OPTIMIZATION OF A CLASS OF LATENT THERMAL-ENERGY STORAGE-SYSTEMS WITHMULTIPLE PHASE-CHANGE MATERIALS

This paper presents an analysis of a class of latent thermal energy st orage (LTES) system. The analysis is based on a simplified model that allows the system performance to be evaluated in terms of a small set of parameters, While still retaining the main thermodynamic aspects as sociated with their operation. This analysis therefore permits the bro ad-based application potential of these systems to be viewed. The pape r also discusses the applicability of the model to practical systems. This paper analyzes LTES with multiple energy storage cells and multip le phase-change materials (PCMs). The most general case of infinite en ergy storage cells and PCMs is solved, for the charge process only, as well as for the overall charge-discharge process. The results yield t he optimum phase change temperature, expressed as a continuous functio n of position along the LTES. The method is equally applicable to the case of a finite number of storage cells. An example of the applicatio n of tile method to this case is also included. The results show the o ptimum phase change temperatures for each of the problems being consid ered, along with the corresponding optimum exergetic efficiencies. The solutions to the optimization problems are surprisingly simple to exp ress, considering the difficulty of the problems, and indicate the pot ential advantages of using LTES with multiple PCMs.