Coupled Heat and Mass Transfer With One Discrete Sublimation Moving Interface and One Desorption Mushy Zone

The present work discusses coupled heat and mass transfer during freeze-drying of a rigid product, as well as accelerated freeze-drying where sublimation and desorption occur concurrently. A desorption mushy zone model was developed to describe the desorption drying. An exact solution was obtained for coupled heat and mass transfer with one discrete sublimation moving interface and one desorption mushy zone where mass transfer is controlled by both Fick and Darcy laws. The effects of several parameters on the sublimation and desorption are analyzed and discussed.

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Exact Solution of Coupled Heat and Mass Transfer with One Discrete Sublimation Moving Interface and One Desorption Mushy Zone in a Cylindrically Symmetrical Porous Space

International Journal of Fluid Mechanics Research ◽

10.1615/interjfluidmechres.v25.i4-6.120 ◽

1998 ◽

Vol 25 (4-6) ◽

pp. 578-587

Author(s):

Sh.-W. Peng ◽

G.-Q. Chen

Keyword(s):

Mass Transfer ◽

Exact Solution ◽

Mushy Zone ◽

Heat And Mass Transfer ◽

Porous Space ◽

Moving Interface

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Solution of heat and mass transfer problems with non-linear coefficients

Tyumen State University Herald Physical and Mathematical Modeling Oil Gas Energy ◽

10.21684/2411-7978-2019-5-4-10-20 ◽

2019 ◽

Vol 5 (4) ◽

pp. 10-20

Author(s):

Boris G. Aksenov ◽

Yuri E. Karyakin ◽

Svetlana V. Karyakina

Keyword(s):

Mass Transfer ◽

Exact Solution ◽

Numerical Methods ◽

Heat And Mass Transfer ◽

Unknown Function ◽

Comparison Theorems ◽

Upper And Lower Bounds ◽

Maximum Deviation ◽

Approximate Methods ◽

Nonmonotonic Dependence

Equations, which have nonlinear nonmonotonic dependence of one of the coefficients on an unknown function, can describe processes of heat and mass transfer. As a rule, existing approximate methods do not provide solutions with acceptable accuracy. Numerical methods do not involve obtaining an analytical expression for the unknown function and require studying the convergence of the algorithm used. The value of absolute error is uncertain. The authors propose an approximate method for solving such problems based on Westphal comparison theorems. The comparison theorems allow finding upper and lower bounds of the unknown exact solution. A special procedure developed for the stepwise improvement of these bounds provide solutions with a given accuracy. There are only a few problems for equations with nonlinear nonmonotonic coefficients for which the exact solution has been obtained. One of such problems, presented in this article, shows the efficiency of the proposed method. The results prove that the proposed method for obtaining bounds of the solution of a nonlinear nonmonotonic equation of parabolic type can be considered as a new method of the approximate analytical solution having guaranteed accuracy. In addition, the proposed here method allows calculating the maximum deviation from the unknown exact solution of the results of other approximate and numerical methods.

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