Effect of natural convection on melting performance of eccentric horizontal shell and tube latent heat storage unit

In order to improve melting rate of latent heat storage system, the effect of natural convection during melting process in eccentric horizontal shell and tube storage unit is investigated in this study. The melting performance in different eccentricity (e) and boundary temperature (Tw) is obtained through experiment research and numerical simulation. During the experiment study, the temperature variations at different positions are measured. Then, the temperature and fluid field, movement of the phase interface are analyzed by numerical simulation. With the increase of eccentric distance, the natural convection dominated area increases, so the melting rate is improved. The eccentric geometry with e = 30 mm and Tw = 80 °C results in a 57% decrease in the total melting time. The special attention is paid on the evolution of natural convection and the heat transfer mechanism during the melting process, so the parameter of time-average heat transfer coefficient (h¯) is proposed. h¯ is relatively higher in an eccentric geometry which illustrate the heat transfer efficiency is improved. The variation of h¯ also reflects transformation of the heat transfer characteristic in concentric unit and eccentric unit.