NUMERICAL INVESTIGATION ON ENHANCING INDOOR THERMAL ENVIRONMENT OF SOLAR GREENHOUSES THROUGH NOVEL ACTIVE HEAT STORAGE AND RELEASE WALL

To mitigate the issue of a thermally stable layer in block-bearing walls of solar greenhouses, which restricts the utilization of free solar energy at night, leading to a significant temperature disparity between daytime and nighttime indoor air, this paper introduces a novel active heat storage and discharge composite wall featuring a gravity circulation annular tube. The model is established based on heat transfer theory, incorporating the unsteady heat transfer of the wall, coupling it with the heat balance equation of indoor air, and executing numerical simulations utilizing Matlab. The results indicate that in cold regions during winter, the new active thermal storage wall elevates the indoor air temperature by 1.21 °C at night, marking a 13.12% increase compared to a wall lacking a gravity circulation annulus. Moreover, the daily effective temperature accumulation is 7.88 °C·h higher, representing a 4.84% improvement over a wall without a gravity circulation annulus. The average daily heat load experiences a reduction of 4769.24 W/d, accounting for a 17.35% decrease compared to a wall without a gravity circulation annulus. This innovative wall enhances the active heat storage and release capabilities, facilitating the transfer of more solar energy for nighttime use. It effectively curtails excessive daytime room temperatures, augments nighttime room temperatures, and minimizes the daily variation in indoor air temperature. Such improvements are conducive to the four-stage variable temperature management of crops, promoting the rapid growth of winter crops. © 2024 Science Press. All rights reserved.