Application of phase change material on solar-greenhouse back wall and its effects on indoor thermal environment and cucumber production in winter

Abstract

The configuration of the solar greenhouse building wall and the thermal properties of the building materials directly impact wall insulation, heat storage characteristics, and, consequently, the thermal environment within the greenhouse. To address the variations in wall heat storage during the design and construction of solar greenhouses, this study aims to integrate solar energy effectively with phase change heat storage technology. Utilizing Energy Plus, the study simulates and verifies the heat storage and release performance of phase change materials on the greenhouse's back wall. The research also explores the warming effect of these materials on cucumber growth. The findings reveal that the composite phase change greenhouse (PC) wall exhibits an average heat release of 60.47 W/m2, maintaining an average temperature of 21.09 °C. In comparison, the heat release from the back wall of the traditional greenhouse (CK) increases by 14.03 W/m2, resulting in a temperature rise of 1.91 °C. Additionally, the substantial heat released by the phase change wall raises the average ground temperature to 18.26 °C through heat conduction, exceeding CK by 3.07 °C. Despite this, the maximum temperature remains below 25 °C, creating an ideal growth temperature for cucumbers and fostering vigorous growth. Furthermore, cucumber quality indicators, such as soluble sugar and VC content, significantly improve, demonstrating a 28.5 % increase in the single fruit weight of cucumbers. In conclusion, the composite phase change greenhouse outperforms the traditional greenhouse in heat storage capacity. The heat storage wall effectively enhances the overall thermal environment, insulation, and heat storage performance, ultimately leading to increased cucumber yield and quality.