Дисертації: "Thermal renewable energy"

1

Hinke, Themba D. "Hot thermal storage in a variable power, renewable energy system." Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/42645.

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Approved for public release; distribution is unlimited
This thesis outlines the design of a renewable energy heat generation system with thermal storage for DOD facilities. The DOD is seeking to implement an increased percentage of renewable energy systems at its facilities in order to improve energy security and reduce energy costs. The intermittent nature of renewable energy generation, however, presents a major challenge to full implementation. This shortfall can be overcome by targeted facility-scale energy storage that allows for increased use of renewable-only systems. Since a large percentage of the electric energy used in both residential and commercial facilities is for space and water heating, thermal storage is a viable solution. Presented in this thesis is a method for designing, analyzing, and sizing a facility-scale thermal storage system. The results demonstrate thermal storage is a more cost-effective option when compared to alternatives like battery storage. In addition to being cheaper, thermal storage systems are safer, more reliable, and have a longer life cycle.

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2

Macbeth, John Noel. "A thermal charge system for variable electrical supplies from renewable sources." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=202380.

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In a time of a fast growing renewable electricity generation sector, there are challenges regarding the integration of such generation with current transmission infrastructure. Such challenges include problems associated with the intermittent power output of renewable energy sources and the inability to control there output to meet varying electrical demand. Using part of this available energy for the provision of domestic heating loads may help bridge the gap between supply and demand. The use of intermittent electrical energy sources for charging water based thermal energy stores was identified as a research gap. This research project studies the use of intermittent electrical supplies from wind turbines for the provision of space heating and hot water in domestic buildings. It also addresses how solar water heating may be incorporated into the same thermal energy storage unit to create a hybrid system. This thesis outlines and analyses two charge strategies that may be used to promote stratification in water based thermal energy stores when adding intermittent electrical energy. The first makes use of multiple heating elements switched on in sequence (direct system) while the second uses buoyancy forces to take cool water from the bottom of the tank, pass it through the heating element and then place it back in at the top of the tank at a higher temperature (side-arm). The research method includes; 1) a simplified theoretical simulation of direct and side-arm configurations in the transient system simulation software (TRNSYS) to identify system performance when charged from wind and solar energy; 2) a detailed theoretical representation of the side-arm charge mechanism with a modulating valve for TRNSYS; 3) an empirical validation of the detailed theoretical model of the side-arm charge cycle. Outcomes from the simplified theoretical model indicate that the side-arm configuration may have benefits over the direct configuration due to reduced heat loss from the tank, reduced auxiliary energy consumption and increased solar collector performance. The detailed theoretical representation of the side-arm was calibrated using the empirical data gathered. From this, important parameters affecting the performance of the side-arm charge cycle are evaluated. These include the effects of tank height, operating temperature and the power range from the intermittent electrical supply. It is identified that the assumptions made in the simple model are not possible to reproduce in real life and that an analysis using the complex model must be made in order to evaluate any potential benefits of the side-arm over a direct configuration.

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3

Aldaouab, Ibrahim. "Optimization and Control of Smart Renewable Energy Systems." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1567770026080553.

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4

Xiang, Yetao. "Experimental and computational investigation of building integrated PV thermal air system combined with thermal storage." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/42743/.

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Issues from global warming with increased CO2 emissions have been to a main concern over world. As an example in the UK, the energy demand in the domestic sector has risen by 17% in 2010 compared with that of 1970. Applying renewable energy is widely agreed to be the most effective and promising way to solve the problem where solar energy and photovoltaic technology have been greatly developing from the last century. Photovoltaic combines with Phase Change Material (PV/PCM) system is a hybrid solar system which uses phase change material to reduce the PV temperature and to store energy for other applications. This thesis aims to investigate the performance of a designed building integrated photovoltaic thermal system (BIPVT) with PCM as thermal storage for building applications. The research objectives are to increase the building integrated photovoltaic (BIPV) efficiency by incorporating PCM while utilising the stored heat in PCM for controlling indoor conditions and reduce the total building energy consumption. The research starts with solar energy convection technologies including solar thermal and solar photovoltaic. Then a combined technology named photovoltaic thermal system (PVT) was introduced and discussed. Research work on a different type of PVT using water and air as thermal energy medium was further reviewed and discussed. An analytical approach investigation was presented on a PVT system and the results were used to design the experiment work on PV/PCM configuration. Experiments have been carried out on a prototype PV/PCM air system using monocrystalline photovoltaic modules. Transient simulations of the system performance have also been performed using a commercial computational fluid dynamics (CFD) package based on the finite volume method. The results from simulation were validated by comparing with experimental results. The results indicated that PCM is effective in limiting temperature rise in PV device and the heat from PCM can enhance night ventilation and decrease the building energy consumption to achieve indoor thermal comfort for certain periods of time. An entire building energy simulation with designed PV/PCM air system was also carried out under real weather condition of Nottingham, UK and Shanghai, China. The result also shows a market potential of PV/PCM system and a payback time of 11 years in the UK condition if using electrical heater.

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5

Assembe, Cedric Obiang. "Integrated solar photovoltaic and thermal system for enhanced energy efficiency." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2387.

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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016.
South Africa has raised concerns regarding the development of renewable energy sources such as wind, hydro and solar energy. Integration of a combined photovoltaic and thermal system was considered to transform simultaneous energy into electricity and heat. This was done to challenge the low energy efficiency observed when the two solar energy conversion technologies are employed separately, in order to gain higher overall energy efficiency and ensure better utilization of the solar energy. Therefore, the notion of using a combined photovoltaic and thermal system was to optimize and to improve the overall PV panel efficiency by adding conversion to thermal energy for residential and commercial needs of hot water or space heating or space cooling using appropriate technology. The PV/T model constructed using water as fluid like the one used for the experimental work, presented a marginal increase in electrical efficiency but a considerable yield on the overall PV/T efficiency, because of the simultaneous operation by coupling a PV module with a thermal collectors.

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6

Pietruschka, Dirk. "Model based control optimisation of renewable energy based HVAC Systems." Thesis, De Montfort University, 2010. http://hdl.handle.net/2086/4022.

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During the last 10 years solar cooling systems attracted more and more interest not only in the research area but also on a private and commercial level. Several demonstration plants have been installed in different European countries and first companies started to commercialise also small scale absorption cooling machines. However, not all of the installed systems operate efficiently and some are, from the primary energy point of view, even worse than conventional systems with a compression chiller. The main reason for this is a poor system design combined with suboptimal control. Often several non optimised components, each separately controlled, are put together to form a ‘cooling system’. To overcome these drawbacks several attempts are made within IEA task 38 (International Energy Agency Solar Heating and Cooling Programme) to improve the system design through optimised design guidelines which are supported by simulation based design tools. Furthermore, guidelines for an optimised control of different systems are developed. In parallel several companies like the SolarNext AG in Rimsting, Germany started the development of solar cooling kits with optimised components and optimised system controllers. To support this process the following contributions are made within the present work: - For the design and dimensioning of solar driven absorption cooling systems a detailed and structured simulation based analysis highlights the main influencing factors on the required solar system size to reach a defined solar fraction on the overall heating energy demand of the chiller. These results offer useful guidelines for an energy and cost efficient system design. - Detailed system simulations of an installed solar cooling system focus on the influence of the system configuration, control strategy and system component control on the overall primary energy efficiency. From the results found a detailed set of clear recommendations for highly energy efficient system configurations and control of solar driven absorption cooling systems is provided. - For optimised control of open desiccant evaporative cooling systems (DEC) an innovative model based system controller is developed and presented. This controller consists of an electricity optimised sequence controller which is assisted by a primary energy optimisation tool. The optimisation tool is based on simplified simulation models and is intended to be operated as an online tool which evaluates continuously the optimum operation mode of the DEC system to ensure high primary energy efficiency of the system. Tests of the controller in the simulation environment showed that compared to a system with energy optimised standard control the innovative model based system controller can further improve the primary energy efficiency by 19 %.

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7

Shah, Nazari Hoda. "Examining the potential for design and renewable energy to contribute to zero energy housing in Queensland." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/75650/1/Hoda_Shah%20Nazari_Thesis.pdf.

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This was a comparative study of the possibility of a net zero energy house in Queensland, Australia. It examines the actual energy use and thermal comfort conditions of an occupied Brisbane home and compares performance with the 10 star scale rating scheme for Australian residential buildings. An adaptive comfort psychometric chart was developed for this analysis. The house's capacity for the use of the natural ventilation was studied by CFD modelling. This study showed that the house succeeded in achieving the definition of net zero energy on an annual and monthly basis for lighting, cooking and space heating / cooling and for 70% of days for lighting, hot water and cooking services.

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8

Humm, Jason Christopher. "An organic rankine cycle heat engine using a rock thermal battery as the heat source." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/10960.

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Organic Rankine cycles (ORC) have unique properties that are well suited to power generation from low grade heat sources. It is envisaged that a domestic scale ORC Heat Engine can be developed that will be able to run off heat stored in a solar charged rock thermal battery. The use of a thermal battery as the heat source for the ORC system will provide the user with electricity during the day and for a number of hours into the night. The concept presented consists of four key components: rock thermal battery, 1 kW scroll expander, condenser and working fluid pump.

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9

Kettenis, Christos. "Electrical supply and demand in Cyprus : optimal use of renewable energy sources in electricity production." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/electrical-supply-and-demand-in-cyprus-optimal-use-of-renewable-energy-sources-in-electricity-production(3861cfcb-8a74-4087-a114-4e0dc9557202).html.

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As fossil fuel usage has been proven to have a negative impact on human health and the environment, the world has embraced the usage of renewable energy sources, mainly for energy production. In Cyprus, solar energy is the most potent renewable source and this can be seen by the vast majority of the population using solar water heaters in their households. This thesis explores the usage of solar energy for electricity and domestic hot water production at a residential level by presenting the designs of three solar-thermal concept systems for achieving this task; the first being the basic design of all three without any form of storage, the second is fitted with thermal latent heat storage and the third is fitted with a natural gas boiler instead. The optimal solution is the second concept system that is capable of storing thermal energy around the year thus having a nearly uninterrupted operation, reducing the dependency on fossil fuel produced electricity and emissions. The thesis also explored the usage of siloxane organic compounds as working fluids for a low temperature Rankine cycle, which had a significant impact in the increase of the thermal-to-electrical efficiency of the cycle, raising it to nearly 25%, greater than the efficiency of best acclaimed photovoltaic collector currently available. Lastly, taking into account a typical household’s demand profile and by allowing the optimal system to operate as part of the national electrical network continuously, the size of the system’s components could be reduced significantly making it more feasible for installing in a typical household’s premises. However, due to the non-existence of these components in the within the project’s specifications, the thesis could not include a useful economic analysis for a more realistic comparison with a similar sized photovoltaic system.

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10

Chen, Tianyu. "Simulation of the thermal and electrical performance of a novel PVT-PCM system." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49210/.

