Theory Of Trapezoidal Cycle And Its Thermodynamic Principles

The conventional organic Rankine cycle(ORC)is confined by the actual working fluids,and the physical property of the working substance is quantitative.Therefore,we can not proceed he theoretical or general law research.Based on trapezoidal cycle(TPC)and its theoretical model,The mathematical relationship of independent variables for the shape and physical property of saturated line of working fluid is established(slope of saturated liquid line,slope of saturated gas line and critical temperature).The model of working fluid for simulating linear saturated line is established.And then the mathematical model of the cycle performance and the saturation line and physical property of the working fluid is established.The general thermodynamic law of the influence of the property of working fluids on the cycle performance is studied theoretically.Researched the transformation relationship between trapezoidal cycle,Carnot cycle and triangle cycle(TLC),and the work out put(and extreme value work),thermal efficiency and energy efficiency,APR and its upper and lower limit relation between them.Based on the physical model of simulating saturated line and TPC,the influences of the physical properties of working fluids on the cycle performance were studied.Studied on the heat source shift temperature of the working fluids in the circulation and its corresponding optimization characteristics.Based on the linear saturated model,the general laws of cycle performance were studied and the guiding roles of the simplified model of the working fluids to the actual circulation were analyzed.The results show that: The TLC and the Carnot cycle are the upper and lower boundary cycles of the TPC.The relationships between the there work out put(and extreme value work),efficiency and energy efficiency,APR has the upper and lower bounds.The effects of the physical properties of working fluilds to the cycle thermal efficiency and net work output in simulating saturated line model are obtained.The theoretical expressions and characteristics of heat source shift temperature in linear saturated line working fluids are obtained.It is found that the maximum thermal efficiency of the cycle is related to the dry and wet properties of the refrigerant.