Effect of row-crossing header configuration on refrigerant distribution in a two row/four pass parallel flow minichannel heat exchanger

R-410A distribution was experimentally studied for a parallel flow heat exchanger having two row/four pass configuration. The heat exchanger had inlet, intermediate and row-crossing headers. Tests were conducted for the mass flux from 70 to 130 kg/m(2) s with inlet quality 0.2 and exit superheat 5 degrees C. The insert hole size was varied from 2.0 mm to 6.0 mm. Results showed that the optimum insert hole diameter was 4.0 mm. At the hole diameter, thermal degradation was 0.4-5.1%, which increased as mass flux decreased. Flow distribution at the inlet header generally followed the well-known trend. More liquid flowed into downstream channels as mass flux increased. At the intermediate headers, more liquid was supplied into upstream channels. The flow distribution at the front row was not dependent on the insert hole size. On the other hand, the flow distribution at the rear row was heavily dependent on the insert hole size. (C) 2015 Elsevier Ltd. All rights reserved.