Research On A Novel Combined Power And Refrigeration Cycle And The Separation Performance Of Zeotropic Mixture

Energy,as a significant driving force for the human society,has brought lots of bad effects,such as environment problem.Many combined cycles have been proposed to solve these problems.The combined cycles have higher energy conversion efficiencies with energy cascade utilization.And they could be driven by low temperature heat source(<200℃),such as industrial waste heat,geothermal energy,etc.The combined power and ejector-refrigeration cycle based on organic Rankine cycle and ejector refrigeration cycle is one of them.It could utilize the low temperature heat source efficiently and has a simple structure.However,the heat transfer process in the generator and condenser could generate much exergy destruction.In this paper,the combined power and ejector-refrigeration cycle(cycle C)performance with zeotropic mixture is analyzed.The result shows that the cycle with zeotropic mixture has higher exergy efficiency compared to that with pure fluid.And the cycle performance varies as the fluid composition changes.With MFt=50%,the cycle exergy efficiency achieves the maximum value of 9.77%,but the cycle thermal efficiency,refrigeration output and entrainment ratio yield the minimum value of 7.92%,43.11 kW and 0.063,respectively.The entrainment ratio is so small that it is hard to realize in the engineering project.The parametric analysis result indicates that the evaporating temperature,generating temperature and the condensing temperature have great effect on the cycle performance.The cycle exergy is more sensitive to the generating temperature variation.A new combined power and ejector-refrigeration cycle based on the organic Rankine cycle and ejector-refrigeration cycle with zeotropic mixture is proposed in this paper.There are two forms: cycle A and cycle B.The expanded mixture from the expander is cooled to two-phase flow in the condenser,and then is separated into two parts: saturated vapor and saturated liquid.And the saturated vapor or liquid enters the power cycle or the refrigeration cycle.It is found that,compared with cycle C,cycle B generates more refrigeration output and has higher exergy and thermal efficiency.The parametric analysis shows that the generating temperature,evaporating temperature,condensing temperature,pressure ratio and the vapor quality of condenser have great effect on the cycle performance.A new liquid-vapor separator called T-junction separator is applied in the new combined cycle as a main component.The separation performance and the pressure drop of the two-phase organic fluid in the vertical impacting T-junction is investigated experimentally.It is found that not all the fluids could be separated in this separator with no control.The two-phase R600 a is separated into the two exits with the almost same vapor quality.And there is little difference between the inlet and outlets for R601.In contrast,the zeotropic mixture M could be totally separated into vapor and quality.And the increase of the cooling water inlet temperature could weaken the difference of the vapor quality and the fluid composition between the two outlets.The pressure drop in the T-junction separator is also investigated experimentally.It is found that the pressure drop of the exit flow increases as the mass flow rate and vapor quality of inlet flow increase,and decreases as the cooling water temperature increases.At last,a pressure drop model for the organic fluid R600 a and R601 is proposed in this paper.And the model could predict the pressure drop accurately compared with the experiment data.