNS). The present study tries to evaluate different RANS turbulence models in the three-dimensional simulation of the whole domain of an isothermal, low Re (Re = 2125, 3461, and 4555), free, turbulent round jet. For this evaluation the simulation results from two two-equation (low Re k-ε and low Re shear stress transport (SST) k-ω), a transition three-equation (k-kl-ω), and a transition four-equation (SST) eddy-viscosity turbulence models are compared with hot-wire anemometry measurements. Due to the importance of providing correct inlet boundary conditions, the inlet velocity profile, the turbulent kinetic energy (k), and its specific dissipation rate (ω) at the nozzle exit have been employed from an earlier verified numerical simulation. Two-equation RANS models with low Reynolds correction can predict the whole domain (initial, transition, and fully developed regions) of the round jet with prescribed inlet boundary conditions. The transition models could only reach to a good agreement with the measured mean axial velocities and its rms in the initial region. It worth mentioning that the round jet anomaly is still present in the turbulent region of the round jet predicted by the low Re k-ε. By comparing the k and the ω predicted by different turbulence models, the blending functions in the cross-diffusion term is found one of the reasons behind the more consistent prediction by the low Re SST k-ω. 

  • 274.
    Ghahremanian, Shahriar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Investigation in the near-field of a row of interacting jets2015In: Journal of Fluids Engineering - Trancactions of The ASME, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 137, no 12, article id 121202Article in journal (Refereed)
    Abstract [en]

    Multiple interacting jets (confluent jets) are employed in many engineering applications, and the significant design factors must be investigated. Computational fluid dynamics (CFD) is used to numerically predict the flow field in the proximal region of a single row of round jets. The numerical results that are obtained when using the low Reynolds k-∈ are validated with the experimental data that are acquired by particle image velocimetry (PIV). PIV was used to measure mean velocity and turbulence properties in the proximal region of a row of six parallel coplanar round air jets with equidistant spacing at low Reynolds number (Re = 3290). The low Reynolds k-∈ underpredicts the streamwise velocity in the onset of the jets' decay. The characteristic points are determined for various regions between two neighboring jets. The comparison of the merging point (MP) and the combined point (CP) computed from measurements and simulations shows good agreement in the different regions between the jets. In this study, a computational parametric study is also conducted to determine the main effects of three design factors and the interactions between them on the flow field development using response surface method (RSM). The influences of the inlet velocity, the spacing between the nozzles, and the diameter of the nozzles on the locations of the characteristic points are presented in the form of correlations (regression equations). CFD is used to numerically predict the characteristic points for a set of required studies, for which the design values of the simulation cases are determined by the Box-Behnken method. The results indicate that the spacing between the nozzles has a major impact on the flow characteristics in the near-field region of multiple interacting jets. The RSM shows that the inlet velocity has a marginal effect on the merging and CPs. All of the square terms are removed from the response equations of MP, and only one two-way interaction term between inlet velocity and spacing remains in the regression model with a marginal effect. The square of the nozzle diameter contributes in the regression equations of CP in some regions between the jets.

  • 275.
    Ghahremanian, Shahriar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy engineering. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy engineering. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Numerical and experimental verification of initial, transitional and turbulent regions of free turbulent round jet2011In: 20th AIAA Computational Fluid Dynamics Conference 2011, 2011Conference paper (Refereed)
    Abstract [en]

    Three-dimensional simulation of the whole domain (initial, transition and fully developed regions) of round jet is essential in order to predict and to study the flow behavior of multiple jets (e.g. confluent jets). According to authors knowledge, numerical prediction of round jet with RANS models that has been presented by other researchers, are only in two-dimensional (axisymmetric) and mostly for the fully developed region. The inlet boundary conditions,  inlet velocity profile, turbulent kinetic energy and its dissipation rate at the diffuser exit has been governed from an earlier verified numerical simulation. In the present paper, results of three-dimensional modeling of isothermal, free, turbulent round jet with two two-equation (Low Re  and SST ), a transition three-equation ( ) and a transition four-equation (SST) eddy-viscosity turbulence models with resolved inlet profiles are compared and validated with hot-wire anemometry. This study shows that numerical simulation of round jet with SST  gives good agreement with measured mean longitudinal velocities, while transition models could only predict the initial region of round jet.

  • 276.
    Ghahremanian, Shahriar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Linköping University.
    Svensson, Klas
    Tummers, Mark J.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Linköping University.
    Near-field development of a row of round jets at low Reynolds numbers2014In: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 55, no 8, p. 1789-Article in journal (Refereed)
    Abstract [en]

    This article reports on an experimental investigation of the near-field behavior of interacting jets at low Reynolds numbers (Re = 2125, 3290 and 4555). Two measurement techniques, particle image velocimetry (PIV) and laser Doppler anemometry (LDA), were employed to measure mean velocity and turbulence statistics in the near field of a row of six parallel coplanar round jets with equidistant spacing. The overall results from PIV and LDA measurements show good agreement, although LDA enabled more accurate measurements in the thin shear layers very close to the nozzle exit. The evolution of all six coplanar jets showed initial, merging, and combined regions. While the length of the potential core and the maximum velocity in the merging region are Reynolds number-dependent, the location of the merging points and the minimum velocity between jets were found to be independent of Reynolds number. Side jets at the edges of the coplanar row showed a constant decay rate of maximum velocity after their core region, which is comparable to a single round jet. Jets closer to the center of the row showed reducing velocity decay in the merging region, which led to a higher maximum velocity compared to a single round jet. A comparison with the flow for an in-line array of 6 x 6 round jets showed that the inward bending of streamwise velocity, which exists in the near field of the 6 x 6 jet array, does not occur in the single row of coplanar jets, although both setups have identical nozzle shape, spacing, and Reynolds number.