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This study provides an insight into the fundamentals of PV performance enhancement under different environmental conditions. The study also presents a new concept of PCM integrated PVT system which has a better performance from both electrical and thermal perspectives. The study employs both analytical and computational techniques to investigate the PV performance under the effect of different parameters such as wind speed, solar radiation level, ambient temperature and additional cooling condition. A parametric analysis of the PCM is also carried out under different solar radiation level, water inlet temperature and flow speed. Additional analysis regarding to the effects of PCM’s thermal physical properties against its thermal performance is also presented. A validation analysis is carried out prior to the parametric analysis to ascertain the reliability of the CFD models used, the prediction result of the CFD model is compared with analytical calculations as well as data from literature. The study found that the active water cooling is the best solution which can provide guaranteed performance enhancement regardless effects of ambient conditions. The novel PVT-PCM system is found to have a noticeable electrical performance enhancement over conventional PV panel as well as having the ability to store a significant amount of thermal energy. It is found that the PVT-PCM system has much lower PV cell temperature (maximum temperature reduction of 36.5°C and 38.3°C respectively) compared to conventional PV systems when used in both Nottingham and Shanghai area, hence provide up to 5.4kWh (5.7kWh in Shanghai) more energy per unit module. The stored thermal energy could be utilized to provide moderate heating to air and/or water. The air preheated by PVT-PCM system could satisfy space heating requirement during April to October in Nottingham without any additional energy consumption. On the other hand, the preheated water could reduce boiler heating energy from up to 20% and 41% respectively for Nottingham and Shanghai climate. The overall performance benefits of the proposed PVT-PCM system could be greater if used in hotter climates. Finally, a cost analysis was carried to prove the whole system is financially feasible for use in both climates of Nottingham and Shanghai with a discounted payback period of 10.67 and 12.83 years respectively.

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11

Gavronski, Jorge Dariano. "Carvão mineral e as energias renováveis no Brasil." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/15450.

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O aumento da população e o desenvolvimento da economia criam a necessidade de expansão de mais de quatro mil Megawatts da energia nova por ano no Sistema Interligado Nacional (SIN). O sistema elétrico brasileiro é peculiar, devido a sua grande capacidade, extensão continental e grande dependência na energia renovável hídrica. Outra peculiaridade é a capacidade potencial de inserção de outras formas da energia renováveis “verdes” no sistema. Embora as vantagens ambientais das energias renováveis, elas têm limitações, são variáveis e dependentes das condições climáticas. Para que o setor elétrico brasileiro possa atuar com confiabilidade com mais energia renovável deve haver concomitante mais energia firme de origem térmica disponível. Assim o trabalho analisa, na perspectiva global, o estado da arte e as tendências das fontes de geração elétrica, sob o ponto de vista de disponibilidade, preço e sustentação ambiental. De forma especial, o trabalho analisa as opções de geração térmica no Brasil. Conclui pela necessidade do Brasil priorizar o uso dos recursos disponíveis dentro de suas fronteiras como o carvão mineral para garantir a geração térmica elétrica auto-suficiente. O trabalho demonstra as vantagens sociais e de desenvolvimento de uma indústria do carvão para as regiões produtoras. Aponta também a necessidade de implementação de tecnologias modernas a fim de atender à legislação ambiental, que gradativamente deve aumentar as restrições das emissões poluentes, na medida em que as tecnologias forem desenvolvidas.
The population and economy growth in Brazil generate the necessity of an expansion higher than four thousand Megawatts of new electric energy per year. The Brazilian Electrical System is peculiar because of its continental extension and also its strong dependence in renewable energy (hydro). Another reason for its peculiarity is the potential of inserting other forms of renewable and “green” energy in the system. Although the environmental advantages of the “renewable”, these kinds of energies are variable and dependant of the weather conditions. In order to the electrical system be more reliable, its operation must be combined with a larger addition of thermal energy. Thus this report analyses thermal generation option in Brazil. Looking at the developed countries trends in diversify power generation, the article indicates the advantages and the priority of using, in Brazil, internal resources like coal to guarantee the self-sufficient thermal generation electrical capacity. The dissertation demonstrates the social advantages to develop the coal industry for the producers region, witch are poor areas in Brazil. The proposition points the need of implement modern technologies in order to attend the environmental legislation, which must increase the emissions restrictions as these technologies are developed.

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12

Wang, Guangyao. "An Investigation of Phase Change Material (PCM)-Based Ocean Thermal Energy Harvesting." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/100989.

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Phase change material (PCM)-based ocean thermal energy harvesting is a relatively new method, which extracts the thermal energy from the temperature gradient in the ocean thermocline. Its basic idea is to utilize the temperature variation along the ocean water depth to cyclically freeze and melt a specific kind of PCM. The volume expansion, which happens in the melting process, is used to do useful work (e.g., drive a turbine generator), thereby converting a fraction of the absorbed thermal energy into mechanical energy or electrical energy. Compared to other ocean energy technologies (e.g., wave energy converters, tidal current turbines, and ocean thermal energy conversion), the proposed PCM-based approach can be easily implemented at a small scale with a relatively simple structural system, which makes it a promising method to extend the range and service life of battery-powered devices, e.g, autonomous underwater vehicles (AUVs). This dissertation presents a combined theoretical and experimental study of the PCM-based ocean thermal energy harvesting approach, which aims at demonstrating the feasibility of the proposed approach and investigating possible methods to improve the overall performance of prototypical systems. First, a solid/liquid phase change thermodynamic model is developed, based on which a specific upperbound of the thermal efficiency is derived for the PCM-based approach. Next, a prototypical PCM-based ocean thermal energy harvesting system is designed, fabricated, and tested. To predict the performance of specific systems, a thermo-mechanical model, which couples the thermodynamic behaviors of the fluid materials and the elastic behavior of the structural system, is developed and validated based on the comparison with the experimental measurement. For the purpose of design optimization, the validated thermo-mechanical model is employed to conduct a parametric study. Based on the results of the parametric study, a new scalable and portable PCM-based ocean thermal energy harvesting system is developed and tested. In addition, the thermo-mechanical model is modified to account for the design changes. However, a combined analysis of the results from both the prototypical system and the model reveals that achieving a good performance requires maintaining a high internal pressure, which will complicate the structural design. To mitigate this issue, the idea of using a hydraulic accumulator to regulate the internal pressure is proposed, and experimentally and theoretically examined. Finally, a spatial-varying Robin transmission condition for fluid-structure coupled problems with strong added-mass effect is proposed and investigated using fluid structure interaction (FSI) model problems. This can be a potential method for the future research on the fluid-structure coupled numerical analysis of AUVs, which are integrated with and powered by the PCM-based thermal energy harvesting devices.
Doctor of Philosophy

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13

Elsanusi, Omer. "THERMAL ENERGY STORAGE WITH MULTIPLE FAMILIES OF PHASE CHANGE MATERIALS (PCM)." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/dissertations/1852.

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The world is facing a major challenge when it comes to proper energy utilization. The increasing energy demand, the depleting fossil fuel resources and the growing environmental and ecological concerns are factors that drive the need for creative solutions. Renewable energy resources such as solar sit in the center of these solutions. Due to their intermittent nature, development of energy storage systems is crucial. This dissertation focused on the latent thermal energy storage systems that incorporate phase change materials (PCM). The main goal was to enhance the heat transfer rates in these systems to address the low melting (energy storage stage) and solidification (recovery stage) rates that are caused by the PCMs’ low thermal conductivity values. The application of multiple PCMs (m-PCMs) with varying melting temperatures in several arrangements was investigated. The effects of applying m-PCMs on the conduction heat transfer and on the natural convection heat transfer in both horizontally and vertically oriented heat exchangers were studied. This was followed by an optimization study of the PCMs’ melting temperatures and the working fluid flow rate. Further heat transfer enhancement using metal fins was also investigated. Numerical models were developed and validated. Results are reported and discussed. Significant enhancement in both complete melting time and energy storage capacity was obtained by the m-PCMs in series arrangement. This enhancement is more pronounced in the vertically oriented system. The working fluid flow rate was found to have a limited effect during the melting stage. However, it seems to be crucial in the solidification stage.

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14

Niaparast, Shervin. "ENERGY ANALYSIS OF A SOLAR BLIND CONCEPT INTEGRATED WITH ENERGY STORAGE SYSTEM." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-131419.

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The use of an attached sunspace is one of the most popular passive solar heating techniques. One of the main drawbacks of the sunspace is getting over heated by the sun energy during the hot season of the year. Even in northern climates overheating could be problematic and there is a considerable cooling demand. Shading is one of the most efficient and cost effective strategies to avoid overheating due to the high irradiation especially in the summer. Another strategy is using ventilation system to remove the excess heat inside the sunspace. However this rejected energy can be captured and stored for future energy demands of the sunspace itself or nearby buildings. Therefore the Solar blind system has been considered here for the shielding purpose in order to reduce the cooling demand. By considering the PV/T panels as the solar blind, the blocked solar energy will be collected and stored for covering part of the heating demand and the domestic hot water supplies of the adjacent building. From a modeling point of view, the sunspace can be considered as a small-scale closed greenhouse. In the closed greenhouse concept, available excess heat is indeed utilized in order to supply the heating demand of the greenhouse itself as well as neighboring buildings. The energy captured by PV/T collectors and the excess heat from the sunspace then will be stored in a thermal energy storage system to cover the daily and seasonal energy demand of the attached building. In the present study, a residential building with an attached sunspace with height, length and width of 3, 12 and 3.5 meters respectively has been assumed located in two different locations, Stockholm and Rome. Simulations have been run for the Solar blind system integrated with a short-term and a long-term TES systems during a year to investigate the influence of the sunspace equipped with a PV/T Solar blind on the thermal behavior of the adjacent building. The simulated results show that the Solar blind system can be an appropriate and effective solution for avoiding overheating problems in sunspace and simultaneously produce and store significant amount of thermal energy and electricity power which leads to saving considerable amount of money during a year.

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15

Olsen, Lindsay M. "Initial investigation of a novel thermal storage concept as part of a renewable energy system." Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34716.

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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, it may not be copyrighted.
Approved for public release; distribution is unlimited
This thesis forms part of a larger study that aims to develop a renewable energy demonstration plant at the Naval Postgraduate School Turbopropulsion Laboratory. The architecture and design approach of the demonstration plant is outlined in this thesis. While all the components of the system are commercially available, the integration of the components is challenging. The results of the design approach presented the optimal way of integrating wind turbines, an electrical system, chiller units, and thermal storage tanks. Modular ice thermal tanks with polypropylene tubing were chosen for storage. The ice thermal storage units were selected over battery storage as they are more cost effective and potentially safer. A statistical analysis was performed using wind data from Monterey Airport, which was beneficial for choosing which wind turbines to implement in the system. The analysis determined that total energy captured by two, 4-kW vertical axis wind turbines was 2,554.8 kW-hours annually. Additionally, ANSYS Fluent was used to analyze the ice growth around the tubing at various ice and tube thicknesses. The ANSYS Fluent analysis showed that ice thickness affects the ice volume growth and change in enthalpy change more than wall thickness affects these conditions.

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Bruce, Robert Alasdair Wilson. "Impacts of variable renewable generation on thermal power plant operating regimes." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20387.

