Experimental investigation on the influence of nanofluids used as heat transfer fluid in phase change material based thermal energy storage system

Abstract

The present study investigated the enhancement of energy conservation under the principles of pure substances that exercise phase change throughout charging and discharging processes. This work primarily focused on the thermal energy storage system, where the working medium charges the PCM namely (paraffin wax and stearic acid) that is normally encapsulated in spherical balls. The potentiality in charging of working medium was examined upon blending heat transfer fluid with four nanoparticles (Al2O3, CuO, TiO2, and MgO). Several volume concentration levels (0.2%, 0.5%, and 0.8%) were considered for afore mentioned nanoparticles under the influence of assumed flow rates (2, 4, and 6 L per minute). The experiments were carried out with various nanofluids used as heat transfer fluid for different flow rates and volume concentrations. The results showed that there is a considerable amount of reduction in charging time, in case of 6 L per minute, 0.8% volume concentration and PCM as paraffin wax, around 27.22% for TiO2 nanofluid, 36.66% for Al2O3 nanofluid, 40.90% for CuO nanofluid, and 63.63% for MgO nanofluid, and PCM used as stearic acid, around 26.31% for TiO2 nanofluid, 42.10% for Al2O3 nanofluid, 47.36% for CuO nanofluid, and 68.42% for MgO nanofluid, when compared with water as the conventional heat transfer fluid. From the results, it was observed that the effect of particle concentration played an important role in the heat transfer process. During the discharging process, 210 L of hot water withdrawn with paraffin wax used as PCM and 198 L of hot water withdrawn with stearic acid used as