Exergetic performance assessment of an integrated solar energy system (original) (raw)
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Journal of Cleaner Production , 2012
The serious environmental degradation of our planet in the past century and the limitation of supplies of conventional fuels have led humanity to search for new energy forms. The housing sector has a big environmental impact and it makes a good candidate for changes to be implemented in order to make steps towards a sustainable society. This study deals with the exergy analysis and the Life Cycle Assessment (LCA) of solar systems for space heating, cooling and hot domestic water production. These systems will be applied to a residence in the wide Thessaloniki area, in Northern Greece. The analysis is based on the given energy needs of an average house. Furthermore, a photovoltaic system (PV) will be used for electricity production. Besides Solar energy, the existing geothermal field will be utilized via heat pumps. The system is designed to exploit solar and geothermal energy and an exergy analysis of the different elements of the system is performed so that improvements can be achieved in its efficiency and its cost be reduced. It has been shown that the exergy efficiency of the solar systems and the geothermal system are relatively low. Since almost all of the environmental impacts of the renewable energies are connected to the manufacturing of the devises for their utilization, the environmental impacts will be analyzed only at the manufacturing stage. The use of Life Cycle Assessment (LCA) will be used. It has been shown that the use of solar cooling has the highest environmental impact. This analysis applies for all regions since the energy needs could be adjusted and the solar radiation of that region taken into consideration.
2016
The development of air-conditioning systems that run on renewable energy sources will save electrical energy, which is mainly produced by the burning of fossil fuels. These systems will significantly reduce carbon emissions, and as a result environmental pollution and global warming effects of indoor climate control will be reduced. Among the various renewable energy sources, solar energy has proven to be the best option for air-conditioning because the maximum load on an air-conditioning system for cooling coincides with the period of greatest solar radiation input from the sun. Utilization of energy resources is related to sustainable development. To achieve sustainable development, increasing the energy efficiencies of processes utilizing sustainable energy resources plays an important role. Exergy, which is based on the second law of thermodynamics, is a useful tool to analyze energy systems, must be considered during their evaluation and modeling. Exergy analysis has been widel...
Renewable energy, Exergoeconomic, Cogeneration system, Solar power Increasing environmental pollutions and the expense of fossil fuels necessitates employment of efficient instruments and easily producible clean sources as abasic solution to this problem. Cogeneration systems are used for their high performance with a performance of approximately eighty-five percent Cogeneration production system with renewable energy source is the best solution to fuel suitable and high cost Amon all renewable energy sources, use of solar power is of interest. Solar power is the best choice because it's free and clean. This project illustrates the analyzed exergy and eregyeconomic simulations of solar hybrid cycle. Thermo economic and exergoeconomic analysis where used in this research, with exergoeconomic we can analyze cycle cost, payback period and exergy performance. Case study for this project was a building with 480 m² or square meters area in Zahedan, Iran. In this study, a small scale hybrid solar heating, cooling and power generation set-up including solar collector, screw expender auxiliary heater, adsorption chiller, etc., was proposed and extensively investigated.
Solar air conditioning systems and their applicability—An exergy approach
The energy use in the building sector for space heating, cooling and water heating, in the European Union Based, reaches the level of on 40% of the total used energy. The building sector is the biggest user of energy, having surpassed the transportation and industry sectors. Additionally, the energy transformation processes and the use of energy are responsible for 94% of the total emissions of CO 2, with 45% coming from the building sector. The applicability of solar cooling in Greece was investigated in a medical centre in Igoumenitsa. The use of thermal solar system in the medical centre creates significant environmental benefits in the area of climate change with the reduction of CO 2 emissions. The investment cost of such a solar thermal system (70 kW, AB absorption technology and a collector area of 291 m 2 ) reaches the level of 600D /m 2 of solar collector area.
Fuel and Energy Abstracts, 2010
A solar assisted absorption refrigeration system (SAARS) was designed for acclimatizing of villas in Mardin which is located in Turkey and the performance of the system under different temperatures was analyzed by using MATLAB. Hourly cooling load calculation of the villas was done between 15th of May and 15th of September by considering the season for the cooling. Cooling capacity
Journal of Modern Green Energy
Background: Concentrated solar power (CSP) technology has been gaining more and more attention due to its inherent sustainable merit. Further promotion of sustainability requires the effective utilization of concentrated solar thermal radiations which can achieve through combined cooling, heat and power. In this context, the key objective of the research carried out in the present study was to propose and develop a novel solar thermal-driven combined cooling, heating, and power system for producing power of 7MW. Objective: The objective of the study is to reduce heat loss at various places and to increase the overall energy and exergy efficienices of the system. The effect of very influencing parameters like direct normal irradiance (DNI), extraction pressure, turbine back pressure, turbine inlet pressure, and pump inlet temperature were ascertained on energy and exergy efficiencies for the trigeneration system. In addition, the model was extended to incorporate the evaluation to id...
