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RESEARCH PAPERS: Electronic Cooling

# Performance Evaluation of Liquid Flow With PCM Particles in Microchannels

[+] Author and Article Information
K. Q. Xing

Department of Mechanical and Materials Engineering,  Florida International University, Miami, FL 33174

Y.-X. Tao

Department of Mechanical and Materials Engineering,  Florida International University, Miami, FL 33174taoy@fiu.edu

Y. L. Hao1

Department of Mechanical and Materials Engineering,  Florida International University, Miami, FL 33174

1

Present address: Department of Power Engineering, Southeast University, Nanjing 210096, Jiangsu, P. R. China

J. Heat Transfer 127(8), 931-940 (Mar 07, 2005) (10 pages) doi:10.1115/1.1929783 History: Received April 24, 2004; Revised March 07, 2005

## Abstract

A two-phase, non thermal equilibrium-based model is applied to the numerical simulation of laminar flow and heat transfer characteristics of suspension with microsize phase-change material (PCM) particles in a microchannel. The model solves the conservation of mass, momentum, and thermal energy equations for liquid and particle phases separately. The study focuses on the parametric study of optimal conditions where heat transfer is enhanced with an increase in fluid power necessary for pumping the two-phase flow. The main contribution of PCM particles to the enhancement of heat transfer in a microsize tube is to increase the effective thermal capacity and utilize the latent heat effect under the laminar flow condition. An effectiveness factor $εeff$ is defined to evaluate the heat transfer enhancement compared to the single-phase flow heat transfer and is calculated under different wall heat fluxes and different Reynolds numbers. The comparison is also made to evaluate the performance index, i.e., the ratio of total heat transfer rate to fluid flow power (pressure drop multiplied by volume flow rate) between PCM suspension flow and pure water single-phase flow. The results show that for a given Reynolds number, there exists an optimal heat flux under which the $εeff$ value is the greatest. In general, the PCM suspension flow with phase change has a significantly higher performance index than the pure-fluid flow. The comparison of the model simulation with the limited experimental results for a MCPCM suspension flow in a $3mmdia$ tube reveals the sensitivity of wall temperature distribution to the PCM supply temperature and the importance of characterizing the phase change region for a given tube length.

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## Figures

Figure 1

Schematic diagram of fluid and PCM particle suspension flowing through a heated tube

Figure 2

Temperature of carrier fluid: L∕D=100, Re=167, Tf,0=Tp,0=295K, εp,0=0.25, fp,l,0=0, qw=50W∕cm2

Figure 3

Temperature of NPCM particle: L∕D=100, Re=167, Tf,0=Tp,0=295K, εp,0=0.25, fp,l,0=0, qw=50W∕cm2

Figure 4

Liquid mass fraction inside of NPCM particle: L∕D=100, Re=167, Tf,0=Tp,0=295K, εp,0=0.25, fp,l,0=0, qw=50W∕cm2

Figure 5

Effectiveness factor and performance index of slurry at Re=90

Figure 6

Effectiveness factor and performance index of slurry at Re=167

Figure 7

Effectiveness factor and performance index of slurry at Re=300

Figure 8

Effectiveness factor and performance index of slurry at Re=600

Figure 9

Maximum εeff and corresponding qw(W∕cm2) as a function of Reynolds number

Figure 10

Q∕P ratio of slurry and pure water at Re=90

Figure 11

Q∕P ratio of slurry and pure water at Re=167

Figure 12

Q∕P ratio of slurry and pure water at Re=300

Figure 13

Q∕P ratio of slurry and pure water at Re=600

Figure 14

Local heat transfer coefficient along the channel: Re=90, qw=50W∕cm2

Figure 15

Local heat transfer coefficient along the channel: Re=167, qw=50W∕cm2

Figure 16

Local heat transfer coefficient along the channel: Re=300, qw=50W∕cm2

Figure 17

Local heat transfer coefficient along the channel: Re=600, qw=50W∕cm2

Figure 22

Liquid mass fraction inside of PCM particle: T0=309.9K, εp,0=0.1, Re=200, dp=100μm, Ste=2.0

Figure 21

Liquid mass fraction inside of PCM particle: T0=309.85K, εp,0=0.1, Re=200, dp=100μm, Ste=2.0

Figure 20

(a, b) Comparison of simulation results with the experimental data reported in (18) under the following conditions: εp=0.1, Re=200, dp=100μm, T0=309K. The effect of the uncertainty in the inlet fluid temperature on the wall temperature is clearly shown.

Figure 19

Effect of solid volume fraction on εeff:Re=300, qw=30W∕cm2

Figure 18

Distribution of local heat transfer coefficients where εeff,max and qw,max occur at a given Reynolds number

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