Numerical study on performance enhancement of shell-and-tube latent heat storage unit

A compound enhancement method was proposed to improve the latent heat storage (LHS) performance of a shell-and-tube LHS unit, which is consisted of internal enhanced tube (ET) and multiple phase change material (PCM). Numerical validations on the presented method were performed based on comparisons of four different LHS cases: case 1 (basic case); case 2 (simple enhancement case); case 3 and 4 (compound enhancement cases). The results show that the simple enhancement case can only enhance PCM melting rate at the first half of the LHS tube; the compound enhancement case can obtain the synergy enhancement effect for the whole LHS tube. Compared with case 2, the PCM melting time is reduced by 37.3% and 17.4%, the total charging time is reduced by 25.6% and 16.9% for case 3 and case 4 respectively. For case 3, although the PCM melting time and charging time are the shortest, the total thermal energy storage (TES) capacity is reduced by 26.9% due to the lower PCM melting enthalpy. For case 4, not only the melting time and charging time can be obviously reduced, but also the total TES capacity is augmented by 6.6%.