Title: Entropy generation of mixed convection in a vertical parallel plate microchannel with asymmetric wall heat flux

Authors: Ugur Akbulut

Addresses: Faculty of Engineering, Department of Mechanical Engineering, Recep Tayyip Erdogan University, Rize 53100, Turkey

Abstract: In this study, the results of a parametric analysis of the entropy generation of mixed convection in a vertical parallel plate microchannel with asymmetric wall heat flux are presented. The fluid flow was assumed as Newtonian and fully developed. Analytical equations were derived to estimate the entropy generation and a specific MATLAB code was created to solve the governing equations. The effects of the modified mixed convection parameter (Gr_q/Re), the Brinkman number (Br), the Knudsen number (Kn), and the ratio of wall heat flux (r_q) on the entropy generation are presented and discussed. The results revealed that, while increment of Kn reduces the entropy generation, conversely, increment of Br/τ enhances it. For each condition analysed, the entropy generation number related to heat transfer (N_R) is smaller than the entropy generation number related to fluid friction (N_F), indicating that N_F is dominant on the total entropy generation number (N_S).

Keywords: second law; thermodynamics; entropy generation; mixed convection; vertical parallel plate microchannels; asymmetric heat flux; Bejan number; Knudsen number; Grashof number; Brinkman number; Newtonian fully developed fluid flow; heat transfer.

DOI: 10.1504/IJEX.2015.072911

International Journal of Exergy, 2015 Vol.18 No.4, pp.462 - 479

Received: 17 Jun 2014
Accepted: 17 Dec 2014
Published online: 07 Nov 2015 *

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