Simulation And Experimental Research On Indoor Environment Of Solar Greenhouse Under Natural Ventilation Conditions

Affected by solar radiation and plant transpiration,the indoor temperature and humidity in the solar greenhouse are too high at noon,while ventilation can reduce the temperature and humidity in the greenhouse and regulate the airflow distribution.Therefore,it is necessary to grasp the changing laws of various environmental factors in the solar greenhouse under natural ventilation conditions and formulate a reasonable ventilation plan.Therein takes solar greenhouses in Jinan,Shandong and Shouguang,Weifang as the research object,uses CFD technology to simulate and predict the indoor environment of solar greenhouses under natural ventilation conditions,and design experiments for comparison and verification.The main research contents are as follows:The heat mass exchange among environmental factors in the heliostat under natural ventilation conditions is analyzed,and models of the solar greenhouse without and with planted crops are established and validated using experimental data.The distribution of environmental factors inside the greenhouse is obtained by simulating and analyzing the temperature and humidity fields and airflow fields inside the greenhouse and conducting experimental tests.It is found that the indoor temperature and humidity in the solar greenhouse are distributed more uniformly in the horizontal direction,and there are certain differences in the vertical direction.After ventilation,the indoor temperature and humidity will be decreased to varying degrees,and the overall indoor temperature and humidity of the solar greenhouse without crops will change more,while the temperature and humidity of the heliostat with crops near the ground will change less and the middle and upper parts will change more.Based on the experimentally verified model of the solar greenhouse,the indoor environment of the solar greenhouse with three ventilation modes: the lower vent alone,the upper vent alone and the upper and lower vents are simultaneously opened are simulated.It is found that when the lower vents are opened separately for ventilation and the upper and lower vents are opened for ventilation at the same time,a circulating vortex is formed inside the solar greenhouse,and the cooling effect is obvious;when the lower vents are opened alone for ventilation,the temperature on the south side of the greenhouse is significantly lower than that on the north side;When the upper and lower vents are opened at the same time,the temperature and humidity distribution and airflow distribution are more even;when the upper vents are opened separately for ventilation,the cooling effect in the greenhouse is not obvious,and the dehumidification effect is better.This research is expected to provide theoretical guidance on ventilation for crop growers in solar greenhouses.