Thermal energy and thermo-economic analysis of PCM-TES for space heating based on low-temperature waste heat: An experimental and numerical study

Great potential for using low-temperature waste heat for energy savings has been revealed in recent years. In this study, a novel PCM-TES unit integrated into a fresh air system was proposed to effectively utilize low-temperature waste heat to address shortcomings of preheating outdoor air for space heating. An experimental setup was built to investigate the heat storage and release performance of proposed unit. Well-validated CFD simulations further parametrically studied PCM thermal characteristics to HTF’s velocity and temperature changes. Energy and thermo-economic analyses were employed to evaluate unit potentials across three Chinese cities with different climate zones. The results showed that charging process was completed in 142–253 min at water temperatures of 55–60 °C; discharging process efficiency increased by 36.10% as the air velocity increased from 2 to 4 m/s. EPI revealed that, theoretically, the system could handle up to 28.2% of the heating demand. Energy and economic analysis indicated the system’s significant potential in colder climates, with Harbin achieving average energy savings of 7.93% and 13.48% over Qingdao and Chongqing, respectively, and cost savings up to 67.65% and 229.61% compared to those cities. This study is expected to shed light on the utilization of low-temperature waste sources for indoor space heating.