Slug oscillations and heat transfer performance in the start-up stage of oscillating heat pipes (OHPs) with different surface wetting characteristics were investigated experimentally. The inner surfaces of the OHPs were superhydrophilic surface, hydrophilic surface, copper, hydrophobic surface, and superhydrophobic surface, respectively. There was a thin liquid film between the vapor bubble and the surface in the hydrophilic OHP which was different from hydrophobic OHP. Results showed that start-up performance was improved in hydrophilic OHP due to the low flow resistance and deteriorated in hydrophobic OHP as opposed to the copper OHP. Heat transfer results showed that wall temperature fluctuations were observed at the start-up stage. Compared with the copper OHP, start-up time and start-up temperature were reduced by 100 s and 3.32–4.41 °C in the hydrophilic OHP at the start-up stage. Slug oscillation frequency and temperature oscillation amplitude increased with heat input; however, slug oscillation amplitude increased first and then decreased with heat input. Compared with the copper OHP, with the increasing of 0–57% in slug oscillation amplitude and 0–100% in slug oscillation frequency, the thermal performance was enhanced by 0–67% in the hydrophilic OHP. Although the slug oscillation frequency in the superhydrophobic OHP was higher than that in the copper OHP, with the decreasing of 0–70% in the slug oscillation amplitude, the thermal resistance in superhydrophobic OHP was significantly increased and was 1.5–5 times higher than that in the copper OHP.

References

References
1.
Tong
,
B. Y.
,
Wong
,
T. N.
, and
Ooi
,
K. T.
,
2001
, “
Closed-Loop Pulsating Heat Pipe
,”
Appl. Therm. Eng.
,
21
(
18
), pp.
1845
1862
.
2.
Khandekar
,
S.
,
Charoensawan
,
P.
,
Groll
,
M.
, and
Terdtoon
,
P.
,
2003
, “
Closed Loop Pulsating Heat Pipes—Part B: Visualization and Semi-Empirical Modeling
,”
Appl. Therm. Eng.
,
23
(
16
), pp.
2021
2033
.
3.
Lin
,
Z.
,
Wang
,
S.
,
Huo
,
J.
,
Hu
,
Y.
,
Chen
,
J.
,
Zhang
,
W.
, and
Lee
,
E.
,
2011
, “
Heat Transfer Characteristics and LED Heat Sink Application of Aluminum Plate Oscillating Heat Pipes
,”
Appl. Therm. Eng.
,
31
(
14–15
), pp.
2221
2229
.
4.
Borgmeyer
,
B.
, and
Ma
,
H. B.
,
2007
, “
Experimental Investigation of Oscillating Motions in a Flat Plate Pulsating Heat Pipe
,”
J. Thermophys. Heat Transfer
,
21
(
2
), pp.
405
409
.
5.
Ji
,
Y.
,
Chen
,
H.
,
Kim
,
Y. J.
,
Yu
,
Q.
,
Ma
,
X.
, and
Ma
,
H. B.
,
2012
, “
Hydrophobic Surface Effect on Heat Transfer Performance in an Oscillating Heat Pipe
,”
ASME J. Heat Transfer
,
134
(
7
), p.
074502
.
6.
Ji
,
Y.
,
Xu
,
C.
,
Ma
,
H.
, and
Xinxiang
,
P.
,
2013
, “
An Experimental Investigation of the Heat Transfer Performance of an Oscillating Heat Pipe With Copper Oxide (CuO) Microstructure Layer on the Inner Surface
,”
ASME J. Heat Transfer
,
135
(
7
), p.
074504
.
7.
Hao
,
T. T.
,
Ma
,
X. H.
,
Lan
,
Z.
,
Li
,
N.
,
Zhao
,
Y. Z.
, and
Ma
,
H. B.
,
2014
, “
Effects of Hydrophilic Surface on Heat Transfer Performance and Oscillating Motion for an Oscillating Heat Pipe
,”
Int. J. Heat Mass Transfer
,
72
, pp.
50
65
.
8.
Hao
,
T. T.
,
Ma
,
X. H.
,
Lan
,
Z.
,
Li
,
N.
, and
Zhao
,
Y. Z.
,
2014
, “
Effects of Superhydrophobic and Superhydrophilic Surfaces on Heat Transfer and Oscillating Motion of an Oscillating Heat Pipe
,”
ASME J. Heat Transfer
,
136
(
8
), p.
082001
.
9.
Khandekar
,
S.
,
Schneider
,
M.
,
Schäfer
,
P.
,
Kulenovic
,
R.
, and
Groll
,
M.
,
2003
, “
Thermofluid Dynamic Study of Flat-Plate Closed-Loop Pulsating Heat Pipes
,”
Microscale Thermophys. Eng.
,
6
(4), pp.
303
317
.
10.
Khandekar
,
S.
,
Dollinger
,
N.
, and
Groll
,
M.
,
2003
, “
Understanding Operational Regimes of Closed Loop Pulsating Heat Pipes: An Experimental Study
,”
Appl. Therm. Eng.
,
23
(
6
), pp.
707
719
.
11.
Liu
,
X.
