This work describes the experimental setup, method, and results of utilizing a micrometer to move an adjustable orifice immediately in front of an array of microchannels. Research by others indicates potential for significant improvement in delaying critical heat flux and increasing heat transfer coefficients when placing an orifice in front of each individual channel of a microchannel array. The experimental setup in this work allows incremental orifice size changes. This ability allows the experimentalist to find which orifice size provides enough pressure drop immediately in front of the channels to reduce oscillations. The design also allows for rapid change of orifice size without having to remove and replace any components of the test setup. Signal analysis methods were used to identify frequency and amplitude of pressure and temperature oscillations. Low mass flux experiments (300 kg m−2 s−1 and 600 kg m−2 s−1 of R134a in a pumped loop) showed reduced channel wall temperatures with smaller orifice sizes. The orifice concept was found to be effective at reducing oscillations for the higher 600 kg m−2 s−1 flow rate, but the data indicate that wall temperature reduction with inlet orifice use is not solely due to elimination of oscillations. Signal analysis was an effective method of identifying oscillations without the availability of pictorial representation of flow patterns in the channels.

References

References
1.
Bergles
,
A. E.
, and
Kandlikar
,
S. G.
,
2005
, “
On the Nature of Critical Heat Flux in Microchannels
,”
ASME J. Heat Transfer
,
127
, pp.
101
107
.10.1115/1.1839587
2.
Kuan
,
W. K.
, and
Kandlikar
,
S. G.
,
2006
, “
Experimental Study on the Effect of Stabilization on Flow Boiling Heat Transfer in Microchannels
,”
Proceedings of 4th International Conference on Nanochannels, Microchannels and Minichannels
,
Limerick, Ireland
, pp. 53–60,
ASME
Paper No. ICNMM2006-96045.10.1115/ICNMM2006-96045
3.
Park
,
J. E.
,
Thome
,
J. R.
, and
Michel
,
B.
,
2009
, “
Effect of Inlet Orifice on Saturated CHF and Flow Visualization in Multi-Microchannel Heat Sinks
,”
Proceedings of 25th Annual IEEE Semiconductor Thermal Measurement and Management Symposium
,
San Jose, CA
,
Mar. 15–19
, pp.
1
8
.
4.
Koşar
,
A.
,
Kuo
,
C.
, and
Peles
,
Y.
,
2006
, “
Suppression of Boiling Flow Oscillations in Parallel Microchannels by Inlet Restrictors
,”
ASME J. Heat Transfer
,
128
, pp.
251
260
.10.1115/1.2150837
5.
Boure
,
J. A.
,
Bergles
,
A. E.
, and
Tong
,
L. S.
,
1973
, “
Review of Two-Phase Flow Instability
,”
Nucl. Eng. Des.
,
25
, pp.
165
192
.10.1016/0029-5493(73)90043-5
6.
Kandlikar
,
S. G.
,
Kuan
,
W. K.
,
Willistein
,
D. A.
, and
Borrelli
,
J.
,
2006
, “
Stabilization of Flow Boiling in Microchannels Using Pressure Drop Elements and Fabricated Nucleation Sites
,”
ASME J. Heat Transfer
,
128
, pp.
389
396
.10.1115/1.2165208
7.
Xu
,
J.
,
Liu
,
G.
,
Zhang
,
W.
,
Li
,
Q.
, and
Wang
,
B.
,
2009
, “
Seed Bubbles Stabilize Flow and Heat Transfer in Parallel Microchannels
,”
Int. J. Multiphase Flow
,
35
, pp.
773
790
.10.1016/j.ijmultiphaseflow.2009.03.008
8.
Bhide
,
R. R.
,
Singh
,
S. G.
,
Sridharan
,
A.
, and
Agrawal
,
A.
,
2011
, “
An Active Control Strategy for Reduction of Pressure Instabilities During Flow Boiling in a Microchannel
,”
J. Micromech. Microeng.
,
21
, p.
035021
.10.1088/0960-1317/21/3/035021
9.
Wang
,
G.
,
Cheng
,
P.
, and
Bergles
,
A. E.
,
2008
, “
Effects of Inlet/Outlet Configurations on Flow Boiling Instability in Parallel Microchannels
,”
Int. J. Heat Mass Transfer
,
51
, pp.
2267
2281
.10.1016/j.ijheatmasstransfer.2007.08.027
10.
Lu
,
C. T.
, and
Pan
,
C.
,
2008
, “
Stabilization of Flow Boiling in Microchannel Heat Sinks With a Diverging Cross-Section Design
,”
J. Micromech. Microeng.
,
18
, p.
075035
.10.1088/0960-1317/18/7/075035
11.
Phelan
,
P. E.
,
Gupta
,
Y.
,
Tyagi
,
H.
,
Prasher
,
R. S.
,
Cattano
,
J.
,
Michna
,
G.
,
Zhou
,
R.
,
Wen
,
J.
,
Jensen
,
M.
, and
Peles
,
Y.
,
2010
, “
Energy Efficiency of Refrigeration Systems for High-Heat-Flux Microelectronics
,”
ASME J. Therm. Sci. Eng. Appl.
,
2
, p.
031004
.10.1115/1.4003041
12.
Beckwith
,
T. G.
,
Marangoni
,
R. D.
, and
Lienhard
V,
J. H.
,
1993
,
Mechanical Measurements
, 5th ed.,
Addison-Wesley Publishing Company
,
Reading
, pp.
183
184
, Chap. 5.
13.
Lynn
,
P. A.
,
1998
,
Introductory Digital Signal Processing With Computer Applications
,
John Wiley & Sons
,
New York
, pp.
149
153
, Chap. 5.
14.
Lee
,
J.
, and
Mudawar
,
I.
,
2005
, “
Two-Phase Flow in High-Heat-Flux Micro-Channel Heat Sink for Refrigeration Cooling Applications: Part II—Heat Transfer Characteristics
,”
Int. J. Heat Mass Transfer
,
48
, pp.
941
955
.10.1016/j.ijheatmasstransfer.2004.09.019
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