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Tobacco Science & Technology, 2010, 8, p. 5-9., ISSN.1002-0861

Dynamic analysis of strips humidifying process based on diffusion model

1. Key Laboratory of Tobacco Processing Technology, CNTC, Zhengzhou 450001, P.R. China; 2. Technology Center of China Tobacco Hebei Industrial Corporation, Shijiazhuang 050051, P.R. China

In order to study the absorption of strips and the migration rate of moisture in strips during processing, B2F strips were studied dynamically under a temperature range of 60-80 °C and relative humidity range of 60%-90% by an online device on the presumptions that: 1) The test piece is homogeneous and of even initial temperature; 2) Coupling effect and temperature difference in the test piece are negligible during heat and mass transfer process; 3) The distortion and expansion effects of the test tobacco during humidifying are ignored, and the thickness of the test tobacco is represented by its mean, 3×10-4 m; 4) The humidifying process follows Fick's second law, the dynamic model of humidifying process, which describes the effects of temperature and humidity, was established; the model was modified and verified. The results showed that: 1) At the same temperature, effective diffusion coefficient De decreased with the increase of relative humidity; while De increased with the rise of temperature at the same relative humidity; 2) The modified model could describe the humidifying process of B2F strips in the environment of higher temperature and relative humidity, the verified experimental data well agreed with the calculated values by the model, and correlation coefficient R2 was >0.95.