THERMAL PERFORMANCE OF MULTITUBE LATENT HEAT STORAGE USING A METAL MATRIX FOR SOLAR APPLICATIONS: NUMERICAL STUDY

This study presents an analysis of multitube shell and tube latent heat thermal energy storage system (LHTES) for medium-temperature solar applications (similar to 200 degrees C) to evaluate its thermal performance during discharging operation. As the present commercially available organic PCM possesses very low thermal conductivihy, a metal matrix, acting as a thermal conductivity enhancer, is embedded in the annular space saturated with PCM. A numerical model, consisting of momentum and two-temperature nonequilibrium energy equations coupled with enthalpy technique for phase change of PCM, is developed and validated with experimental results. Further, parametric studies are conducted by varying the porosity and pore diameter of the metal matrix for estimating entropy generation, second law efficiency, and thermal performance index (TPI). The study finds that the second law efficiency increases with the decrease in the porosity and pore diameter. However, the TPI decreases with increase in porosity, while the pore diameter has no significant effect on it.