Feasibility Study on the Prototype Microchannel Evaporator for the Residential Air-Conditioning Application

The present study was aimed to test the feasibility of the prototype microchannel evaporator for the residential air-conditioning application using R-22 refrigerant under wet condition. Eight prototype evaporators were manufactured and tested using a psychrometric calorimeter. Each evaporator consisted of two or three parallel flow heat exchangers connected with return pipes. The parallel flow heat exchanger had 41 parallel microchannel tubes that brazed to the inlet and outlet headers. The tube had 8 rectangular ports with the hydraulic diameter of 1.3mm. The louvered fin had louver angle of 27°, louver pitch of 1.4mm and flow depth of 18.8mm. The cooling capacities of the different test evaporators were severely changed as both mass flow rate and inlet quality were increased due to the flow mal-distribution in the evaporator. The cooling capacity was increased as the vertical inclination angle of the evaporator increased. The condensate under wet condition was also measured. The flow area ratio of the evaporator affected the most seriously among the test parameters on the cooling capacity. Pressure drops on both refrigerant and air sides for the best prototype evaporator were 28.6kPa and 2.5mmAq, respectively.