Important factors affecting the thermal resistance and thermal diffusivity of vapor chambers. (5th November 2017) - Huang, Chien
Highlights: Comparison of thermal resistance in vapor chambers under various types of Experiment Setup. The lowest resistance was observed for VC under constant temperature conditions. Measurement of thermal diffusivity in vapor chamber using the Angstrom method. Thermal diffusivity of vapor chamber was 36 times higher than that of copper plate. Abstract: This paper discusses a number of important parameters associated with the measurement of thermal resistance and thermal diffusivity in vapor chambers (VCs). Thermal resistance and thermal diffusivity are representative indicators of VC performance. In this paper, we measured thermal resistance using four distinct Experiment Setups. Our empirical results demonstrate that thermal resistance values depend largely on how the experiment is set up. We also examined two different condensation methods in the measurement of thermal resistance. Condensation condition 1 uses cooling water with an input temperature fixed at 20 °C and the flow rate fixed at 10 g/s. Condition 2 involved fixing the temperature of the top surface of the vapor chamber by adjusting the temperature of the cooling water according to the input power. In experiments, the lowest thermal resistance was 0.135 °C/W under condensation condition 1 and 0.023 °C/W under condensation condition 2. We also developed a device for the measurement of thermal diffusivity based on the Angstrom method. We then measured (under experimental conditions) the thermal diffusivity of four pure metals for comparison with standard reference values. The thermal diffusivity values were measured as follows: VC (44.04 cm 2 /s) and copper plate (1.219 cm 2 /s).