The Simulation Of Double-layer Membrane Technology In The Granary Temperature Control

Horizontal bin is currently one of the most popular types of granary constructions.Horizontal bins have been vigorously promoted on a large scale owing to many advantages,such as wide regional using, simple construction, large storage, and easy to maintenance and so on since imported from the Soviet Union during the early period of the founding of People’s Republic of China. With the development of science and technology, some previous horizontal bins with poor hardware conditions which have had the difficulty in meeting the requirements of grain storage come to meet with the problem of large energy consumption.Therefore, these early granaries need modern reconstruction and transformation in order to enhance the comprehensive economic benefit and reduce the storage energy consumption.The reconstruction activities of horizontal bins usually utilize the erection of heat insulation roof, construction of insulation materials in bins, setting the sealing glass to increase the tightness and thermal insulation of granary, reducing the effect of wall heat transfer for the purpose of maintaining appropriate temperature in granary; however, these methods have some shortcomings. Aiming at solving these present problems, this thesis bring forward the method of laying the double-layer membrane on the piles of grain in granaries.With a flow of cold air through the double-layer membranes, the heat transfer between grain piles and the double-layer membrane and the effect of airtight gasbag of heat insulation caused by the double-layer membrane will bring an appropriate storage temperature in the grain piles under the condition of relatively high temperature in the external environment.In this thesis, by using the method of Computational Fluid Dynamics(CFD), the author established the corresponding model of the granary based on experimental data, and in the process of simulation loaded the model with some actual variables of external environment and solar radiation data to minimize the error of the simulation. Then the author compared the simulated data with the measured results to validate that the CFD has good feasibility and reliability when simulating the environment inside the barn, and in subsequent trials, analyzed further the model of granary with double-layer membrane using CFD method.In order to identify the best thickness of the double-layer membrane, the authorcalculated the theoretical values based on the formula, and achieved simulation values through the corresponding CFD model analysis, then had a contrast with each other, after that the author conducted verification analysis so as to find out the best thickness of double-layer membrane. Additionally, the author identified the best speed and the best temperature of the flow of cold air through the double-layer membrane in the same way, thus to lay a foundation of the subsequent studies on the application of double-layer membrane technology regarding the reconstruction of horizontal bins.