Thermal Process Simulation And Optimization Design Of Active Heat Storage-release System In Solar Greenhouses

Since its birth,solar greenhouse had been widely used because of the excellent thermal insulation and storage performance of the north wall.With the deepening of scientific research,the limitations of its passive thermal storage performance were gradually concerned by the industry.The XXX team proposed a research method for the active heat storage and release of the solar greenhouse,and completed the continuous upgrade of multiple generations of equipment.In order to further optimize the heat collection and release performance of the sixth-generation active heat storage-release system,and to improve the stability of system operation,it was based on previous research.This article was first established the heat exchange model between the active heat storage-release system and the surrounding environment,and then optimized and improved the water supply mode,water circulation system and aluminum alloy fins of the sixth generation active heat storage-release system,and carried out field tests.To explored the heating effect and system performance under different weather conditions.The solar greenhouse heat collecting curtain wall was designed and verified by experiments to explore the feasibility,heating effect and performance of the heat collecting curtain wall.The main conclusions were as follows:(1)The thermal process model of the active heat storage-release system of the solar greenhouse was constructed.The heat collection and release flow model was in good agreement with the test value.In the heat collection stage,The average relative error was 5.3%in the heat collecting stage and 4.0%in the heat releasing stage,indicated that the model was correct.(2)After optimization,the operation of the active heat storage-release system was more stable and reliable,running the active heat storage-release system at night could significantly increase the air temperature in the test area,compared with the control area,the average night temperature of the solar greenhouse could be increased by 2.7,2.2 and 1.9℃.Under three different weather conditions,the heat collection per unit area was 4.6,3.7,and 2.6 MJ/m~2,respectively,and the heat output per unit area was4.1,3.4,and 3.1 MJ/m~2,respectively;the average heat collection power was 183.1,146.5,and 105.W/m~2,the average heat release power was 163.2,134 and 121.1 W/m~2;the coefficient of performance was 3.8,3.1 and 2.8 respectively;The average heat collection efficiency is 56.5%,68.2%and 73.8%respectively.During the night heating period,the active heat storage-release system had a significant impact on the temperature distribution in the test area.In the experimental area,the temperature difference between the South and the back was large.Under different weather conditions,the maximum temperature difference within the plant population could reached 2.8℃,2.6℃and 2.4℃respectively..The improved system was more energy-saving.When the heat collection was similar,compared with the sixth generation active heat storage-release system,the average daily power consumption was reduced by 20%,the average energy saving rate was increased by 6.7%.(3)The heat collection curtain wall system was used as the back wall of the solar greenhouse.When the system was turned on,the maximum temperature difference between indoor and outdoor can reached31.5℃.As a heating device,the heat-collecting curtain wall system had a significant heating effect.In cloudy and sunny weather conditions,the night temperature increases by 2.6 and 2.7℃respectively compared with the control area,and compared with the active heat storage and release system,the night temperature increases respectively 0.7 and 0.8℃.The heat collection curtain wall system had superior heat collection and release performance.During the test,the heat collection per unit area was 7.6～12.9MJ/m~2,the heat release was 8.0～10.5 MJ/m~2,and the coefficient of performance was 3.5～5.3.Compared with electric heating,the energy saving rate was 76.2%～80.8%,and the heat collection efficiency was46.9%～58.7%,The heat collection efficiency of the system is 46.9%～58.7%.The construction and installation cost of the heat collection curtain wall system is low,the management is simple,and it is suitable for popularization and use in the solar greenhouse.