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Research Papers: Energy Systems Analysis

# Entropy Generation in Laminar Forced Convective Water Flow Due to Overloading Toward the Microscale

[+] Author and Article Information
Pallavi Rastogi

Department of Aerospace Engineering,
Indian Institute of Technology Bombay,
Powai 400076, Mumbai, India
e-mail: pallavirastogi@aero.iitb.ac.in

Professor
Department of Aerospace Engineering,
Indian Institute of Technology Bombay,
Powai 400076, Mumbai, India
e-mail: spm@aero.iitb.ac.in

Contributed by the Advanced Energy Systems Division of ASME for publication in the JOURNAL OF ENERGY RESOURCES TECHNOLOGY. Manuscript received August 4, 2017; final manuscript received February 24, 2018; published online April 9, 2018. Assoc. Editor: Reza Sheikhi.

J. Energy Resour. Technol 140(8), 082002 (Apr 09, 2018) (8 pages) Paper No: JERT-17-1407; doi: 10.1115/1.4039608 History: Received August 04, 2017; Revised February 24, 2018

## Abstract

In this theoretical study, a fully developed laminar convective water flow in a circular tube is “convectively overloaded” toward the microscale, by decreasing the tube diameter below 1 mm. The entropy generation rate ($S˙gen$) is obtained (with and without the viscous dissipation term) for a given rate of heat removal using a fixed rate of coolant (water) flow. The uniform wall heat flux and mass flux in a tube increase toward the micro-scale, which is “thermal and flow overloading,” respectively. The variations of—$S˙gen$ due to fluid friction, fluid conduction heat transfer, and their total ($S˙gen,tot$), toward the micro-scale, are analyzed. Since $S˙gen,tot$ remains more or less the same toward the microscale, it is worth overloading a tube for miniaturization up to the laminar-flow limit.

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## Figures

Fig. 1

Schematic of convective Hagen–Poiseuille water flow through circular tube

Fig. 2

Entropy generation due to fluid friction, toward the microscale

Fig. 3

Entropy generation due to heat conduction in fluid, toward the microscale: (a) radial heat conduction in fluid and (b) axial heat conduction in fluid

Fig. 4

Entropy generation due to convective heat transfer, toward the microscale

Fig. 5

Dimensionless entropy generation due to convective heat transfer, toward the microscale

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