This paper deals with vaporization heat transfer in a small diameter closed two-phase thermosyphon with a long evaporator and a short condenser, filled with water as operating fluid. The internal diameter of the evaporator is equal to 6.4 mm and the length-to-diameter ratio at the evaporator is equal to 166. A similar geometry is commonly used in vacuumed tube solar collectors. In the present investigation, the input power to the evaporator is provided by means of an electrical resistance wire wrapped around the external wall of the tube, while a water jacket is built at the condenser to reject the heat. The performance of the thermosyphon is described by using the wall temperature and the overall thermal resistance for different operating conditions: input power at the evaporator, cooling water temperature at the condenser, and inclination of the thermosyphon (30 deg, 60 deg, and 90 deg tilt angle to the horizontal plane). The present experimental data cover a range of heat flux between 1700 and 8000 W/m2 and saturation temperature between 28 °C and 72 °C. The vaporization heat transfer coefficients are compared with some correlations for closed two-phase thermosyphons displaying large disagreement. A new correlation is presented, which accurately predicts the present experimental values and other data by independent labs taken in closed two-phase thermosyphons, varying geometry and operating fluid (water, R134a, and ethanol).

References

References
1.
Faghri
,
A.
,
1995
,
Heat Pipe Science and Technology
,
Taylor Francis
, Washington, DC.
2.
Reay
,
D. A.
,
Kew
,
P. A.
, and
McGlen
,
R. J.
,
2014
,
Heat Pipes
,
6th ed.
,
Butterworth-Heinemann
,
Oxford, UK
.
3.
Faghri
,
A.
,
2012
, “
Review and Advances in Heat Pipe Science and Technology
,”
ASME J. Heat Transfer
,
134
(
12
), p.
123001
.
4.
Jouhara
,
H.
, and
Robinson
,
A. J.
,
2010
, “
Experimental Investigation of Small Diameter Two-Phase Closed Thermosyphons Charged With Water, FC-84, FC-77 and FC-3283
,”
Appl. Therm. Eng.
,
30
(
2–3
), pp.
201
211
.
5.
Del Col
,
D.
,
Padovan
,
A.
, and
Filippeschi
,
S.
,
2012
, “
Comparative Analysis of Two-Phase Thermosyphons Solar Collectors
,”
16th International Heat Pipe Conference (IHPC)
,
Lyon, France
,
May 20–24
.
6.
Jafari
,
D.
,
Franco
,
A.
,
Filippeschi
,
S.
, and
Di Marco
,
P.
,
2016
, “
Two-Phase Closed Thermosyphons: A Review of Studies and Solar Applications
,”
Renew. Sustain. Energy Rev.
,
53
, pp.
575
593
.
7.
Smith
,
K.
,
Robinson
,
A. J.
, and
Kempers
,
R.
,
2018
, “
Confinement and Vapour Production Rate Influences in Closed Two-Phase Reflux Thermosyphons—Part B: Heat Transfer
,”
Int. J. Heat Mass Transf.
,
120
, pp.
1241
1254
.
8.
Smith
,
K.
,
Siedel
,
S.
, and
Robinson
,
A. J.
,
2013
, “
Visual Study of Fluid Dynamics in Wickless Transparent Heat Pipes
,”
17th International Heat Pipe Conference (IHPC)
,
Kampur, India
,
Oct. 13–17
.
9.
Smith
,
K.
,
Kempers
,
R.
, and
Robinson
,
A. J.
,
2018
, “
Confinement and Vapour Production Rate Influences in Closed Two-Phase Reflux Thermosyphons Part A: Flow Regimes
,”
Int. J. Heat Mass Transf.
,
119
, pp.
907
921
.
10.
Imura
,
H.
,
Kusuda
,
H.
,
Ogata
,
J.-I.
,
Miyazaki
,
T.
, and
Sakamoto
,
N.
,
1979
, “
Heat Transfer in Two-Phase Closed-Type Thermosyphons
,”
Trans. Jpn. Soc. Mech. Eng.
,
45
, pp.
712
722
.
11.
Robinson
,
A. J.
,
Smith
,
K.
,
Hughes
,
T.
