Research On Vacuum Plate Glass's Performance Of Heat Transfer And Its Stress Caused By Supporting

Diligently seeking such a material, which is good at both transparence and thermal insulation, is always an important task for scientific and technical workers in greenhouse horticulture . Vacuumplane glass, as a new material in 21st century, is the champion by following excellent performances: anti-aged, heat preservation, transparence, and infrared reflection. Researching the vacuum plane glass to utilize its huge function is the crucial sector to the future development of horticulture.The systematic theoretical and experimental research to the heat-transfer performance of vacuum plane glass and the glass's stress field which is caused by supporting is made in this study. The vacuum glass specimen for experimental research is made successfully. The results got from the research will be good for the glass designing, manufacturing as well as its industrialization.(1) The heat transfer of vacuum glass based on the theory of thin-air transfer heat in the free-molecule state, the theory of Low-E coating's transfer heat and the theory of coupled radiation and conduction in glass was deeply analyzed. At last the calculation model of heat transfer of vacuum glass with Low-E coating was established.(2) Using diffuse-non-gray-surface model, the physical process of radiation heat transfer fluxes from vacuum glass with Low-E coating was precisely simulated. The reflectivity and transmissivity of Low-E vacuum glass were fully considered in this model. The conclusion that Low-E layer of vacuum glass has a great contribution to heat resistance is gained in the end.(3) The controlling equation of heat transfer through vacuum plane glass was established on the basis of the theory of coupled radiation and conduction. The question is resolved by the method of Exponential Kernel Approximation, dimensionlessness and linearization.(4) The heat-transfer approach of low-E vacuum glass was analyzed amply in this thesis, meanwhile the heat balance equation was established. By the solution of heat balance equation and the analysis of heat-transfer approach, the calculation method of the heat transmission coefficient was gained. At last the fact that vacuum glass with Low-E outside prior to inside was concluded.(5) Through the hot-box experiment, which can take out air from the glass meanwhile, three kind of curves of heat transmission coefficient related with vacuum pressure —the curve of common vacuum glass, vacuum glass with inside coating and vacuum glass with outside coating were drawn. The result that heat transmission coefficient decreases along with vacuum pressure's decline was gained. After vacuum descends to 0.313 pa and enters the state of free molecule heat transfer, it is not obvious to the decrease of heat transmission coefficient caused by the decline of vacuum pressure. This indicates that as long as the pressure in vacuum cavity keeps below 0.313 pa , heat insulation effect can be achieved.(6) By the Simulations for the actual work environment of glass vacuum, the conclusion that exterior wind velocity can influence heat transmission coefficient obviously was gained. This provides abasis for establishing standard of environment parameter in the greenhouse overlaying materials' test.(7) Vacuum glass sample is manufactured successfully in the experiment. The craft of supporting, agglutinating, putting shore is all developed well.(8) A mathematical model of stress distribution in vacuum glass was established by using crunode method.(9) Analyzing the mathematical model, which has been established with the finite element method, the vacuum glass's strut-stress distribution was gained.(10), A precise stress distribution color chart which shows many important characteristic parts was drawn by using ANSYS software to analyze vacuum glass's stress and strain field. Eventually a basically consistent result between the theoretical calculation and the software analysis is obtained.