STUDY OF TWO-DIMENSIONAL FLOW-BOILING MORPHOLOGICAL CHARACTERISTICS IN THE MICRO GAP WITH SURFACE WETTABILITY ON HOT SPOT

摘要

Thermal management is one of the most challenging problems of electronic devices today. As technology becomes increasingly miniaturized, extremely localized heat dissipation leads to the challenge of keeping devices away from overheating. Flow-boiling microchannel heat-sinks exploit the highly efficient thermal energy transport of phase change from liquid to vapor. However, the excessive consumption of liquid-phase by highly localized heat source causes the two-phase flow maldistribution, leading to greatly reduced heat transfer coefficient, high-pressure loss, and limited flow rate. In this study, we investigate two-dimensional flow-boiling morphological characteristics in a microgap with hydrophilic coating on hot-spot. The experiments are carried out on a Stainless Steel plate having a micro gap depth of 254 μm using deionized water with inlet at room temperature. A partial hydrophilic surface is created on the hot-spot (surface above the heater) which forms a wettability difference along the metal plate. A wide range of mass flux and heat flux are considered to quantify heat transfer coefficient. In addition, high-speed flow visualizations are performed to characterize the nucleation and bubble dynamics inflow boiling.