On the effective thermal conductivity of the vapour region in vapour chamber heat spreaders

摘要

The vapour chamber is an efficient heat transfer device used mainly to spread heat from concentrated heat sources to larger heat sinks. It achieves this through two phase heat transfer. This paper presents an experimental and numerical investigation into vapour chambers. Experimental measurements of spreading resistance of a copper-water vapour chamber, together with the development of a conduction based numerical model, were used to determine the effective thermal conductivity of the vapour region. In this simplified model, all vapour chamber components were replaced with effective conduction regions. The effective thermal conductivity of the vapour region has been seldom explored in vapour chamber literature with most modelling approaches of this type assuming or otherwise neglecting the contribution of vapour region. It was obseived that the effective thermal conductivity of vapour was 2400 W/mK at the largest heat source size of 35 mm x 35 mm and 1900 W/mK at the smallest heat source size of 20 mm x 20 mm. These values were expected to be functions of phase change and vapour flow processes. These results for effective thermal conductivity of the vapour region, for a range of area ratios, provide guidance to thermal designers of vapour chambers. (C) 2019 Elsevier Ltd. All rights reserved.