A convective heat transfer enhancement technique and the experimental methods used to quantify the improvement in heat transfer and subsequent differential pressure are introduced. The enhancement technique employed time varying magnetic fields produced in a pipe to cause the ferromagnetic particles of a particle laden fluid (mineral oil and iron filings) to be attracted to and released from a heated pipe wall. The ferromagnetic particles acted not only to advect heat from the pipe wall into the bulk fluid but they also significantly modified the flow field, disrupted the boundary layer, allowed cooler fluid to reach the high temperature pipe wall, increased thermal energy transfer directly to the fluid, and contributed to the overall improvement in heat transfer rate. The experimental method utilized to quantify an increased effectiveness of convective heat transfer used an apparatus designed to replicate an internally cooled fin, whose surface temperature was measured with an IR camera. These temperature measurements were utilized to calculate the convective heat transfer coefficient $(h)$ of the fluid within the pipe. The enhancement technique demonstrated a 267% increase in heat transfer coefficient with only a corresponding 48% increase in flow differential pressure for an electromagnetic switching frequency of 2 Hz. It is also found that there were optimum magnetic field switching frequencies for both enhancement and differential pressure magnitudes.

1.
Webb
,
R. L.
, 1994,
Principles of Enhanced Heat Transfer
,
Wiley
,
New York
.
2.
Eastman
,
J. A.
,
Choi
,
S. U. S.
,
Yu
,
W.
, and
Thompson
,
L. J.
, 2001, “
Anomalously Increased Effective Thermal Conductivities of Ethylene Glycol Based Nanofluids Containing Copper Nanoparticles
,”
Appl. Phys. Lett.
0003-6951,
78
(
6
), pp.
718
720
.
3.
Xuan
,
Y.
, and
Li
,
Q.
, 2003, “
Investigation on Convective Heat Transfer and Flow Features of Nanofluids
,”
J. Heat Transfer
0022-1481,
125
, pp.
151
155
.
4.
Eastman
,
J. A.
,
Phillpot
,
S. R.
,
Choi
,
S. U. S.
, and
Keblinski
,
P.
, 2004, “
Thermal Transport in Nanofluids
,”
Annu. Rev. Mater. Res.
1531-7331,
34
, pp.
219
246
.
5.
Ganguly
,
R.
,
Sen
,
S.
, and
Puri
,
I. K.
, 2004, “
Heat Transfer Augmentation Using a Magnetic Fluid Under the Influence of a Line Dipole
,”
J. Magn. Magn. Mater.
0304-8853,
271
, pp.
63
73
.
6.
Tangthieng
,
C.
,
Finlayson
,
B. A.
,
Maulbetsch
,
J.
, and
,
T.
, 1999, “
Heat Transfer Enhancement in Ferrofluids Subjected to Steady Magnetic Fields
,”
J. Magn. Magn. Mater.
0304-8853,
201
, pp.
252
255
.
7.
Hishida
,
K.
, and
Maeda
,
M.
, 1994, “
Enhancement and Control of Local Heat Transfer Coefficients in a Gas Flow Containing Soft Magnetic Particles
,”
Exp. Heat Transfer
0891-6152,
7
, pp.
55
69
.
8.
Li
,
L. J.
et al.
, 2005, “
Heat Transfer Augmentation in 3D Internally Finned and Microfinned Helical Tube
,”
Int. J. Heat Mass Transfer
0017-9310,
48
(
10
), pp.
1916
1925
.
9.
Liao
,
Q.
, and
Xin
,
M. D.
, 1995, “
Experimental Investigation on Forced Convective Heat Transfer and Pressure Drop of Ethylene Glycol in Tubes With Three-Dimensional Internally Extended Surface
,”
Exp. Therm. Fluid Sci.
,
11
(
4
), pp.
343
347
. 0894-1777