Simulation And Experiment Study Of Quasi-two-stage Vapor Cycle System For Aircraft

With the development of the aviation technology and the overall performance of the aircraft,the heat load for ECS became more severe.Because of the air cycle refrigeration system is unable to meet the requirements of the environmental control system,small vapor cycle refrigeration system will become the future development direction of environmental control system.In order to study for the small aircraft vapor cycle refrigeration system,this paper has conducted a series of experiments for R134 a refrigerant cycle refrigeration system with customized devices.According to the quasi-two-stage vapor cycle refrigeration system,a lumped parameter MATLAB Simulink dynamic model of evaporator and condenser is established by moving boundary method.A quasi-two-stage compressor model is constituted by combining the compression model with the flashtank model,and calculating the pressure and the flow rate of the intermediate refrigerant supply by iteration.Each model is integrated into a quasi-two-stage compression evaporative cooling system to study the dynamic characteristics of an airborne quasi-two-stage evaporative refrigeration system.The results of simulation and experiment were compared to validate the model.Cases of dynamic compressor speed and coolant parameters have been studied using this method.The response pattern of thermodynamic properties of vapor cycle refrigeration systems and its components are analyzed.And the influence of different parameters on the system performance is studied.The simulation indicated an uprising trend of the economizer pressure,compressor power,condensing pressure and cooling capacity when the compressor rotation speed increased,in contrast the evaporation pressure decreased.The flow rate of secondary refrigerant variation raised a greater influence on the economizer than it is to the system parameters.When the temperature of secondary refrigerant or coolant was arising,the compressor power,economizer pressure,evaporation pressure and condensing pressure responded positively.Compressor power and condensation pressure amongst were mainly affected by the change of coolant temperature,while the rest influenced parameters varied with the coolant temperature.If a step change added to the compressor rotation speed,the pressure relevant parameters quickly to the change while those of the heat exchange took much more time.In component where the step change is triggered,the responding time is shorter than the others.