Enhancing Heat Recovery Ventilator Efficiency with Heat Storage System by Using Phase Change Materials
摘要
Ventilation is crucial for maintaining comfortable and healthy indoor air quality. However, it inherently increases building energy loads by introducing unconditioned outdoor air. While heat recovery ventilators mitigate this energy loss, further enhancing their heat exchange efficiency remains a significant challenge. To address this issue, this study proposes a thermal energy storage duct utilizing phase change materials to precondition the airflow and alleviate the thermal load on the ventilation system. Large-scale environmental chamber experiments were conducted under strictly controlled parameters. The evaluations included summer conditions with an indoor temperature of 24 °C and an outdoor temperature of 35 °C, alongside winter conditions with an indoor temperature of 22 °C and an outdoor temperature of 2 °C. The study evaluated 4 kg of octadecane with a melting point of 28 °C for summer cooling and a material with a 20 °C melting point for winter heating. Results demonstrated that the endothermic phase transition in summer reduced the outdoor air temperature by an average of 1 °C for 235 min, which enhanced the overall heat exchange efficiency by 9.6 %. Under winter conditions, the exothermic heat release from the storage duct effectively preheated the incoming outdoor air by 2 °C for 150 min. This led to a 2 % improvement in heat exchange efficiency and a 0.2 K increase in the supply air temperature. Physically, these findings indicate that the substantial latent heat capacity of the phase change material acts as a thermal buffer. This mechanism delays transient temperature fluctuations and reduces the dry bulb temperature difference across the heat exchanger. Consequently, integrating these thermal storage ducts presents a highly effective passive strategy for diminishing building energy consumption caused by ventilation.