Abstract

The laminar, thermally developing flow of gases in a two-dimensional parallel plate channel is studied here. Using computational fluid dynamics (CFD), the combined effects of convection and real gas radiation are explored. Gas mixtures composed of H2O, CO2, and N2 are considered. To account for radiation in the participating medium, the Spectral Line Weighted-sum-of-gray-gases model is used. The model formulation, verification, and validation are provided through published articles written by the primary author. The predictions made for the case of combined convection and radiation are compared to the solution for the classical pure convection case, known as the Graetz solution. The scenario studied here involves the channel walls maintained at constant temperature, either heated to a temperature higher than the gas inlet temperature or cooled to a temperature lower than the gas inlet temperature. The influence and strength of real gas radiation is explored and quantified for several variables, including temperature difference between the inlet gas and the wall, channel width, total gas pressure, and gas composition. The two articles which are the basis of this thesis provide extensive comparison between the classical Graetz solution and the predictions involving real gas radiation. Numerical comparisons are made using quantities such as convective and radiative wall heat fluxes, local mean temperature, and local convective, radiative, and total Nusselt number. Extensive comparisons between the case of gas cooling and gas heating are made. The research presented here reveals that the addition of real gas radiation effects on thermally developing gas flows results in a dramatic departure from the predictions of the convection-only Graetz solution. The inclusion of radiation yields a much more rapid change in gas temperature in the channel. The local Nusselt number (convective, radiative, and total) are higher in magnitude for the case of a radiatively participating medium. Generally, any change in parameters that enhances the gas radiation transfer fosters greater departure from the convection-only solution In the Graetz solution, assuming consistent properties and temperature differences, the inclusion of real gas radiation yields widely different predictions for cooling and heating. However, significant differences exist between the cases of gas cooling and heating with gas radiation.

Degree

MS

College and Department

Ira A. Fulton College of Engineering; Mechanical Engineering

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2024-04-09

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd13550

Keywords

real gas radiation, convection, parallel plate channel, CFD

Language

english

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