  • 277.
    Ghahremanian, Shahriar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Linköping University.
    Svensson, Klas
    Tummers, Mark J.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Near-field mixing of jets issuing from an array of round nozzles2014In: International Journal of Heat and Fluid Flow, ISSN 0142-727X, E-ISSN 1879-2278, Vol. 47, p. 84-100Article in journal (Refereed)
    Abstract [en]

    This article presents results of an experimental study of the confluence of low Reynolds number jets in the near field of a 6 x 6 in-line array of round nozzles. Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) were employed to measure mean velocities and turbulence statistics. The comparison of the results from PIV and LDA measurements along different cross-sectional profiles and geometrical centerlines showed good agreement. However, LDA enabled more accurate results very close to the nozzle exits. The evolution of all the individual jets in the array into a single jet showed flow regions similar to twin jets (i.e., initial, converging including mixing transition, merging and combined regions). The lateral displacements play an important role for a confluent jet, where all jets to some degree are deflected towards the center of the nozzle plate. The jet development in terms of velocity decay, length of potential core and lateral displacement varies significantly with the position of the jet in the array. A comparison with single jet and twin jets flow showed considerable differences in velocity decay as well as location and velocity in the combined point. The flow field of confluent jets showed asymmetrical distributions of Reynolds stresses around the axis of the jets and highly anisotropic turbulence. Additionally, the lateral displacement as well as the turbulence development in the proximal region of the studied confluent jet was shown to be dependent on Reynolds number. 

  • 278.
    Ghasemi, Milad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Hammodi, Hassan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Moosavi Sigaroodi, Homan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Parallel-Powered Hybrid Cycle with Superheating “Partially” by Gas Turbine Exhaust2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    It is of great importance to acquire methods that has a sustainable solution for treatment and disposal of municipal solid waste (MSW). The volumes are constantly increasing and improper waste management, like open dumping and landfilling, causes environmental impacts such as groundwater contamination and greenhouse gas emissions. The rationalization of developing a sustainable solution implies in an improved way of utilizing waste resources as an energy source with highest possible efficiency. MSW incineration is by far the best available way to dispose the waste. One drawback of conventional MSW incineration plants is that when the energy recovery occurs in the steam power cycle configuration, the reachable efficiency is limited due to steam parameters. The corrosive problem limits the temperature of the superheated steam from the boiler which lowers the efficiency of the system. A suitable and relatively cheap option for improving the efficiency of the steam power cycle is the implementation of a hybrid dual-fuel cycle.

    This paper aims to assess the integration of an MSW incineration with a high quality fuel conversion device, in this case natural gas (NG) combustion cycle, in a hybrid cycle. The aforementioned hybrid dual-fuel configuration combines a gas turbine topping cycle (TC) and a steam turbine bottoming cycle (BC). The TC utilizes the high quality fuel NG, while the BC uses the lower quality fuel, MSW, and reaches a total power output of 50 MW.  Using a high-quality fuel in cogeneration can prove to be beneficial for improving and enhancing the overall plant profitability and efficiency while eliminating the corrosion problems with conventional MSW firing. The need for few interconnections between the different subunits in a parallel-fueled system allows for a wider range of operation modes and leaves room for service modes of the subunit. The hybrid dual-fuel cycle will be assessed for optimal cycle configuration and evaluated to how it compares to the sum of two separate single-fuel plants with optimal cycle configurations. Investigation of such aspects is a very important issue in order to be able to fully promote an implementation of hybrid combined cycle. The work presented herein also concentrates on investigating scenarios that include a full-load and part-load analysis in both condensing and combined heat and power (CHP) mode of operation.

    Through simulations and evaluation of obtained data, the results strengthens the fact that the electrical efficiency of hybrid configurations increases at least with 2% in condensing mode and 1,5% in CHP mode, comparing it to the sum of two separate single-fuel units of similar scale. The simulations show increased electrical efficiencies when running the BC in part-load and the TC in full load, with a higher NG to MSW ratio. The results also indicated that it is possible to extract more power output from the cycle by operating in CHP mode, due to more energy being utilized from the input fuel. 

  • 279.
    Ghashami, Bahman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    A New Power Storage, Cooling Storage, and Water Production Combined Cycle (PCWCC)2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Fresh water shortage and hot weather are common challenges in many countries of the world. In the other hand, the air conditioning systems which are used for indoor cooling cause peak electricity demand during high temperatures hours. This peak hour demand is very important since it is more expensive and mainly is supplied by fossil fuel power plants with lower efficiencies compare to base load fossil fuel or renewable owe plants. Moreover, these peak electricity load fossil fuel power plants cause higher green house gas emission and other environmental effects. So, all these show that any solution for these problems could make life better in those countries and all over the world.In this thesis, a new idea for a Power storage, Cooling storage, and Water production Combined Cycle (PCWCC) is introduced and reviewed. PCWCC is combination of two thermal cycles, Ice Thermal Energy Storage (ITES) and desalination by freezing cycle, which are merged together to make a total solution for fresh water shortage, required cooling, and high peak power demand. ITES is a well known technology for shifting the electricity demand of cooling systems from peak hours to off-peak hours and desalination by freezing is a less known desalination system which is based on the fact that the ice crystals are pure and by freezing raw water and melting resulted ice crystals, pure water will be produced. These two systems have some common processes and equations and this thesis shows that by combining them the resulted PCWCC could be more efficient than each of them. In this thesis, the thermodynamic equations and efficiencies of each PCWCC sub-systems are analyzed and the resulted data are used in finding thermodynamics of PCWCC itself. Also, by using reMIND software, which uses Cplex to find the best combinations of input/output and related processes, the cost of produced fresh water and cooling from PCWCC is compared with total cost of fresh water and cooling produced by each sub-systems of PCWCC in three sample cities all over the world, Kerman, Dubai, and Texas. These cities are chosen since they have similar ambient temperature trend with different electricity and fresh water tariff's. The results show that, the PCWCC is economical where there is a significant electricity price difference between ice charging and ice melting hours, off-peak and peak hours, of the day or when the fresh water price is high compare to electricity price. The results also show that how the revenue from fresh water could cover the used electricity cost and make some income as well.