, and
Filippeschi
,
S.
,
2018
, “
Heat and Mass Transfer for a Small Diameter Thermosyphon With Low Fill Ratio
,”
Joint 19th IHPC and 13th IHPS
,
Pisa, Italy
,
June 10–14
, Paper No. 324.
12.
Londoño Pabón
,
N. Y.
,
Couto Vieira
,
G. S.
,
Warmling Milanez
,
K.
, and
Mantelli
,
M.
,
2018
, “
Performance of a Small Diameter Two-Phase Closed Thermosyphon in Geyser Boiling Condition
,”
Joint 19th IHPC and 13th IHPS
,
Pisa, Italy
,
June 10–14
, Paper No. 388.
13.
Lemmon
,
E. W.
,
Huber
,
M. L.
, and
McLinden
,
M. O.
,
2010
, “
NIST Standard Reference Database 23: Reference Fluid Thermodynamic and Transport Properties-REFPROP
,” Version 9.0, National Institute of Standard and Technology, Standard Reference Data Program, Gaithersburg, MD.
14.
Padovan
,
A.
, and
Del Col
,
D.
,
2010
, “
Measurement and Modeling of Solar Irradiance Components on Horizontal and Tilted Planes
,”
Sol. Energy
,
84
(
12
), pp.
2068
2084
.
15.
Joint Committee for Guides in Metrology (JCGM)
,
2008
, “
Evaluation of Measurement Data—Guide to the Expression of Uncertainty in Measurement
,” Bureau International des Poids et Mesures (BIPM), Sèvres, France, accessed Mar. 8, 2019, http://www.bipm.org/en/publications/guides/gum.html
16.
Shabgard
,
H.
,
Xiao
,
B.
,
Faghri
,
A.
,
Gupta
,
R.
, and
Weissman
,
W.
,
2014
, “
Thermal Characteristics of a Closed Thermosyphon Under Various Filling Conditions
,”
Int. J. Heat Mass Transf.
,
70
, pp.
91
102
.
17.
Cooper
,
M. G.
,
1984
, “
Saturation Nucleate Pool Boiling—A Simple Correlation
,”
Institution of Chemical Engineers Symposium Series
, Leeds, UK, pp.
785
793
.
18.
Grooten
,
M. H. M.
, and
van der Geld
,
C. W. M.
,
2009
, “
Predicting Heat Transfer in Long R-134a Filled Thermosyphons
,”
ASME J. Heat Transfer
,
131
(
5
), p. 051501.
19.
Verein Deutscher Ingenieure, VDI-Gesellschaft Verfahrenstechnik und Chemieingenieurwesen, (GVC)
,
2010
,
VDI Heat Atlas
,
Springer
, Berlin.
20.
Cooper
,
M. G.
,
1984
, “
Heat Flow Rates in Saturated Nucleate Pool Boiling—A Wide-Ranging Examination Using Reduced Properties
,”
Adv. Heat Transfer
,
16
, pp.
157
239
.
21.
Kew
,
P. A.
, and
Cornwell
,
K.
,
1997
, “
Correlations for the Prediction of Boiling Heat Transfer in Small-Diameter Channels
,”
Appl. Therm. Eng.
,
17
(
8–10
), pp.
705
715
.
22.
Franco
,
A.
, and
Filippeschi
,
S.
,
2010
, “
Experimental Analysis of Heat and Mass Transfer in Small Dimension, Two-Phase Loop Thermosyphons
,”
Heat Pipe Sci. Technol.
,
1
(
2
), pp.
163
182
.
23.
Franco
,
A.
, and
Filippeschi
,
S.
,
2012
, “
Closed Loop Two-Phase Thermosyphon of Small Dimensions: A Review of the Experimental Results
,”
Microgravity Sci. Technol.
,
24
(
3
), pp.
165
179
.
24.
Jafari
,
D.
,
Di Marco
,
P.
,
Filippeschi
,
S.
, and
Franco
,
A.
,
2017
, “
An Experimental Investigation on the Evaporation and Condensation Heat Transfer of Two-Phase Closed Thermosyphons
,”
Exp. Therm. Fluid Sci.
,
88
, pp.
111
123
.
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