A system integrating greenhouse surplus heat storage-release and positive pressure ventilation for heating and cooling

Efficient year-round production of the Chinese solar greenhouse (CSG) requires integrated thermal management. Existing active heat storage-release systems perform well in greenhouse heating but lack cooling capability, limiting climate regulation and cost-effectiveness. This study proposes a system integrating greenhouse surplus heat storage-release and positive pressure ventilation for heating and cooling (SHVS). Centered around a combined air conditioning unit, the system collects surplus CSG air heat for nighttime heating during cold seasons via surface coolers with internal air circulation, and achieves cooling in warm seasons using evaporative wet pads under positive pressure ventilation. Field tests showed the system maintained a daily average heat collection rate of 36.3 W m−2, peaking at 58.1 W m−2, and delivered a daily heat release of 0.41 MJ m−2. During operation, the average nighttime air temperature inside the CSG was 18.5 °C higher than outdoors, 4.4 °C above the unheated scenario. For greenhouse heating, the system achieved a coefficient of performance (COP) of 6.4 for heat collection and 4.8 across the entire heating process. In summer, the system provided 0.0158 m s−1 greenhouse ventilation and decreased the average CSG air temperature by 3.0 °C compared to natural ventilation, at a power consumption of 14.7 W m−2. Its energy efficiency ratio (EER) for evaporative cooling reached 11.8. The system achieved an average cooling efficiency of 90.6%, with water consumption ranging from 0.040 to 0.047 g m−2 s−1. The proposed integrated system, which demonstrated good performance in greenhouse heating, cooling, and energy savings, facilitates sustainable CSG cultivation.