| 摘要: |
| 有效质扩散系数是干燥传质研究的重要基础数据之一，现有有效扩散系数研究大多侧重于考虑温度而忽视含水率、干燥收缩变形的影响。本文建立了刺参干燥有限元模型和有效扩散系数计算模型，以含水率数据的模拟值与实验值之差最小为优化目标，计算得到有效扩散系数值，对比分析了干燥收缩及干燥温度和含水率因素对刺参有效扩散系数的影响。研究表明：收缩变形、温度及含水率等因素均对有效扩散系数影响较大，同时考虑上述3个影响因素得到的有效扩散系数比只考虑温度及含水率影响时小3.9%~14.6%，而考虑收缩变形和温度影响得到的有效扩散系数比只考虑温度影响时小8.7%~14.5%，且刺参有效质扩i数均随干燥温度和含水率的升高而增加。考虑收缩、温度和含水率等对有效扩散系数的影响后，刺参干燥模型模拟得到的含水率与实验值吻合最好，相关系数高于0.994。模拟得到的刺参内部有效扩散系数按由内向外逐渐降低的规律分布，干燥从1 h进行至15 h，内外扩散系数差值由6.4×10-10 m2/s减至0.9×10-10 m2/s，中心处质扩散系数则由14.6×10-10 m2/s降至8.9×10-10 m2/s。 |
| 关键词: 热泵 传质 扩散系数 干燥 刺参 |
| DOI： |
| Received:September 25, 2017 |
| 基金项目:山东省自然基金资助项目（ZR2014EL029）和天津市自然科学基金重点项目(16JCZDJC33900)资助。 |
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| Study on Effective Diffusivity of Sea Cucumbers with Heat Pump Drying |
|
Zhao Haibo1, Yang Zhao2, Dai Jiaao3, Qiao Lingmin3, Zhang Lingling3
|
| (1.School of Ocean, Yantai University;2.School of Mechanical Engineering, Tianjin University;3.School of Civil Engineering, Yantai University) |
| Abstract: |
| The effective diffusivity is an important parameter for mass transfer research on the drying of sea cucumbers. The dependence of the effective diffusivity on temperature has been adopted in current studies, while the effects of moisture content and shrinkage have often been ignored. Therefore, in this paper, a finite element dry model is built and the diffusivity determination method based on the model is applied to study the diffusivity in sea cucumber heat pump drying. The influences of shrinkage during heat pump drying, temperature and moisture content on diffusivity have been studied and analyzed. The results show that the drying shrinkage, temperature, and moisture content affect the effective diffusivity greatly. The effective diffusivities, as determined by considering the effects of shrinkage, temperature and moisture content, are 3.9-14.6% lower than those considering the effects of temperature and moisture content The effective diffusivities determined by considering the effects of shrinkage and temperature are 8.7-14.5% lower than those only considering the effect of temperature. The effective diffusivity increases with both temperature and moisture content. Models considering drying shrinkage and influence of temperature and moisture content on diffusivity can preferably predict moisture content variation in line with the experimental values, with a coefficient of correlation higher than 0.994. The effective diffusivity decreases along the radial direction in the sea cucumber. As drying proceeds from 1 to 15 h, the difference in effective diffusivity between the center and the surface of sea cucumber reduces from 6.4 × 10-10 m2/s to 0.9 × 10-10 m2/s, and the effective diffusivity in the center decreases from 14.6×10-10 m2/s to 8.9×10-10 m2/s. |
| Key words: heat pump mass transfer effective diffusivity drying sea cucumber |
