Transient melting flow of a NePCM comprising GNPs in a semi-elliptical latent heat thermal energy storage unit

A cutting-edge achievement alleviating the shortage of energy sources and mitigating environmental pollution is latent heat thermal energy storage (LHTES). This system employs quality phase change materials (PCMs) to provide both large thermal capacity and slight temperature variation. This numerical work investigates the effects of structural parameters of a semi-elliptical LHTES unit, including aspect ratio (AR) and inclination angle (γ). In the semi-elliptical LHTES unit, heat is transferred from water as HTF to the PCM improved with graphite nanoplatelets (GNPs) through an interface copper wall. The investigation found that the melting time for AR = 0.5 decreases about 12% compared to that of AR = 1.0. Also, the LHTES unit of AR = 0.5 shows the highest power of the system, around 13.9% more than the unit having AR = 1.0. Furthermore, the temperature fluctuations are suppressed at lower ARs. Angular deviation of the system from the horizontal state is associated with an increase in the melting time, leading to a decrease in the unit power. It is seen that the unit of nano-plates mass fraction of φ = 1.0% has the highest power, 7.2% more than that of pure PCM.