Experimental Study on the Evaporation and Condensation Heat Transfer Characteristics of a Vapor Chamber

Abstract

A vapor chamber can meet the cooling requirements of high heat flux electronic equipment. In this paper, based on a proposed vapor chamber with a side window, a vapor chamber experimental system was designed to visually study its evaporation and condensation heat transfer performance. Using infrared thermal imaging technology, the temperature distribution and the vapor–liquid two-phase interface evolution inside the cavity were experimentally observed. Furthermore, the evaporation and condensation heat transfer coefficients were obtained according to the measured temperature of the liquid near the evaporator surface and the vapor near the condenser surface. The effects of heat load and filling rate on the thermal resistance and the evaporation and condensation heat transfer coefficients are analyzed and discussed. The results indicate that the liquid filling rate that maximized the evaporation heat transfer coefficient was different from the liquid filling rate that maximized the condensation heat transfer coefficient. The vapor chamber showed good heat transfer performance with a liquid filling rate of 33%. According to the infrared thermal images, it was observed that the evaporation/boiling heat transfer could be strengthened by the interference of easily broken bubbles and boiling liquid. When the heat input increased, the uniformity of temperature distribution was improved due to the intensified heat transfer on the evaporator surface.

Collisions of Two-Phase Liquid Droplets in a Heated Gas Medium

“…The modeling results in [13] indicate that using a nozzle with a smaller diameter reduces the penetration depth of the aerosol flow, the size of a droplet, and its velocity. The research findings [14] reveal that the rate of evaporation and boiling heat transfer can be increased by the interaction of easily broken bubbles. Gas bubbles in moving droplets undergo transformation even on a short section of their way due to their movement and collisions, as shown by Xu et al [15].…”

Compact Model of a Screen under Fan-Induced Swirl Conditions Using a Porous Media Approach

“…The heat generated by the PCBs must be removed from each of these levels via an appropriate cooling strategy. There are several cooling strategies (liquid cooling [1,2], two-phase cooling [3] and spray cooling [4,5], among others), but the most commonly employed technique is air cooling using an axial fan to produce air movement for reasons of safety and availability. Problems arise as the axial fan is usually placed together with an electromagnetic compatibility (EMC) screen, which mainly plays the role of reducing electromagnetic interferences in the device but it also keeps dust from entering.…”