NUMERICAL STUDY OF SOLAR ENERGY STORAGE BY PCM IN NONCIRCULAR CHANNEL

Abstract

A numerical study was carried out for solidification of a phase-change- material in noncircular channels with convectively cooled walls. Specifically three geometries were considered viz, square, equilateral triangle and rectangle of various aspect ratios. The enthalpy- temperature formulation was used and solved iteratively using implicit finite - difference method. After its accuracy had been established, the solution method was used to obtain results for the solidified fraction, dimensionless heat transfer rates, temperature variation and solid - liquid interface position, all as a function of time. The results are presented graphically with Ste•Fo as a correlating parameter, thereby facilitating their use for all Stefan values in the range investigated. The results indicate that the time required for the complete solidification in case of triangular channel is less as compared to the square and rectangular channels. Heat transfer rates was relatively constant at lower values of Biot number, which is desirable for thermal energy storage. Correlation in the form of equations suitable for the 'design of PCM storage in non-circular containers have also been presented for practical application of the present results