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The integration of variable renewable energy sources (VRE) is likely to cause fundamental and structural changes to the operation of future power systems. In the United Kingdom (UK), large amounts of price-insensitive and variable-output wind generation is expected to be deployed to contribute towards renewable energy and carbon dioxide (CO2) emission targets. Wind generation, with near-zero marginal costs, limited predictability, and a limited ability to provide upward dispatch, displaces price-setting thermal power plants, with higher marginal costs, changing flexibility and reserve requirements. New-build, commercial-scale, and low-carbon generation capacity, such as CO2 capture and storage (CCS) and nuclear, may impact power system flexibility and ramping capabilities. Low-carbon generation portfolios with price-sensitive thermal power plants and energy storage are therefore likely to be required to manage increased levels of variability and uncertainty at operational timescales. This work builds on a high-resolution wind reanalysis dataset of UK wind sites. The locations of existing and proposed wind farms are used to produce plausible and internally consistent wind deployment scenarios that represent the spatial distribution of future UK wind capacity. Temporally consistent electricity demand data is used to characterise and assess demand-wind variability and net demand ramp events. A unit commitment and economic dispatch (UCED) model is developed to evaluate the likely operating regimes of thermal power plants and CCS-equipped units across a range of future UK wind scenarios. Security constraints for reserve and power plant operating constraints, such as power output limits, ramp rates, minimum up/down times, and start-up times, ensure the operational feasibility of dispatch schedules. The load factors, time spent at different loads, and the ramping and start-up requirements of thermal power plants are assessed. CO2 duration curves are developed to assess the impacts of increasing wind capacity on the distribution of CO2 emissions. A sensitivity analysis investigates the impacts of part-load efficiency losses, ramp rates, minimum up/down times, and start-up/shut-down costs on power plant operating regimes and flexibility requirements. The interactions between a portfolio of energy storage units and flexible CO2 capture units are then explored. This multi-disciplinary research presents a temporally-explicit and detailed assessment of operational flexibility requirements at full 8760 hour resolution, highlighting the non-linear impacts of increasing wind capacity. The methodological framework presented here uses high spatial-and temporal-resolution wind data but is expected to provide useful insights for other VREbased power systems to mitigate the implications of inadequate flexibility.

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Rizea, Steven Emanoel. "Optimization of Ocean Thermal Energy Conversion Power Plants." Master's thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5462.

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A proprietary Ocean Thermal Energy Conversion (OTEC) modeling tool, the Makai OTEC Thermodynamic and Economic Model (MOTEM), is leveraged to evaluate the accuracy of finite-time thermodynamic OTEC optimization methods. MOTEM is a full OTEC system simulator capable of evaluating the effects of variation in heat exchanger operating temperatures and seawater flow rates. The evaluation is based on a comparison of the net power output of an OTEC plant with a fixed configuration. Select optimization methods from the literature are shown to produce between 93% and 99% of the maximum possible amount of power, depending on the selection of heat exchanger performance curves. OTEC optimization is found to be dependent on the performance characteristics of the evaporator and condenser used in the plant. Optimization algorithms in the literature do not take heat exchanger performance variation into account, which causes a discrepancy between their predictions and those calculated with MOTEM. A new characteristic metric of OTEC optimization, the ratio of evaporator and condenser overall heat transfer coefficients, is found. The heat transfer ratio is constant for all plant configurations in which the seawater flow rate is optimized for any particular evaporator and condenser operating temperatures. The existence of this ratio implies that a solution for the ideal heat exchanger operating temperatures could be computed based on the ratio of heat exchanger performance curves, and additional research is recommended.
ID: 031001365; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Marcel Ilie.; Title from PDF title page (viewed May 8, 2013).; Thesis (M.S.M.E.)--University of Central Florida, 2012.; Includes bibliographical references (p. 77-78).
M.S.M.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering; Mechanical Systems

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18

Allan, James. "The development and characterisation of enhanced hybrid solar photovoltaic thermal systems." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/11624.

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A photovoltaic thermal solar collector (PVT) produces both heat and electricity from a single panel. PVT collectors produce more energy, for a given area, than conventional electricity and heat producing panels, which means they are a promising technology for applications with limited space, such as building integration. This work has been broken down into 3 subprojects focusing on the development of PVT technology. In the first subproject an experimental testing facility was constructed to characterise the performance of PVT collectors. The collectors under investigation were assembled by combining bespoke thermal absorbers and PV laminates. Of the two designs tested, the serpentine design had the highest combined efficiency of 61% with an 8% electrical fraction. The header riser design had a combined efficiency of 59% with an electrical fraction of 8%. This was in agreement with other results published in literature and highlights the potential for manufacturers of bespoke thermal absorbers and PV devices to combine their products into a single PVT device that could achieve improved efficiency over a given roof area. In the second project a numerical approach using computational fluid dynamics was developed to simulate the performance of a solar thermal collector. Thermal efficiency curves were simulated and the heat removal factor and heat loss coefficient differed from the experimental measurements by a maximum of 12.1% and 2.9% respectively. The discrepancies in the findings is attributed to uncertainty in the degree of thermal contact between the absorber and the piping. Despite not perfectly matching the experimental results, the CFD approach also served as a useful tool to carry out performance comparisons of different collector designs and flow conditions. The effect of 5 different flow configurations for a header collector was investigated. It was found that the most efficient design had uniform flow through the pipe work which was in agreement with other studies. The temperature induced voltage mismatch, that occurs in the PV cells of PVT collector was also investigated. It was concluded that the temperature variation was not limiting and the way in which PV cells are wired together on the surface of a PVT collector did not influence the combined electrical power output.

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Aldubyan, Mohammad Hasan. "Thermo-Economic Study of Hybrid Photovoltaic-Thermal (PVT) Solar Collectors Combined with Borehole Thermal Energy Storage Systems." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1493243575479443.

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20

Kamanzi, Janvier. "Thermal electric solar power conversion panel development." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2527.

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Thesis (DTech (Engineering))--Cape Peninsula University of Technology, 2017.
The world has been experiencing energy-related problems following pressuring energy demands which go along with the global economy growth. These problems can be phrased in three paradoxical statements: Firstly, in spite of a massive and costless solar energy, global unprecedented energy crisis has prevailed, resulting in skyrocketing costs. Secondly, though the sun releases a clean energy, yet conventional plants are mainly being run on unclean energy sources despite their part in the climate changes and global warming. Thirdly, while a negligible percentage of the solar energy is used for power generation purposes, it is not optimally exploited since more than its half is wasted in the form of heat which contributes to lowering efficiency of solar cells and causes their premature degradation and anticipated ageing. The research is geared at addressing the issue related to unsatisfactory efficiencies and anticipated ageing of solar modules. The methodology adopted to achieve the research aim consisted of a literature survey which in turn inspired the devising of a high-efficiency novel thermal electric solar power panel. Through an in-depth overview, the literature survey outlined the rationale of the research interest, factors affecting the performance of PVs as well as existing strategies towards addressing spotted shortcomings. While photovoltaic (PV) panels could be identified as the most reliable platform for sunlight-to-electricity conversion, they exhibit a shortcoming in terms of following the sun so as to maximize exposure to sunlight which negatively affects PVs’ efficiencies in one hand. On the other hand, the inability of solar cells to reflect the unusable heat energy present in the sunlight poses as a lifespan threat. Strategies and techniques in place to track the sun and keep PVs in nominal operational temperatures were therefore reviewed.

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Hodgins, Neil. "High speed electrical power takeoff for oscillating water columns." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4642.

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This thesis describes research into electrical power takeoff mechanisms for Oscillating Water Column (OWC) wave energy devices. The OWC application is studied and possible alternatives to the existing Induction Generator (IG) are identified. The Permanent Magnet Generator (PMG) is found to be the most promising. Results showed that the IG could almost match the output of the PMG if it could be operated significantly above its rated capacity. This improvement would require only limited changes to the overall OWC system. The ability to operate overloaded is determined by the losses and cooling of the IG. The losses in a suitable IG were measured in tests at Nottingham University. Steady state measurements were made of the cooling ability of the OWC airflow at the LIMPET wave power plant operated by Wavegen (the sponsor company) on Islay. Thermal modelling combining the loss and cooling measurements allowed the maximum capacity of the induction generator in an OWC to be found. A simplified model that accurately represents this system is proposed for use in system design and generator control.

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Bhardwaj, Abhinav. "Metallic Encapsulation for High Temperature (>500 °C) Thermal Energy Storage Applications." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5843.

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Deployment of high temperature (>500 °C) thermal energy storage in solar power plants will make solar power more cost competitive and pave the way towards a sustainable future. In this research, a unique metallic encapsulation has been presented for thermal energy storage at high temperatures, capable of operation in aerobic conditions. This goal was achieved by employing low cost materials like carbon steel. The research work presents the unique encapsulation procedure adopted, as well as various coatings evaluated and optimized for corrosion protection. Experimental testing favored the use of 150 μm of nickel on carbon steel for corrosion protection in these conditions. These metallic encapsulations survived several thermal cycles at temperatures from 580 °C to 680 °C with one encapsulation surviving for 1700 thermal cycles.

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Saadon, Syamimi. "Modeling and simulation of a ventilated building integrated photovoltaic/thermal (BIPV/T) envelope." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0049.

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La demande d'énergie consommée par les habitants a connu une croissance significative au cours des 30 dernières années. Par conséquent, des actions sont menées en vue de développement des énergies renouvelables et en particulier de l'énergie solaire. De nombreuses solutions technologiques ont ensuite été proposées, telles que les capteurs solaires PV/T dont l'objectif est d'améliorer la performance des panneaux PV en récupérant l’énergie thermique qu’ils dissipent à l’aide d’un fluide caloporteur. Les recherches en vue de l'amélioration des productivités thermiques et électriques de ces composants ont conduit à l'intégration progressive à l’enveloppe des bâtiments afin d'améliorer leur surface de captation d’énergie solaire. Face à la problématique énergétique, les solutions envisagées dans le domaine du bâtiment s’orientent sur un mix énergétique favorisant la production locale ainsi que l’autoconsommation. Concernant l’électricité, les systèmes photovoltaïques intégrés au bâtiment (BIPV) représentent l’une des rares technologies capables de produire de l’électricité localement et sans émettre de gaz à effet de serre. Cependant, le niveau de température auquel fonctionnent ces composants et en particulier les composants cristallins, influence sensiblement leur efficacité ainsi que leur durée de vie. Ceci est donc d’autant plus vrai en configuration d’intégration. Ces deux constats mettent en lumière l’importance du refroidissement passif par convection naturelle de ces modules. Ce travail porte sur la simulation numérique d'une façade PV partiellement transparente et ventilée, conçu pour le rafraichissement en été (par convection naturelle) et pour la récupération de chaleur en hiver (par ventilation mécanique). Pour les deux configurations, l'air dans la cavité est chauffé par la transmission du rayonnement solaire à travers des surfaces vitrées, et par les échanges convectif et radiatif. Le système est simulé à l'aide d'un modèle multi-physique réduit adapté à une grande échelle dans des conditions réelles d'exploitation et développé pour l'environnement logiciel TRNSYS. La validation du modèle est ensuite présentée en utilisant des données expérimentales du projet RESSOURCES (ANR-PREBAT 2007). Cette étape a conduit, dans le troisième chapitre du calcul des besoins de chauffage et de refroidissement d'un bâtiment et l'évaluation de l'impact des variations climatiques sur les performances du système. Les résultats ont permis enfin d'effectuer une analyse énergétique et exergo-économique
The demand of energy consumed by human kind has been growing significantly over the past 30 years. Therefore, various actions are taken for the development of renewable energy and in particular solar energy. Many technological solutions have then been proposed, such as solar PV/T collectors whose objective is to improve the PV panels performance by recovering the heat lost with a heat removal fluid. The research for the improvement of the thermal and electrical productivities of these components has led to the gradual integration of the solar components into building in order to improve their absorbing area. Among technologies capable to produce electricity locally without con-tributing to greenhouse gas (GHG) releases is building integrated PV systems (BIPV). However, when exposed to intense solar radiation, the temperature of PV modules increases significantly, leading to a reduction in efficiency so that only about 14% of the incident radiation is converted into electrical energy. The high temperature also decreases the life of the modules, thereby making passive cooling of the PV components through natural convection a desirable and cost-effective means of overcoming both difficulties. A numerical model of heat transfer and fluid flow characteristics of natural convection of air is therefore undertaken so as to provide reliable information for the design of BIPV. A simplified numerical model is used to model the PVT collector so as to gain an understanding of the complex processes involved in cooling of integrated photovoltaic arrays in double-skin building surfaces. This work addresses the numerical simulation of a semi-transparent, ventilated PV façade designed for cooling in summer (by natural convection) and for heat recovery in winter (by mechanical ventilation). For both configurations, air in the cavity between the two building skins (photovoltaic façade and the primary building wall) is heated by transmission through transparent glazed sections, and by convective and radiative exchange. The system is simulated with the aid of a reduced-order multi-physics model adapted to a full scale arrangement operating under real conditions and developed for the TRNSYS software environment. Validation of the model and the subsequent simulation of a building-coupled system are then presented, which were undertaken using experimental data from the RESSOURCES project (ANR-PREBAT 2007). This step led, in the third chapter to the calculation of the heating and cooling needs of a simulated building and the investigation of impact of climatic variations on the system performance. The results have permitted finally to perform the exergy and exergoeconomic analysis

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Roy, Michael Joseph. "Hydrodeoxygenation of lignin model compounds via thermal catalytic reactions." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45752.