  • 280.
    Gille, Ida
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Granat, Frida
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    En undersökning om bygglovsprocessen och dess svårigheter: Fallstudie Gävle2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The building permit process can be extensive and seen as a difficult process for private individuals who are not familiar with the subject. The building permit process is regulated by the Swedish planning and building act.

    A case study has been carried out in Gävle municipality to find out if the building permit process can be simplified for individuals. To get an overview of what is required to apply for building permits has Gävle's building permit process, laws and regulations been reviewed.

    The study is partially based on interviews with Gävle Municipality which was done orally and partially on a survey which was sent to individuals in order to find out which steps they found difficult.The survey were sent online to 341 private individuals who applied for building permits in 2013. 125 people participated, which gave a response rate of 36.7%.

    The result of the study has led to suggestions for improvement. These include interest from those who applied for building permits that the municipality develops brochures. The brochures should describe which documents are needed to apply for building permits as well as how it should be designed. The applicants would also like to see a change in how a building permit is submitted. Today it is submitted by hand but there is an interest to submitting it via an E-service or by E-mail. Results from the survey also showed that Gävle website should be updated so that it becomes more easily descriptive and available regarding what is needed to apply for a building permit. In addition to this, there are two larger propositions from the Swedish government that would change the Swedish planning and building act so that the building permits process becomes easier and more efficient and to increase the possibility to make smaller building operations without having to apply for building permits.

  • 281. Giovinazzo, Carine
    et al.
    Bonfiglio, Luc
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Karlsson, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Ray Tracing Modelling of an Asymmetric Concentrating PVT2014In: EuroSun 2014 Proceedings, 2014Conference paper (Refereed)
    Abstract [en]

    Photovoltaic thermal (PVT) collectors are able to produce both heat and electricity from the same area. The studied PVT collector is an asymmetric Compound Parabolic Collector (CPC) which is composed two parts: a quarter of a circle and a parabola. This reflector design belongs to the MaReCo (Maximum Reflector Collector) family. The main advantages of this collector design are the reduction of material cost due to concentration and the increase cell efficiency by reducing its working temperature through active cooling.Tonatiuh is a Monte Carlo ray tracing software that is able to simulate the interaction between the sunlight and a concentrating collector. A script was written to repeat the process and simulate the course of the year. The data was processed using Matlab and the annual received radiation on both receiver sides was obtained.A collector model was drawn in Tonatiuh and its material properties were described. Incremental changes were used both to validate the models results and to assess the impact of each change. The first model had only the reflector geometry and the receiver with perfect properties while the final model had a very accurate description of the studied collector and its properties. The final model performed 21% worse than the initial with ideal properties. Additionally, the homogeneity of the solar radiation on the receiver was analyzed and the 3D effective solar radiation graph was plotted. Finally, it was found that over the year, the receiver under concentration produces 13% more energy than the flat side of the receiver, at the best tilt, for both 0º and 60º of latitudes.

  • 282.
    Glaumann, Mauritz
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Environmental assessment of buildings and building materials2010In: Sustainable Construction: A life Cycle Approach in Engineering. International Training School, Malta 2010 / [ed] Braganca L et al, Malta: Faculty for the Built Environment, University of Malta , 2010, p. 99-150Chapter in book (Other academic)
  • 283.
    Glaumann, Mauritz
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Malmqvist, Tove
    KTH Royal Institute of Technology, School of Architecture and the Built Environment,, Division of Environmental Strategies Research, Department of Urban Studies, Environmental Strategies Research - fms.
    Wallhagen, Marita
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Selecting environmental assessment tool for buildings2011In: Proceedings of 6th World Sustainable Building Conference, SB11 Helsinki, October 18-22, 2011, Helsinki, 2011, Vol. 1, p. Abstract 162-163Conference paper (Refereed)
  • 284.
    Gomes, João
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Bastos, Sílvio
    Instituto Politécnico de Castelo Branco, Portugal.
    Henriques, Mafalda
    Instituto Politécnico de Castelo Branco, Portugal.
    Diwan, Linkesh
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Olsson, Olle
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. olle@solarus.com.
    Evaluation of the impact of stagnation temperatures in different prototypes of low concentration PVT solar panels2015In: ISES Solar World Congress 2015, Conference Proceedings, 2015, p. 993-1004Conference paper (Refereed)
    Abstract [en]

    Photovoltaic thermal (PVT) solar panels produce both thermal and electric power from the some area. This paper concerns a PVT design where the series connected strings of cells are laminated using silicone to an aluminium receiver where the heat transfer fluid flows. An evaluation of the impact of reaching high temperatures in the cell structural integrity and performance is presented. Eight small test receivers were made in which the following properties were varied: Size of the PV cells, type of silicone used to encapsulate the PV cells, existence of a strain relief between the cells, size of the gap between cells and type of cell soldering (line or point soldering). These test receivers were placed in an oven for one hour, under eight different monitored temperatures. The temperature of the last round was set at 220°C which well exceeds the highest temperature the panel design can reach. Before and after each round in the oven, the following tests were conducted to the receivers: Electroluminescence (EL) test, IV-curve, diode function, and visual inspection. The test results showed that the receivers made with the transparent silicone and strain relief between cells experienced less micro-cracks and lower degradation in maximum power. No prototype test receiver lost more than 30% of its initial power, despite the large cell breakage shown in some receivers. Prototype receivers with transparent (softer) silicone showed much far less cracks and power decrease when compared to red (harder) silicone receivers. As expected, larger cells are more prone to develop micro-cracks after exposure to thermal stress. Additionally, existing micro-cracks tend to grow in size into larger micro-cracks relatively fast with thermal stress. The EL imaging taken during our experiment leads us to observe that it seems far easier for existing cracks to expand than for new cracks to appear.

