Numerical analysis of the paraffin wax–air spiral thermal energy storage unit

A two-dimensional computer simulation is presented for conjugate heat transfer and solid–liquid phase change, concurrently occurring within a domain of the paraffin wax–air spiral thermal energy storage unit during its charging and discharging. The numerical model is based on local energy balances in a set of curvilinear control-volumes (the domain of the unit is divided into), and on the enthalpy approach to account for the latent heat effect. The results obtained are compared with the experimental data, reported in the authorsʹ earlier paper (Banaszek J., Domañski R., Rebow M. and El-Sagier F., Experimental study of solid–liquid phase change in a spiral thermal energy storage unit, Applied Thermal Engineering 19 (1999) 1253–1277), to find out that the proposed numerical model is a reliable and sufficiently accurate calculation tool, although some incongruity between calculated and measured temperature of the paraffin wax exists. The reasons for this discrepancy are thoroughly analyzed and discussed in the paper.