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Lignin is an important component of biomass accounting for up to 30% by weight but up to 40% of the total energy content of the plant. As the push towards alternative fuels develops, more and more amounts of lignin will be gathered and used predominately as low grade boiler fuel to run primary processes. We argue there is usefulness in the conversion of lignin into value added specialty chemicals and fuels. In this work, a new approach for hydrodeoxygenation of lignin model compounds using platinum as the catalyst and organic solvent as the reaction medium was conducted, and the results were compared with those obtained using water as the reaction medium. It is shown that the organic solvent, with its increased hydrogen solubility, is able to hydrogenate the model compound with the same effect at lower temperature, hydrogen pressure, and time.

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Ma, Chenwen. "Retrofitting a Single-family Home with Increased Use of Renewable Energy." Thesis, KTH, Installations- och energisystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215962.

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Buildings account for up to 40% of the total energy use in the world. Directives from the European Union have pointed out the significance of increasing the energy efficiency in buildings. New regulation in countries like Sweden has established that new buildings should fulfil regulations of Nearly Zero Energy Buildings (NZEB), providing the opportunity for renewable energy technologies to achieve these goals. In this paper, the retrofitting potential of renewable energy technologies for a single-family home in Sweden was investigated.The present work studied the characteristics of several renewable energy technologies and their applications for a single-family home in Sweden, including biomass, solar photovoltaics, solar thermal, heat pump, and small-scale wind turbine. Three renewable energy technologies (solar thermal, heat pump and small-scale wind turbine) and one renovation method (window) were selected to investigate. The analysis was made of the current energy use and the potential energy (and cost) savings from each retrofitting of these facilities by means of simulation models using IDA ICE software. The study results show that the proposed renewable energy technologies are technically feasible and economically viable as a source of alternative renewable energy in order to produce clean energy and reduce electricity bills for an electric-heated single-family home located in Sweden. Moreover, the combined retrofitting scheme consist of solar thermal system and window renovation was also proposed and explored. As a result the energy performance of the single-family home would satisfy the nearly-zero energy building requirements and thermal comfort could be maintained at an acceptable level.

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Anderson, Matthew John. "Economic and Environmental Analysis of Cool Thermal Energy Storage as an Alternative to Batteries for the Integration of Intermittent Renewable Energy Sources." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51195.

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The balance of the supply of renewable energy sources with electricity demand will become increasingly difficult with further penetration of renewable energy sources. Traditionally, large stationary batteries have been used to store renewable energy in excess of electricity demand and dispatch the stored energy to meet future electricity demand. Cool thermal energy storage is a feasible renewable energy balancing solution that has economic and environmental advantages over utility scale stationary lead-acid batteries. Two technologies, ice harvesters and internal-melt ice-on-coil cool thermal energy storage, have the capability to store excess renewable energy and use the energy to displace electricity used for building cooling systems. When implemented by a utility, cool thermal energy storage can replace large utility scale batteries for renewable energy balancing in utility regions with high renewable energy penetration. The California Independent System Operator (CAISO) region and the Electric Reliability Council of Texas (ERCOT) are utility regions with large solar and wind resources, respectively, that can benefit from installation of cool thermal energy storage systems for renewable energy balancing. With proper scheduling of energy dispatched from cool thermal energy storage, these technologies can be effective in displacing peak power capacity for the region, in displacing traditional building cooling equipment, and in recovering renewable energy that would otherwise be curtailed.
Master of Science

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Linde, Daniel. "Evaluation of a Flat-Plate Photovoltaic Thermal (PVT) Collector prototype." Thesis, Högskolan Dalarna, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:du-24061.

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This Master thesis, in collaboration with Morgonsol Väst AB, was completed as a part of the Solar Energy engineering program at Dalarna University. It analyses the electrical and thermal performance of a prototype PVT collector developed by Morgonsol Väst AB. By following the standards EN 12975 and EN ISO 9806 as guides, the thermal tests of the collector were completed at the facility in Borlänge. The electrical performance of the PVT collector was evaluated by comparing it to a reference PV panel fitted next to it. The result from the tests shows an improved electrical performance of the PVT collector caused by the cooling and a thermal performance described by the linear efficiency curve ηth=0.53-21.6(Tm-Ta/G). The experimental work in this thesis is an initial study of the prototype PVT collector that will supply Morgonsol Väst with important data for future development and research of the product.

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Louw, Andre Du Randt. "Discrete and porous computational fluid dynamics modelling of an air-rock bed thermal energy storage system." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86233.

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Thesis (MScEng)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Concentrating solar power promises to be a potential solution for meeting the worlds energy needs in the future. One of the key features of this type of renewable energy technology is its ability to store energy effectively and relatively cheaply. An air-rock bed thermal energy storage system promises to be an effective and reasonably inexpensive storage system for concentrating solar power plants. Currently there is no such storage system commercially in operation in any concentrating solar power plant, and further research is required before such a system can be implemented. The main research areas to address are the thermal-mechanical behaviour of rocks, rock bed pressure drop correlations and effective and practical system designs. Recent studies have shown that the pressure drop over a packed bed of rocks is dependant on various aspects such as particle orientation relative to the flow direction, particle shape and surface roughness. The irregularity and unpredictability of the particle shapes make it difficult to formulate a general pressure drop correlation. Typical air-rock bed thermal design concepts consist of a large vertical square or cylindrical vessel in which the bed is contained. Such system designs are simple but susceptible to the ratcheting effect and large pressure drops. Several authors have proposed concepts to over-come these issues, but there remains a need for tools to prove the feasibility of the designs. The purpose of this paper is to investigate aDEM-CFD coupled approach that can aid the development of an air-rock bed thermal energy storage system. This study specifically focuses on the use of CFD. A complementary study focusses on DEM. The two areas of focus in this study are the pressure drop and system design. A discrete CFD simulation model is used to predict pressure drop over packed beds containing spherical and irregular particles. DEM is used to create randomly packed beds containing either spherical or irregularly shaped particles. This model is also used to determine the heat transfer between the fluid and particle surface. A porous CFD model is used to model system design concepts. Pressure drop and heat transfer data predicted by the discrete model, is used in the porous model to describe the pressure drop and thermal behaviour of a TES system. Results from the discrete CFD model shows that it can accurately predict the pressure drop over a packed bed of spheres with an average deviation of roughly 10%fromresults found in literature. The heat transfer between the fluid and particle surface also is accurately predicted, with an average deviation of between 13.36 % and 21.83 % from results found in literature. The discrete CFD model for packed beds containing irregular particles presented problems when generating a mesh for the CFD computational domain. The clump logic method was used to represent rock particles in this study. This method was proven by other studies to accurately model the rock particle and the rock packed bed structure using DEM. However, this technique presented problems when generating the surface mesh. As a result a simplified clump model was used to represent the rock particles. This simplified clump model showed characteristics of a packed bed of rocks in terms of pressure drop and heat transfer. However, the results suggest that the particles failed to represent formdrag. This was attributed to absence of blunt surfaces and sharp edges of the simplified clumpmodel normally found on rock particles. The irregular particles presented in this study proved to be inadequate for modelling universal characteristics of a packed bed of rocks in terms of pressure drop. The porous CFD model was validated against experimental measurement to predict the thermal behaviour of rock beds. The application of the porous model demonstrated that it is a useful design tool for system design concepts.
AFRIKAANSE OPSOMMING: Gekonsentreerde sonkrag beloof om ’n potensiële toekomstige oplossing te wees vir die wêreld se groeiende energie behoeftes. Een van die belangrikste eienskappe van hierdie tipe hernubare energie tegnologie is die vermoë om energie doeltreffend en relatief goedkoop te stoor. ’n Lug-klipbed termiese energie stoorstelsel beloof om ’n doeltreffende en redelik goedkoop stoorstelsel vir gekonsentreerde sonkragstasies te wees . Tans is daar geen sodanige stoorstelsel kommersieël in werking in enige gekonsentreerde sonkragstasie nie. Verdere navorsing is nodig voordat so ’n stelsel in werking gestel kan word. Die belangrikste navorsingsgebiede om aan te spreek is die termies-meganiese gedrag van klippe, klipbed drukverlies korrelasies en effektiewe en praktiese stelsel ontwerpe. Onlangse studies het getoon dat die drukverlies oor ’n gepakte bed van klippe afhanklik is van verskeie aspekte soos partikel oriëntasie tot die vloeirigting, partikel vormen oppervlak grofheid. Die onreëlmatigheid en onvoorspelbaarheid van die klip vorms maak dit moeilik om ’n algemene drukverlies korrelasie te formuleer. Tipiese lug-klipbed termiese ontwerp konsepte bestaan uit ’n groot vertikale vierkantige of silindriese houer waarin die gepakte bed is. Sodanige sisteem ontwerpe is eenvoudig, maar vatbaar vir die palrat effek en groot drukverliese. Verskeie studies het voorgestelde konsepte om hierdie kwessies te oorkom, maar daar is steeds ’n behoefte aanmetodes om die haalbaarheid van die ontwerpe te bewys. Die doel van hierdie studie is om ’n Diskreet Element Modelle (DEM) en numeriese vloeidinamika gekoppelde benadering te ontwikkel wat ’n lug-klipbed termiese energie stoorstelsel kan ondersoek. Hierdie studie fokus spesifiek op die gebruik van numeriese vloeidinamika. ’n Aanvullende studie fokus op DEM. Die twee areas van fokus in hierdie studie is die drukverlies en stelsel ontwerp. ’n Diskrete numeriese vloeidinamika simulasie model word gebruik om drukverlies te voorspel oor gepakte beddens met sferiese en onreëlmatige partikels. DEM word gebruik om lukraak gepakte beddens van óf sferiese óf onreëlmatige partikels te skep. Hierdie model is ook gebruik om die hitte-oordrag tussen die vloeistof en partikel oppervlak te bepaal. ’n Poreuse numeriese vloeidinamika model word gebruik omdie stelsel ontwerp konsepte voor te stel. Drukverlies en hitte-oordrag data, voorspel deur die diskrete model, word gebruik in die poreuse model om die drukverlies- en hittegedrag van ’n TES-stelsel te beskryf. Resultate van die diskrete numeriese vloeidinamikamodel toon dat dit akkuraat die drukverlies oor ’n gepakte bed van sfere kan voorspel met ’n gemiddelde afwyking van ongeveer 10%van die resultatewat in die literatuur aangetref word. Die hitte-oordrag tussen die vloeistof en partikel oppervlak is ook akkuraat voorspel, met ’n gemiddelde afwyking van tussen 13.36%en 21.83%van die resultate wat in die literatuur aangetref word. Die diskrete numeriese vloeidinamika model vir gepakte beddens met onreëlmatige partikels bied probleme wanneer ’n maas vir die numeriese vloeidinamika, numeriese domein gegenereer word. Die "clump"logika metode is gebruik om klip partikels te verteenwoordig in hierdie studie. Hierdiemetode is deur ander studies bewys om akkuraat die klip partikel en die klip gepakte bed-struktuur te modelleer deur die gebruik van DEM. Hierdie tegniek het egter probleme gebied toe die oppervlak maas gegenereer is. As gevolg hiervan is ’n vereenvoudigde "clump"model gebruik om die klip partikels te verteenwoordig. Die vereenvoudigde "clump"model vertoon karakteristieke eienskappe van ’n gepakte bed van klippe in terme van drukverlies en hitte oordrag. Die resultate het egter getoon dat die partikels nie vorm weerstand verteenwoordig nie. Hierdie resultate kan toegeskryf word aan die afwesigheid van gladde oppervlaktes en skerp kante, wat normaalweg op klip partikels gevind word, in die vereenvoudigde "clump"model. Die oneweredige partikels wat in hierdie studie voorgestel word, blykomnie geskik tewees vir die modellering van die universele karakteristieke eienskappe van ’n gepakte bed van klippe in terme van drukverlies nie. Die poreuse numeriese vloeidinamika model is met eksperimentele metings bevestig omdie termiese gedrag van klipbeddens te voorspel. Die toepassing van die poreuse model demonstreer dat dit ’n nuttige ontwerp metode is vir stelsel ontwerp konsepte.

