Study On Irreversible Thermodynamics Of Heat Transfer Process In Organic Rankine Cycle

Based on the second law of thermodynamics and the theory of irreversible thermodynamics,this paper presents an irreversible thermodynamics analysis of the cyclic heat transfer process of organic Rankine Cycle(ORC),and presents an irreversible parameter,which characterizes the heat transfer process in the thermodynamic cycle.Cycle external heat transfer process irreversibility,said the temperature difference due to heat transfer caused by the external heat transfer process of the loss rate.The theoretical model of the irreversibility of the heat transfer process is established.The relationship between the irreversibility and the net output power,thermal efficiency and the efficiency is discussed.The theoretical relation of heat transfer irreversibility in organic Rankine cycle is defined and deduced.The deviation and applicable range of the model are calculated.It is shown that the theoretical model can be used to simulate the organic Rankine cycle,and the deviation between theoretical model and actual organic Rankine cycle calculated value is less than 5%.The effective heat energy ratio of the heat source is proposed and defined,which indicates that it is the maximum thermal efficiency between the heat source and the ambient temperature.The irreversible degree of heat transfer has a transition temperature of the heat source.When the heat source temperature is less than the heat source transition temperature,the irreversible degree has the minimum value;it is an optimization of condition,but the optimization condition is different from that of the net work.When the heat source temperature is higher than the heat source transition temperature,the irreversibility decreases monotonically with the evaporation temperature.The variation law of irreversibility with inlet temperature,evaporation temperature,temperature difference of narrow point and Jacob number was studied.The irreversible degree of irreversibility is analyzed by the irreversibility theory model.The relationship between the irreversibility and the net work,thermal efficiency and efficiency is analyzed.It is shown that the irreversible theoretical model is consistent with the actual variation of organic Rankine Cycle.