Numerical Analysis Of Hot-Blast Heated Greenhouse Thermal Environment

With the fast development of the computer technology, the computing power of CFD (Computational Fluid Dynamics) software, like FLUENT, has got great improvement, which results in revolutionary advancement in the design study. The field of vision of greenhouse structural designing was broadened by applying CFD method in the greenhouse researches, showing CFD's great potential in scientific and practical application.This dissertation took the Venlo-Type glasshouse in the campus of Zhejiang University of Technology as the research object, analyzed the greenhouse thermal environment under hot-blast heating conditions, and verified the primary factors affecting greenhouse thermal environment, upon which based the reasonable simplifications for the CFD model. Then definition of the computation domain, the form of the flow field governing equations, and the choice of rapids model and radiation model as well were proposed for CFD simulation.Experiments in the greenhouse under hot-blast heating condition were performed to collect data about temperature distribution inside the greenhouse both in vertical and horizontal directions, and weather data outside as well, providing data resources for the set of parameters in the CFD model. Data analysis was carried out to complete the definition of the boundary conditions and the establishment of the CFD validation model. The greenhouse thermal environment under hot-blast heating was simulated employing the CFD model constructed before. The numerical results got good agreement with the experiment data, which confirmed the accuracy of the definition of the boundary conditions and the validity of the CFD model.Further investigations into the hot-blast pipeline, the critical part in the greenhouse heating system, were conducted to find out the relations between the performance of the hot-blast pipeline and its geometry design. In order to obtain a balanced spatial distribution of heat quantity, tests were performed under the experiment conditions to optimize the geometry design of the hot-blast pipeline.At last, the CFD method was used to simulate the hot-blast heating effects urtder different greenhouse structure configurations like the use of the thermal curtain and the arrangement of the hot blast pipeline. Suggestions were proposed in perspective of the heating system design and the environment control strategy.