Experimental study on the thermal characteristics of a 3D thermosyphon heat sink

Abstract

Phase change heat transfer has received extensive attention in the thermal management of electronic devices. Most studies of heat pipe or vapor chamber were limited to one- or two-dimensional heat transfer mode. Enhancing the phase change heat transfer to three-dimensional mode in heat sinks and exploring the thermal behavior of the heat sinks deserve a dedicated study. In this paper, a three-dimensional thermosyphon (3D-TS) heat sink combining the superiorities of the vapor chamber, thermosyphon and folded fins was experimentally investigated. The experimental reliability was validated and consolidated by the heat loss analysis, and an iteration method was proposed to estimate the saturation temperature to facilitate the in-depth analysis of the results. The coupling characteristics of the air forced convection and phase change heat transfer, and the effects of the heating power and air volume flow rate on the thermal resistance of 3D-TS were involved in the discussion. The main results indicate that the overall thermal resistance exhibits a negative correlation with the heating power and the air volume flow rate. The lowest thermal resistance of 0.14 K·W−1 was achieved with Qtotal = 300 W and 100 CFM air volume flow rate. High temperature on the folded fins indicates that the phase change heat transfer extends from the flat vapor chamber to the vertical thermosyphon tubes. It is also found that for a small heating power, a relatively large air volume flow rate is not able to further reduce the overall thermal resistance due to inadequate phase change intensity. The proposed heat sink is expected to solve the heat dissipation problems for densely packed electronic devices, which can produce favorable performance according to the input heating power and appropriate air volume flow rate.