Experimental and Numerical Investigation of Melting Process in PCM Storage

Thermal energy storage (TES) technologies have been developed using Phase Change Materials (PCM) at various power plants to utilize waste heat sources. The melting process of PCM has been investigated experimentally and numerically to construct a fundamental database of TES systems. D-Mannitol was selected as a PCM for medium TES systems in this study. The experimental apparatus consisted of the cartridge heater, thermocouples, test tube, acryl tube, vacuum pump, pressure indicator, volt slider and shunt resistance. The temperatures near the cartridge heater were measured by K-type thermocouples. The heat inputs were ranged from 10W to 15W. As a result, temperature of D-mannitol increased with time linearly under the solid state until the fusion temperature. When D-mannitol changed from the solid phase to the liquid phase, temperatures remained constantly due to the latent heat. Moreover, the numerical simulation was conducted using the commercial CFD code, ANSYS FLUENT. As a result of the numerical simulation, it was understood that the melting process was affected by the natural convection at the inner wall. As the heat flux of the cartridge heater input from the inner wall, the liquid fraction increased from the inner wall to the outer wall. The numerical result was compared with the experimental data. It was understood that the temperature of numerical simulation was approximately consistent with that of the experiment during the phase change process.