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Bialobrzeski, Robert Wetherill. "Optimization of a SEGS solar field for cost effective power output." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/24631.

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Banerjee, S. "Ocean energy assessment : an integrated methodology." Thesis, Coventry University, 2011. http://curve.coventry.ac.uk/open/items/16196d0d-e671-489a-ba71-f20cdb6c8df3/1.

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The huge natural energy resources available in the world’s oceans are attracting increasing commercial and political interest. In order to evaluate the status and the degree of acceptability of future Ocean Energy (OE) schemes, it was considered important to develop an Integrated Assessment Methodology (IAM) for ascertaining the relative merits of the competing OE devices being proposed. Initial studies included the gathering of information on the present status of development of the ocean energy systems on wave, OTEC and tidal schemes with the challenges faced for their commercial application. In order to develop the IAM, studies were undertaken for the development and standardization of the assessment tools focussing on: • Life Cycle Assessment (LCA) on emission characteristics. • Energy Accounting (EA) studies. • Environmental Impact Assessment (EIA) over different environmental issues. • Resource captures aspects. • Defining economy evaluation indices. The IAM developed from such studies comprised of four interrelated well defined tasks and six assessment tools. The tasks included the identification of the modus operandi on data collection to be followed (from industry) for assessing respective OE devices, and also advancing relevant guidelines as to the safety standards to be followed, for their deployment at suitable sites. The IAM as developed and validated from case studies in ascertaining relative merits of competing OE devices included: suitable site selection aspects with scope for resource utilisation capability, safety factors for survivability, scope for addressing global warming & energy accounting, the environmental impact assessment both qualitatively and quantitatively on different environmental issues, and the economic benefits achievable. Some of the new ideas and concepts which were also discovered during the development of the IAM, and considered useful to both industry and researchers are given below: • Relative Product Cost (RPC) ratio concept- introduced in making an economic evaluation. This is considered helpful in sensitivity analysis and making design improvements (hybridising etc) for the cost reduction of OE devices. This index thus helps in making feasibility studies on R&D efforts, where the capital cost requirement data and life span of the device is not well defined in the primary stages of development. • Determination of the threshold limit value of the barrage constant - considered useful in determining the efficacy of the planning process. The concept ascertained the relative efficiency achieved for various barrage proposals globally. It could also be applied to suggest the revisions required for certain barrage proposals and also found useful in predicting the basin area of undefined barrage proposal for achieving economic viability. • Estimations made on the future possibility of revenue earnings from the by-products of various OTEC types, including the scope of chemical hubs from grazing type OTEC plants. • Determination of breakeven point- on cost versus life span of wave and OTEC devices studied, which is useful in designing optimum life of the concerned devices. The above stated multi-criterion assessment methodology, IAM, was extended leading to the development of a single criterion model for ascertaining sustainability percent achievable from an OE device and termed IAMs. The IAMs was developed identifying 7 Sustainability Development Indices (SDI) using some the tools of the IAM. A sustainability scale of 0-100 was also developed, attributing a Sustainability Development Load Score (SDLS) percentage distribution pattern over each SDIs, depending on their relative importance in achieving sustainability. The total sum of sustainability development (SD) gained from each SDI gave the IAMs (for the concerned device), indicating the total sustainable percentage achieved. The above IAMs developed, could be applied in ranking OE devices alongside the unsustainable coal power station. A mathematical model of estimating the IAMs was formulated, in order to ascertain the viability to the sustainable development of any energy device. The instruments of IAM and IAMs which have been developed would be helpful to the OE industry in ascertaining the degree of acceptability of their product. In addition it would also provide guidelines for their safe deployment by assessing the relative merits of competing devices. Furthermore, IAM and IAMs would be helpful to researchers undertaking feasibility studies on R&D efforts for material development research, ‘hybridization studies’ (as also new innovations), cost reduction, the performance improvement of respective devices, and any economic gains. With future advancements in OE systems and the availability of field data from large scale commercial applications, the specific values/data of the IAM & IAMs may be refined, but the logic of the models developed in this research would remain the same.

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Панкевич, О. Д., О. С. Сторожук та К. В. Юхимчук. "Використання відновлювальних джерел енергії для підвищення енергоефективності житлової будівлі". Thesis, ВНТУ, 2018. http://ir.lib.vntu.edu.ua//handle/123456789/24268.

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Анотація:

Розглянуто актуальні питання підвищення енергетичної ефективності житлових будівель. Визначено пріоритетні заходи, що сприяють зменшенню споживання енергії, внаслідок використання відновлювальних джерел енергії.
The urgent issues of increasing the energy efficiency of residential buildings are considered. Priority measures that reduce the consumption of energy due to the use of renewable energy sources are identified.

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Myska, Martin. "Possibilities with Stirling Engine and High Temperature Thermal Energy Storage in Multi-Energy Carrier System : An analysis of key factors influencing techno-economic perspective of Stirling engine and high-temperature thermal energy storage." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-53407.

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Small and medium-scale companies are trying to minimise their carbon footprint and improve their cash flow, renewable installations are increasing all over the Europe and are expected to do so in following years. However, their dependency on the weather cause pressure on matching the production with demand. An option how to challenge this problem is by using energy storage. The aim of this project is to determine techno-economic benefits of Stirling engine and high temperature thermal energy storage for installation in energy user system and identify key factors that affect the operation of such system. In order to determine these factors simulations in Matlab were conducted. The Matlab linear programming tool Optisolve using dual-simplex algorithm was used. The sensitivity analysis was conducted to test the energy system behaviour. Economic evaluation was done calculating discounted savings. From the results, it can be seen the significant benefit of SE-HT-TES installation is the increased self-consumption of the electricity from PV installation. While the self-consumption in cases when there was no energy storage implemented was around 67 % and in one case as low as 50 % with the SE-HT-TES the value has increased up to 100 %. Energy cost savings are 4.7 % of the cost for the original data set and go up to 6.2 % when simulation with load shift was executed. Simulations have also shown that energy customer with predictable energy demand pattern can achieve higher savings with the very same system. It was also confirmed that for users whose private renewable production does not match load potential savings are 30 % higher compared to the system where energy load peak is matching the PV production peak. Simulations also shown that the customers located in areas with higher electricity price volatility can benefit from such system greatly.

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33

Llovera, Bonmatí Albert. "Market role, profitability and competitive features of thermal power plants in the Swedish future electricity market with high renewable integration." Thesis, Uppsala universitet, Elektricitetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-330392.

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The Swedish energy market is currently undergoing a transition from fossil fuels to renewable energy sources, including a potential phase-out of nuclear power. The combination of a phase-out with expansion of intermittent renewable energy leads to the issue of increased fluctuations in electricity production. Energy-related organizations and institutions are projecting future Swedish energy scenarios with different possible transition pathways. In this study the market role of thermal power plants is assessed in two future scenarios. The fast start-up time of gas turbines means that they can balance out fluctuations. Given that a large share of reports already studies costs of the system, this report instead investigates the profitability, potential market roles, and competitive features of these technologies in the future market.

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34

Gils, Hans Christian [Verfasser], and André [Akademischer Betreuer] Thess. "Balancing of intermittent renewable power generation by demand response and thermal energy storage / Hans Christian Gils. Betreuer: André Thess." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1081367563/34.

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35

Panayiotou, Gregoris. "Thermal performance of dwellings in Cyprus and approaches for energy conservation." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/9204.

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Energy has always been the dominant driving force for the socio-economic development of mankind. Nowadays, the global energy system is highly depended on fossil fuels. A great share of the final energy consumption, over 40%, in the EU-27 is consumed by the existing building stock whereas dwellings account for 66.62% of this. Thus, the need to increase the energy performance of dwellings is an important instrument in the efforts to lessen Europe’s energy dependency. In order to define measures to increase the energy performance of dwellings a deeper understanding of their characteristics should be gained. Unfortunately, in Cyprus there is a gap in knowledge on this aspect. In this thesis the characteristics of the dwellings in Cyprus are defined through a sample of 500 dwellings. The results revealed that more than 80% of dwellings in Cyprus do not have thermal insulation installed on their envelope. From this it is clear that the definition of the optimum thermal insulation material to be applied in dwellings is very important. Thus, the commercially available thermal insulation materials and topologies used in Cyprus were reviewed and defined through a market survey and the typical dwelling was modelled. The effect of the application of thermal insulation to its energy behaviour was simulated using TRNSYS. This resulted in the definition of the optimum thermal insulation materials and topologies to be applied in both new and existing dwellings. Accordingly, the application of advanced commercially available materials such as Phase Change Materials (PCM) to the envelope of the typical dwelling was investigated. The energy savings achieved by the addition of a PCM layer on the envelope of the typical dwelling was found to be 28.6%. The optimum PCM case was also combined with the optimum thermal insulation combination and an energy saving of 68% was predicted. The incorporation of Renewable Energy Sources (RES) to the typical dwelling was also simulated and studied. Specifically, two types of standalone RES systems were initially evaluated; a solely photovoltaic (PV) system and a hybrid PV-Wind system. The results showed that the solely PV system is a much better option due to the very high solar potential of Cyprus in comparison to the poor wind profile of the island. Subsequently, a grid-connected PV system was also evaluated and the results showed that when a RES system is grid-connected the cost of the system is reduced to half of that of the standalone cases. This research has revealed that the optimum topology combinations to be applied in both new and existing dwellings in Cyprus is thermal insulation plaster or thermal insulation bricks (only for new dwellings) on the external walls combined with expanded polystyrene on the roof. These results will provide valuable information that will assist both engineers and architects in the efficient design of dwellings in Cyprus. The investigation of the application of macroencapsulated PCM showed that these materials are not yet an economically viable solution for application in Cyprus The findings also show that a solely PV system is the optimum RES system to be applied in Cyprus especially when it is grid-connected. The findings of this project are useful for individuals, house builders and designers as well as policy makers for the design of energy saving subsidy schemes.