  • 285.
    Gomes, João
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Diwan, Linkesh
    Instituto Superior Tecnico, Av. Rovisco Pais, Lisboa, Portugal .
    Bernardo, Ricardo
    Energy and Building Design, Lund University, Lund, Sweden .
    Karlsson, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Minimizing the impact of shading at oblique solar angles in a fully enclosed asymmetric concentrating PVT collector2014In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 57, p. 2176-2185Article in journal (Refereed)
    Abstract [en]

    PVT collectors produce both electricity and heat from the same area. PVT collectors with low concentration factor allow both stationary and tracking configurations. For stationary or single axis tracking, the daily variation in the solar incidence angle can cause significant shading in concentrating collectors. Shading has a larger impact on PV than on thermal collectors and thus the evaluations was more focused on the electrical part. Several prototype versions of a novel design for a concentrating asymmetric PVT collector have been tested and compared. One tested improvement was replacing the reflective end gables with transparent end gables. Another improvement was to use different cell sizes. These actions were expected to minimize the impact of the shading at oblique solar incidence angles. The second action was found to be more beneficial than the first. Measurements were also performed in the solar simulator to fully understand the impact of shading in cell strings with 1/6 the size of standard cells. The latest version of the PVT was found to have, at 25 °C and 1000w/m2, a collector efficiency of 13,7%, a cell area efficiency of 20,3% and an electrical power output of 237W. Lower side of the receiver was producing 58% of the total power.

  • 286.
    Gomes, João
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Solarus Sunpower Sweden AB.
    Junge, Jana
    Karlsson, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Defining an annual energy output ratio between PV and solar thermal2014In: EuroSun 2014 Proceedings, 2014Conference paper (Refereed)
    Abstract [en]

    Photovoltaics (PV) and solar thermal (ST) collectors are often competing between themselves not only because the investment capacity is limited but also because the energy demand and roof space is limited and both types of panel provide energy which can be converted to a different type of energy under a certain efficiency. Therefore, it makes sense to develop a ratio that quantifies the difference in annual energy output between standard ST and PV for different locations. This ratio is useful, for example, to support the decision between installing ST or PV, when combined with other local specific information such as the value of heat and electricity for a specific location and application, the system complexity and efficiency, and others.A market survey was conducted for assessing the average performance specifications of the panels. Simulations were conducted and several ratios were plotted in the world map. Despite the large variations occurring due to local climate, the ratio increases at lower latitudes due to two factors: a) the efficiency of a PV panel is reduced with the increase of air temperature while, in solar thermal, the effect is the opposite; b) Under low intensity solar irradiance, the efficiency of a PV panel is maintained while a solar thermal collector can have its efficiency reduced to zero. For latitudes lower than 66º, the ratio flat plate at 50ºC to PV is ranging from 1,85 to 4,46 while in the ration between vacuum tube at 50ºC and PV from 3,05 to 4,76.

  • 287.
    Gomes, João
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Luc, B.
    Ecole Polytechnique Universitaire de Montpellier, France .
    Carine, G.
    Ecole Polytechnique Universitaire de Montpellier, France .
    Fernandes, C. A. F.
    Instituto Superior Técnico, Universidade de Lisboa, Portugal .
    Torres, J. P. N.
    Instituto Superior Técnico, Universidade de Lisboa, Portugal .
    Olsson, Olle
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Costa Branco, P. J.
    Instituto Superior Técnico, Universidade de Lisboa, Portugal .
    Nashih, S. K.
    Analysis of different C-PVT reflector geometries2016In: Proceedings - 2016 IEEE International Power Electronics and Motion Control Conference, PEMC 2016, IEEE, 2016, p. 1248-1255, article id 7752175Conference paper (Refereed)
    Abstract [en]

    One of the main advantages of solar concentrating photovoltaic-thermal collectors (C-PVT) is that these systems are all-in-one module type. For this reason, they are associated to less area and material requirements. Nevertheless, these systems require a more complex analysis in order to improve their performances, since the two types of energy conversion are related to the different demands and their cross effects. In the overall analysis, the collector geometry and the used materials for all their components will be crucial to ensure the system reliability. This study presents preliminary work about re-designing the reflector of C-PVT collectors currently produced in the Swedish SME Solarus Sunpower AB with a comparative analysis on an annual basis of the solar radiation that reaches the collector. For the work accomplished, an open-source advanced object-oriented Monte Carlo ray tracing program (Tonatiuh) is used. For low latitudes, two reflector shapes have been selected since they ensure better performances than the current Solarus reflector. These two new designs achieve both the performance and cost-effectiveness objectives: for the same aperture area and for a thinner box, the collector is 7% to 10% more effective and 18% cheaper.

