Entropy Generation Analysis for Microscale Forced Convection in Thermal Entrance Region

Abstract

An analytical study on entropy generation considering viscous dissipation effect in the circular microchannel is reported. The fluid flow is steady, laminar, hydrodynamically fully developed and thermally developing. In the first law analysis, appropriate dimensionless variables are applied to solve the energy equation in the thermal entrance region of microchannel. Subsequently the obtained temperature field is used to derive an expression for entropy generation rate. The effect of Knudsen number and Brinkman number on the entropy generation rate and Bejan number in different axial location is presented.

Entropy Generation Analysis for Various Cross-sectional Ducts in Fully Developed Laminar Convection with Constant Wall Heat Flux

“…The expression μ is fluid viscosity. The expression "entropy generation" can be defined dimensionless for comparison which is as follows: 9The dimensionless total entropy generation based on the flow stream heat capacity rate (ṁ/c p ) is defined as: (10) In this equation η 1 and η 2 are:…”

“…The reason is that heat transfer rate is reduced with increase of aspect ratio in a constant heat flux. Vandadi and Aghanajafi [10] considered entropy generation analysis for micro scale forced convection in thermal entrance region. In this study the effect of Knudsen number and Brinkman number on the entropy generation rate and Bejan number in different axial location is presented.…”