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36

Das, Barun Kumar. "Optimisation of stand-alone hybrid energy systems for power and thermal loads." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2018. https://ro.ecu.edu.au/theses/2150.

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Stand-alone hybrid energy systems are an attractive option for remote communities without a connection to a main power grid. However, the intermittent nature of solar and other renewable sources adversely affects the reliability with which these systems respond to load demands. Hybridisation, achieved by combining renewables with combustion-based supplementary prime movers, improves the ability to meet electric load requirements. In addition, the waste heat generated from backup Internal Combustion Engines or Micro Gas Turbines can be used to satisfy local heating and cooling loads. As a result, there is an expectation that the overall efficiency and Greenhouse Gas Emissions of stand-alone systems can be significantly improved through waste heat recovery. The aims of this PhD project are to identify how incremental increases to the hardware complexity of hybridised stand-alone energy systems affect their cost, efficiency, and CO2 footprint. The research analyses a range of systems, from those designed to meet only power requirements to others satisfying power and heating (Combined Heat and Power), or power plus both heating and cooling (Combined Cooling, Heating, and Power). The majority of methods used focus on MATLAB-based Genetic Algorithms (GAs). The modelling deployed finds the optimal selection of hardware configurations which satisfy single- or multi-objective functions (i.e. Cost of Energy, energy efficiency, and exergy efficiency). This is done in the context of highly dynamic meteorological (e.g. solar irradiation) and load data (i.e. electric, heating, and cooling). Results indicate that the type of supplementary prime movers (ICEs or MGT) and their minimum starting thresholds have insignificant effects on COE but have some effects on Renewable Penetration (RP), Life Cycle Emissions (LCE), CO2 emissions, and waste heat generation when the system is sized meeting electric load only. However, the transient start-up time of supplementary prime movers and temporal resolution have no significant effects on sizing optimisation. The type of Power Management Strategies (Following Electric Load-FEL, and Following Electric and Following Thermal Load- FEL/FTL) affect overall Combined Heating and Power (CHP) efficiency and meeting thermal demand through recovered heat for a system meeting electric and heating load with response to a specific load meeting reliability (Loss of Power Supply Probability-LPSP). However, the PMS has marginal effects on COE. The Electric to Thermal Load Ratio (ETLR) has no effects on COE for PV/Batt/ICE but strongly affects PV/Batt/MGT-based hybridised CHP systems. The higher thermal than the electric loads lead to higher efficiency and better environmental footprint. Results from this study also indicate that for a stand-alone hybridised system operating under FEL/FTL type PMS, the power only system has lower cost compared to the CHP and the Combined Cooling, Heating, and Power (CCHP) systems. This occurs at the expense of overall energy and exergy efficiencies. Additionally, the relative magnitude of heating and cooling loads have insignificant effects on COE for PV/Batt/ICE-based system configurations, however this substantially affects PV/Batt/MGT-based hybridised CCHP systems. Although there are no significant changes in the overall energy efficiency of CCHP systems in relation to variations to heating and cooling loads, systems with higher heating demand than cooling demand lead to better environmental benefits and renewable penetration at the cost of Duty Factor. Results also reveal that the choice of objective functions do not affect the system optimisation significantly.

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Usta, Yasemin. "Simulations Of A Large Scale Solar Thermal Power Plant In Turkey Using Concentrating Parabolic Trough Collectors." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612800/index.pdf.

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In this study, the theoretical performance of a concentrating solar thermal electric system (CSTES) using a field of parabolic trough collectors (PTC) is investigated. The commercial software TRNSYS and the Solar Thermal Electric Components (STEC) library are used to model the overall system design and for simulations. The model was constructed using data from the literature for an existing 30-MW solar electric generating system (SEGS VI) using PTC&rsquo
s in Kramer Junction, California. The CSTES consists of a PTC loop that drives a Rankine cycle with superheat and reheat, 2-stage high and 5-stage low pressure turbines, 5-feedwater heaters and a dearator. As a first approximation, the model did not include significant storage or back-up heating. The model&rsquo
s predictions were benchmarked against published data for the system in California for a summer day. Good agreement between the model&rsquo
s predictions and published data were found, with errors usually less than 10%. Annual simulations were run using weather data for both California and Antalya, Turkey. The monthly outputs for the system in California and Antalya are compared both in terms of absolute monthly outputs and in terms of ratios of minimum to maximum monthly outputs. The system in Antalya is found to produce30 % less energy annually than the system in California. The ratio of the minimum (December) to maximum (July) monthly energy produced in Antalya is 0.04.

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38

Eller, Michael R. "Utilizing Economic and Environmental Data from the Desalination Industry as a Progressive Approach to Ocean Thermal Energy Conversion (OTEC) Commercialization." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1733.

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Ocean Thermal Energy Conversion (OTEC) is a renewable energy technology that has to overcome several key challenges before achieving its ultimate goal of producing baseload power on a commercial scale. The economic challenge of deploying an OTEC plant remains the biggest barrier to implementation. Although small OTEC demonstration plants and recent advances in subsystem technologies have proven OTEC’s technical merits, the process still lacks the crucial operational data required to justify investments in large commercial OTEC plants on the order of 50-100 megawatts of net electrical power (MWe-net). A pre-commercial pilot plant on the order of 5-10 MWe-net is required for an OTEC market to evolve. In addition to the economic challenge,OTEC plants have potential for adverse environmental impacts from redistribution of nutrients and residual chemicals in the discharge plume. Although long-term operational records are not available for commercial sizeOTEC plants, synergistic operational data can be leveraged from the desalination industry to improve the potential for OTEC commercialization. Large capacity desalination plants primarily use membranes or thermal evaporator tubes to transform enormous amounts of seawater into freshwater. Thermal desalination plants in particular possess many of the same technical, economic, and environmental traits as a commercial scale OTEC plant. Substantial long-term economic data and environmental impact results are now widely available since commercial desalination began in the 1950s. Analysis of this data indicates that the evolution of the desalination industry could be akin to the potential future advancement of OTEC. Furthermore, certain scenarios exist where a combined OTEC-desalination plant provides a new opportunity for commercial plants. This paper seeks to utilize operational data from the desalination industry as a progressive approach towards OTEC commercialization.

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39

Farah, Hamad. "Hybrid solar system for heat and electric demands in a simple housing within Sweden and China." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-40596.

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The access to ideal heating and power techniques has always been highly thought after.This is mainly due to the development in housing architecture and the cold nature of certain regions which has led to an increase in popularity of the heating market and modernised heating technologies. The current DH systems make use of CHP plants for thegeneration of power and electricity. These CHP plants for the most part, are powered through biomass and during winter periods the demand for heating is highly increased.The biggest issue with relying on biomass solely is the constant need to burn wasteproducts which not only results in increasing the demand for consuming in more waste,but also results in producing remains (by-products) that cannot be broken down further and hence might require the utilization of land-space (landfills) for their disposal. Solar modules on the other hand, have gained increased popularity in the recent age. This is mainly due their extremely high flexible ability in converting solar irradiance intoelectrical and thermal energies. This study will try to provide a comprehensive study intothe utilization of a hybrid solar system that combines a standard PV module with a flat-plate collector through estimating the energy demands for a simple housing within Sweden and China. This will be the main aim of the study, however the possibilities of integrating this hybrid solar system alongside current DH systems will mostly be discussed in the first sections to proof the possibility of executing such a system. The theoretical work carried out will only include simulations of having just separate,standalone PV and flat-plate collector modules. However, designing a hybrid solar and DH system will not be the major focus of this study. The results at the end of the report,concluded that the electrical production for the Swedish case were noticeably higher thanthat of the Chinese case in spite of maintaining the same load values through both cases and higher solar irradiation for the Chinese case. Due to PVsyst simulation constraints,the results show that the investment cost of the Swedish PV (electrical component) module was about 3.6 times greater than that of the Chinese which could possibly mean that the Swedish case has a bigger PV module area than the Chinese case in order to meetel ectricity demand monthly. However, when it came to the thermal energy production, it was possible to assume different collectors cases and hence an area of 7m2 was chosen for the Swedish perspective while an area of 4m2 has been considered for the Chinese case. The thermal useful energy values where then compared with heating demands for both of the cases. Finally, the thesis concluded that there was no requirement for having an integrated DH network within the standalone houses, having small electricity and heat demand and hence, it might be more beneficial to have an integrated DH and solar system within more densely populated housing areas.
Efterfrågan på tillgången till idealisk uppvärmning och effektiva tekniker har alltid varithög. Detta beror främst på utvecklingen inom arkitektur och den kalla naturen i vissaregioner som har lett till en ökad popularitet av värmemarknaden och moderniseradevärmeteknologiert. De nuvarande fjärrvärme-systemen använder kraftvärmeverk förproduktion av kraft och elektricitet. Dessa kraftvärmeanläggningar drivs till stor delgenom biomassa och under vinterperioderna ökar efterfrågan på uppvärmning mycket.Det största problemet med att förlita sig på biomassa enbart är det ständiga behovet avatt bränna avfallsprodukter som inte bara resulterar i att öka efterfrågan på konsumtionav fler avfallsprodukter utan också resulterar i att producera rester (biprodukter) sominte kan brytas ned ytterligare och därmed kan kräva användning av markutrymme fördeponering. solar-moduler å andra sidan har ökat popularitet under de senaste åren.Detta beror främst på deras extremt höga flexibla förmåga att konvertera solbestrålningtill elektrisk och termisk energi. Denna studie kommer att försöka tillhandahålla enomfattande studie av användningen av ett hybridsolsystem som kombinerar en standardPV-modul med en flatplate collector för att simulera en solar-modul samt caselera enfristående version genom att uppskatta energikraven för en enkel bostad i Sverige ochKina. Detta kommer att vara huvudmålet med studien, men möjligheterna att integreradetta hybrida solsystem tillsammans med nuvarande DH-system kommer mestadels attdiskuteras i de första avsnitten för att bevisa möjligheten att utföra ett sådant system. Detteoretiska arbetet som utförs kommer endast att innehålla simuleringar av att bara ha enfristående PV- och flatplate collector module, men att utforma ett hybrid sol- och DHsystemkommer inte att vara huvudfokus för denna studie. Resultaten i slutet avrapporten drog överraskande slutsatsen att den elektriska produktionen för den svenskacaselen var märkbart högre än den för den kinesiska caselen trots att de båda caselernabibehöll samma belastningsvärden och högre solbestrålning för den kinesiska caselen.Detta kan förklaras av skillnaden i modulpriser vid simulering genom PVsyst därinvesteringskostnaden för den svenska PV-modulen (elektrisk komponent) var ungefär3,6 gånger större än den för kinesiska, vilket innebär att PVsyst antar ett störremodulområde för svensk modul och därmed mer energiproduktion. Men när det kom tillvärmeenergiproduktionen, var det möjligt att anta olika samlarfall och följaktligen valdesett område på 7m2 för det svenska perspektivet medan ett område på 4m2 har beaktatsför den kinesiska och värmevärden för användbar energi där jämfördes sedan med dekrav som krävs för uppvärmning i båda fallen. Slutligen drog avhandlingen slutsatsen attdet inte fanns något krav på att ha ett integrerat DH-nätverk i de fristående husen ochdärför kan det vara mer fördelaktigt att ha ett integrerat DH och solsystem i tätarebebyggda bostadsområden.

