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Comparison of various methods for evaluation of combined heat and mass transfer in laminar falling films with constant film velocity. 1. Numerical method.

Number: pap. n. 87

Author(s) : MITTERMAIER M., MEYER T., ZIEGLER F.

Summary

In the present study comprising of two parts we compare various methods describing combined heat and mass transfer in an ab- or desorbing laminar falling film. While one method utilizes a numerical finite difference approach (part I), the other method uses the Laplace transform (part II) to provide an analytical solution to the problem. Both solutions are compared to the established one published by Grigor’eva and Nakoryakov using the Fourier method. Temperature and concentration profiles in the film, the development of the interface temperature and concentration, as well as the absorbed mass flux are presented and compared among the approaches for various flow lengths, wall temperatures, Lewis numbers. For certain boundary conditions the results of the Fourier method deviate from both the numerical approach and the Laplace transform, while the latter two approaches show very good agreement for all conditions. Moreover, the solutions of the approaches presented converge against the short-term solution proposed also by Grigor’eva and Nakoryakov. The study is presented in two parts. In this first part the derivation of the numerical solution is presented and the results are compared to the established Fourier solution. In the second part the Laplace method is introduced and the results are compared to the numerical solution. Due to a short computation time the analytical model obtained with the Laplace transform is suitable for implementation into process simulation, whereas the numerical approach may easily be extended to account for additional effects, such as hydrodynamic behavior or variable transport and thermodynamic properties.

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Pages: 10 p.

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Details

  • Original title: Comparison of various methods for evaluation of combined heat and mass transfer in laminar falling films with constant film velocity. 1. Numerical method.
  • Record ID : 30014368
  • Languages: English
  • Source: International sorption heat pump conference (ISHPC2014), College Park, United States, March 31-April 2, 2014.
  • Publication date: 2014/03/02

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