切片胡萝卜热风干燥过程中传热模拟分析与试验研究

Heat-transmission Simulation and Experiment Research of Sliced Carrot During Drying

物料内部湿热扩散过程是干燥设备和干燥技术研究的基础。干燥过程中,物料内部的湿、热扩散是同时发生的,本文综合湿热扩散过程,提出了切片胡萝卜内部传热模型和内部传质模型,运用第三边界条件进行了传热过程的模拟,并作了实验验证。结果表明:模拟值和实测值十分接近,最大相对偏差小于1.8%;因此用该模型模拟胡萝卜片干燥中传热过程是可行的。模拟结果还显示:物料内各处温度变化不同;在整个干燥过程中,各层的温度梯度随干燥时间先变大,随后逐渐变小,到干燥后期,各层温度趋于一致。

Internal heat diffusion process is the base of the study on drying mechanism and technology. In this paper, the simultaneous moisture and heat diffusion equation with heat-moisture diffusion have been developed and used to solve simulation of heat-transmission. The third boundary constraint model has been considered. Internal heat diffusion is simulating together with internal moisture diffusion. Application was conducted and predicated results agree with the experimental data on the whole. The internal temperature of slice carrot isn＇t identical to the surface temperature during drying. During the whole drying process, the temperature grades in the slice carrot increase first and then diminish with the drying time going, and lastly, the internal temperature is identical.