Ventilation Simulation And Optimization Of Active Heat Storage Solar Greenhouse Based On CFD

Sunlight greenhouse is the unique greenhouse types in the north area of our country,it has been widely used in Chinese agricultural production,and has become the main greenhouse production types.To simulate the flow field in greenhouse based on computational fluid dynamics(CFD)software is an important means to study the flow field in greenhouse.In this study,through CFD simulation of active thermal storage solar greenhouse with different insulation back wall materials,active thermal storage solar greenhouse with different fan operating conditions and active thermal storage solar greenhouse with different air outlet layout,the thermal performance and the influence of air flow movement,combined with the measured results to verify the effectiveness of the model,so as to determine the impact of different materials insulation back wall on the heat storage capacity of the greenhouse.And optimize the position of air outlet and fan operating conditions.Through experimental research and numerical analysis,the following results are obtained:1.Compared with the state of not running the fan,after the fan was started,the internal temperature of the greenhouse could be effectively reduced during the day,and the internal temperature of the greenhouse could be improved at night.No matter in the state of natural ventilation during the day or in the state of closed at night,the active heat storage and release system in the greenhouse could significantly reduce the temperature difference in the growing zone of the greenhouse plants,making the internal space tem perature of the greenhouse more uniform and consistent.At the same time,the wind speed in the growing area of greenhouse plants after the fan was started was higher than that in the growing area of greenhouse plants when the fan was not started,which was conducive to plant growth.2.The single tuyere active heat storage and release system was easy to form air short circuit in the vertical direction,and only part of the air flowing out of the tuyere entered the plant growing area,and part flowed upward into the upper space along the film,which couldn’t effectively participate in the space air heat and humidity exchange in the plant growing area.The air in the outlet of the multi-tuyere active heat storage and release system directly entered the plant growing area,which could fully carry out heat and humidity exchange,especially at night,could effectively improve the space temperature of the plant growing area.3.After the fan was started,the temperature of the greenhouse with multiple outlet active heat storage and release system in the daytime was lower than that of the greenhouse with single outlet active heat storage and release system,and the temperature of the greenhouse with multiple outlet active heat storage and release system in the nig ht was higher,and the temperature difference of the greenhouse with multiple outlet active heat storage and release system in the plant growing area was lower than that of the greenhouse with single outlet active heat storage and release system in the daytime and night.Multi-tuyere active heat storage and release system greenhouse space temperature was more uniform,more consistent.Meanwhile,the wind speed in the growing area of the greenhouse with multiple tuyere active heat storage and release system was higher than that in the greenhouse with single tuyere active heat storage and release system,which was conducive to plant growth.4.Changed the wind speed of the air outlet of the multi-outlet active heat storage and release system.Compared with the greenhouse of the multi-outlet active heat storage and release system with different wind speed of the air outlet,when the wind speed of the ai r outlet was less than 0.8m/s,with the wind speed of the air outlet rising,the internal temperature of the greenhouse of the multi-outlet active heat storage and release system would decrease under the blower operating condition during the day;under the blower operating condition at night,the internal temperature of the greenhouses with multi-outlet active heat storage and release system increased,the temperature difference of the inlet and outlet of the pipeline increased,and the active heat storage and release system played a better role.However,when the wind speed of the outlet reached 1.2m/s and 1.5m/s,the internal temperature of the greenhouse decreased at night,and the inlet and outlet temperature of the pipeline of the active heat storage and release system decreased.The wind speed of the outlet above 1.2m/s weakened the effect of the active heat storage and release system.