Modelling and simulations of wet porous medium convective drying

IF 1.5 4区 工程技术 Q3 ENGINEERING, MECHANICAL
Yicun Tang, Yuan Zhang, Jingchun Min
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引用次数: 0

Abstract

In the convective drying of a wet porous medium by hot air, the medium surface exposed to the air fluid may experience three stages namely the fully wet, partly wet, and fully dry stages. At the fully wet stage, the medium surface is fully covered by a water film, with the convective moisture transfer taking place all over the medium surface; at the partly wet stage, the medium surface is partly covered by water film, with the convective moisture transfer occurring only at the wet surface where free water is present. In this research, a theoretical model is presented to simulate the convective drying of a wet porous medium, and experiments on hot air convective drying of a wet porous sand layer are carried out to investigate the sand layer temperature and water content variations during the drying, in which the sand layer thickness is 4 mm, the initial water film thickness is 0.4 mm, and the hot air temperatures are 45, 60 and 75℃, respectively. Inverse calculations are conducted to get some insight into the water film coverage function based on the experimental data, which is necessary for quantitatively evaluating the effective moisture transfer surface area when calculating the convective moisture transfer at the partly wet stage. By combining the coverage function with the wet porous medium drying model, a comprehensive model is obtained. Calculations are implemented to simulate the convective drying of the wet porous sand layer, and the effects of the two constants included in that function on the wet sand layer drying characteristics are discussed. The calculation results are compared with the experimental data, they agree very well, supporting the effectiveness o
湿多孔介质对流干燥的建模与模拟
在热空气对湿多孔介质进行对流干燥时,暴露在空气流体中的介质表面可能会经历三个阶段,即完全湿润、部分湿润和完全干燥阶段。在完全湿润阶段,介质表面完全被水膜覆盖,对流传湿在整个介质表面进行;在部分湿润阶段,介质表面部分被水膜覆盖,对流传湿只在存在自由水的湿表面进行。本研究提出了模拟湿多孔介质对流干燥的理论模型,并对湿多孔砂层进行了热空气对流干燥实验,研究了干燥过程中砂层温度和含水量的变化,其中砂层厚度为 4 毫米,初始水膜厚度为 0.4 毫米,热空气温度分别为 45、60 和 75℃。根据实验数据对水膜覆盖函数进行了反演计算,以便在计算部分湿润阶段的对流传湿时,对定量评估有效传湿表面积有所帮助。通过将覆盖函数与湿多孔介质干燥模型相结合,可以得到一个综合模型。计算模拟了湿多孔砂层的对流干燥,并讨论了该函数中包含的两个常数对湿砂层干燥特性的影响。计算结果与实验数据进行了比较,两者吻合得很好,证明了该模型的有效性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Enhanced Heat Transfer
Journal of Enhanced Heat Transfer 工程技术-工程:机械
CiteScore
3.60
自引率
8.70%
发文量
51
审稿时长
12 months
期刊介绍: The Journal of Enhanced Heat Transfer will consider a wide range of scholarly papers related to the subject of "enhanced heat and mass transfer" in natural and forced convection of liquids and gases, boiling, condensation, radiative heat transfer. Areas of interest include: ■Specially configured surface geometries, electric or magnetic fields, and fluid additives - all aimed at enhancing heat transfer rates. Papers may include theoretical modeling, experimental techniques, experimental data, and/or application of enhanced heat transfer technology. ■The general topic of "high performance" heat transfer concepts or systems is also encouraged.
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