Open-cell rigid polyurethane foam was taken as core material of the vacuum insulated panel, and the effects of open-cell ratio, density, cell-diameter and intensity on adiabatic performance of the vacuum insulated panel were simply discussed. The effect of vacuum degree on it is also discussed. The pre-treated craft of vacuum insulated panel manufacture is introduced too. If the open-cell rigid polyurethane foam was taken as the core-material and pretreated craft was carried, the vacuum insulated panel’s thermal conductivity can be less than 10mW/(m•K).
This paper researched the mechanism and model of moisture transfer in the core material of VIP- glass fiber, and introduced the vacuum drying technology to enhance the gas molecules’ movement under vacuum, accelerate the speed of water vaporization and avoid voids adhesion to overcome the adsorption resistance. The article also designed the equipment to provide experimental possibilities for the theoretical study.
Vacuum insulation panels are distinguished by their outstandingly low thermal conductivity, which is approximately 0.004 W/ (m • K) to 0.01 W/ (m • K), only 33% to 10% of that of the traditional heat preservation materials. The heat preservation mechanism of vacuum insulation panels is elaborated in the study. The thermal conductivity of the vacuum insulation panel made in our lab were below 0.01 W/ (m • K). By analysis and calculation, with this kind of VIPs applied to refrigerated containers, its exciting properties can save energy consumption by more than 20% compared with traditional heat preservation materials.
The pre-cooling device was built and the columnar cabbage was taken as the study object in this paper. The heat and mass transfer mathematical models for the cylindrical shape vegetable were built and the experimental method was introduced to prove them. The comparison and analysis, under the certain vacuum degree of the vacuum chamber, was done between the simulation and the experiment. And the differences of the vacuum degree in the chamber, the temperature change of the cabbage, the relative humidity in the chamber and the cabbage mass loss, in the experiment and the simulation, were all recorded. The reason of the parameters variance and existent deference was also analyzed in this paper. The mathematical models and the result were useful for the study on the cylindrical vegetable vacuum pre-cooling technology.
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