Thermal performance and behavior analysis of SiO2, Al2O3 and MgO based nano-enhanced phase-changing materials, latent heat thermal energy storage system

The phase-changing material-based thermal energy storage method is one of the most prominent energy storage techniques used to store waste heat and surplus energy. The efficiency of the PCM-based energy storage system can be further modified by doping of nanoparticles. In the present study, the comparative effects of Al2O3, MgO, and SiO2 nanodoping on thermal performance and the overall thermal behavior of PCM-based LHTES systems have been examined experimentally and numerically. Furthermore, the impact of Al2O3, MgO, and SiO2-based nanoparticles on the charging and discharging rate, time, heat flux, and overall enthalpy is also studied. It is found that due to the inclusion of Al2O3, MgO, and SiO2 nanoparticles, the charging rate is significantly increased by 33.8%, 33.8%, and 41% for Al2O3, MgO, and SiO2 NEPCMs, respectively, in comparison to the PCM. The discharging rate is also increased by 19.6%, 25%, and 30% for Al2O3, MgO, and SiO2-based NEPCMs, respectively. However, the inclusion of nanomaterials decreases the control volume and enhances the dynamic viscosity, which further curtails the thermal energy storage capacity of the LHTES system. Also, the optimum value of the nano inclusions is determined by experimenting with SiO2 doped PCM samples. It was observed that for a 0.1-0.3% rise in volume concentration, charging rates show maximum enhancements, which offers a rapid decline for a 0.3-0.5% rise in volume concentration. Therefore, an optimum volume concentration of 0.3% is established. Furthermore, it was also observed that SiO2 doped PCM samples show a comparatively better thermal response than the other NEPCM samples, making them highly suitable for commercial applications. However, similar studies are further required to identify such potential nano-inclusions.