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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A Prefeasibility Study of Integrating Woodroll  Gasification Technolgoy into Ovako Steel Heab replacing  Fossil Fuels in Hofors.

Moner Lasheras, Alodia Baldesca January 2012 (has links)
No description available.
2

Systemanalys av termisk samverkan mellan solceller och värmepump i flerbostadshus : Modellering och scenarioanalyser av innovativa systemutformningar samt  väderförhållanden med fokus på energi, klimat och ekonomi / System analysis of thermal cooperation between photovoltaics and exhaust air heat pump in apartment buildings : Modeling and scenario analysis of innovative system configurations and weather conditions with focus on energy, climate and economy

Green, Gustav January 2018 (has links)
Att arbeta mot minskad klimatpåverkan är centralt i dagens samhälle och ett måste för en hållbar utveckling. Ett omdiskuterat område är utfasningen av äldre, fossilt baserad, elproduktion för att ge plats åt förnybar elproduktion. Det vill säga ”grön el”. Solceller, en typ av grön el, har under de senaste åren blivit billigare. Detta kan ses på den ökade installerade effekten varje år bland flerbostadshus från att Sverige började med ekonomiska bidrag till solceller år 2006. Solceller får en ökad verkningsgrad av högre instrålning men även av en lägre celltemperatur. Samtidigt gynnas värmepumpar, som är vanligt för fastighetsuppvärmning, av ett ökat COP om den tillkopplade köldbäraren når värmepumpen med en högre temperatur vilket ökar potentialen att leverera värme. Då solceller gynnas av låg temperatur och värmepumpen gynnas av hög köldbärartemperatur finns det ett motiv för värmeväxling mellan enheterna – termisk samverkan. Syftet med examensarbetet blir att öka kunskap genom en systemanalys om hur solceller och värmepump kan samverka i ett energi- och kostnadseffektivare energisystem via termisk samverkan. I examensarbetet har två modeller av en fastighets energisystem byggts; med och utan termisk samverkan mellan värmepump och solceller. I energisystemet ingår fastighetens värme- och elsystem och är placerat i Karlstad. Värmesystemet består av frånluftvärmepump med fjärrvärme som spets och elsystemet består av fastighets- och hushållsel samt solceller. Resultat från modellerna jämförs med varandra med fokus på inköp av el och fjärrvärme, försäljning av el, koldioxidutsläpp och ekonomi. Resultatet från båda modellerna har även undersökts och jämförts i 8 scenarier. Scenarierna ändrar på systemutformning och väderfaktorer, exempelvis optimering av elproduktion eller byte av geografisk placering. Modellerna är byggda i Matlabs modelleringsprogram Simulink och grundas på energibalanser. Data fås från intressenten av detta arbete (HSB Värmland), produktblad för solpanelerna (där en solpanel är en matris av solceller), egna mätningar från fastigheten, antaganden och liknande försök från vetenskapliga artiklar. Koldioxidutsläpp från el baseras på marginalelsprincipen. Resultatet av ett energisystem i en fastighet i Karlstad med termisk samverkan mellan solceller och frånluftvärmepump bidrar till minskat koldioxidutsläpp på 1239 kg/år och 448 kg/år för kort respektive lång sikt. Årskostnaden minskar med 290 kr/år vilket gör det svårt att motivera termisk samverkan ur ett ekonomiskt perspektiv. Detta för att investeringskostnaden maximalt får nå 7250 kr över 25 år för att termisk samverkan ska vara ekonomiskt gynnsamt. Inköpet av el minskar och försäljningen av el samt inköpet av fjärrvärme ökar. Årsmedelvärdet för värmepumpens COP ökar från 4,56 till 5,30 och årsmedelvärdet för solcellernas verkningsgrad ökar från 21,15 till 21,16 %. Ett samverkande system har potentialen att bli mer attraktivt om elpriset ökar. I scenarioanalysen uppkommer ett scenario, när elproduktionen från solcellerna optimeras, som medför betydligt lägre årskostnad från ett termiskt samverkande system jämfört med andra scenarier. Detta scenario medför reglering av köldbärarflöde, värmeväxlararea och tillsätter extern kylning. Årskostnaden av ett termiskt samverkande system minskas med 1920 kr/år till följd av denna systemutformning. Eftersom flera regleringar behöver göras anses detta scenario som komplicerat att få praktiskt genomförbart. Ett scenario, när det samverkande systemet utformas utan frånluftåtervinning, är potentiellt ekonomiskt gynnsamt för nybyggnation av värmesystem. Scenariot medför att ett termiskt samverkande system ger minskad årskostnad jämfört mot ett icke-samverkande system med frånluftåtervinning. Det förväntas att nya värmesystem kan konstrueras utan frånluftåtervinning och därmed minska investeringskostnaden för nybyggnation. Eftersom investerings- och driftkostnader av frånluftåtervinning inte har hanterats i detta arbete behövs det vidare studier. Termisk samverkan blir mer gynnsamt i varmare länder än Sverige men bidrar inte till minskat koldioxidutsläpp i lika hög grad. Det uppkom att om energisystemet placeras i Kiruna ökar både årskostnaden och koldioxidutsläppen. När energisystemet placeras i Lund var resultaten liknande mot i Karlstad. Detta för att klimatdata från Lund efterliknar klimatdata från Karlstad. När energisystemet placerades och jämfördes i Aten (Grekland) minskade årskostnaden och bidrog till minskat koldioxidutsläpp. Årskostnaden för systemet placerat i Aten blev lägre än årskostnaden i Lund men koldioxidutsläppet i Aten blev högre än koldioxidutsläppet i Lund. Eftersom systemet i Lund medför lägre koldioxidutsläpp än i Kiruna och Aten kan det finnas en brytpunkt