The Simulation Research Of Mechanical Ventilation Cooling Effect On Venlo-type Greenhouse In Chongqing

The greenhouse is one of the main facilities of agricultural facilities, while inside the greenhouse crop growth and development mainly depends on the genetic and environmental factors, genetic decided to crop growth and development potential, and the environment is to determine the degree of this potential is possible. Suitable for greenhouse environment is particularly important, therefore, environmental regulation and control are the core of the greenhouse crop production. The greenhouse of Chongqing region currently exists a problem that high temperature had leaded to the crops can’t growth in the summer, so the utilization of greenhouses is generally lower. Greenhouse ventilation is a major factor what affect indoor environment, through the ventilation in greenhouse can let the matter and energy exchange between internal environment and environment effectively control the greenhouse temperature, humidity, CO2concentration, thus achieve to the best condition for crop growth inside the greenhouse, and therefore it is necessary to study the greenhouse ventilation.This paper is mainly based on Fluent software of CFD Computing platform, in summer, under the condition of mechanical ventilation, to simulate and research the temperature field and flow field of Chongqing area Venlo type glass greenhouse by CFD method, set up the same as the measured size of greenhouse3d model, and through compares and analyzes the simulation results with experiments and the test data, we can get a conclusion that the CFD model simulation is accurate and reliable. Base on the result, using the model to predict the distribution of temperature field and air flow field inside the greenhouse in different wet curtain fan and wet curtain installation height, different height and the number of different greenhouse launch configuration conditions, discusses the distribution of temperature in the greenhouse under different cases, and to explore the greenhouse internal cooling effect of different structure scheme, and put forward the structure optimization scheme, to provide Venlo type glass greenhouse structure optimization design in Chongqing region and theoretical reference in greenhouse environment control. The main research contents, research methods and conclusions were as follows:(1) Simulation studies took the different installation height of fan and wet curtain in greenhouse as the breakthrough point, it is concluded that the air flow field and the distribution of the temperature field inside the greenhouse under different installation height, the simulation results show that the higher the equipment installation height can make the temperature gradient distribution of the vertical direction and horizontal direction gradually easing inside the greenhouse. (2) the wet curtain in greenhouse to configure different height and the increase of the length of the greenhouse as the breakthrough point of the simulation, took1.5m and2.0m specifications of the wet curtain to configuring respectively to32m,48m and64m long greenhouse, simulate and study the distribution of temperature field and flow field in greenhouse.The research results show that wet curtain height from1.5m to2.0m, will expand the greenhouse internal cooling area, provide suitable growth environment for crops what higher canopy height;Don’t change the fan power, only increase the wet curtain height of the greenhouse,48m length range can ensure the greenhouse achieve a better cooling effect, while the length of greenhouse more than64m,cooling effect is limited to a certain extent, can consider to increase the number of fan or fan power.Comprehensive analyze the simulation results on different fan and wet curtain installation height, the wet curtain of different height and the number of greenhouse space size configuration. To summary and analysis the change and distribution of temperature inside the Venlo-type glass greenhouse in Chongqing area, to analyze the relationship between each other, and compare the cooling effect under various working conditions, put forward more reasonable type suitable for Chongqing area Venlo greenhouse cooling scheme, and put forward reasonable Suggestions for greenhouse structural design. In order to give a reference and theoretical basis for structure optimization design for wet curtain and fan cooling system of Venlo-type greenhouse in Chongqing.