  • 288.
    Gomez, Adrian
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Energy audit of a bakery in Sweden2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In order to reach the European aim for a sustainable growth, the “Triple 20 by 2020”, the energy audit in every sector is one of the keys of the success. In order to carry on with the energetical development, sustainability and future energy efficient systems, the energy efficiency in the industry is one of the most important matters. The Swedish industry uses 147 TWh of energy per year, which represents the 39% of the total final energy use and also the biggest energy user of the three sectors. The food processing industry only uses a 3% of the total Swedish industrial energy use, however this is 4410 GWh per year, what still has high possibilities to reduce the use of energy through different energy efficiency measures.The present study consists on an energy audit of a small-medium industrial bakery in Ockelbo, Sweden, by starting with the compilation of a few energy efficiency measures that are usually carried out on the energy audits. Then those measures have been tried to implement in the bakery in order to reduce the energy use and therefore the costs, which are the principal aims of the study, together with the approach to future energy efficiency ideas. However, the lack of electrical measure equipment has been a big limitation for the study. The method, that has been the guideline for the energy audit, is the Energy management procedure, which is a widely used method on different energy audits. The main measures that have been proposed are regarding the auxiliary processes like lighting and the compressed air system, additionaly, changes regarding the power contract and the installed power of they bakery are presented. Also different future possibilities for the heat recovery are analyzed and discussed like using the waste heat for preheating tap water for the dough processes. Additionally this study contains a wide explanation of the Swedish electrical bills that every company has to pay and probably many of them do not understand.If the presented energy efficiency measures are implemented the electrical energy use can be reduced with at least 23109 kWh per year. In terms of money, the cost savings are at least 57781 SEK per year with an investment of 106300 SEK.

  • 289.
    Gomez, Adrian
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Bomhus Energi.
    Identification and evaluation of internal leakages of a BFB Boiler integrated within a pulp and paper mill.2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Alternative fuels like biomass have become really popular in the last decades as a substitute to fossil fuels. One of the most used technologies in Sweden for the obtention of the energy from the biomass is its direct combustion in a boiler. Bomhus Energi is a company with the purpose of creating steam and district heating for Billerudkorsnäs pulp and paper mill in Gävle and district heating for the city by operating a biomass BFB boiler. Despite being a quite new boiler, there are many sources of errors, losses and unnecessary costs. Between huge number of different losses that can happen in this kind of industrial boilers, the concern about internal leakages is not usually popular among plant designers and operators. This often leads to forget about them or not giving the importance that they could have.This study consists on, firstly, an analysis of different boiler equipment that have potential possibilities of internal leakages by mass and energy balances and by the tracking of possible mass losses. The second point of this thesis is to evaluate the cost of internal leakages that could have happen before, in order to be aware of how important they are. Additionally, measures are proposed in order to avoid or reduce the duration of the internal leakages, where the most common problem is the ignorance of their existence. This study focuses partially on the valve condition and maintenance. It is highly important to carry out valve maintenance procedures at least once per year during the general stop of the plant. Checking and verifying valve perfect conditions, can avoid a waste of a huge quantity of money just by replacing some internal elements that are possibly damaged due to the extreme working conditions. This small damages in valve can lead to a non-proper water tightening, which will be increasing its leakage over time. In the present paper, possible internal leakages through the valves belonging to the feedwater, steam drum, preheater and pressure vessel in general have been the principal aim. The key of this study was to take into account that biggest part of the draining system and valves that are supposed to be closed end in the Bottom blowdown tank. By then a deep study was done regarding this tank. The results show that there is a clear relationship between mass that is getting loss from feedwater tank and pressure vessel and the necessary cooling flow in the bottom blowdown tank. This means that if the cooling flow increases at the same rate as a possible leakage in mass and energy balance, there is an internal leakage somewhere in the system. The author proposes add an alarm to the DCS system in order to alert the plant operations of possible internal leakages. On the other hand, this paper also recommends to carry out a general valve maintenance per year and check which of them could be leaking, a general stop is the perfect time for carrying it out.In conclusion, the study finds that internal leakages can be even automatically detected if the system is provided with the necessary tools for it. The study concludes that internal leakages are not impossible to detect and their cost is non-negligible: the latest two internal leakages in the boiler, happened in the last two years, were from the feedwater draining system and from the steam drum heating loop with a total cost of 200,000 SEK (4240 SEK/day during 47 days) and 263,000 SEK (2120 SEK/day during 124 days) respectively. Additionally, days after the study, the plant general stop was carried out, finding that 12 valves were leaking due to internal damage. The cost of repairing the broken or damaged elements were almost negligible compared with the expected savings estimated in 2 Million SEK per year.

  • 290.
    Gordon, Line
    et al.
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden.
    Crona, Bea
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden; Global Economic Dynamics and the Biosphere Program, Royal Swedish Academy of Sciences, Stockholm, Sweden.
    Henriksson, Patrik
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden; WorldFish, Jalan Batu Maung, Bayan Lepas, Penang, Malaysia.
    van Holt, Tracy
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden; Global Economic Dynamics and the Biosphere Program, Royal Swedish Academy of Sciences, Stockholm, Sweden; Leonard N Stern School of Business, Center for Sustainable Business, New York, NY, United States.
    Jonell, Malin
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden.
    Lindahl, Therese
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden; Beijer Institute of Ecological Economics, Royal Swedish Academy of Sciences, Stockholm, Sweden.
    Troell, Max
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden; Beijer Institute of Ecological Economics, Royal Swedish Academy of Sciences, Stockholm, Sweden.
    Barthel, Stephan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering. Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden.
    Deutsch, Lisa
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden.
    Folke, Carl
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden; Global Economic Dynamics and the Biosphere Program, Royal Swedish Academy of Sciences, Stockholm, Sweden; Beijer Institute of Ecological Economics, Royal Swedish Academy of Sciences, Stockholm, Sweden.
    Haider, L. Jamila
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden.
    Rockström, Johan
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden.
    Queiroz, Cibele
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden.
    Rewiring food systems to enhance human health and biosphere stewardship.2017In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 12, no 10, article id 100201Article in journal (Refereed)
    Abstract [en]