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40

Thirkill, Adam. "Evaluating the uncertainty in the performance of small scale renewables." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19122.

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The successful delivery of low-carbon housing (both new and retrofitted) is a key aspect of the UK s commitment to an 80% reduction in carbon emissions by 2050. In this context, the inclusion of small-scale building-integrated renewable energy technologies is an important component of low carbon design strategies, and is subject to numerous regulation and incentive schemes (including the Renewable Heat Incentive (RHI)) set up by government to encourage uptake and set minimum performance benchmarks. Unfortunately there are numerous examples of in-use energy and carbon performance shortfalls for new and retrofitted buildings this is termed the performance gap . Technical and human factors associated with building subsystem performance, which are often not considered in design tools used to predict performance, are the root cause of performance uncertainty. The research presented in this doctoral thesis aims to develop and apply a novel probabilistic method of evaluating the performance uncertainty of solar thermal systems installed in the UK. Analysis of measured data from a group of low carbon retrofitted dwellings revealed that the majority of buildings failed to meet the designed-for carbon emissions target with an average percentage difference of 60%. An in-depth case study technical evaluation of one of these dwellings showed significant dysfunction associated with the combined ASHP/solar thermal heating system, resulting in a performance gap of 94%, illustrating that the performance gap can be regarded as a whole-system problem, comprising a number of subsystem causal factors. Using a detailed dataset obtained from the UK s largest field trial of domestic solar thermal systems, a cross-cutting evaluation of predicted vs. measured performance similarly revealed a discrepancy with a mean percentage difference in predicted and measured annual yield of -24%. Having defined the nature and extent of underperformance for solar thermal technology in the UK, causal factors influencing performance were mapped and the associated uncertainty quantified using a novel knowledge-based Bayesian network (BN). In addition, the BN approach along with Monte Carlo sampling was applied to the well-established BREDEM model in order to quantify performance uncertainty of solar thermal systems by producing distributions of annual yield. As such, the modified BN-based BREDEM model represents a significant improvement in the prediction of performance of small-scale renewable energy technologies. Finally, financial analysis applied to the probabilistic predictions of annual yield revealed that the current UK RHI scheme is unlikely to result in positive returns on investment for solar thermal systems unless the duration of the payments is extended or electricity is the primary source of heating.

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41

Zeid, Nayef. "An Overview of PVT Module for the Extraction of Electricity and Heat." Thesis, Högskolan i Gävle, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-33998.

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The study sets out to review various literatures concerning photovoltaic/thermal (PVT) modules for the extraction of electricity and heat, it also reviews different PVT collectors as well as their performance. The study provides an understanding of a system that fully supports ecological society by promoting the use of solar modules from a different scope in future global resolutions. Furthermore, it looks into renewable energy in Sweden, solar energy and PVT systems, operational principles of hybrid PVT collectors, PVT applications, PVT market and legal face of PVT in Sweden among others. Among other social benefits, PVT system contributes enormously to energy savings and energy consumption which in turn lowers CO2 emissions. The review shows that PVT modules can provide homes and industries with 100% renewable electricity and heat that is affordable. This paper adopts systematic literature review, as it allows thorough cross-examination of various publications regarding the subject.

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42

Demirocak, Emre Dervis. "Thermodynamic And Economic Analysis Of A Solar Thermal Powered Adsorption Cooling System." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610110/index.pdf.

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In this thesis, yearly performance of the solar adsorption cooling system which is proposed to be installed to a residential building in Antalya is theoretically investigated in detail. Firstly, thermodynamic designs of the adsorption cooling cycle for three different types of cycles which are intermittent, heat recovery and heat &
mass recovery cycles are presented. Secondly, adsorption characteristics of three adsorbent/adsorbate pairs which are zeolite-water, silica gel-water and activated carbon-methanol are given. Following this, load side (i.e., building) of the system is designed and parameters that should be considered in building design are presented. Then, solar-thermal cooling system design methodology with an emphasis on solar fraction is presented. In addition, system parameters effecting the performance of the adsorption cooling system are analyzed and results are presented. Finally, economic analysis is done in order to understand the economic feasibility of the solar-thermal cooling systems compared to conventional cooling systems. TRNSYS is used for the yearly simulations and an integrated model of the overall system is developed in TRNSYS. Since energy consumption and performance investigations of environment-dependent systems such as building HVAC, refrigeration systems and solar collectors usually require weather information, typical meteorological year (TMY) data for Antalya is also generated in order to be used in the analysis of the system parameters.

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43

Strand, Anna. "Optimization of energy dispatch in concentrated solar power systems : Design of dispatch algorithm in concentrated solar power tower system with thermal energy storage for maximized operational revenue." Thesis, KTH, Kraft- och värmeteknologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264410.

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Concentrated solar power (CSP) is a fast-growing technology for electricity production. With mirrors (heliostats) irradiation of the sun is concentrated onto a receiver run through by a heat transfer fluid (HTF). The fluid by that reaches high temperatures and is used to drive a steam turbine for electricity production. A CSP power plant is most often coupled with an energy storage unit, where the HTF is stored before it is dispatched and used to generate electricity. Electricity is most often sold at an open market with a fluctuating spot-prices. It is therefore of high importance to generate and sell the electricity at the highest paid hours, increasingly important also since the governmental support mechanisms aimed to support renewable energy production is faded out since the technology is starting to be seen as mature enough to compete by itself on the market. A solar power plant thus has an operational protocol determining when energy is dispatched, and electricity is sold. These protocols are often pre-defined which means an optimal production is not achieved since irradiation and electricity selling price vary. In this master thesis, an optimization algorithm for electricity sales is designed (in MATLAB). The optimization algorithm is designed by for a given timeframe solve an optimization problem where the objective is maximized revenue from electricity sales from the solar power plant. The function takes into consideration hourly varying electricity spot price, hourly varying solar field efficiency, energy flows in the solar power plant, start-up costs (from on to off) plus conditions for the logic governing the operational modes. Two regular pre-defined protocols were designed to be able to compare performance in a solar power plant with the optimized dispatch protocol. These three operational protocols were evaluated in three different markets; one with fluctuating spot price, one regulated market of three fixed price levels and one in spot market but with zero-prices during sunny hours. It was found that the optimized dispatch protocol gave both bigger electricity production and revenue in all markets, but with biggest differences in the spot markets. To evaluate in what type of powerplant the optimizer performs best, a parametric analysis was made where size of storage and power block, the time-horizon of optimizer and the cost of start-up were varied. For size of storage and power block it was found that revenue increased with increased size, but only up to the level where the optimizer can dispatch at optimal hours. After that there is no increase in revenue. Increased time horizon gives increased revenue since it then has more information. With a 24-hour time horizon, morning price-peaks will be missed for example. To change start-up costs makes the power plant less flexible and with fewer cycles, without affect income much.
Koncentrerad solkraft (CSP) är en snabbt växande teknologi för elektricitets-produktion. Med speglar (heliostater) koncentreras solstrålar på en mottagare som genomflödas av en värmetransporteringsvätska. Denna uppnår därmed höga temperaturer vilket används för att driva en ångturbin för att generera el. Ett CSP kraftverk är oftast kopplat till en energilagringstank, där värmelagringsvätskan lagras innan den används för att generera el. El säljs i de flesta fall på en öppen elmarknad, där spotpriset fluktuerar. Det är därför av stor vikt att generera elen och sälja den vid de timmar med högst elpris, vilket också är av ökande betydelse då supportmekanismerna för att finansiellt stödja förnybar energiproduktion används i allt mindre grad för denna teknologi då den börjar anses mogen att konkurrera utan. Ett solkraftverk har således ett driftsprotokoll som bestämmer när el ska genereras. Dessa protokoll är oftast förutbestämda, vilket innebär att en optimal produktion inte fås då exempelvis elspotpriset och solinstrålningen varierar. I detta examensarbete har en optimeringsalgoritm för elförsäljning designats (i MATLAB). Optimeringsscriptet är designat genom att för en given tidsperiod lösa ett optimeringsproblem där objektivet är maximerad vinst från såld elektricitet från solkraftverket. Funktionen tar hänsyn till timvist varierande elpris, timvist varierande solfältseffektivitet, energiflöden i solkraftverket, kostnader för uppstart (on till off) samt villkor för att logiskt styra de olika driftlägena. För att jämföra prestanda hos ett solkraftverk med det optimerade driftsprotokollet skapades även två traditionella förutbestämda driftprotokoll. Dessa tre driftsstrategier utvärderades i tre olika marknader, en med ett varierande el-spotpris, en i en reglerad elmarknad med tre prisnivåer och en i en marknad med spotpris men noll-pris under de soliga timmarna. Det fanns att det optimerade driftsprotokollet gav både större elproduktion och högre vinst i alla marknader, men störst skillnad fanns i de öppna spotprismarknaderna. För att undersöka i vilket slags kraftverk som protokollet levererar mest förbättring i gjordes en parametrisk analys där storlek på lagringstank och generator varierades, samt optimerarens tidshorisont och kostnad för uppstart. För lagringstank och generator fanns att vinst ökar med ökande storlek upp tills den storlek optimeraren har möjlighet att fördela produktion på dyrast timmar. Ökande storlek efter det ger inte ökad vinst. Ökande tidshorisont ger ökande vinst eftersom optimeraren då har mer information. Att ändra uppstartkostnaden gör att solkraftverket uppträder mindre flexibelt och har färre cykler, dock utan så stor påverkan på inkomst.

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44

Ebrahim, Mila. "Performance Evaluation of a Photovoltaic/Thermal (PVT) Collector with Numerical Modelling." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302122.

