Research On Performance Of Dual-pressure ORC Coupled Jet Refrigeration Power And Cooling Co-generation System

There are great amount of low-grade heat sources in nature and in the industrial production process.If appropriate technology is used to convert them efficiently,it will produce huge economic and ecological benefits.Based on dual-pressure evaporation organic Rankine cycle(DORC)and ejector refrigeration cycle(ERC),this paper constructs two novel types of combined power and cooling systems,the DEPCC-LG,which uses liquidejection ejector and the DEPCC-LG which uses gas-ejection ejector.Based on matlab,the system thermodynamics and technology economic model were established,and the effect of the key operating parameters on both the thermodynamic performance and technology economic performance was studied.The system performance and working fluid selection were optimized by utilizing the genetic algorithm.For DEPCC-LG,a net power output of 13.58 k W,and cooling output of 3.85 k W are obtained under given conditions,the corresponding thermal efficiency,exergy efficiency and total unit product cost(SUCP)are 14.25%,47.78% and 182.86$/MWh.The results of parameter analysis show that the outlet temperature and dryness of the low-pressure steam generator,and the working fluid mass flow ratio of high-pressure stage to low-pressure stage have a significant effect on cooling output of the system.There are optimal values for the low-pressure evaporation temperature and the dryness of lowpressure steam generator outlet.The working fluid mass flow ratio of highpressure stage to low-pressure stage should not be too small.For DEPCC-GG,net power output of 10.41 k W,and cooling output of 5.89 k W are obtained under given conditions,the corresponding thermal efficiency,exergy efficiency and SUCP of the system are 17.55%,37.16% and 216.91$/MWh.The parameter analysis results show that increasing the outlet temperature and dryness of the low-pressure steam generator is benefit to improve cooling output,but decreases the net power output.There exist optimal values of high-pressure evaporation temperature,the low-pressure evaporation temperature and the low-pressure steam generator outlet dryness,if these parameters deviate from the optimal values,the exergy efficiency will decrease and the SUCP of the system will increase.Taking the system thermal efficiency,exergy efficiency and SUCP as the objective functions,the multi-objective function optimization is performed based and the optimal solution is given.Under optimized operating conditions,the DEPCC-LG system has higher exergy efficiency and lower SUCP than the DEPCC-GG system.Exergy Analysis results show that,for DEPCC-LG,the condenser and the two steam generators are the components generate much exergy destruction in the system,for DEPCC-GG system,the ejector is the main component generates most exergy destruction in the system.Under the condition that the heat source inlet temperature is 433.15K-523.15 K,the system’s adaptability to the working fluids R227 ea,R236ea,R245 fa,R600,R600 a,R601,R601 a,R1234yf and R1234 ze was investigated,and the optimal working fluid selection of the system under different heat source inlet temperature conditions is given.