Research On Drying Mechanism And Drying Technology Of Sweet Potato Vermicelli

The vermicelli is a deep-processed product made of sweet potato with high nutrition. China is a large country not only in sweet potato production but also in sweet potato consumption. The drying process have direct and significant affects to quality of sweet potato vermicelli, but now the drying approach is also same traditional method—in natural sunlight drying. The drying machinery has not been widely used in production of sweet potato vermicelli.It is because the drying machine did not meet the need of production. Such as, the production efficiency is not high enough to reach the degree of automation, vermicelli can not guarantee the quality, and so on. According to these, this paper presents the technology drying of sweet potato vermicelli, optimizes drying machine and drying process to achieve its standardization and standardized.The research projects are divided into three parts.At first, through the analysis porous medium's drying principle ,explores sweet potato vermicelli drying mechanism, establishes the mathematical model , provides the rationale for its drying production ; Second, carries on the experiment and design to the sweet potato vermicelli's drying technology and drying machinery, optimizes the drying parameter including drying temperature, air relative humidity and drying time, gets the optimization and takes this to the design of drying machinery, examines the vermicelli quality produced by these parameters, judges whether it satisfies the production requirement; Third, analyses the drying process by the method of variable-mass thermodynamic, calculates its wet air consumption rate and dry efficiency, for the design and application for the machine.At present, the porous medium drying theories which is more widespread is established in the continuous medium supposition model.This paper summaries the different point of the different theories about the wet material interior water migration method and migration agent, analyses the nature of the water in the sweet potato vermicelli, establishes the mathematical model of the drying process.Through the single factor experiment of the drying parameter to sweet potato vermicelli, analyses by the statistical software, defines the sectional combination drying parameter is :First dry with the high temperature at 60℃for 15 minutes; then drying temperature is gradually reduced to 55℃, 50℃, 40℃, each piece of drying time was 6 minutes, 6 minutes, 5 minutes. Establishes sweet potato vermicelli quality testing system, its measure target mainly has swelling capacity,boiling fastness, break-rate, boiling-lose and so on.Tests the vermicelli quality produced by the optimized parameter and it achieves to the production efficiency and production quality optimized request.Designs the baker combined the optimized dry parameters of sweet potato vermicelli, places the heat source, hot-air generator,platoon wet air blower and the other parts,controls the temperature of each section through pressure groups; designs the vermicelli-box's size meet to both dry efficiency and dry effect; designs the transmission system including axes, bearings, gears, chain wheels, electromotors. Based on three-dimensional design software Pro / ENGINEER platform, completes virtual assembling and designing of the baker.Analyses the drying process by the method of variable-mass thermodynamic, establishes the mass-conservation equation and heat requirement equation,calculates its wet air consumption rate and dry efficiency, for analyzing the baker's material and energy balance.