Energy saving effects of integrated implementation of a multi-layered heat exchange duct and energy recovery ventilation system

Energy recovery ventilation (ERV) systems can effectively reduce air-conditioning loads while providing outdoor air via ventilation. However, significant challenges remain in improving their heat exchange performance in confined residential spaces and ensuring effective use in cold regions. Preheating or bypassing the supply air can be an effective defrosting strategy for ERV systems; however, additional energy consumption and energy recovery losses are unavoidable. This study proposed a novel integrated multi-layered heat exchange duct (HED) and ERV system as a pretreatment device with four operating modes achieved using eight adjustable dampers. This integrated system is intended to improve the total system performance and condensation and frosting resistance of ERV systems in cold regions. Numerical models of the integrated HED–ERV system were used to calculate the energy-saving performance of different modes under various climatic conditions. In addition, segmented numerical calculations were used to determine changes in the condensation and frosting limits of the ERV and integrated systems. The results showed that the integrated system further enhanced the sensible heat recovery compared with the ERV system, with the addition of the HED expanding the applicable air conditions for the ERV by –20.5 ℃. The optimal control modes demonstrated improvements in the coefficient of energy (COE) during the cooling season, and the maximum improvement reached 25.3% during the best month. During the heating season, the applicable operating range of the ERV system was extended, and its resistance to condensation and frost was significantly improved.