Experimental Research Of Organic Rankine Cycle System And Optimization Based On Exergy Analysis

With the development of economy,the demand for energy in countries all over the world increases sharply.The unreasonable use of energy will not only cause a waste of energy,but also have an impact on the environment.Driven by the concept of carbon peak and carbon neutralization,Improve energy efficiency,Recovery and utilization of waste heat resources is an effective way to solve the energy problem.The organic Rankine cycle system generates electricity by using the heat in the low temperature heat source.It is a low temperature waste heat utilization technology that converts low quality energy into high quality energy.Can achieve the goal of making full use of energy,.At present,the technology is not fully mature,There is a lot of room for optimization to improve the system,Optimization of organic Rankine cycle system,In this paper,under the combination of experiment and mathematical analysis,The experiment and optimization of organic Rankine cycle system based on exergy analysis are carried out.The experiment of organic Rankine circulation system was established,The system uses R142 b as the circulating working medium,The heat source temperatures are 70℃,73℃ and80℃,Performance test of expander speed under 400r/min-1600r/min condition,Analyze the experimental data,The heat absorption of the system increases with the increase of expander speed,The change trend of heat absorption of the system at the same speed of the expander is related to the temperature of the heat source,The system has the maximum output power when the speed of the expander is adjusted,The output power of the system is greatly affected by the speed of the expander and the temperature of the heat source,When the heat source temperature is 80℃ and the speed of the expander is 800r/min,the thermoelectric efficiency of the system is the highest,which is 6.67%,When the heat source temperature is 70℃ and73℃,the thermoelectric efficiency of the system does not have the optimal result in the expander speed range.The study of organic Rankine circulation system by using the method of exergy analysis shows that,Results of the conventional exergy analysis at the temperature of each heat source,The speed adjustment of expander has little effect on the efficiency of system heat exchanger.The evaporator of the system is the most efficient component,The change of the speed of the expander has a great influence on the efficiency of the expander,With the increase of the rotational speed of the expander,the exergy destruction of each part of the system shows an upward trend,The exergy destruction of working fluid pump has little influence on the change of expander speed,The main components of the system with large exergy wear and tear are expander,evaporator and condenser,Account for 92% or 96% of the total exergy destruction of the system,The expander is the main source of irreversible destruction of the system.The results of advanced exergy analysis of the system at a heat source temperature of80℃ show that,The exergy damage of system components is mainly endogenous and avoidable,The change of the speed of the expander has a great influence on it,The improvement potential of the system decreases gradually with the increase of the rotational speed of the expander.Comparison of actual cycle with ideal cycle and inevitable cycle,The increase of expander speed increases the exergy efficiency gap between evaporator,condenser and working fluid pump.The exergy efficiency of the expander is similar at the speed of 800r/min.The inevitable endogenous exergy destruction of the evaporator accounts for the vast majority,although the exergy destruction is large,but the potential for improvement is small.Most of the expander damage can avoid endogenous damage and has great potential for improvement.The gap between the expander and the advanced level can be shortened by adjusting the rotational speed,The main destruction of condenser is inevitable endogenous destruction,which is less affected by the adjustment of expander speed.However,the increase of expander speed will avoid the increase of endogenous exergy destruction,and then the potential for improvement will be reduced,Most of the damage of working fluid pump can avoid endogenous exergy destruction,which is related to the adjustment of expander speed,The decrease of the rotational speed of the expander will reduce the avoidable endogenous exergy destruction of the working medium pump,improve the potential for improvement,and the working medium pump can have higher operation efficiency.