Thermodynamics analyses of porous microchannels with asymmetric thick walls and exothermicity: an entropic model of micro-reactors

Elliott, A., Torabi, M. and Karimi, N. (2017) Thermodynamics analyses of porous microchannels with asymmetric thick walls and exothermicity: an entropic model of micro-reactors. Journal of Thermal Science and Engineering Applications, 9(4), 041013. (doi: 10.1115/1.4036802)

Abstract

This paper presents a study of the thermal characteristics and entropy generation of a porous microchannel with thick walls featuring uneven thicknesses. The system accommodates a fully developed flow while the solid and fluid phases can include internal heat sources. Two sets of asymmetric boundary conditions are considered. The first includes constant temperatures at the surface of the outer walls, with the lower wall experiencing a higher temperature than the upper wall. The second case imposes a constant heat flux on the lower wall and a convection boundary condition on the upper wall. These set thermal models for micro-reactors featuring highly exothermic or endothermic reactions such as those encountered in fuel reforming processes. The porous system is considered to be under local thermal non-equilibrium (LTNE) condition. Analytical solutions are, primarily, developed for the temperature and local entropy fields and then are extended to the total entropy generation within the system. A parametric study is, subsequently, conducted. It is shown that the ratio of the solid to fluid effective thermal conductivity ratio and the internal heat sources are the most influential parameters in the thermal and entropic behaviours of the system. In particular, the results demonstrate that the internal heat sources can affect the entropy generation in a non-monotonic way and, that the variation of the total entropy with internal heat sources may include extremum points. It is, further, shown that the asymmetric nature of the problem has a pronounced effect on the local generation of entropy.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Karimi, Dr Nader and Elliott, Mr Alexander
• Authors: Elliott, A., Torabi, M., and Karimi, N.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Journal of Thermal Science and Engineering Applications
• Publisher: American Society of Mechanical Engineers
• ISSN: 1948-5085
• ISSN (Online): 1948-5093
• Published Online: 22 May 2017