Two-dimensional transient thermal analysis of PCM canister of a heat pipe receiver under microgravity

High temperature phase change material (PCM) is used as a thermal storage medium of a heat pipe receiver in an advanced solar dynamic system. With both void cavity and phase change considered, thermal performance of the heat pipe receiver was numerically analyzed under microgravity. The results indicate that the PCM contained in the integrated heat pipe performs the averaging function of heat loads. Normal working of wick ensures the uniformity of the heat pipe, thus heat pipe receiver alleviates thermal spot and thermal ratcheting. Void cavity influences the process of phase change. The thermal resistance of void cavity is much higher than that of PCM canister wall. Void cavity prevents heat transfer. PCM melts slowly during sunlight periods and freezes slowly during eclipse periods with the effect of void cavity. Void cavity reduces the utility and thermal storage ability of PCM. The temperature gradient in the PCM zone is very significant because of void cavity. So the thermal stress of heat pipe receiver may increase, and the lifetime may decrease. The research results can be used to guide the designing and optimization of PCM canister for heat pipe receiver. (C) 2010 Elsevier Ltd. All rights reserved.