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Heat and Mass Transfer

, Volume 48, Issue 3, pp 487–496 | Cite as

Forced convection performance of a MEPCM suspension through an iso-flux heated circular tube: an experimental study

  • C. J. HoEmail author
  • J. B. Huang
  • C. P. Chen
  • P. S. Tsai
  • Y. M. Yang
Original

Abstract

The paper examines experimentally forced convection performance of a microencapsulated phase change material (MEPCM) suspension through an iso-flux heated circular tube. Forced convection experiments have been undertaken using the pure water or MEPCM suspensions as the working fluid. The heat transfer performance of the MEPCM suspension was gauged in terms of local/average heat transfer coefficients and temperature control effectiveness along the tube wall compared with that obtained for the pure water.

Keywords

Nusselt Number Wall Temperature Phase Change Material Heat Transfer Enhancement Local Heat Transfer 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols

cp

Specific heat, (J kg−1 K−1)

cp,eff

Effective specific heat, (J kg−1 K−1)

\( c_{p,\,mf}^{*} \)

Specific heat ratio, \( c_{p,\,m} /c_{p,\,f} \)

\( d_{i}^{ + } \)

Inner diameter of tube, (m)

\( d_{o}^{ + } \)

Outer diameter of tube, (m)

\( d_{p}^{ + } \)

diameter of MEPCM particle, (m)

f

Darcy friction factor, \( - \Updelta p(d_{i}^{ + } /l^{ + } )/(\rho_{f} u_{b}^{ + 2} /2) \)

h

Heat transfer coefficient, (W m−2 K−1)

hls

Latent heat of fusion, (J kg−1)

I

Electric current, (A)

k

Thermal conductivity, (W m−1 K−1)

\( l_{d}^{ + } \)

Length of downstream section, (m)

\( l_{h}^{ + } \)

Length of heated section, (m)

\( l_{u}^{ + } \)

Length of upstream section, (m)

Nu

Nusselt number

Δp

Pressure drop, (Pa)

Pef

Peclet number based on base fluid properties, \( u_{b}^{ + } d_{i}^{ + } /\alpha_{f} \)

Pem

Peclet number on suspension properties, \( u_{b}^{ + } d_{i}^{ + } /\alpha_{m} \)

Q

Volumetric flow rate, (cm3 min−1)

q

Heat input, (W)

\( q^{\prime \prime } \)

Heat flux, (W m−2)

\( r^{ + } \)

Radial coordinate, (m)

\( r_{i}^{ + } \)

Inner radius of tube, (m)

\( r_{o}^{ + } \)

Outer radius of tube, (m)

Ref

Reynolds number based on base fluid properties, \( \rho_{f} u_{b}^{ + } d_{i}^{ + } /\mu_{f} \)

\( Sb_{in,\,m}^{*} \)

Inlet subcooling factor based on suspension properties, (T M  − T in )/ΔT ref,m

\( Ste_{m}^{*} \)

Modified Stefan number based on suspension properties, \( c_{p,\,m} \Updelta T_{ref,\,m} /h_{ls} \)

\( t_{w}^{ + } \)

Tube wall thickness, (m)

T

Temperature, (K)

TM

Melting temperature of phase change material

Tmean

Mean temperature, (K)

\( \Updelta T_{ref,\,f} \)

Reference temperature difference, (K), \( q_{i}^{\prime \prime } r_{i}^{ + } /k_{f} \)

\( \Updelta T_{ref,\,m} \)

Reference temperature difference, (K), \( q_{i}^{\prime \prime } r_{i}^{ + } /k_{m} \)

\( u_{b}^{ + } \)

Bulk fluid velocity, (m s−1)

V

Electric voltage, (Volt)

x+

Axial coordinates, (m)

Greek symbols

α

Thermal diffusivity, (m2 s−1)

εh

Local heat transfer effectiveness, h m /h f

\( \varepsilon_{{\bar{h}}} \)

Average heat transfer effectiveness, \( \bar{h}_{m} /\bar{h}_{f} \)

\( \varepsilon_{{\theta_{w} }} \)

Effectiveness of wall temperature suppression

θ

Dimensionless temperature, \( (T - T_{in} )/\Updelta T_{ref,\,f} \)

μ

Dynamic viscosity, (kg m−1 s−1)

ρ

Density, (kg m−3)

ϕ

Volume fraction

ω

Mass fraction

Subscripts

b

Bulk quantities

d

Downstream

eff

Effective quantities

f

Base fluid

h

Heated section

i

Inner surface of tube

in

Inlet

m

Suspension

o

Outer surface of tube

out

Outlet

p

MEPCM particle

pcm

Phase change material

u

Upstream

w

Tube wall

Superscripts

+

Dimensional quantities

Notes

Acknowledgments

The present study was supported by National Science Council (NSC) of ROC in Taiwan under Project Nos. NSC94-2212-E006-101 and NSC95-2212-E006-233.

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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • C. J. Ho
    • 1
    Email author
  • J. B. Huang
    • 1
  • C. P. Chen
    • 1
  • P. S. Tsai
    • 2
  • Y. M. Yang
    • 3
  1. 1.Department of Mechanical EngineeringNational Cheng Kung UniversityTainanTaiwan, ROC
  2. 2.Department of Chemical and Material EngineeringNational Kaohsiung University of Applied SciencesKaohsiungTaiwan, ROC
  3. 3.Department of Chemical EngineeringNational Cheng Kung UniversityTainanTaiwan, ROC

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