Experimental And Numerical Simulationg Study On The Greenhouse Thermal And Humidi Environment For Cherry

Solar greenhouse because of its unique structure can provide suitable growth environment for crops,effectively overcome the impact of adverse external conditions,to meet people’s demand for off-season vegetables,and high economic benefits,so it has been widely used,has become an important pillar of China’s agricultural development.The greenhouse thermal environment plays a key role in the growth of plants.Therefore,the study of inside the environment of the greenhouse is important for the development of greenhouses.Reasonably improve the enclosure structure of the greenhouse,use the size of the vent to control the thermal and humid environment in the greenhouse,provide a suitable growth environment for the cherry greenhouse,and improve the economic benefits of the greenhouse.Firstly,an experimental study was carried out on the cherry greenhouse in Yantai.12monitoring instruments were installed in the greenhouse to measure the temperature and humidity of the cherry greenhouse during the whole growth cycle.In different growth periods,cherries require different environmental conditions on the greenhouse.By comparing the requirements of the suitable cherry growing environment.the environment including the temperature and humidity cannot meet the normal growth of the cherry.In the winter,the night temperature was lower than 0℃and the sustaining low temperature causes the death of the cherry tree.In the spring cherry greenhouse,the daytime temperature exceeds 30℃and the relative humidity is more than 80%of the number of days accounts for more than half,which affects the cherry growth in the greenhouse.The temperature of the sweet cherry greenhouse is too low in winter and likely to cause many problem such as cherry frostbite,consider the traditional cold-proof ditch on the limitation to the cherry on the insulation of the sunlight greenhouse,and the horizontal vertical insulation scheme can replace the cold-proof ditch.Therefore,this article applied the horizontal vertical insulation scheme used on the building to the cherry greenhouse.A numerical simulation was conducted to analyse the variation of soil layer and air temperatures in the cherry greenhouse after using the horizontal and vertical insulation board in the cherry greenhouse.The simulation results show that after laying the insulation board in the cherry greenhouse,the greenhouse soil temperature and the air temperature increased,the average of 2~oC and 0.74~oC respectively.Therefore,the horizontal vertical insulation scheme can reduce the horizontal heat loss of the ground and achieve good heat-insulation effect in the cherry solar greenhouse.In addition,it can increase the cherry greenhouse temperature,and provide a suitable growth environment for the cherry growth.Finally,the temperature and relative humidity of the cherry greenhouse are very high and can be adjusted by natural ventilation in spring based experimental study.However,there is no specific basis for the operation management method.Therefore,a simulation study of natural ventilation in the cherry greenhouse was conducted to study the effects of outdoor temperature,ambient wind speed,the inlet opening size of the natural ventilation inlet opening,the outlet opening size on the indoor environment.Results show that when the outdoor temperature is higher than 18℃,cherry greenhouses should be properly ventilated.Whether it is to increase the wind speed of the air inlet or increase the size of the air inlet and outlet,it will play a certain role in cooling the greenhouse,but must keep into the outlet is open,to ensure the efficiency of natural ventilation.Reasonable natural ventilation can improve indoor environment and economic benefits of cherry greenhouse.