Author(s)

B. Agostini & M. Habert

Abstract

This paper presents measurements performed on a transparent gravity driven twophase loop. For this purpose a small channel thermosyphon was manufactured completely out of borosilicate glass and equipped with a 100 nm semi-transparent ITO layer as a direct current heating evaporator. Thus flow patterns could be observed in the evaporator and at the same time the total thermal resistance was calculated with the heater temperature. Influence of heat flux and filling ratio on the thermal resistance and pressure oscillations were investigated. 1 Introduction Gravity driven two-phase loops (or thermosyphons) are very widespread devices the nuclear industry, solar heating, computer cooling and chemical engineering, but their use for thermal management of power electronics has been recognised only lately. However, articles on this application are becoming more and more frequent in the literature. Thermosyphon heat-exchangers allow the use of dielectric fluids and pumpless operation and still benefit from very high heat transfer coefficients. For example Perpina et al [1] recently published an article investigating thermal cycles of thermosyphon cooled traction IGBT modules. Thermosyphons using small channels are particularly appealing for their compactness and low material and fluid use. Although few data are available with the new dielectric fluids at the required working temperatures and channel diameters, available studies on different thermosyphon configurations are helpful to outline some trends.

Keywords