Papers by Keyword: Exergy Analysis

Abstract: To assess the efficiency and performance of a solar-powered fish drying system, a comprehensive exergetic analysis was conducted. The system was developed to enhance fish preservation in coastal and inland communities using renewable energy. The study evaluates the dryer’s thermodynamic behaviour based on the second law of thermodynamics, identifying energy losses and optimization opportunities. Key parameters such as solar irradiance, thermal energy, exergy destruction, and exergetic efficiency were analyzed. Results revealed that the solar-powered dryer achieved a maximum thermal and exergetic efficiencies of 72% and 54% respectively, demonstrating sustainability and viability for off-grid applications. The analysis supports the system’s potential for energy optimization and food preservation in low-resource settings.

Abstract: Flared natural gas emissions are one of the main sources of environmental pollution and global warming. To recover this gas, the presence of impurities like CO₂ in high concentrations forces oil producers to escape from investing in such intensive processing. Several implementations of no flaring methods have been reported in the literature, however, there have been limited concerning the bulk-CO₂ natural gases. This research developed an innovative idea for the use of the SOFC CHP system to recover flared bulk-CO₂ associated gas of Neem-Field in Western Sudan. The exergy of the system and the performance of the SOFCs are investigated in this paper, in addition to environmental and economic analysis. The simulation (Cycle-Tempo^©) results demonstrate that the proposed system can generate 1 MW electrical power and 0.068 MW thermal energy with efficiency approached 43.3% (based on LHV). The exergy analysis showed that 38% of system losses occurred in the air preheaters. Instead of conventional gas-burning, recovering the flared gas reduced the equivalent CO₂ GHGs emissions by 80%. Overall, the novel solution found to be environmentally friendly, and economically appealing with a total capital investment estimated to be US$1.175 million and a cost of electricity (COE) of 4.07 cents per kWh.

Abstract: In this paper, a numerical analysis of flow and temperature distribution of a small raised-floor data centre is conducted in order to evaluate the thermal performance of the data centre. The flow patterns and temperature profiles established leads to a detailed exergy analysis of the data centre, which results in better understanding of irreversibilities in room airspace. The impact of the rack location in the data centre room and the airflow direction through perforated tiles on the thermal performance of the data centre is investigated using first-law and second-law of thermodynamics.

Abstract: Living organisms are open dissipative thermodynamic systems that rely on mechano-thermo-electrochemical interactions to survive. Plant physiological processes allow plants to survive by converting solar radiation into chemical energy, and store that energy in form that can be used. Mammals catabolize food to obtain energy that is used to fuel, build and repair the cellular components. The exergy balance is a combined statement of the first and second laws of thermodynamics. It provides insight into the performance of systems. In this paper, exergy balance equations for both mammal’s and green plants are presented and analyzed.

Abstract: In this paper an improved method for fuel cost apportionment of a combined power cum a desalination plant is presented. The conventional analysis for cogeneration systems has been, hitherto, the energetic (enthalpy) method which is useful for efficiency evaluation purposes, but it may not be fully accurate for capturing the “quality of fuel energy” consumed by processes in producing two or more useful effects, e.g., electricity and water. An exergy destruction procedure is proposed for the cost apportionment of fuel energy consumed where the available work potential of expanding stream can be fully accounted for cost distribution of the designed processes. For example, the turbines, that is used for power generation, exploits mainly the sensible-energy changes of high enthalpy steam undergoing expansion at high pressures and temperatures, whilst the thermally-activated desalination processes, such as the multi-effect distillation (MED), needed only the high latent-heat of bled-steam but at low pressures that has negligible work potential if the steam were to be used in the turbines. From this analysis, the incurred exergy destruction by the desalination processes is only 2%-7% of the total destruction available to the plant with bled-steam up to 50% of the total flow. We examined the ratio of exergy destruction consumed by the water to power production and, such a ratio is used as a basis for the fuel-cost determination in the cogeneration plant. It captures not only the realistic exergetic value of bled-steam of MED desalination, but it exposes the major shortcomings of the conventional enthalpy changes where a disproportion share of the input fuel cost, up to 32% of the total fuel input, may have been erroneously apportioned and giving an unfair valuation of the operational water cost.

Abstract: The paper presents a study of a thermal assessment of an Organic Rankine Cycle (ORC) energized by heat absorbed from a parabolic trough collector (PTC) located in Derna, Libya. Both the ORC and PTC are modeled using the IPSEpro software. The simulation results are used to evaluate the system performance using energy and exergy analysis. The study showed the PTC collector was the main contributor of the energy and exergy losses within the PTC system and the evaporator within in the ORC. At this specific weather conditions, the ORC was able to produce about 3 MW electrical powers from the powered PTC heat. Moreover, exergy efficiency of the PTC was 47.7 %, the heat engine was 23.3 % and for the overall system (PTC and ORC) was 11.1 %.

Abstract: The present work deals with thermodynamic analysis of a R-134a/R-23 cascade refrigeration system to evaluate the maximum COP and the minimum temperature difference (D_T) corresponding to , by considering different operating parameters. The operating parameters includes: the condensing () and evaporating temperature () of R-134a and the condensing () and evaporating temperature () of R-23. A computational model has been developed for the considered system to evaluate the and D_T corresponding to based on the thermodynamic principles. A mutilinear regression analysis has been carried out to evaluate two correlations for calculating and minimum D_T considering the above operating parameters. The exergy analysis of the system is also performed to determine the irreversibility losses of the system as well as for the components. It has been found that the total exergy destruction rate of the system is lower at minimum .

Abstract: The objective of present study is to conduct exergy analysis on flat plate solar photovoltaic thermal (PV/T) hybrid system. The solar insolation, current, voltage, inlet and outlet air temperature of the cooling duct, ambient air temperature, and solar panel surface temperature are the major parameters used to calculate the energy and exergy efficiency. An amended electrical efficiency is used to estimate the electrical output and performance of PV/T hybrid system. Further, an enriched equation for the exergy efficiency of a PV/T hybrid system has been used for exergy analysis. Finally, parametric studies have been carried out. An extensive energy and exergy analysis is carried out to calculate the electrical and thermal parameters. The experimental results are in good agreement with the earlier studies. In addition to that, the electrical efficiency, thermal efficiency, electrical thermal efficiency, overall energy efficiency and exergy efficiency of PV/T hybrid system is found to be about 9.78%, 24.22%, 27.17%, 44.84% and 11.23% respectively.

Abstract: Currently, most of the boilers in power plant are designed by the heat balance based on first law of thermodynamics only, and it analyses the condition of using energy from the perspective of quantity of energy. However, The real energy utilization should be justified not only from the quantity but also from the quality, because the quality of energy based on second law of thermodynamics can reflect the irreversibility in processes and components. In order to revealing the real energy losses, we must establish exergy analysis model of 130t/h Biomass-Fired Boiler. This article calculates the exergy losses of all kinds of boiler surface and the overall exergy efficiency of boiler, together with exergy distribution characters analysis result of 130t/h Biomass-Fired Boiler. The results obtained open out the greatest exergy loss and the place to generate these losses of boiler, and provide scientific gist for improving utilization of boiler energy.

Abstract: A new energy recovery system based on scroll expander is presented according to the characteristics of low-grade energy in this paper. It is discussed for the expression of the system efficiency and its influential factors with the method of Exergy Analysis. And the influence curves of relationship between the expander’s inlet pressure and system efficiency are obtained through computer simulation and laboratory experiments. The test result of the comparison of different the recycling system shows that the recycling method based on scroll expander is more efficiently than others in the area of recycling low-grade energy.