| Technical fields such as waste heat recovery,energy-saving,environmental protection and power generation are closely related to the Organic Rankine cycle(ORC),and it plays an important role in low-temperature waste heat power generation.This paper analyzes a GT-ORC combined cycle that uses the ORC to re-utilize the waste heat of gas turbine(GT)flue gas.It has a strong capacity for waste heat recovery and can be used to solve many key problems such as the use of a large amount of flue gas waste heat and environmental thermal pollution.However,the research on the gas turbine-ORC combined cycle is not yet complete.Therefore,this paper takes the waste heat recovery of gas turbine flue gas as the background to study the thermodynamic process and performance of ORC.The following studies have been carried out:Firstly,based on the thermodynamic analysis of the ORC,the main research is to study the influence of expander inlet temperature and pressure on the power ratio,thermal efficiency,exergy efficiency,and net output power.The research results show that while keeping other parameters unchanged,the inlet temperature and pressure of the expander are the main factors that affect the thermal efficiency and net output power.Except for the work ratio,other parameters decrease with the gradual increase of the inlet temperature of the expander and increase with the gradual increase of the inlet pressure of the expander.This difference is mainly caused by the change in the mass flow of the working fluid in the system.The net output work and thermal efficiency are mainly positively correlated with the critical temperature of the working fluid.R141 b is selected as the working fluids of the ORC system in the combined cycle.Then,a method for screening the mixed working fluid combination of the ORC is proposed.Based on the relationship between the temperature slip and difference pinch point of the condenser and the boiling point difference method,the performance parameters of eight mixed working fluids systems were compared and analyzed.The research shows that the net output work and thermal efficiency of the four mixed working fluids containing R141 b are better than those of other mixed working fluids.When the mass ratio of butane/R141 b is(0.9/0.1)and(0.8/0.2),the thermal efficiency and net output power are higher than those of other mixed and pure working fluid systems.The net output power and thermal efficiency of R141 b are higher than that of some mixed working fluids,indicating that the net output power and thermal efficiency of mixed working fluids are not necessarily greater than that of pure working fluids.The different mass ratios directly affect the performance of the system.Among them,butane/R141b(0.2/0.8)has the best performance overall.Lastly,this study is about energy and exergy analysis of the combined cycle of gas turbine integrated with ORC.The advanced exergy analysis splitting exergy destruction rate into endogenous,exogenous,avoidable and unavoidable parts to provide detailed information about improvement potential of the system components.The results of advanced exergy analysis show that the cycle has high potential for efficiency improvement.The research shows that the thermal efficiency of the GT-ORC system is 28.42 %,the exergy efficiency is 37.42 %,and the output power is 114.64 MW,which has a good thermal performance.The exergy loss of gas turbine-ORC system is mainly determined by two factors: the structure of system components and the interaction between different components of the system.In the optimization work,the emphasis should be placed on improving the performance of the system components,especially the heat exchange components such as the evaporator and condenser,which have certain guiding significance for the actual production design. |
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