Modelling and experimental verification of the thermal performance of an active solar heat storage-release system in a Chinese solar greenhouse

An active solar heat storage-release (AHS) system that stores solar energy in a water storage tank can supplement heat to raise the air temperature in Chinese solar greenhouses (CSGs) during cold winter nights. To quantify such heat transfer processes and to improve the performance of AHS systems, a tank temperature model was developed. The model was calibrated and validated, and it can predict water temperatures in the storage tank with an average accuracy of 0.4 °C. The model was used to determine the required solar collector area and storage tank volume under various desired air temperatures in different greenhouses. In two cases, greenhouses with a ground area of 272 m2 and roughly 62 m2 of solar collectors were installed to maintain temperatures above 12 °C under Beijing climate conditions. To facilitate a 1 °C increase in the air temperature set-point, approximately 2 m2 of additional solar collectors and 0.1 m3 of additional storage tanks are needed.