Thermofluid characteristics of two-phase flow in micro-gap channels

Microgap coolers provide direct contact between chemically inert, dielectric fluids and the back surface of an active electronic component, thus eliminating the significant interface thermal resistance associated with thermal interface materials and/or solid-solid contact between the component and a microchannel cold plate. This study focuses on the two-phase thermo-fluid characteristics of a dielectric liquid, FC- 72, flowing in an asymmetrically-heated chip-scale micro-gap channel, 10 mm wide by 37 mm long, with channel heights varying from 110 mum to 500 mum and channel wall heat fluxes of 200 kW/m² (20 W/cm²). The two-phase, area-averaged heat transfer coefficients of FC-72 reached 15.5 kW/m²-K, significantly higher than the single phase FC-72 values, thus providing cooling capability in the range associated with water under forced convection. Data obtained for single phase water yielded very good agreement with predictions for the convective heat transfer coefficients and served to validate the accuracy of the experimental apparatus and measurement technique.