PCM storage system with integrated active heat pipe

The use of the latent heat of phase change materials (PCM) is considered a promising approach to store heat at a nearly constant temperature for direct steam generation (DSG), but the poor thermal conductivity of commonly available storage materials imposes severe limitations on storage performance. A new method is proposed to overcome the limitations of the low thermal conductivity. The approach is to physically decouple the evaporator pipes from the PCM, thus allowing independent sizing of each component. The thermal link between the two components is done via evaporation and condensation of a heat transfer fluid (HTF), according to the principle of a heat pipe. Pumping the liquid HTF provides active control of the heat pipe operation. The new concept is modeled and compared to the conventional design of conduction based PCM annulus around the steam pipe. An example case shows a significant advantage in performance of the active heat pipe configuration due to its reduced thermal resistance. © 2013 The Authors. Published by Elsevier Ltd. Selection and peer review by the scientific conference committee of SolarPACES 2013 under responsibility of PSE AG.