Exergetic Studies on Domestic and Industrial Solar Water Heaters
International Conference on Information Engineering, Management and Security 2014, 2014
For a Solar Water Heater ,solar energy coming from sun in the form of solar radiations in infinite amount, when these solar radiations falls on any absorbing surface, then they gets converted into the heat, this heat is used for heating the water. Present study based on exergy theory. Exergy analysis is conducted with an objective of providing methods to save cost and to increase the efficiency of solar water heater. The calculation of exergy losses is also done. To optimize and allocate losses in energy systems exergy analysis has been widely used. Exergy is the indication for loss of available energy due to the creation of entropy in irreversible thermal systems or thermodynamic processes. The exergy loss in a system or process component is decided by multiplying the absolute temperature of the surroundings by the entropy increase. Exergy is defined as a maximum useful work that can be done by a system interacting with an environment. In the design, simulation and performance evaluation of energy systems Exergy analysis has been widely used.
Framework for analysis of solar energy systems in the built environment from an exergy perspective
Renewable Energy, 2010
Exergy analysis is a more powerful tool than mere energy analysis for showing the improvement potential of energy systems. Direct use of solar radiation instead of degrading other high quality energy resources found in nature is advantageous. Yet, due to physical inconsistencies present in the exergy analysis framework for assessing direct-solar systems commonly found in literature, high exergy losses arise in the conversion process of solar radiation in direct-solar systems. However, these losses are disregarded in indirect-solar systems. In this paper, contradictions and physical inconsistencies which result from including the conversion of solar radiation only for direct-solar systems are shown. An evaluation framework physically coherent for systems making direct and indirect use of solar radiation is derived and its physical correctness is thoroughly discussed. Results from case studies using the proposed framework are presented and compared with the conventional approach, enabling their direct comparison and better understanding of the benefits and correctness of the proposed method. The new method allows recognizing clearly the suitability of direct-solar systems, being appropriate for highlighting more sustainable energy supply systems. Although this paper focuses on building systems, the framework might be used for exergy analysis of direct-solar systems in the context of other energy uses.
Energy Conversion and Management, 2020
In the present research work, three novel topologies (Configuration-1, Configuration-2 and Configuration-3) of solar energy driven combined cooling, heating and power (CCHP) system are proposed to identify eco-friendly system for future energy demand and human comfort. The proposed CCHP systems consist of solar thermal evacuated U-tube collector, organic Rankine cycle for power, ejector refrigeration cycle for cooling and heat exchanger for heating. Through theoretical analysis, the thermodynamic (energy and exergy) performances of all three configurations are investigated by utilizing solar energy and compared by estimating the objective functions like performance index, irreversibility, exergy efficiency, net work output, heating output, entrainment ratio and cooling output. The objective functions are analyzed on the basis of generator temperature, evaporator temperature, condenser temperature and solar intensity as decision variables. The practical feasibility of the proposed systems is discussed as well. It is revealed that configuration-1 has maximum overall exergy efficiency and power output while configuration-3 has maximum performance index and heating output as compared to other configurations. Configuration-2 has maximum cooling output as compared to other configurations. In overall, Configuration-3 is best considering higher energy performance, lower number of components (compactness), wider operating range and energy demand flexibility while other configurations also have their merits.
Exergy analysis of solar assisted double effect absorption refrigeration system
Renewable Energy, 1998
Exergy or the available energy is based on the second law of thermodynamics and goes back to Maxwell and Gibbs. It is the exergy content and not the energy content, that truly represents the potential of the substance to cause change. Exergy is the only rational basis for evaluating the system performance. The aim of this project is to study in detail the exergy variation in the solar assisted absorption system. The influence of the cycle parameters are analysed on the basis of first law and second law effectiveness and the results indicated various ways of improving system performance by better design. Also a better quality of the evaporator has more effect on the system performance than the better quality of other components. It was shown that second law analysis quantitatively visualizes losses within a system and gives clear trends for optimization.