Heat and mass transfer and thermodynamic analysis of power-law fluid flow in a porous microchannel

Mahnaz Javidi Sarafan,Nader Karimi,Rasool Alizadeh,Abolfazl Fattahi,Mostafa Valizadeh Ardalan

doi:10.1007/s10973-020-09679-8

Abstract

Transfer of heat and mass and thermodynamic irreversibilities are investigated in a porous, parallel-plate microreactor in which the working fluid is non-Newtonian. The investigated microreactor features thick flat walls with uneven thicknesses, which can be subject to different thermal loads. The dimensionless governing equations of the resultant asymmetric problem are first derived theoretically and then solved numerically by using a finite volume technique. This results in two-dimensional solutions for the velocity, temperature and concentration fields as well as the distributions of Nusselt number and local and total entropy generations. The results clearly demonstrate the significance of the numerical value of the power-law index and departure from Newtonian behavior of the fluid. In particular, it is shown that by increasing the value of power-law index the Nusselt number on the wall decreases. This leads to the intensification of the temperature gradients in the system and therefore magnifies the local and total entropy generations. Also, it is shown that the wall thickness and thermal asymmetry can majorly affect the heat transfer process and thermodynamic irreversibility of the microreactor. It is noted that the current work is the first comprehensive study of heat transfer and entropy generation in porous micro-chemical reactor with non-Newtonian, power-law fluid.

Highlights

Catalytic porous microchannels, where catalytic channels of small sizes filled with porous media, have received increased interest in traditional and advanced chemical and energy technologies in the last decade
Among the massive aspects that require in-depth investigation for catalytic porous microchannels, transport processes and entropy generation are of vital importance as they are directly related to the overall performance of a catalytic porous microchannel
Numerical analysis of thermal transport and entropy generation of a typical catalytic porous microchannel filled with power-law fluids has been conducted

Summary

Introduction

Catalytic porous microchannels, where catalytic channels of small sizes filled with porous media, have received increased interest in traditional and advanced chemical and energy technologies in the last decade. They investigated the effects of various parameters pertinent to the porous medium, the non-Newtonian fluid and the chemical reaction on the velocity, temperature and concentration distributions, as well as mean Nusselt and Sherwood numbers.

Results

Conclusion