i lokalt klimat där koldioxidutsläppen är som lägst från ett samverkande system. / It is discussed in today’s society to reduce the carbon dioxide emissions by replacing old, fossil fueled, electricity production with new, renewable and “green” ways of producing electricity. Photovoltaics have lately become cheaper which can be seen by looking at the increase in installed electric power from apartment buildings for each year in Sweden. This is mainly caused by the introduction of subsidies towards photovoltaics in 2006 from the Swedish state. The efficiency of photovoltaics increases when the solar radiation is higher but decreases with increasing cell temperature of the photovoltaic cells. The COP of heat pumps, which is commonly used for heating apartment buildings, is increased with increased brine temperature which increases the potential of heating. This means that photovoltaics can benefit from a cold brine while heat pumps can benefit from a higher brine temperature by heat exchanging with photovoltaics. Thermal cooperation is possible. The purpose of the study is to do a system analysis of how photovoltaics and heat pump can cooperate in an energy and cost-efficient energy system through thermal cooperation. Two models, of an energy system in an apartment building located in Karlstad, have been built in this study; with and without thermal cooperation between heat pump and photovoltaics. The energy system is divided in two subsystems; heating and electricity system. The heating system consists of an exhaust air heat pump with district heating during peaks and the electricity system consists of the electricity demand from the apartment building and photovoltaics. The results of the models are compared with focus on purchase of electricity and district heating, selling of electricity, carbon dioxide emissions and economical costs. The results from the models have also been analyzed and compared in 8 different scenarios. The scenarios change the configuration of the energy system and weather factor. Examples of scenarios that have been analyzed are optimization of electricity production and change of geographical location. The models are built in Matlabs modeling program Simulink and are based on energy balances. Data is gathered with help from HSB Värmland, product sheet of the solar panels (one solar panel is a matrix of several photovoltaics), own measurements, assumptions and similar studies from scientific articles. Carbon dioxide emissions are based on the merit order curve for electricity production (“marginal-energy-principle”). An energy system in Karlstad with thermal cooperation, between photovoltaics and exhaust air heat pump, contributes to reduced carbon dioxide emissions by 1239 kg/year (short term) and 448 kg/year (long term). However, it is hard to warrant thermal cooperation from an economical perspective with th. This is because the investment costs of an energy system with thermal cooperation is only allowed to reach a maximum of 7250 kr over 25 years for it to be economically profitable. The amount of electricity that needs to be purchased decreases and the amount of electricity that is sold as well as district heating purchased increases. The yearly average COP of the heat pump increases from 4,56 to 5,30 and the yearly average solar panel efficiency increases from 21,15 to 21,16 %. If the price of electricity increases, then thermal cooperation will become more profitable. One scenario from the scenario analysis stands out in comparison with other scenarios due to reduced yearly costs from a cooperating system of 1920 kr/year. This is when the electricity production from the photovoltaics are optimized. However, this scenario requires adjustments in brine flow, heat exchanger area and external cooling which can cause practical complications. One scenario has the potential to become economically profitable with the construction of new heating systems. This is when the exhaust air recycling is removed from the heating system. The removal of exhaust air recycling in a cooperating system contributes to lower yearly costs but not as low as a cooperating system with exhaust air recycling. However, this might mean that the construction of new heating systems can be profitable without exhaust air recycling because the investment cost of the exhaust air recycling is removed. Since this study has not taken investment and operating costs of exhaust air recycling into account, further studies are needed to determine this. Thermal cooperation is more profitable in warmer countries than Sweden but does not contribute to as low reduction in carbon dioxide emissions. When the energy system is placed in Kiruna, Sweden, it causes both the yearly cost and carbon dioxide emissions to increase. The energy system is placed in Lund, Sweden, yielded similar results as if the system was placed in Karlstad, Sweden. The yearly cost and carbon dioxide emissions decreased when the energy system was placed in Athens, Greece. However, when comparing the energy systems in Athens and Lund, Athens had the lower yearly cost but higher carbon dioxide emissions. Since the energy system placed in Lund contributes to the lowest carbon dioxide emissions in comparison to both Kiruna and Athens then there might be a break point in relation to local climate where the emissions are the lowest possible.
3

Energikartläggning och utredning av alternativa energikällor för ett enfamiljshus i timmer byggt år 1850

Kapke, Holger, Gustafsson, Ingmar January 2015 (has links)
No description available.
4

