果蔬真空低温干燥箱搁板的传热分析及试验研究

Simulation and Experimental Test of Heat Transfer of Shelf in Vacuum Drying Chamber

搁板是果蔬真空低温干燥设备的核心部件之一,本文以实验室果蔬真空低温干燥箱搁板为基础,分析了其传热过程,模拟其加热搁板的温度分布。并且,将猕猴桃作为试验样品,搁板作为研究核心,通过试验,研究了加热介质流速和搁板温度均匀性的关系,验证了搁板的温度分布情况。同时,试验表明提高加热介质的流速能够降低搁板加热介质进出口的温差。设计改进搁板后,搁板温度分布表明,搁板的传热均匀性得到了改善。

The heat transfer of the shelf in the vacuum drying chamber was physically modeled, empirically approximated, numerically simulated, and experimentally tested. The impacts of the vacuum drying conditions, such as the pressure, shelf＇s structure and temperature distribution, type and flow rate of heating medium, on the drying rate of kiwi fruit slice were evaluated. The simulated results show that the flow rate of the running medium,responsible for heating-up the shelf, has a major impact on the uniformity of temperature distribution of the shelf and temperature drop from the inlet to the outlet of the heating pipe. The experimental results reveal that an increase of the flow rate of the heating medium con- siderably reduced the temperature difference between the inlet and outlet of the shelf heating pipes. The modified shelf achieved an improved uniformity of temperature distribution, an increased heat transfer, and a reduced energy-consumption.