Finite-element analysis of cyclic heat transfer in a shell-and-tube latent heat energy storage exchanger

The physical module of a shell-and-tube latent heat thermal storage exchanger consists of a tube which is surrounded by an external coaxial cylinder made up of a phase-change material (PCM). A heat-transfer fluid flows through the tube to store or extract thermal energy from the PCM. Two alternative operation modes are possible. One option is to introduce hot and cold fluids (for charge and discharge processes, respectively) from the same end of the tube. The other is to introduce the hot and cold fluids from different ends of the tube. A finite-element model is developed to simulate the inherently cyclic thermal process involved as a result of the alternating melting and freezing processes in the storage exchanger. Computations have been carried out to investigate the effects of the two different operation modes. Numerical results provide guidance for selection of the appropriate mode. (C) 1997 Elsevier Science Ltd.