Experimental investigation of the novel melting point modified Phase–Change material for heat pump latent heat thermal energy storage application

Highlights: • Novel melting point modified SAT CPCMs for heat pump applications were proposed. • SAT–AC CPCM owns the melting point of 47.8 °C and the latent heat of 219.8 kJ/kg. • The overall efficiency of the system with novel SAT–AC CPCM was enhanced by 5.2%. • The average outlet temperature of novel–CPCM unit was 4 °C higher than SAT CPCM. The thermal properties of the heat storage medium integrated with the heat pump (HP) should be suitable for the desired application in terms of providing thermal comfort for the end–users and matching the operation condition of the HP. In this study, a novel melting point modified composite phase–change material (CPCM) was developed for air–source HP. We concluded that sodium acetate trihydrate (SAT) modified with 10 wt% acetamide, 4 wt% nucleator, and 4 wt% thickener, which yielded the desired melting point (47.8 °C) and high latent heat (219.8 kJ/kg) presented better thermal reliability than the other component groups. The coefficient of performance of HP with novel CPCM was significantly enhanced compared to that of SAT CPCM, in which the maximum difference was 13.2%. Moreover, the average temperature of the discharging water drained from the novel CPCM unit was 4 °C higher than that of the control group. The overall efficiency of the heating system containing novel CPCM shows an increasing trend with a higher flow rate within a certain range. The system exhibits a payback period of about 5 years and a high bill saving of HK$6627.62 (US$861.59) over a 10-year analysis compared with conventional heaters.