Investment analysis for solar PV cells in Sweden

Wollein, Jonathan January 2017 (has links)
No description available.
5

Adaptation of Solar Energy Driven Absorption Chillers for Air Conditioning in Commercial Building

Kalinga, Ranjith Shantha De Silva January 2017 (has links)
The most recent analysis of energy usage in the country reveled that nearly 50% of the power generation is used for air conditioning and mechanical ventilation most of which is used by commercial organizations. The grid generation mix that contains a high percentage of fossil fuel makes such energy usage environment unfriendly. Although absorption refrigeration is an old technique its economical application is limited to applications where cheap or waste heat energy is available despite decades of R&D, due to low COP, high initial cost and larger size. Heat input at Moderately high (over 120ᵒC) temperature and need to release large amount of heat to the environment through liquid or air cooling makes absorption chiller less conducive in cooling. Yet, being a tropical country, Sri Lanka has a better potential in adopting solar driven absorption refrigeration, if the chillers are operated at low temperature heat input that also promotes efficiency in storage that is mandatory due to fluctuation of energy source, subject to economic feasibility. The project aims designing and modeling of a solar power driven absorption chiller system that is adoptable to a selected medium size commercial organization. The proposed system uses heat energy around 100ᵒC and reusing fraction of energy expelled to the environment by suitably modifying operating parameter and thereby increasing efficiency of the system. Reduction of such heat losses and reducing heat input is achieved with the use of secondary heat exchange (brine) system that optimizes the energy usage. This arrangement will make efficient usage of solar heat storage, even in the considerable absence of solar power. System modeling and simulation of both basic double effect chiller and its modified versions were carried out and compared to evaluate improvement. The simulation of the modified system was used to obtain working parameters of the chiller so that a suitable solar collector, chilled water and heat rejection systems can be designed. Operational conditions of the cooling system are measured by the state sensors that feed inputs to the control system to achieve the optimum efficiency and their technical details are also included in the report.
6

Test Grids for Reliability analysis : Analysing interruptions and developing test grids based on Mälarenergi Elnät distribution grid

Eld, Jonas, Melin, Jens January 2017 (has links)
The purpose of this degree project is to examine power outages that has occurred during the years 2009 and 2016 on Mälarenergi Elnät distribution grid. Interruptions that has occurred on 10 kV voltage level and on overhead lines or underground cable was examined. The examined interruptions are based on the DARWin data from Mälarenergi Elnät. The examined interruptions resulted in four different test grids. Test grid A are overhead line grid in rural area, test grid B are mixed grid in rural area, test grid C are underground cable grid in semi urban area and test grid D are underground cable grid in urban area. Test grid C and D which have the highest customer density were then used for reliability analysis. The reliability analysis was performed using Microsoft Excel. The main focus for the reliability analysis were the impact of different sectioning times. Another focus for the reliability analysis was introducing breakers at key-points in test grid C. The primarily cause of interruptions on overhead line grids are weather related events and on underground cable grids it is digging and fabrication or material errors. It is concluded that with quicker sectioning times, the reliability of the grid increases linearly. The introduction of breakers at key-points in the grid results in increased reliability.
7

Microgrid Economics : Incentivizing Self-Consumption of Solar Electricity in a DC Microgrid

El Gohary, Fouad January 2019 (has links)
No description available.
8

CFD simulation and analysis of glazing bar effects on heat and airflow inside a two-pane window

Etxeberria, Aitor January 2019 (has links)
No description available.
9

Energy analysis of a house and proposals for improvements

Torre, Andoni January 2019 (has links)
No description available.
10

Strategier för energieffektiv ombyggnation och drift av Sundsvalls sjukhus / Strategies for energy efficient renovations and operations at Sundsvall hospital

Olsson, Jonas January 2019 (has links)
Sundsvall hospital has many facilities that are heated by electrical air heating and the exhaust air is ventilated through so called exhaust windows. This leads to high air flows and temperature gradients in the rooms. In connection with renovations of building component M09 at the hospital the heat system is replaced with waterborne radiator heating, new supply air devices are installed and the external walls are reinsulated. This thesis aims to investigate how the exhaust windows is affected by lowered air flows and an alternative heating system and how optimal operations is achieved and also what should be prioritized in future renovations. In this thesis two identical rooms, one with the old electrical air heating and the other with waterborne radiators, was investigated. Air temperature, surface temperature and heating power was measured in both rooms with different air flows and heating losses was calculated. IDA ICE is a software for simulations of energy and indoor climate where the measured values was compared with the simulated in IDA ICE to verify a simulation model. IDA ICE was then used to calculate yearly energy use and thermal comfort for different operations and reinsulation thicknesses for both heating systems.  The results show that the energy use is mainly affected by the air flow in the room and not as much the heating system or thickness of reinsulation. The thermal comfort is improved with radiator-heating and thicker reinsulation increases the number of hours the room is too hot but the overall thermal comfort is better. The life cycle cost can be lowered with a thinner reinsulation in the room with radiator heating but not in the room with electrical air heating.

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