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In Photovoltaic/Thermal (PVT) technology, both PV and solar thermal technology are integrated in the same module for simultaneous electricity and heat production. Research has shown that there are multiple benefits from integrating PVT collectors with a ground source heat pump (GSHP) system, since it allows for seasonal storage of thermal energy over the year. Furthermore, it leads to reduced operating temperatures for the PVT collectors which can increase efficiency and lifetime. The aim of this study is to present the electric and thermal performance of a PVT collector developed by Solhybrid i Småland AB, for different environmental and fluid inlet conditions that can occur when PVT collectors are connected to a GSHP system. Furthermore, the performance of this PVT design is evaluated with ASHRAE (Standard 93-2003), to allow for comparison with other PVT collector designs, with values on the overall heat loss coefficient (UL) and heat removal factor (FR). The modelling tool used for the study is the software COMSOL Multiphysics, which uses the finite element method to solve the partial differential equations in heat transfer and fluid flow problems. Based on the performance curves, the thermal and electrical efficiency of the collector is approximately 48.0-53.4% and 19.0-19.2% respectively at a reduced temperature of zero and irradiance levels of 800-1000 W/m2 for the mass flow rate of 0.026 kg/sm2 which was determined as most suitable to increase thermal performance. Furthermore, these results resulted in a heat removal factor (FR) and overall heat loss coefficient (UL) of 0.56-0.62 and 53.4-53.5 W/m2 K respectively. The results on the performance of the PVT collector in different weather conditions shows that the inlet water temperature can significantly affect operating time and the amount of thermal energy that can be extracted during the year, especially if the collector operates in a colder climate like Sweden. To assess the accuracy of the created model, future work includes experimental testing of the studied PVT collector.
En panel med kombinerad teknik av både solceller och termisk solfångare (PVT) kan producera både elektricitet och värme samtidigt. Forskning har visat att det kan finnas flera fördelar med att integrera PVT-paneler med ett bergvärmesystem, eftersom det mjliggör lagring av termisk energi över året. Dessutom leder ett sådant system till lägre drifttemperaturer som kan öka PVT-panelens effektivitet och livslängd. Syftet med studien är att presentera den elektriska och termiska prestandan av en PVT-panel utvecklat av Solhybrid i Småland AB för olika driftförhållanden som kan uppstå på grund av olika väderförhållanden och inlopps-temperaturer när panelerna är kopplade till ett bergvärmesystem. Vidare utvärderas prestandan för denna panel med ASHRAEmetoden (standard 93-2003), för att möjliggöra jämförelse med andra PVT-paneler. Modelleringsverktyget som använts i studien är mjukvaran COMSOL Multiphysics, som använder finita elementmetoden för att lösa partiella differentialekvationer i värmeöverförings-och flödesproblem. Baserat på prestandakurvorna som presenteras i resultatet, är den termiska och elektriska verkningsgraden approximativt 48.0-53.4% respektive 19.0-19.2% för en reducerad temperatur med värdet noll, en solstrålning mellan 800-1000 W/m2, för en massflödeshastighet på 0.026 kg/sm2 som beslutades som den mest lämpliga för att öka den termiska prestandan. Resultaten resulterade i en värmeavledningsfaktor (FR) och total värmeförlustkoefficient (UL) på 0.56-0.62 respektive 53.4-53.5 W/m2 K. Resultaten på PVT-panelens prestanda under olika väderförhållanden visar att vattnets inloppstemperatur kan påverka drifttiden och mängden termisk energi som kan extraheras under året avsevärt, speciellt i nordiskt klimat. För att bedöma korrektheten i resultaten och den skapade modellen rekommenderas experimentell testning av den studerade PVT-panelen.

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Caglar, Ahmet. "Design And Experimental Testing Of An Adsorbent Bed For A Thermal Wave Adsorption Cooling Cycle." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614754/index.pdf.

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Poor heat and mass transfer inside the adsorbent bed of thermal wave adsorption cooling cycles cause low system performance and is an important problem in the adsorbent bed design. In this thesis, a new adsorbent bed is designed, constructed and tested to increase the heat and mass transfer in the adsorbent bed. The adsorbent bed is constructed from a finned tube in order to enhance the heat transfer. Additionally, the finned bed geometry is theoretically modeled and the model is solved time dependently by using Comsol Multiphysics software program. The distributions of dependent variables, i.e. temperature, pressure and amount adsorbed, are simulated and plotted in Comsol Multiphysics. In the model, the dependent variables are computed by solving the energy, mass and momentum transfer equations in a coupled way and their variations are investigated two-dimensionally. The results are presented with multicolored plots in a 2-D domain. Furthermore, a parametric study is carried out for determining factors that enhance the heat and mass transfer inside the adsorbent bed. In this parametric study, the effects of several design and operational parameters on the dependent variables are investigated. In the experimental study, the finned tube is tested using natural zeolite-water and silica gel-water working pairs. Temperature, pressure and amount adsorbed variations inside the adsorbent bed at various operating conditions are investigated. After that, a second adsorbent bed with a larger size is constructed and tested. The effect of the particle diameter of the adsorbent is also investigated. The experimental and theoretical results are compared.

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46

Karki, Bipin. "Experimental and Life Cycle Analysis of a Solar Thermal Adsorption Refrigeration (STAR) Using Ethanol - Activated Carbon." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1524583058600568.

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47

Schön, Gustav. "NUMERICAL MODELLING OF A NOVEL PVT COLLECTOR AT CELL RESOLUTION." Thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-212731.

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Solar photovoltaic-thermal (PVT) modules produce heat and power via a heat exchanger attached to the rear of the PV cells. The novel PVT collector in this study is previously untested and therefore its behaviour and thermo-electric performance due to fluid channel configuration and in various climate and operating conditions are unknown. Moreover, the working fluid flowing through the heat exchanger cause a temperature gradient across the module such that a cell near the inlet and a cell near the outlet may have significant temperature differences. PV cells are sensitive to temperature; however the most common way to simulate power output from a PVT is to use the average temperature and ignore the gradient. In this study, a single diode PV model is incorporated into a commercial thermal solver to co-simulate the thermal and electrical output of a novel PVT module design with cell level resolution. The PVT system is modelled in steady state under various wind speeds, inlet temperatures, ambient temperatures, flow rates, irradiation, convection coefficients from coolant and back of the module and two different fluid channel configurations. The results show that of the controllable variables, the inlet temperature has the highest influence of the total power output and that a parallel flow of the fluid channel configuration is preferable. The difference between the cell resolution and the module resolution simulations do not motivate the use of a higher resolution numerical simulation.
En kombinerad solcellspanel och solvärmefångare (PVT) producerar värme och elenergi på samma yta genom att en värmeväxlare upptar värmen från baksidan av solcellspanelen. Den PVT som berörs i denna studien är nyutvecklad och har aldrig tidigare testats, vilket medför att data för hur den beter sig samt dess termo-elektiska prestanda saknas för olika driftförhållanden samt flödeskonfigurationer. Vidare ger mediet som flödar genom värmeväxlaren upphov till en temperaturgradient, vilken kan innebära en påtaglig skillnad i temperatur mellan solcellerna i solcellspanelen vid mediets in- respektive utlopp. Trots solcellers temperaturkänslighet, så sker simulering i allmänhet med avseende på panelens medeltemperatur istället för att hänsyn tas till denna temperaturgradient. I den här studien implementeras en så kallad ”single diode”-modell i en kommersiell numerisk mjukvara termiska beräkningar för att samsimulera termiskt och elektriskt effektuttag ur den nyutvecklade PVT-designen. Designen modelleras statiskt under givna variationer av vindhastighet, inloppstemperatur, omgivande temperatur, flödeshastighet, solinstrålning och konvektionskoefficienter för mediet samt baksidan av modulen. Resultaten visar att kontrollerbara variabler som inloppstemperatur har högst inverkan på den totala effekten samt att en parallell flödeskonfiguration lämpar sig bäst. Studien visar också att skillnaden mellan simulering på cellnivå och modulnivå inte motiverar en numerisk beräkningsmetod med upplösning satt till solcellsnivå.

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Gimeno, Furió Alexandra. "On the use of nanofluids to enhance the direct absorption of solar radiation." Doctoral thesis, Universitat Jaume I, 2019. http://hdl.handle.net/10803/666638.

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The present thesis evaluates the potential of solar nanofluids as direct absorption solar collectors and to generate steam. Nowadays, as energy consumption continues to rise while conventional energy are close to begin exhausted, there is an increasing demand for renewable energy technologies, especially solar thermal. Currently, solar thermal energy systems include numerous losses due to the heat transfer processes, thus, nanofluids have been proposed to enhance the solar collectors efficiency through the direct sunlight absorption. In this work, optical properties of different nanofluids carbon based have been characterised in order to study their suitability as direct absorption solar collectors.
La presente tesis trata de evaluar el potencial de los nanofluidos solares para absorber directamente la radiación solar e intentar generar vapor. Como el consumo de energía continúa aumentando y las fuentes de energía convencionales se están agotando, aparece como excelente alternativa, el uso de las energías renovables, concretamente, la energía solar térmica. Los sistemas actuales de energía solar térmica presentan numerosas pérdidas debido a los procesos de transferencia de calor, por ello, se han propuesto los nanofluidos solares como absorbedores de la radiación y fluidos de transferencia de calor y así, mejorar la eficiencia del proceso de generación de vapor en las centrales solares térmicas. En este trabajo, se ha realizado la caracterización de las propiedades ópticas de diferentes nanofluidos solares basados en nanopartículas de carbón para estudiar su idoneidad en la aplicación solar térmica.

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Vacek, Tomáš. "Posouzení možnosti připojení kogenerační výrobny 138 MW v Prostějově." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219083.

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The goal of this project is to test the possibility to connect the Cogenerational generation of power 138 MW (still in the development stage) to the control room 110 kV in Prostejov production. This merge would product the electrical energy as well as the heat energy for all local area. In this dissertation we will be considering the solution of the steady state (stationary state) of system with the voltage level of 110kV, as well as the influence of the generation of power on this system, there by the suggesting a connection. The Congenerational production indicates higher effectiveness in the transformation of energy during primary production process due to the production of heat energy as well as the electrical energy from the primary power sources. In our country, as well as around the world, commonly used fuels are fossil fuels- coal, crude oil, and gas. As the demand for energy grows, those supplies are slowly running out. Not to mention that those fuels have a negative environmental impact. They are a source of carbon, which causes damage to the atmosphere and leads to global warming. Power plants which do not produce carbon are much safer for the environment, and much more productive. However, the residue of this energy is challenging to dispose of. Nuclear energy has common attributes with renewing the sources of energies that are extremely friendly to our environment. Nuclear power plants also produce enough energy and with the usage of Fourth generation reactors, they will be able to recycle the nuclear fuels. Today, more importance is put on renewing sources which are more gentle for the environment. In the near future, CEZ Company, the largest producer of electric energy is planning to use water energy. Water energy comes from water plants or dams. Other ecological forms of energy include geothermal and solar energies. These two types of energy are not as applicable for our geographical position. Geothermal energy is commonly used on islands where there is an abundance of natural hot springs. The most discussed source of energy is bioenergy. It uses natural wood sources, recycled wood products, and applies bioenergy as a main source for thermal power plants.

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Macoszek, Pavel. "Kogenerační jednotky na rostlinný olej." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220164.

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The thesis is focused on cogeneration units on vegetable oil. The first chapter contains basic information about the production, supply and consumption of electric energy in the Czech Republic and about renewable energy sources. The following chapter is devoted to possibilities of use oil kinds of phytomass in the Czech Republic, or products made from them. Next chapter is mentioned on legislation allowing the use of used cooking oils for energy purposes. It contains a summary of the laws and regulations and options regarding subsidies for electric and heat power. The main objective of these chapters is to explain the issue of the establishment and operation of cogeneration units on vegetable oil. The following chapters are devoted to the design and study of simultaneously operated cogeneration unit on the vegetable oil with a combustion engine and the calculation of economic operation running. The reason of study is to evaluation, which on based of the input values and calculation methods determine the economic efficiency of the project cogeneration unit on vegetable oil under mode purchase price and mode green bonus. Appreciation is also given to the overall legal review and responsibilities of cogeneration units on vegetable oil.

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