Gas-Liquid Distributions in Upward Multi-Pass Channels of Compact Evaporator

The gas-liquid flow distributions in multi-pass upward parallel channels that simulate the evaporator for the automobile air-conditioning system were examined experimentally. Attention was directed to the influences of the backpressure condition at the branch outlets and of the flow-inlet condition at the header entrance on the gas-liquid distributions to the branches. Experiments were conducted in an isothermal air-water flow system. The influence of the backpressure condition on the flow distributions changed depending on the flow-inlet condition. In the stratified-flow inlet, the backpressure condition was highly influential in both the air and water distributions, and the uniform water distribution that was ideal for the evaporators could not be achieved even if air was distributed uniformly to all branches. In the mist-flow inlet, the water distribution was insensitive to the backpressure conditions and its uniformity was improved in comparison with that in the stratified-flow inlet.