Numerical investigation and performance analysis of a compact finned-tube heat exchanger uniformly filled with a phase change material for solar hot water production

Abstract

The use of phase change materials (PCMs) in latent heat storage (LHS) devices presents great benefits to solar thermal energy systems. Indeed, in contrast to sensible heat storage, PCMs provide high energy density and energy retrieval at constant temperature. Nevertheless, the limitation of LHS application is the low conductivity of PCMs, hence, the need to develop heat transfer enhancement techniques. In this context, a LHS unit consisting of a compact finned-tube heat exchanger filled with an organic Moroccan PCM was studied numerically. A mathematical model was developed and validated using an experimental set-up of the storage unit. The three-dimensional computational fluid dynamics (CFD) model was used to study the effect of varying the heat transfer fluid (HTF) inlet temperature and flow rate of the system performance. Temporal variation of the PCM temperature inside the tank was observed during charging and discharging, as well as the time required by both processes and their mean powers. Some noteworthy results have been found which can be useful in design and operation of the solar energy LHS system.