    Food lies at the heart of both health and sustainability challenges. We use a social-ecological framework to illustrate how major changes to the volume, nutrition and safety of food systems between 1961 and today impact health and sustainability. These changes have almost halved undernutrition while doubling the proportion who are overweight. They have also resulted in reduced resilience of the biosphere, pushing four out of six analysed planetary boundaries across the safe operating space of the biosphere. Our analysis further illustrates that consumers and producers have become more distant from one another, with substantial power consolidated within a small group of key actors. Solutions include a shift from a volume-focused production system to focus on quality, nutrition, resource use efficiency, and reduced antimicrobial use. To achieve this, we need to rewire food systems in ways that enhance transparency between producers and consumers, mobilize key actors to become biosphere stewards, and re-connect people to the biosphere

  • 291.
    Green, Linnea
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Ett designförslag som minskar skamkänslor för ungdomar med typ 1-diabetes2016Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Ungdomar med typ 1 diabetes känner sig ofta annorlunda på grund av sin diabetes. När ungdomarna behandlar diabetesen utanför hemmet medförs ofta en uppmärksamhet från omgivningen som kan uppfattas negativ. I de fall uppmärksamheten uppfattas negativ leder det till att personen med diabetes skäms över sin sjukdom och över att vara annorlunda. Skamkänslorna kan i en del fall leda till en ignorans mot sjukdomen som kan leda till förhöjt blodsocker och ketoacidos vilket är livshotande.

    Syftet med detta designprojekt är att med hjälp av en cirkulär designprocess utforma ett koncept och produktförslag som är anpassat till målgruppens behov och önskemål, och som löser ovan nämnda problematik. Detta planerar jag ska leda till att ungdomar med typ 1 diabetes alltid ska känna sig trygga med att behandla sin sjukdom, även utanför hemmets trygga vrå.

    Konceptets egenskaper och former är framtagna med hjälp av en fokusgrupp beståendes av ungdomar i åldrarna 14- 22, samt med hjälp av två sjuksköterskor från barndiabetesmottagningen på Gävle Sjukhus. Information och underlag är grundat i svaren på intervjuer, övningar samt i litteratur. Arbetet resulterade i en smidig och diskret blodsockermätare med allt-i-ett funktion, med namnet Miment. Mätsekvensen för blodsockertagning kortas inte bara ner i antal steg utan kan även göras snabbare och mer diskret i jämförels med de hjälpmedel som idag finns att tillgå på marknaden. Jag har skapat detta koncept genom att lyssna till de verkliga behov och problem som ungdomarna i min fokusgrupp har uttryckt. Jag tror bestämt att det är den viktigaste pusselbiten till att skapa ett hjälpmedel som gör att användaren (ungdomar med typ 1 diabetes) inte ska skämmas över sin sjukdom.

  • 292.
    Grundberg, Per
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Häll, Fredrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energieffektivisering av en Hälsingegård med avseende på bevarandekrav2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Sedan år 2012 finns det sju stycken Hälsingegårdar på UNESCOs världsarvslista. Detta har medfört att intresset för dessa gårdar har ökat både inom Sverige men även internationellt. En Hälsingegård karakteriseras av den detaljrikedom och de träarbeten som präglar byggnaden både exteriört och interiört. Husets tapeter och målningar interiört är även något som kännetecknar huvudbyggnaden på en Hälsingegård.

    Syftet med denna studie var att undersöka i vilken utsträckning det går att energieffektivisera en Hälsingegård med avseende på problematiken som uppstår genom att byggnaden har ett kulturhistoriskt värde och bevarandekrav. Energieffektiviseringen strävade till en början efter att byggnaden skulle uppfylla krav som ställts av Boverket på specifik energianvändning för småhus i regionen. Idag bedrivs en uthyrningsverksamhet i samarbete med Bo på Hälsingegård som erbjuder turister övernattningsmöjligheter på Hälsingegården under sommarmånaderna. Studien undersökte även vilket energibehov byggnaden har vid en uppvärmning och förlängning av uthyrningssäsongen med två och en halv månad.

     

    Studien genomfördes med följande metoder; litteraturstudier, platsbesök, energibalansberäkningar, fuktberäkningar och en kostnadsberäkning. Stor vikt lades vid platsbesöken vilket sedan använts som underlag för de övriga metoderna. För en av de föreslagna åtgärderna genomfördes en analys för att se om åtgärden bidrog till ökad risk för fuktproblem.

     

    Genomförandet av dessa metoder har lett fram till olika åtgärder som sänker byggnadens energibehov utan att gestaltningen påverkas. Energibehovet under ett år minskade med 38 procent och under sommarmånaderna maj till september minskade energibehovet med 61 procent genom de åtgärder som presenteras i studien. Att klara målet på 75 kWh/m2 Atemp år, var något som inte gick att uppfylla med de åtgärder som föreslogs i denna studie. Fuktanalysen av den kontrollerade åtgärden visar att risken för fuktproblem minskade efter åtgärden.

  • 293.
    Gråby, Marcus
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Martinsson, Christian
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Fuktegenskaper hos en funktionsfärg med  termokeramisk membran-teknologi2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Swedish company ThermoGaia AB has sole sales rights in the Nordic region for

    ThermoShield® brand, which the company markets under its own brand

    Termoskydd. The paint is marketed with properties such as energy savings by heat

    reflection and solves moisture problems because the paint can both be diffusion

    open or closed due to climatic conditions and function like a variable vapor barrier.

