Flow boiling heat transfer coefficients of CO2 are measured in a horizontal smooth tube with inner diameter 6.1mm. The test tube is heated by a secondary fluid maintaining constant wall temperature conditions. Heat transfer coefficients are measured at evaporation temperatures of 15 and 30°C, mass flux from 100to400kgm2s, and heat flux from 5to15kWm2 for qualities (vapor mass fractions) ranging from 0.1 to 0.8. The characteristics of CO2 flow boiling are explained by CO2 properties and flow patterns. The measured CO2 heat transfer coefficients are compared to other published data. Experiments with R22 were also conducted in the same system and the results show that the heat transfer coefficients for CO2 are 40 to 150% higher than for R22 at 15°C and low mass flux of 200kgm2s mostly due to the characteristics of CO2 nucleate boiling. The presented CO2 heat transfer coefficients indicate the reduction of heat transfer coefficient as mass flux increases at low quality regions and also show that dryout does not occur until the high quality region of 0.8, for mass fluxes of 200 and 400kgm2s. The Gungor and Winterton correlation gives a relatively good agreement with measured data; however it deviates more at lower evaporation temperature and high mass flux conditions.

1.
Hihara
,
E.
, and
Tanaka
,
S.
, 2000, “
Boiling Heat Transfer of Carbon Dioxide in Horizontal Tubes
,”
Proceedings of the Fourth IIR-Gustav Lorenzen Conference on Natural Working Fluids
, Purdue University, pp.
279
284
.
2.
Koyama
,
S.
,
Kuwahara
,
K.
,
Shinmura
,
E.
, and
Ikeda
,
S.
, 2001, “
Experimental Study on Flow Boiling of Carbon Dioxide in a Horizontal Small Diameter Tube
,”
IIR Commission B1 Meeting
, Paderborn, Germany.
3.
Pettersen
,
J.
, 2004, “
Flow Boiling of CO2 in Microchannel Tubes
,”
Exp. Therm. Fluid Sci.
0894-1777,
28
, pp.
111
121
.
4.
Yun
,
R.
,
Kim
,
Y.
,
Kim
,
M. S.
, and
Choi
,
Y.
, 2003, “
Boiling Heat Transfer and Dryout Phenomenon of CO2 in a Horizontal Smooth Tube
,”
Int. J. Heat Mass Transfer
0017-9310,
46
, pp.
2353
2361
.
5.
Yoon
,
S. H.
,
Cho
,
E. S.
,
Hwang
,
Y. W.
,
Kim
,
M. S.
,
Min
,
K.
, and
Kim
,
Y.
, 2004, “
Characteristics of Evaporative Heat Transfer and Pressure Drop of Carbon Dioxide and Correlation Development
,”
Int. J. Refrig.
0140-7007,
27
, pp.
111
119
.
6.
Thome
,
J. R.
, and
Hajal
,
J. E.
, 2004, “
Flow Boiling Heat Transfer to Carbon Dioxide: General Prediction Method
,”
Int. J. Refrig.
0140-7007,
27
, pp.
294
301
.
7.
Bredesen
,
A. M.
,
Hafner
,
A.
,
Pettersen
,
J.
,
Neksa
,
P.
, and
Aflekt
,
P. K.
, 1997, “
Heat Transfer and Pressure Drop for In-tube Evaporation of CO2
,”
Proceedings of the Internatioanl Conference on Heat Transfer Issues in Natural Refrigerants
, University of Maryland, pp.
1
15
.
8.
Høgaard Knudsen
,
H. J.
, and
Jensen
,
P. H.
, 1997, “
Heat Transfer Coefficient for Boiling Carbon Dioxide
,”
Proceedings of the International R&D on Heat Pump, Air Conditioning and Refrigeration Systems
,
Gatlinburg
, Tennessee, pp.
113
122
.
9.
Klein
,
S. A.
, 2004, Engineering Equation Solver, F-Chart Software, V7.205.
10.
Moffat
,
R. J.
, 1988, “
Describing the Uncertainties in Experimental Results
,”
Exp. Therm. Fluid Sci.
0894-1777,
1
, pp.
3
17
.
11.
Loebl
,
S.
