Energy And Exergy Analysis Of Organic Rankine Cycle Using Different Working Fluids

Rapid urbanization and industrialization have led to rapid growth in energy consumption,especially the increase in fossil fuel consumption.However,fossil fuels are the main cause of greenhouse gas emissions,and greenhouse gas emissions have caused serious environmental and health problems.In order to reduce emissions,reduce dependence on fossil fuels,and respond to the energy crisis,it is necessary to improve the energy efficiency of enterprises.About 60%of the low and medium temperature heat energy in the manufacturing industry is directly discharged into the environment.Therefore,the low and medium temperature waste heat recovery is one of the main solutions to control energy costs and reduce greenhouse gas emissions under the conditions of continuous growth in global energy demand.Nowadays,among the waste heat recovery technologies,the Organic Rankine Cycle(ORC)is considered to be an effective solution for low and medium-temperature waste heat recovery for power generation due to its high efficiency,flexibility,simple structure and environmental protection.The important advantage of ORC is that it can be successfully used in various fields of biomass combustion,geothermal systems,and solar power generation systems,and it is very beneficial when the exhaust gas of the gas turbine is in a low-temperature state.This work represents a theoretical and numerical approach for evaluating both energy and exergy analysis of the basic and three modified organic Rankine cycles using Engineering Equation Solver(EES)software.In this analysis,the basic ORC system was modified by incorporating an internal heat exchanger,single-stage regeneration,and double-stage regeneration under the same heat source.R113,R141b,R123,R245fa,and R600a are the fluids used in this study.The calculation and analysis results show that using R113 and R141b as working fluids DSRORC system gives the maximum thermal efficiency(25.16%),(23.02%),exergy efficiency(38.38%),(35.08%),network output(59.73kW),(54.55kW),and the lowest total system exergy loss(40.89kW),(51.06kW)and basic ORC gives the lowest thermal efficiency(19.29%),(17.79%),exergy efficiency(30.07%),(28.04%),network output(48.62kW),(44.84kW),and the highest total system exergy loss(51.83kW),(58.88kW)as compared to other cycles at the evaporator pressure(EVP)of 2.5MPa,respectively.The results also show that if the EVP is increased from 2.5 MPa to 3 MPa,the performance of the basic and three modified ORCs increase with each working fluid,while the total system exergy loss decreases because of the reduction in the temperature difference between the temperature of the hot gas stream getting into the evaporator and the evaporator temperature itself.Therefore,the used exergy and in addition the exergy efficiency are enhanced.Furthermore,it has been concluded that the evaporator played a significant role in ORC systems performance because its exergy loss was maximum,which was enhanced by increasing its pressure.