Second Law Analysis of Laminar Flow in a Circular Pipe Immersed in an Isothermal Fluid

Abstract

Entropy generation and pumping power to heat transfer ratio (PPR) of a laminar flow, for a circular tube immersed in an isothermal fluid, are studied analytically in this paper. Two different fluids, namely, water and ethylene glycol, are chosen to study the influence of fluid properties on entropy generation and PPR. The expressions for dimensionless entropy generation, Bejan number and PPR are derived in a detailed way and their variations with Reynolds number, external Biot number, and the dimensionless temperature difference are illustrated. The results of the analysis are compared with those for a laminar flow in a circular tube with uniform wall temperature boundary condition. Finally, a criterion is established to determine which type of thermal boundary conditions is more suitable for a particular fluid, with respect to its influence on entropy generation.

Entropy generation analysis of laminar flow of a nanofluid in a circular tube immersed in an isothermal external fluid

“…5(c) and 2(c) shows that for the same Reynolds number the entropy generated is higher for watereAl 2 O 3 nanofluid compared to ethylene glycoleAl 2 O 3 nanofluid. This corroborates the conclusion of Anand and Nelanti [24]. This is explained by observing that for same Reynolds number, the velocity of water will be less than that of ethylene glycol (due to disparity in value of viscosity).…”

“…The entropy generation analysis of laminar flow in a tube immersed in an isothermal, external fluid has been carried out by this author in an earlier publication [24] and is presented here in brief:…”

“…The entropy generation analysis for laminar flow in a circular tube immersed in an isothermal external fluid was performed by the author in an earlier publication [24], but that analysis was only for a single phase fluid. The concept of heat transfer enhancement by the introduction of nanoparticles was outside the scope of that paper e but is included in the current paper.…”

Entropy and Mass Distribution in Disc Galaxies

“…The stability and ubiquitous nature of galactic discs suggests that any relative motion of a displaced star will rapidly be dissipated-compared with the time-scale of disc rotation-to allow it to match the specific momentum of gravitational mass at its new position [2]. Detailed analysis, however, remains complex even within a well-defined hydrodynamic system such as laminar flow through a circular pipe [20].…”

Analysis of Effect of Heat Pipe Parameters in Minimising the Entropy Generation Rate

“…A simple procedure for minimising entropy generation in simultaneous heat and mass exchange devices has been illustrated by Narayan et al [12] using modified heat capacity ratio. Second law analysis has been carried out analytically for a circular tube immersed in an isothermal fluid by Anand and Nelanti [13]. Entropy generation and pumping power to heat transfer ratio of a laminar flow was established to determine appropriate thermal boundary conditions for each fluid with optimum entropy generation.…”