Gas-Liquid Distributions of Refrigerant Flows in Multi-pass Channels with Vertical Headers

Influence of heating of branch tubes on liquid distribution characteristics

Abstract

For the gas-liquid two-phase refrigerant flow in the multi-pass channel with a vertical header and horizontal branch tubes that simulates the parallel-flow type heat exchanger used for residential and commercial air conditioners, the influence of evaporation of liquid refrigerant in branch tubes on the gas-liquid distribution characteristics in the channel was experimentally investigated. The test channel had a vertical header with a height of 81.5 mm and 8 horizontal aluminum microchannel branch tubes connected in parallel to the header at a pitch of 10 mm, and all the branch tubes were heated evenly at 20 – 100 W/tube. It was found that the excessive liquid distribution to the lowermost branch tube was suppressed by heating the branch tubes, while the amount of liquid distributed to the upper branch tubes increased. As a result, the uniformity of the liquid distribution was improved by the evaporation of the liquid refrigerant in branch tubes.