Thermal hydraulic performance of the printed circuit heat exchanger in air and helium test loops

Abstract

The wavy channels of a Printed Circuit Heat Exchanger (PCHE) cause physical phenomena such as eddy and recirculation. In its channels both of the overall heat transfer coefficient and the pressure drop are enhanced. We built two test loops to study the thermal-hydraulic performance of a PCHE manufactured by Heatric Company: KAIST Air and Helium Test Loops. The KAIST tests are performed in laminar region. We estimated the fanning factor, overall heat transfer coefficient, and effectiveness based on their experimental data. We developed the empirical correlation for the fanning factor in the micro-wavy channels of the PCHE assuming that the total pressure drop is the sum of friction loss and form loss. From the results of the KAIST Air Test, the fanning factor is the same as that of the semi-circular pipe in the low Reynolds number: when the Reynolds number is lower than 120, the form loss can be negligible. However, the fanning factor in the KAIST Helium Test shows different behavior from that in KAIST Air Test: the loss factor for the pressure drop for Helium flow is much higher than that for air flow. We developed the empirical correlation for the heat transfer coefficient in the micro-wavy channels of the PCHE in the laminar region. The heat transfer coefficient in the PCHE is higher than that in the straight circular tube in the laminar region: it is proportional to the Re number.