, and
Kraus
,
W. E.
, 2004, “
Pool Boiling Heat Transfer of Carbon Dioxide on a Horizontal Tube
,”
Proceedings of the Sixth IIR Gustav-Lorentzen Conference on Natural Working Fluids
,
IIR Commission A1 & A2 Meeting
,
Glasgow
, UK.
12.
Kandlikar
,
S. G.
, 1990, “
A General Correlation for Saturated Two-Phase Flow Boiling Heat Transfer Inside Horizontal and Vertical Tubes
,”
J. Heat Transfer
0022-1481,
112
, pp.
219
228
.
13.
Chen
,
J. C.
, 1966, “
Correlations for Boiling Heat Transfer to Saturated Fluids in Convective Flow
,”
Ind. Eng. Chem. Process Des. Dev.
0196-4305,
5
, pp.
322
339
.
14.
Gungor
,
K. E.
, and
Winterton
,
R. H. S.
, 1986, “
A General Correlation for Flow Boiling in Tubes and Annuli
,”
Int. J. Heat Mass Transfer
0017-9310,
29
, pp.
351
358
.
15.
Gorenflo
,
D.
, 1993, “
Pool Boiling
,” VDI Gesellschaft Verfahrenstechnic und Chemiengenieurwesen, English translation of VDI, Dusseldorf, pp.
Ha
4–Ha
18
.
16.
Steiner
,
D.
, and
Taborek
,
J.
, 1992, “
Flow Boiling Heat Transfer in Vertical Tubes Correlated by Asymptotic Model
,”
Heat Transfer Eng.
0145-7632,
13
, pp.
43
69
.
17.
Gnielinski
,
V.
, 1976, “
New Correlations for Heat and Mass Transfer in Turbulent Pipe and Channel Flow
,”
Int. Chem. Eng.
0020-6318,
16
, pp.
359
368
.
18.
Jang
,
J.
, and
Hrnjak
,
P. S.
, 2003, “
Flow Regimes and Heat Transfer in Condensation of Carbon Dioxide at Low Temperatures
,”
Proceedings of the Second International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics
,
Victoria Falls
, Zambia, Paper number HP1.
19.
Sato
,
T.
, and
Matsumura
,
H.
, 1964, “
On the Conditions of Incipient Subcooled-boiling With Forced Convection
,”
Bull. JSME
0021-3764,
7
, pp.
392
398
.
20.
Fujita
,
T.
, and
Ueda
,
T.
, 1978, “
Heat Transfer to Falling Liquid Films and Film Breakdown II (Saturated Liquid Films With Nucleate Boiling)
.”
Int. J. Heat Mass Transfer
0017-9310,
21
, pp.
109
118
.
21.
Kattan
,
N.
,
Thome
,
J. R.
, and
Favrat
,
D.
, 1998, “
Flow Boiling in Horizontal Tubes: Part 1—Development of a Diabatic Two-Phase Flow Pattern Map
,”
J. Heat Transfer
0022-1481,
120
, pp.
140
147
.
22.
Kattan
,
N.
,
Thome
,
J. R.
, and
Favrat
,
D.
, 1998, “
Flow Boiling in Horizontal Tubes: Part 3—Development of a New Heat Transfer Model Based on Flow Pattern
,”
J. Heat Transfer
0022-1481,
120
, pp.
156
165
.
23.
Gungor
,
K. E.
, and
Winterton
,
R. H. S.
, 1987, “
Simplified General Correlation for Saturated Flow Boiling and Comparison of Correlations With Data
,”
Chem. Eng. Res. Des.
0263-8762,
65
, pp.
148
156
.
24.
Shah
,
M. M.
, 1982, “
Chart Correlation for Saturated Boiling Heat Transfer: Equations and Further Study
,”
ASHRAE J.
0001-2491,
88
, pp.
185
196
.
25.
Wattelet
,
J. P.
,
Chato
,
J. C.
,
Christoffersen
,
B. R.
,
Gaibel
,
J. A.
,
Ponchner
,
M.
,
Kenny
,
P. J.
,
Shimon
,
R. L.
,
Villaneuva
,
T. C.
,
Rhines
,
N. L.
,
Sweeney
,
K. A.
,
Allen
,
D. G.
, and
Heshberger
,
T. T.
, 1994, “
Heat Transfer Flow Regimes of Refrigerants in a Horizontal-tube Evaporator
,” ACRC TR-55, University of Illinois at Urbana-Champaign.
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