Effect of flow direction for the heat transfer performance of refrigerant R-410A evaporation in a plate heat exchanger

This article provides an experimental investigation of the effect of flow direction for refrigerant R-410A evaporated in a plate heat exchanger. Parallel-flow and counterflow arrangements with 2°C and 5°C exit superheat conditions were tested. The refrigerant entered the test section at a vapor quality of 0.24 and evaporated at a saturation temperature of 1.1°C. The experimental results were analyzed by the evaporation heat transfer coefficient and overall average heat transfer coefficient separately. The evaporation heat transfer coefficient in parallel-flow arrangement is higher than that in the case of counterflow arrangement. However, the average heat transfer coefficients are affected not only by the flow direction, but also by the exit superheat condition. The interaction of these two effects causes there to be almost no difference of the average heat transfer performance between these two flow arrangements for low exit superheat condition. While the refrigerant exit superheat is high, the overall heat transfer performance of the parallel-flow case is lower than that of the counterflow case.