Study On Influence Factors Of The Low-Temperature Thin-Layer Drying And Its Optimization

In this paper, we introduce a new type of drying method, called Low-temperature Thin-layer Drying(LTD).we also introduce its development, principles and characteristics. Compared to the conventional drying method, the LTD is a new drying method that could get high product quality, low energy consumption, and most important, it’s no hurt to the environment. Its market application is broad.To understand the drying characteristics of LTD, we made a theoretical analysis of the drying process influencing factors. And we studied its drying process dynamics with the solanum tuberdsm. The study shows:when the heating temperature is between75℃～95℃,the temperature of solanum tuberdsm rise rapidly to about60℃～75℃at the start of drying. Then the temperature remains stable. But the temperature of solanum tuberdsm is always lower than the temperature of the heat source, the temperature difference is between10℃～15℃. Wind speed increases the material the temperature of Solanum tuberdsm can be reduced with the increases of air velocity. The typical constant drying stage is not observed at high heating temperature. It takes less time and faster drying rate to dry the solanum tuberdsm with higher heating temperature, thinner layer thickness, higher air velocity.In order to optimize the drying process and control the product quality, usually we need to create a mathematical model of the drying process. Model studies show, the Two term exponential model can well describe the low-temperature thin purple potato material drying process. And we find the relationship between the model empirical constant k, a and heating temperature T, the layer thickness H and the air velocity V.On the basis of full understanding of the LTD drying characteristic, to optimize the industrial process application, we give several suggestions. The suggestions are improving the formulation of product, searching for the best process parameters, and combining it with other drying method to improve the drying process.