Enhanced condensation heat transfer for dielectric fluid within microchannel heat sink

This study experimentally investigates the condensation of dielectric fluid HFE-7100 within a micro channel heat sink with a hydraulic diameter of 800 gm at a fixed outlet pressure of 110 kPa. The corresponding mass fluxes ranges from 100 to 300 kg m(-2) s(-1) and the vapor mass quality varies from 0.1 to 0.9 with inclinations ranging from 90 degrees (vertical downward) to -90 degrees (vertical upward). In addition, the present study also proposes a novel condensate drainage concept by imposing a micro drainage channel sitting near the corner of the conventional micro-channel to enhance the condensation heat transfer performance. Through this micro drainage design, the condensate will be pulled into the drainage channels effectively, thereby resulting in reducing liquid film thickness and enhancing the two phase heat transfer performance accordingly. The results show that the micro-channel heat sink with micro drainage channel can enhance the heat transfer coefficient in the order 5-15%. In addition, the frictional pressure gradient will be decreased by about 5-25%. For a lower mass flux of the conventional microchannel, the flow visualization indicated that the elongated vapor slug flow patterns may occasionally reveal appreciable stalling or even reversal against main flow direction subject to vertically arrangement, yet this phenomenon is seldom seen for the proposed micro drainage channel. (C) 2016 Elsevier Ltd. All rights reserved.