    These unique features come from a combination of a special binder with ceramic

    beads. The unique properties of the color at varying humidity conditions are in

    particular of interest to study and evaluate, which is also the purpose of the this

    study.

    By experimentally creating two different closed climates with differentiated relative

    humidity between both sides of a material, concentration differences will occur in

    the prevailing vapor concentrations provided that constant temperature prevails.

    Variations in vapor levels create pressure differences that become the driving force

    of the moisture transport that takes place in the form of diffusion that occurs onedimensional.

    The method used in the study is a modified version of the standardized

    cup method. Periodic measurements of weight differences continued until stationary

    conditions were reached. The collected measurement data is then used to calculate

    the water vapor migration.

    The result of the study shows that the color has the ability to have a lower resistance

    if the surrounding climate has low relative humidity, the greater the concentration

    difference between the vapors. When the surrounding climate instead has a high

    relative humidity, the color showed a higher resistance when the greatest

    concentration difference occurs. The study's conclusion from the problem

    formulation is that the causal relationship between the relative humidity and water

    vapor migration for the color tends to change the resistance, depending on the vapor

    content of ambient air, provided that stationary conditions prevail.

  • 294.
    Grönbladh, Alfhild
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Johansson, Jenny
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Nöstl, Anatole
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - applied psychology.
    Nyberg, Fred J
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Hallberg, Mathias
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaceutisk biovetenskap.
    Growth hormone improves spatial memory and reverses certain anabolic androgenic steroid-induced effects in intact rats2013In: Journal of Endocrinology, ISSN 0022-0795, E-ISSN 1479-6805, Vol. 216, no 1, p. 31-41Article in journal (Refereed)
    Abstract [en]

    Growth hormone (GH) has previously been shown to promote cognitive functions in GH deficient rodents. In this study we report effects of GH on learning and memory in intact rats pretreated with the anabolic androgenic steroid nandrolone. Male Wistar rats received nandrolone decanoate (15 mg/kg) or peanut oil every third day for three weeks and were subsequently treated with recombinant human GH (1.0 IU/kg) or saline for ten consecutive days. During the GH/saline treatment spatial learning and memory were tested in the Morris water maze (MWM). Also, plasma levels of insulin-like growth factor 1 (IGF1) were assessed and the gene expression of the GH receptor, Igf1, and Igf2 in hippocampus and frontal cortex was analyzed. The results demonstrated a significant positive effect of GH on memory functions and increased gene expression of Igf1 in the hippocampus was found in the animals treated with GH. In addition, GH was demonstrated to increase the body weight gain and was able to attenuate the reduced body weight seen in nandrolone treated animals. In general, the rats treated with nandrolone alone did not exhibit any pronounced alteration in memory compared to controls in the MWM, and in many cases GH did not induce any alteration. Regarding target zone crossings, considered to be associated to spatial memory, the difference between GH and steroid treated animals was significant and administration of GH improved this parameter in the latter group. In conclusion, GH improves spatial memory in intact rats and can reverse certain effects induced by AAS.

  • 295.
    Gudmundsson, Kjartan
    et al.
    School of Civil and Architectural Engineering, KTH.
    Sjöström, Christer
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Norberg, Peter
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Trinius, Wolfram
    Twumasi, Ebenezer
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Durable and robust vacuum insulation technology for buildings2011In: XII DBMC: 12th International Conference on Durability of Building Materials and Components (Vol. 4) / [ed] Michael A. Lacasse, Vasco Peixoto de Freitas, Helena Corvacho, Porto: FEUP Edições , 2011, , p. 8Conference paper (Refereed)
    Abstract [en]

    Vacuum insulation panels (VIPs) provide unprecedented opportunities for obtaining excellent thermal insulation with light and slender constructions. This article discusses the performance over time of VIPs, and the possibilities to overcome the current problems related to fragility and limited durability. Aerogels are together with fumed silica among the most competitive core materials for VIP's. The use of classical aerogels, as produced in autoclaves is, however, limited due to the high production costs. The fumed silica on the other hand requires vacuum levels that are difficult to maintain with the currently available vacuum envelopes. A material with comparatively smaller pores will on the other hand allow obtaining low thermal conductivity at higher pressure (less vacuum) and will therefore reduce the pressure difference over the envelope. There is therefore much to be gained by reducing the pore size. New cost and performance efficient silica aerogels offers opportunities to enhance the properties of the panels by customizing the pore structure and pore size distribution. Building technologies and how the panels are applied in a manner that improves the structural, thermal and hygroscopic performances of vacuum insulated constructions have been studied and are discussed.

  • 296.
    Guillem Reig, Santiago
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Simulation of moisture alarm for district heating networks2014Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
  • 297.
    Gullberg, Annica
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Biology.
    Andersson, Kristina
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Biology.
    Hussénius, Anita
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Chemistry.
    Danielsson, Anna
    Institutionen för pedagogik, didaktik och utbildningsstudier, Uppsala universitet.
    "Genus är att låta barnen vara dom de är" - hur barnsyn och genusmedvetenhet får ämnesdidaktiska konsekvenser.2012In: Utbildning och lärandeArticle in journal (Other academic)
    Abstract [en]

    This paper reports from a study exploring how an increased knowledge about gender issues can affect pre-school student teachers’ reflections and actions concerning science and technology activities. We have analysed written assignments given to student enrolled in a teacher education programme as well as group discussions that were part of their science and technology courses. One assignment was focused on describing situations during their pre-school placements where the students themselves judged gender to be important. The analysis identifies a reoccurring argumentation among the students that draws on an idea that children need to ‘be who they are’, thus portraying them as having a stable core identity. In this paper we ask what it means to let the children ‘be who they are’ and what the consequences of this view for developing the pre-school according to the curriculum and the education act can be. In doing so, we discuss issues that respectively may promote and hinder pre-school teachers to develop strategies that challenges stereotypical gender patterns. Furthermore, we problematize what consequences this might have for science teaching.

