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Abstract <p>The heat and mass transfer between a wet spherical body (ball) and an external gas medium with electromagnetic energy supply in the infrared frequency range is considered. A linear problem (at constant process parameters) of infrared heating of the body during convective heat and mass transfer between its surface and the external gas medium is formulated and analytically solved—both for the general case of drying process and for the case of drying in the first stage. In formulating the heat conduction problem, it is assumed that the internal heat source caused by the absorption of radiant energy is exponentially distributed over the thickness of the body and that phase transformations during moisture evaporation occur near the surface of the body. The drying intensity is described based on an analytical solution of a linear problem (at constant mass conductivity) of mass conduction (moisture diffusion) for a ball under the boundary condition of mass transfer of the third kind. Solutions to the heating problems are obtained at the local temperature and at the temperature averaged over the volume of the body. Based on these solutions, heating of the ball is numerically modeled, taking into account its drying: the effect of the radiant flux density on the ball heating dynamics is shown. For the first drying stage, it is demonstrated that the particular solution to the problem obtained for this case allows one to calculate the surface temperature of the body and then the drying intensity under conditions of infrared energy supply (at which the body surface temperature is not equal to the wet-bulb temperature). To calculate the body surface temperature for this case, a method of successive approximations is proposed. In this method, the desired temperature is first specified and then calculated using the obtained solution and the Antoine equation, which expresses the dependence of saturated vapor pressure on temperature. Numerical calculations are performed for this case, demonstrating the feasibility of the mathematical model and illustrating the effect of additional (in addition to convective) infrared energy supply on drying intensity. To account for changes in thermophysical characteristics during the process, a piecewise-stepped zonal method is recommended.</p>

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Heat and Mass Transfer in Continuous Infrared Drying of a Spherical Body

  • 期刊论文

  • 发表日期：

    2025年10月1日

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  • S. P. Rudobashta,
  • E. M. Kartashov,
  • G. A. Zueva

摘要

Abstract

The heat and mass transfer between a wet spherical body (ball) and an external gas medium with electromagnetic energy supply in the infrared frequency range is considered. A linear problem (at constant process parameters) of infrared heating of the body during convective heat and mass transfer between its surface and the external gas medium is formulated and analytically solved—both for the general case of drying process and for the case of drying in the first stage. In formulating the heat conduction problem, it is assumed that the internal heat source caused by the absorption of radiant energy is exponentially distributed over the thickness of the body and that phase transformations during moisture evaporation occur near the surface of the body. The drying intensity is described based on an analytical solution of a linear problem (at constant mass conductivity) of mass conduction (moisture diffusion) for a ball under the boundary condition of mass transfer of the third kind. Solutions to the heating problems are obtained at the local temperature and at the temperature averaged over the volume of the body. Based on these solutions, heating of the ball is numerically modeled, taking into account its drying: the effect of the radiant flux density on the ball heating dynamics is shown. For the first drying stage, it is demonstrated that the particular solution to the problem obtained for this case allows one to calculate the surface temperature of the body and then the drying intensity under conditions of infrared energy supply (at which the body surface temperature is not equal to the wet-bulb temperature). To calculate the body surface temperature for this case, a method of successive approximations is proposed. In this method, the desired temperature is first specified and then calculated using the obtained solution and the Antoine equation, which expresses the dependence of saturated vapor pressure on temperature. Numerical calculations are performed for this case, demonstrating the feasibility of the mathematical model and illustrating the effect of additional (in addition to convective) infrared energy supply on drying intensity. To account for changes in thermophysical characteristics during the process, a piecewise-stepped zonal method is recommended.