Numerical simulation and experimental study of a phase change heat accumulation device applicable for waste heat recovery

Solid-liquid phase change latent heat accumulation technology constitutes an industrial waste heat recovery mode, which has extremely good prospects. Through a shell and tube heat exchanger, the phase change latent heat stored in the phase change material (PCM) by absorbing industrial waste heat was used for heating water, thereby realizing an industrial waste heat recovery and utilization. A two dimensional mathematical model for the shell and tube latent heat storage unit (LHSU) intensified by filling with high conductivity porous matrix was established and a phase change heat storage test was conducted simultaneously of a heat storage vessel being filled and one not filled with the porous matrix. The test results show that filling with the porous matrix can effectively improve the heat transfer performance of the PCM. The test data were in relatively good agreement with the calculated ones, having proved the validity of the calculation model. By making use of the model in question, a numerical calculation was performed of a heat storage system using three kinds of PCM (paraffin P116, stearic acid and palmitic acid). It has been found that the heat storage system using palmitic acid has the best thermal performance and can meet very well the design requirements for supplying daily used domestic hot water. The foregoing research findings can offer a definite guide for the design and performance optimization of heat storage systems.