Analytical solution of mass transfer equation with interfacial resistance in food drying

A simplification of boundary conditions of the mass transfer equation in food drying was obtained. An average distribution constant between food and air humidity was introduced. With this simplification, an analytical solution for the mass transfer equation with interfacial resistance was found, and a modified Bi number is proposed. The analytical solution for infinite flat slab was compared to the numerical solution without the simplification. The analytical solution showed a good approximation to the numerical solution. The equation obtained from the analytical solution predicted that for modified Bi numbers greater than 30, the drying curve becomes independent of the boundary conditions, which means that drying is diffusion controlled. Experimental drying curves of carrots were obtained at modified Bi numbers between 10 and 60. The experimental drying curves did not show statistical difference for modified Bi numbers greater than 40, which approaches to the same limit predicted by the analytical solution.

Biot number; Carrots; Drying; Intertfacial mass transfer Atmospheric humidity; Boundary conditions; Food products; Interfaces (materials); Mass transfer; Numerical analysis; Analytical solution; Biot number; Drying curves; Food drying; Interfacial mass transfer; Mass transfer equation; Numerical solution; Drying

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