## THERMAL SCIENCE

International Scientific Journal

### THE EFFECTS OF LONGITUDINAL RIBS ON ENTROPY GENERATION FOR LAMINAR FORCED CONVECTION IN A MICROCHANNEL

**ABSTRACT**

This paper deals with fluid flow, heat transfer and entropy generation in an internally ribbed microchannel. Mass, momentum and energy equations for constant heat flux boundary condition are solved using the finite volume method. Average Nusselt number and Fanning friction factor are reported as a function of rib height at different Reynolds numbers. The effects of non-dimensional rib height, wall heat flux and the Reynolds number on the entropy generation attributed to friction, heat transfer and total entropy generation are explored. The first law indicates that rib height has the great effect on the flow filed and heat transfer. The second law analysis reveals that for any values of Reynolds number and wall heat flux, as rib height grows; the frictional irreversibility increases while, there is a rib height which provides the minimum heat transfer irreversibility. It is found that the optimum rib height with the minimum total entropy generation rate depends on Reynolds number and wall heat flux.

**KEYWORDS**

PAPER SUBMITTED: 2013-09-20

PAPER REVISED: 2014-07-03

PAPER ACCEPTED: 2014-07-06

PUBLISHED ONLINE: 2014-10-05

**THERMAL SCIENCE** YEAR

**2016**, VOLUME

**20**, ISSUE

**6**, PAGES [1963 - 1972]

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