Mocrochannel Evaporators of the Residential Air-Conditioner

Abstract

The objective of present work was to evaluate the performance of microchannel evaporators of the residential air-conditioner using R-22. Six prototype evaporators were manufactured and tested with psychrometric calorimeter test facilities. The test was conducted in two different ways. Each evaporator consisted of two parallel flow type heat exchangers connected with several return pipes. The heat exchanger had 41 microchannel tubes that had 8 rectangular ports with the hydraulic diameter of 1.3 mm. For the vapor compression system (VCS), the flow area ratio and the number of return pipe had a great effect on the cooling capacity. Type 3 with the flow area ratio of 73/ 58% showed best cooling capacity. The effect of the number of circuit and merging manifold on the cooling capacity was relatively small. For the refrigerant circulation system (RCS), the cooling capacity of the test evaporators was a little bit changed as the mass flow rate and inlet quality increased. The effect of mass flow rate on the cooling capacity was slightly superior to that of inlet quality. The effect of the number of circuit on the cooling capacity was different with the result of the VCS, while the effect of merging manifold was negligible. The cooling capacity proportionally increased as the vertical inclination angle of the evaporator increased due to gravity force.