NUMERICAL STUDY OF SOME INFLUENCING PARAMETERS ON MELTING PROCESS OF PHASE CHANGE STORAGE UNITS INTEGRATED WITH A SOLAR WATER HEATER

This work theoretically analyzes the melting process of a phase change material (PCM) packed in thermal energy storage units. The units are filled with paraffin wax and inserted in the water storage tank of a solar water heater to improve the storage capacity. A computer program was built to simulate the performance of the whole system during a typical day between 8 a.m. and 3:45 p.m.. The simulation period was divided into small time intervals of 10 seconds. The Finite Difference Method (FDM) was used to analyze the melting process of the PCM units. Each unit was discretized into a large number of nodes forming a two dimensional grid. The effect of three PCM parameters were studied which are the shape, volume and surface area. The cross-sectional shape included square, annular square, circular and circular annulus bars. It was found that the circular sections provide higher melt ratio than the square sections and that the annular sections are more effective than the solid sections. Increasing the PCM surface area at constant PCM volume significantly increases the melt ratio for all PCM shapes. The system equipped with PCM having the least volume operates more effectively than a system with larger PCM volumes.