Experimental study on CPU cooling system of closed-loop two-phase thermosyphon

Abstract

This paper reports on an indirect cooling method of high-power CPU of notebook computers using a closed-loop two-phase thermosyphon with Fluorinert (FC-72) as the working fluid. The experimental setup consists of an evaporator with an electric heater, a condenser, and flexible tube connecting them. The heater and condenser act as a high-power CPU and a cooling plate located behind the display of a notebook computer, respectively. The evaporator and the condenser have the outer dimensions of 50mm × 50mm × 20mm and 150mm × 200mm × 20mm, respectively. Four possible boiling surfaces of an evaporator were examined, i.e., a smooth surface (Type A), rough one, ones with smooth plate fins and rough plate fins (Type D). Type D evaporator shows the highest performance, i.e., it reduces the temperature at the evaporator/heater interface by about 18% in comparison with that of the smooth surface evaporator (Type A). Type D evaporator keeps the temperature difference between the evaporator/heater interface and the ambient to be around 55 K at the highest heat input Q = 30W. The effects of the heat input Q, the volumetric amount of Fluorinert liquid F in the thermosyphon, and the evaporator type on the heat transfer characteristics of the cooling system were examined experimentally. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(3): 147–159, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20057