Study On Thermal Environment Optimization And Similarity Simulation Of Solar Greenhouse

Ventilation,as the main means of regulating the indoor thermal environment in solar greenhouses,can directly change environmental factors such as indoor temperature,wind speed,relative humidity,and provide a suitable growth environment for crops.In this paper,a solar greenhouse built on PC board is taken as the research object.By using experimental and CFD simulation methods,the optimal air supply scheme for fan coil heating is obtained through comparative analysis,and a method for simulating large greenhouses using similarity principles is proposed.The specific work is as follows:(1)Build a solar greenhouse experimental platform.The experimental solar greenhouse and its heating system have been built,and indoor and outdoor temperature,humidity,wind speed,and other measuring points have been designed and arranged.The indoor and outdoor temperature parameters have been obtained in the mode of no air supply(with or without crops)and with air supply(without crops).(2)Identify and validate greenhouse CFD models.Based on the greenhouse energy balance analysis and comparing the advantages and disadvantages of various models,a standard k-based-ε The CFD models of the model,the DO radiation model,the porous media model,and the component transport model have successfully verified the greenhouse CFD models with and without air supply using indoor and outdoor measured environmental parameters.(3)Optimize the mechanical air supply mode of greenhouse.Using CFD numerical simulation method,the effects of fan coil air supply temperature,air supply angle,air supply speed,and air supply height on the temperature and velocity fields in the plant crop region were simulated and studied.The optimal mechanical air supply method was obtained:the fan coil was 1.35m from the ground,the air supply temperature was 19 ℃,the air supply speed was 3 m/s,and the horizontal direct blowing was performed.(4)A greenhouse similarity simulation method based on virtual media is proposed.It is proposed to apply the similarity theory to the simulation of solar greenhouse,propose a greenhouse similarity simulation method,and derive the corresponding proportions of the variables of the original model and the similar model,as well as the physical properties of the virtual medium of the similar model.The simulation results show that the temperature simulation values at the corresponding measurement points of the two models in the greenhouse are not significantly different,and the temperature field distribution and velocity field distribution are basically consistent,which verifies the feasibility of the CFD similarity simulation method based on virtual media proposed in this paper.