In this paper we report the results of our modeling studies on two-phase forced convection in microchannels using water as the fluid medium. The study incorporates the effects of fluid flow rate, power input and channel geometry on the flow resistance and heat transfer from these microchannels. Two separate numerical models have been developed assuming homogeneous and annular flow boiling. Traditional assumptions like negligible single-phase pressure drop or fixed inlet pressure have been relaxed in the models making analysis more complex. The governing equations have been solved from the grass-root level to predict the boiling front, pressure drop and thermal resistance as functions of exit pressure and heat input. The results of both the models are compared to each other and with available experimental data. It is seen that the annular flow model typically predicts higher pressure drop compared to the homogeneous model. Finally, the model has also been extended to study the effects of nonuniform heat input along the flow direction. The results show that the nonuniform power map can have a very strong effect on the overall fluid dynamics and heat transfer.

1.
Sobhan
C. B.
, and
Garimella
S. V.
, “
A Comparative Analysis of Studies on Heat Transfer and Fluid Flow In Microchannels
,”
Microscale Thermophysical Engineering
, vol.
5
, pp.
293
311
,
2001
.
2.
Kandlikar
S. G.
, “
Fundamental Issues Related to Flow Boiling in Minichannels and Microchannels
,”
Experimental Thermal and Fluid Sciences
, vol.
26
, pp.
389
407
,
2002
.
3.
Thome
J. R.
, “
Boiling in Microchannels: a Review of Experiment and Theory
,”
International Journal of Heat and Fluid Flow
, vol.
25
, pp.
128
139
,
2004
.
4.
Neal
L. G.
, and
Zivi
S. M.
, “
The Stability of Boiling-water Reactor and Loops
,”
Nuclear Science and Engineering
,
30
, pp.
25
38
,
1967
.
5.
J. G. Collier, Convective Boiling and Condensation, McGraw Hill, London, 1972.
6.
Peles
Y. P.
,
Yarin
L. P.
, and
Hetsroni
G.
, “
Thermohydrodynamic Characteristics of Two-phase Flow in a Heated Capillary
,”
International Journal of Multiphase Flow
, vol.
26
, pp.
1063
1093
,
2000
.
7.
Ghiaasiaan
S. M.
and
Abdel-Khalik
S. I
,
2001
, “
Two phase Flow in Microchannels
,”
Advances in Heat Transfer
,
34
pp.
377
394
8.
Damianides, C.A., and Westwater, J.W., 1988, “Two Phase Flow Patterns in a Compact Heat Exchanger and in Small tubes,” Proc. Of 2nd U.K. National Heat transfer Conference, pp. 1257–1268.
9.
Fukano
T.
, and
Kariyasaki
A.
,
1993
, “
Characteristics of Gas-liquid Two phase Flow in a Capillary
,”
Nucl. Engg. Design
,
141
, pp.
59
68
.
10.
Hsu, Y. Y., and Graham, R. W, 1964, “An Analytical and Experimental Study of Thermal Boundary Layer and Ebullition Cycle in Nucleate Boiling, NASA TN-D-594.
11.
Kandlikar
S. G.
,
1990
, “
A general correlation for saturated two-phase flow boiling heat transfer inside vertical and horizontal tubes
,”
ASME Journal of Heat Transfer
,
112
, pp.
219
228
.
12.
Qu
W.
, and
Mudawar
I
, “
Flow Boiling Heat Transfer in Two Phase Microchannel Heat Sinks - II Annular Two Phase Flow Model
,”
2003
,
International Journal of Heat and Mass Transfer
,
46
, pp.
2773
2784
.
13.
Shah, R. K., London, A. L., 1978, Laminar Flow Forced Convection in Ducts: A Source Book for Compact Heat Exchanger Analytical Data - Supl. 1, Academic Press, New York.
14.
Wallis, G.B., 1969, One Dimensional Two Phase Flow, McGraw Hill, New York.
15.
Zhang
L.
,
Koo
J. M.
,
Jiang
L.
,
Asheghi
M.
,
Goodson
K. E.
,
Santiago
J. G.
, and
Kenny
T. W.
,
2002
, “
Measurements and Modeling of Two-phase Flow in Microchannels with nearly constant heat flux boundary conditions
,”
Journal of MEMS
,
11
, pp.
12
19
.
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