,
Chen
,
Y.
, and
Shi
,
M.
,
2013
, “
Dynamic Performance Analysis on Start-Up of Closed-Loop Pulsating Heat Pipes (CLPHPs)
,”
Int. J. Therm. Sci.
,
65
, pp.
224
233
.
12.
Xian
,
H.
,
Yang
,
Y.
,
Liu
,
D.
, and
Du
,
X.
,
2010
, “
Heat Transfer Characteristics of Oscillating Heat Pipe With Water and Ethanol as Working Fluids
,”
ASME J. Heat Transfer
,
132
(
12
), p.
121501
.
13.
Lin
,
Z.
,
Wang
,
S.
,
Chen
,
J.
,
Huo
,
J.
,
Hu
,
Y.
, and
Zhang
,
W.
,
2011
, “
Experimental Study on Effective Range of Miniature Oscillating Heat Pipes
,”
Appl. Therm. Eng.
,
31
(
5
), pp.
880
886
.
14.
Soponpongpipat
,
N.
,
Sakulchangsatjaati
,
P.
,
Kammuang-Lue
,
N.
, and
Terdtoon
,
P.
,
2009
, “
Investigation of the Startup Condition of a Closed-Loop Oscillating Heat Pipe
,”
Heat Transfer Eng.
,
30
(
8
), pp.
626
642
.
15.
Ji
,
Y.
,
Ma
,
H.
,
Su
,
F.
, and
Wang
,
G.
,
2011
, “
Particle Size Effect on Heat Transfer Performance in an Oscillating Heat Pipe
,”
Exp. Therm. Fluid Sci.
,
35
(
4
), pp.
724
727
.
16.
Qu
,
W.
, and
Ma
,
H. B.
,
2007
, “
Theoretical Analysis of Startup of a Pulsating Heat Pipe
,”
Int. J. Heat Mass Transfer
,
50
(
11–12
), pp.
2309
2316
.
17.
Qu
,
J.
,
Wu
,
H.
, and
Cheng
,
P.
,
2012
, “
Start-Up, Heat Transfer and Flow Characteristics of Silicon-Based Micro Pulsating Heat Pipes
,”
Int. J. Heat Mass Transfer
,
55
(
21–22
), pp.
6109
6120
.
18.
Zhao
,
N.
,
Zhao
,
D.
, and
Ma
,
H. B.
,
2013
, “
Ultrasonic Effect on the Startup of an Oscillating Heat Pipe
,”
ASME J. Heat Transfer
,
135
(
7
), p.
074503
.
19.
Xu
,
J. L.
, and
Zhang
,
X. M.
,
2005
, “
Start-Up and Steady Thermal Oscillation of a Pulsating Heat Pipe
,”
Heat Mass Transfer
,
41
(
8
), pp.
685
694
.
20.
Khandekar
,
S.
,
Gautam
,
A. P.
, and
Sharma
,
P. K.
,
2009
, “
Multiple Quasi-Steady States in a Closed Loop Pulsating Heat Pipe
,”
Int. J. Therm. Sci.
,
48
(
3
), pp.
535
546
.
21.
Thompson
,
S. M.
,
Ma
,
H. B.
,
Winholtz
,
R. A.
, and
Wilson
,
C.
,
2009
, “
Experimental Investigation of Miniature Three-Dimensional Flat-Plate Oscillating Heat Pipe
,”
ASME J. Heat Transfer
,
131
(
4
), p.
043210
.
22.
Thompson
,
S. M.
, and
Ma
,
H. B.
,
2010
, “
Effect of Localized Heating on Three-Dimensional Flat-Plate Oscillating Heat Pipe
,”
Adv. Mech. Eng.
,
2
, p.
465153
.
23.
Thompson
,
S. M.
,
Cheng
,
P.
, and
Ma
,
H. B.
,
2011
, “
An Experimental Investigation of a Three-Dimensional Flat-Plate Oscillating Heat Pipe With Staggered Microchannels
,”
Int. J. Heat Mass Transfer
,
54
(
17–18
), pp.
3951
3959
.
24.
Fairley
,
J. D.
,
Thompson
,
S. M.
, and
Anderson
,
D.
,
2015
, “
Time-Frequency Analysis of Flat-Plate Oscillating Heat Pipes
,”
Int. J. Therm. Sci.
,
91
, pp.
113
124
.
25.
Qian
,
B.-T
, and
Shen
,
Z.-Q
,
2006
, “
Super-hydrophobic CuO Nanoflowers by Controlled Surface Oxidation on Copper
,”
J. Inorg. Mater.
,
21
(
3
), pp.
747
752
.http://www.jim.org.cn/EN/10.3724/SP.J.1077.2006.00747
26.
Phan
,
H. T.
,
Caney
,
N.
,
Marty
,
P.
,
Colasson
,
S.
, and
Gavillet
,
J.
,
2011
, “
Flow Boiling of Water in a Minichannel: The Effects of Surface Wettability on Two-Phase Pressure Drop
,”
Appl. Therm. Eng.
,
31
(
11
), pp.
1894
1905
.
You do not currently have access to this content.