Entropy Generation in Convective Heat Transfer and Isothermal Convective Mass Transfer

Abstract

The irreversible generation of entropy for two limiting cases of combined forced-convection heat and mass transfer in a two-dimensional channel are investigated. First, convective heat transfer in a channel with either constant heat flux or constant surface temperature boundary conditions are considered for laminar and turbulent flow. The entropy generation is minimized to yield expressions for optimum plate spacing and optimum Reynolds numbers for both boundary conditions and flow regimes. Second, isothermal convective mass transfer in a channel is considered, assuming the diffusing substance to be an ideal gas with Lewis number equal to unity. The flow is considered to be either laminar or turbulent with boundary conditions at the channel walls of either constant concentration or constant mass flux. The analogy between heat and mass transfer is used to determine the entropy generation and the relations for optimum plate spacing and Reynolds number. The applicable range of the results for both limiting cases are then investigated by non-dimensionalizing the entropy generation equation.

Unsteady evaporation and entropy generation in a Couette flow

“…They compared their expressions by those previously obtained by Bejan 12 and San et al 14,15 22 analyzed entropy creation due to laminar forced convection in the entrance region of concentric annulus. They found that raising the Eckert number causes an increase in entropy production.…”

“…The local and average conductive Nusselt numbers, indicating energy characterization of heat between the outlet wall and the moving fluid, are given in equations (15) and (16), respectively…”

“…Bejan 13 analyzed the fundamental mechanisms responsible for the generation of entropy in heat and fluid flow and on the design trade-off of balancing the heat transfer irreversibility against the fluid flow irreversibility. San et al 14,15 studied the irreversibility generated by heat and mass transfer during coupled conduction-convection transfer in a channel. They showed that entropy creation is related to the gradients of velocity, temperature, concentration, and physical properties of the fluid.…”

Second Law Analysis of Flow, Heat and Mass Transfer Past a Nonlinearly Stretching Permeable Wedge with Temperature Jump and Chemical Reaction

“…The local volumetric rate of entropy generation, S gen (W/m 3 K), in the presence of viscous dissipation, heat transfer and mass transfer is given by [23][24][25]:…”

Numerical analysis of laminar forced convection in concentric rotating cylinders: Entropy generation

“…The entropy generation and its minimization are investigated by many researchers. Bejan 1,2 and San et al 3 are the first who proposed different analytical solutions for the entropy generation equation in several simple flow situations. They introduce the concept of entropy production number and irreversibility distribution ratio, presenting spatial distribution profiles of entropy generation.…”