Experimental investigation of heat transfer coefficient of mini-channel PCHE (printed circuit heat exchanger)

Abstract

Thermal performance of a mini-channel printed circuit heat exchanger (PCHE) with counter-flow configuration is investigated by using nitrogen as the working fluid. The PCHE used in the experiments are two layered (10 channels per layer) and has the hydraulic diameter of 1.83mm. The experiments are conducted for both of single-phase and two-phase flow conditions. In the single-phase flow experiments, nitrogen gas at 114 K – 194 K flows into the cold side channels with Reynolds numbers range from 12100 to 18600. In the two-phase flow experiments, subcooled liquid nitrogen at 85 K – 94 K enters the cold side channels with Reynolds numbers range from 800 to 1600, and exits as two-phase flow after partial evaporation. The exit quality is always maintained less than 1. Room temperature nitrogen gas flows at the hot side channels with Re > 10,000 in the both experimental cases. As a result, the calculation results by Dittus-Boelter correlation well match the experimental data of single-phase flow condition within 5% error, and the reliability of the experimental apparatus is proven. Heat transfer coefficients obtained in the two-phase flow conditions are presented and discussed in this experimental investigation. According to these results, the boiling regime of the cold side flow is speculated as film boiling due to large temperature difference between the wall and the fluid.