In all electronics cooling situations, and many other practical situations, the surface temperature may vary rapidly in the streamwise direction. In these cases, defining the heat transfer coefficient using the adiabatic temperature of the surface instead of the mixed mean temperature of the coolant results in significant benefits. The resulting coefficient, called $hadiabatic,$ is well behaved, being a function only of the geometry and flow characteristics. Calling attention to $Tadiabatic,$ as opposed to $Tmean,$ helps designers identify the root cause of overheating problems and more quickly reach good solutions. The theoretical and practical bases for $hadiabatic$ are presented. Examples of its use in electronics cooling are described to show the operational advantages this approach offers. Turbulence strongly affects heat transfer. A simple, turbulence-based correlation is presented that yields an estimate of the heat transfer coefficient good enough for preliminary design estimates and often as accurate as can be relied on from CFD calculations using present codes.

1.
Arvizu, D. E., and Moffat, R. J., 1982, “The Use of Superposition in Calculating Cooling Requirements for Circuit-Board-Mounted Electronic Components,” Proc. of 32nd Electronic Components Conference, IEEE, Piscataway, NJ, pp. 133–144.
2.
Moffat
,
R. J.
,
1998
, “
What’s New in Convective Heat Transfer?
Int. J. Heat Fluid Flow
,
19
(
2
), pp.
90
101
.
3.
Sellars
,
R. J.
,
Tribus
,
M.
, and
Kline
,
J. S.
,
1956
,
Trans. ASME
,
78
, pp.
441
448
.
4.
Moffat, R. J., 2001, “The Use of hadiabatic in Electronics Cooling and Other Applications,” Proc. of 7th International Workshop on Thermal Investigations of ICs and Systems: THERMINIC 2001, Paris, Sept, IEEE, New York.
5.
Gauche, P., 2001, Using FLOTHERM and the Command Center to Exploit the Principle of Superposition (personal communication).
6.
Anderson, A., and Moffat, R. J., 1990, “Convective Heat Transfer from Arrays of Modules with Non-Uniform Heating: Experiments and Models,” Thermosciences Division Research Report HMT-43, Stanford University.
7.
Moffat, R. J., Arvizu, D. E., and Ortega, A., “Cooling Electronic Components: Forced Convection Experiments With an Air-Cooled Array,” Heat Transfer in Electronic Equipment—1985, ASME, New York, ASME HTD—Vol. 48, pp. 17–28.
8.
Wong
,
H.
, and
Peck
,
R. E.
,
2001
, “
Experimental Evaluation of Air-Cooling Electronics at High Altitudes
,”
ASME J. Electron. Packag.
,
123
, pp.
356
365
.
9.
Moffat
,
R. J.
, and
Anderson
,
A. M.
,
1990
, “
Applying Heat Transfer Coefficient Data to Electronics Cooling
,”
ASME J. Heat Transfer
,
112
, pp.
882
890
.
10.
Anderson
,
A.
, and
Moffat
,
R. J.
,
1992
, “
The Adiabatic Heat Transfer Coefficient and the Superposition Kernel Function: Part I—Data for Arrays of Flat-Packs for Different Flow Conditions
,”
ASME J. Electron. Packag.
,
114
,
14
21
.
11.
Maciejewski
,
P. K.
, and
Moffat
,
R. J.
,
1992
, “
Heat Transfer With Very High Free-Stream Turbulence—Part I: Experimental Data
,”
ASME J. Heat Transfer
,
114
(
4
), pp.
827
833
.
12.
Maciejewski
,
P. K.
, and
Moffat
,
R. J.
,
1992
, “
Heat Transfer With Very High Free-Stream Turbulence—Part II: Analysis of Results
,”
ASME J. Heat Transfer
,
114
(
4
), pp.
834
839
.
13.
Rhee, J., Danek, C. J., and Moffat, R. J., 1993, “The Adiabatic Heat Transfer Coefficient on the Faces of a Cube in an Electronics Cooling Situation,” Proc. of 1993 ASME International Electronics Packaging Conference, Binghamton, NY, Sept, ASME, New York.
14.
Maciejewski
,
P. K.
, and
Anderson
,
A. M.
,
1996
, “
Elements of a General Correlation for Turbulent Heat Transfer
,”
ASME J. Heat Transfer
,
118
, pp.
287
293
.
15.
Denninger
,
M. J.
, and
Anderson
,
A. M.
,
1999
, “
An Experimental Study on the Relationship Between Velocity Fluctuations and Heat Transfer in a Turbulent Air Flow
,”
ASME J. Turbomach.
,
121
(
2
), pp.
288
295
.
16.
Anderson, A. M., and Maciejewski, P. K., 1999, “The Local Variable Model for Turbulent Heat Transfer,” Proc. 33rd National Heat Transfer Conf., Aug, Albuquerque, New Mexico.
17.
Ooi
,
A.
,
Iaccarino
,
G.
,
Durbin
,
P. A.
, and
Behnia
,
M.
,
2002
, “
Reynolds Averaged Simulation of Flow and Heat Transfer in Ribbed Ducts
,”
Int. J. Heat Mass Transfer
,
23
, pp.
750
757
.
18.
Hacker
,
J. M.
, and
Eaton
,
J. K.
,
1997
, “
Measurements of Heat Transfer in a Separated and Re-Attaching Flow With Spatially Varying Thermal Boundary Conditions
,”
Int. J. Heat Fluid Flow
,
18
, pp.
131
141
.
19.
Batchelder
,
K. A.
, and
Eaton
,
J. K.
,
2001
, “
Practical Experience With the Discrete Green’s Function Approach to Convective Heat Transfer
,”
ASME J. Heat Transfer
,
123
, pp.
70
76
.
20.
Ramanathan, S., and Ortega, A., 1996, “A Uniform Flow Effective Diffusivity Approach for Conjugate Forced Convection From a Discrete Rectangular Source on a Thin Conducting Plate,” Paper 0-7803-3325-X, Intersociety Conference on Thermal Phenomena, ITHERM.
21.
Li, Y., and Ortega, A., 1998, “Forced Convection From a Rectangular Heat Source in Uniform Shear Flow: The Conjugate Peclet Number in the Thin Plate Limit,” Paper 0-7803-4475-8/98, Intersociety Conference on Thermal Phenomena, ITHERM.
22.
Moffat, R. J., 2002, “Getting the Most out of Your CFD Program,” ITHERM 2002, 8th Intersociety Conference on Thermal and Thermo-Mechanical Phenomena in Electronic Systems May 29–June 1, San Diego.