Method And Experimental Study On Performance Improvent Of Enhanced Vapor Injection Increasing Variable Frequency Vrf System

Since entering the Chinese market in the 1990 s,VRF(Variable refrigerant flow)has quickly occupied an important part of the central air-conditioning market share due to its superior energy efficiency,easy installation and intelligent management.So far,most inverter VRFs heating capacity is generally low,especially in the low temperature in winter,because of the exchange be low of the outdoor unit condenser,such as frosting in the outdoor unit,serious decay of heating capacity,and low temperature of outlet air.As our country is implementing the energy policy of "Energy Conservation And Emission Reduction",we need to solve these problems to meet our users' requirements.The research is conducted based on the 10 HP 28k W cooling capacity VRF system.Toimprovetheheatingcapacity and perfomance of inverter VRF it in five persrectives: 1.Compressor with EVI((enhanced vapor injection))technology.The compressor will take part of the refrigerant at medium temperature and pressure from condensor and inject into the compressor chamber,thus enhancing the total refrigerant volume and improve the performance of the system;2.Plate heat exchanger as the injection supporting system.The refrigerant from condensor will be evaperated and flow into the compressor chamber,to avoid the liquid slugging;3.EXV as the throttling device.With the adoption of EXV,the refrigerant flow will be more exquisite and accurate,improving the system's performance and efficiency;4.Optimized condenser flow path.The upgraded condenser flow path can enhance theexplosionwith air and improve the heat exchangeeffect;5.Adjustment of air volume of the outdoor blower.In the coordination to minimize the noise level,the increase of air volume can improve the heat exchange capacity in outdoor unit.After the finish of theoretical analysis from the five aspects above,two prototupes are made to verify and test in the enthalpy lab,which can help to carry out the theory into practice.The research is conducted based on the combination of theoretical analysis and laboratory experience.It collects related technical information both nationwide and abroad for market research to know about users' technical requirements and formulate several technical solutions based on competitor analysis and customer needs.After a careful comparison among these solutions,it makes a preliminary decision on the selection of compressor,enhanced vapor injection,expensionvavle,condenser and air flowing of motor.