Implementation of microchannel evaporator for high-heat-flux refrigeration cooling applications

Abstract

While most recently electronic cooling studies have been focused oil removing the heat front high-power-density devices, the present study also explores means of greatly decreasing the device operating temperature. This is achieved by incorporating a microchannel heat sink as air evaporator in an R134a refrigeration loop. This system is capable of maintaining device temperatures below 55 degrees C while dissipating in excess of 100 W/cm(2). It is shown that while higher heat transfer coefficients are possible with greater mass velocities, those conditions are typically associated with wet compression corresponding to evaporator exit quality below unity and liquid entrainment at the compressor inlet. Wet compression compromises compressor performance and reliability as well as refrigeration cycle efficiency and therefore must be minimized by maintaining only slightly superheated conditions at the compressor inlet, or using a wet-compression-tolerant compressor A parametric study of the effects of channel geometry oil heat sink performance points to channels with small width and high aspect ratio as yielding superior thermal performance corresponding to only a modest penalty in pressure drop.