Research On Outdoor Unit Of Heat Pump Air Conditioner Using Micro-channel Heat Exchangers

In recent years,energy shortage and tension of power supply have intensified.In summer,air conditioners consume about 20% of the country's electricity consumption,which leads to higher and higher demands on the energy efficiency of air conditioners.At present,HCFC refrigerant used in domestic air conditioning has damage to atmospheric ozone layer,HFC refrigerant still brings greenhouse effect,and natural refrigerant R290 has flammability.Under the Kigali amendment,countries have agreed to include HFCs in the control list and have set a timetable for phasing down HFCs by 80-85 percent by 2040.Developed countries will first reduce the amount of HFCs from 2019.More than 100 developing countries,including China,will freeze the use of HFCs in 2024,and some,such as India and Pakistan,will do the same from 2028.Under this background,the air conditioning system naturally requires repeated reduction of refrigerant filling.How to effectively use energy-saving measures to improve the energy efficiency of room air conditioners,reduce carbon emissions,and at the same time ease the cost pressure of air conditioner manufacturers has become an important development goal of the air conditioner industry.The advantages of high heat-transfer efficiency,small volume,light weight,low refrigerant charge and easy installation undoubtedly make microchannel heat exchanger one of the most valuable heat exchangers in the future,but its drainage difficulties,rapid frost formation and slow frost removal under low temperature conditions,lead to its limited application in the heat pump outdoor unit.In this paper,the patent and literature of microchannel heat exchanger at home and abroad are analyzed and summarized,it is concluded that horizontal placement of flat tube with new fin is superior to vertical placement of flat tube in drainage effect,improvement of frosting frost,bending of condenser and so on.The parameters analysis of prototype copper fin heat exchanger air conditioner and the parameters test of key system performance.Four important parameters of fin and flat tube were combined by orthogonal experimental method,and 25 sets of simulation parameters were determined.With the help of Coildesigener,a commercial software developed by the university of Maryland,the outdoor micro-channel heat exchanger of the heat pump was simulated,and a better scheme was selected for the open-fin hand plate mold.Then an external cooperator factory was selected to find the best combination of flat tubes.The microchannel heat exchanger with fin and flat tube is assembled into the air conditioning system and tested in the enthalpy difference laboratory,and compared with the target copper tube fin heat exchanger.In addition,the microchannel heat exchanger scheme which can replace the target copper tube fin heat exchanger is determined.Besides,compared with the target copper fin heat exchanger,and finally replaced the target copper fin heat exchanger.Finally,under the same performance conditions,the cost decreases,the filling volume decreases,the weight of the whole machine decreases,the assembly efficiency is improved,and the mass production target can be achieved.