Heat and Mass Transfer

, Volume 48, Issue 10, pp 1825–1835 | Cite as

Effects of the number and distribution of fins on the storage characteristics of a cylindrical latent heat energy storage system: a numerical study

Original

Abstract

A numerical study of the effects of the number and distribution of fins on the storage characteristics of a cylindrical latent heat energy storage system (LHESS) was conducted. Due to the low thermal conductivity of phase change materials (PCMs) used in LHESS, fins were added to the system to increase the rate of heat transfer and charging. Finite elements were used to implement the developed numerical method needed to study and solve for the phase change heat transfer (melting of PCM) encountered in a LHESS during charging. The effective heat capacity method was applied in order to account for the large amount of latent energy stored during melting of the PCM and the moving interface between the solid and liquid phases. The effects of increasing the number and distribution of fins on the melting rate of the PCM were studied for configurations having between 0 and 27 fins for heat transfer fluid (HTF) velocities of 0.05 and 0.5 m/s. Results show that the overall heat transfer rate to the PCM increases with an increase in the number of fins irrespective of the HTF velocity. It was also observed that the total amount of energy stored after 12 h increases nearly linearly with the addition of fins up to 12 fins; further addition of fins increasing the total energy stored by ever smaller amounts.

List of symbols

Dimensional variables

Cp

Heat capacity (J kg−1 K−1)

E

Energy stored (J)

k

Thermal conductivity (W m−1 K−1)

L

Latent heat of fusion (J kg−1)

m

Mass (kg)

P

Pressure (Pa)

r

Radius (m)

r

Cylindrical coordinate (m)

T

Temperature (K)

t

Time (s)

u

Thermal fluid velocity (m s−1)

v

Velocity (m s−1)

X

Solid–liquid interface position (m)

z

Cylindrical coordinate (m)

Greek symbols

η

Efficiency

Viscous dissipation (m2 s−2)

μ

Dynamic viscosity (N s m−2)

ρ

Density (kg m−3)

Non-dimensional variables

n

Normal direction

Subscripts

0

Initial

1

Onset of melting

2

End of melting

eff

Effective

in

Inlet

l

Liquid

p

Pipe

pcm

Phase change material

r

In the r direction

s

Solid

T

Total

z

In the z direction

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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringDalhousie UniversityHalifaxCanada

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