Numerical study on thermal performance characteristics of a cascaded latent heat storage unit

Abstract

This study presents a numerical investigation on a cascaded shell-and-tube 3PCMs latent heat thermal storage unit filled with three types of phase-change materials namely, C24H50, C21H44, and C18H38. The mathematical model is based on the enthalpy method and considers the effect of the natural convection of liquid phase-change material during melting. The transient heat transfer and thermal storage characteristic of the 3PCMs unit are analyzed and compared with those of a 1PCM unit that utilizes C24H50. The influences of heat transfer fluid flow rate and inlet temperature on the efficiency, accumulated energy, and exergy of the latent heat thermal storage unit are studied. Results show that the 3PCMs unit can improve the heat transfer rate greatly and shorten the heat storage time effectively, as much as 58% more energy can be stored than the 1PCM unit at the same charging time. The increase of both inlet temperature and flow rate of the heat transfer fluid will lead to a shorter charging time, whereas the advantage of the 3PCMs unit on storage performance over the 1PCM unit becomes more insignificant.