  • 298.
    Guo, Lihui
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Applicability and potential of wave power in China2010Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Wave power is renewable energy which is environmentally friendly. Unlike most of renewable energy resources, wave energy can produce power all the year. The wave energy is stored in the ocean worldwide and highly concentrated near the ocean surface. It can be captured by wave power devices. Wave power is considered as a competitive energy resource in future.

     

    Waves are generated by wind blows across the surface of sea. Wave energy is one kind of mechanical energy which will be used for electricity generation. Wave power can’t be used directly to generate electricity; at first the wave energy is converted into the other form of useful mechanical energy and then converted into electricity. Wave power has a high potential to be captured and used for generating electricity in future as the technology develops further.

     

    Wave energy has been used since 1890s. There is a lot of energy stored in waves. 94% energy of the ocean stored in the wave, and the other 6% is tidal energy.  Only small a part of the wave power is used for commercial electricity generation today.

     

    The China is a developing country with a very large population which annually consume about 3073TWh electricity of which 496TWh is from renewable energy.  The wave power was less than 1GWh in 2007 (reference from International Energy Agency). The World Energy Council has measured the total useful power of the ocean wave energy to be more than 2TW in the world and corresponding to 6000TWh per year. There is about 70GW useful wave power resources in China, equivalent to an annual useful wave power resource of 200TWh.

     

    The lowest capital cost for the wave power system is today around 0.1Euro/kWh. China will in the future focus on the development electricity generation by wave power. There will be hundreds of new wave power plant built in China during the next twenty years, and the total installed capacity will be larger than 1GW at 2030, which delivers 3TWh annually. This corresponds to less than 1 percent of the total use of electricity in China.

     

    This thesis focuses on the functionality, efficiency and economic pay-off of existing ocean wave power systems, as well as how easy the ocean wave power can produce electricity. Firstly it discusses the physical concepts of wave power, and then focus on the existing wave power systems around the world. It is concluded from the Chinese sea characteristics and the designed conditions of different wave power systems, that the Pelamis and Oyster wave power converters are the best suitable systems for China.

  • 299.
    Gustafsson, Dennis
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Comparing air quality in a training facility: What effects do air balancing have for carbon dioxide reduction?2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The link between a good indoor climate and environmental impacts e.g. global warming and different pollution in the air is something that are important today and will certainly become more important in the future with increased energy prices and new laws.

    Too keep the indoor air quality within limits is it important to have a good and competitive ventilationsystem.

    The ventilations function is mainly to supply fresh air and to remove polluted air from the room. It’s important that the ventilation system works as it should so that the indoor air quality is as good as possible. The lack of good ventilation can create several symptoms such as headaches, nausea, fatigue, poor concentration etc.

    In Sweden are ventilation control mandatory for every newly produced building and this control are repetitive usually every 3-6 years for some types of buildings.

     

    The foundation of this thesis is from a previous degree project performed by a master’s student in 2013 named Ander Barroeta with supervision of Magnus Mattsson and Taghi Karimipanah.

    The thesis was to improve and design a ventilation system in two rooms at a training facility named Friskis & Svettis in Gävle so that the CO2 level did not exceed 1000 ppm.

     

    In this thesis was the main goal to do similar measurements as the previous thesis and compare the results to see what difference air balancing has done to the ventilation system. Field measurements were performed at the training facility were the focus was on carbon dioxide but also on other parameters such as temperature, humidity and air velocity so that air exchange rate could be calculated. With these parameters can evaluations be made to see if air balancing of the ventilation system made any difference in indoor air quality.    

     

    During measurements in one of the training rooms where spinning is exercised was carbon dioxide levels up to 3300 ppm measured which is above the recommended indoor limit at 1000 ppm. If that room should be design to not exceed 1000 ppm must the air exchange rate increase from 6.3 h-1 to 35.1 h-1.

  • 300.
    Gustafsson, Joakim
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Hur utformar man framtidens transportsystem genom en användarcentrerad designprocess?2016Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The research was conducted in order to contribute to the general body of knowledge regarding the prospective transport system GTS Transport System developed by GTS Foundation. This dissertation will explore and further develop the GTS system. This was achieved with the research question: How does the future GTS Transport System look in a user-centered design perspective?

     

    In a design process, a deep and comprehensive research laid the foundation in order to create an understanding of the needs and demands that would need to be fulfilled for the future transport system. The GTS Transport System was carefully studied and analyzed in order to reach a deeper understanding around its visions, ideas and technical solutions. Further it was studied in order to determine how well thought through the different feature where.

     

    Interviews were conducted with a target group of people having a disability; this disclosed certain problems with today’s transport systems. With the support of the data gathered and an analysis, three fictive personas where created with associated scenarios.

     

    An analysis of a future GTS scenario led to the discovery of certain problems and laid the foundation for further establishing areas in need of improvements. The areas that were chosen where stations and stopping places (in the dissertation called Terma).

     

    An idea-generating phase led to new ideas about flow, functions, gates and architecture.

     

    The results of the dissertation led to a concept about how the future transport Terma may be designed. With secure available and innovative gates, a well thought through layout that is available and safe for the people using the transport system. A new concept of flows where created which enabled the vessels to move around and over the building. This results in a smooth and safe travel experience. 

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