Skip to main content

Advertisement

Log in

The cooling heat transfer characteristics of the supercritical CO2 in micro-fin tube

  • Original
  • Published:
Heat and Mass Transfer Aims and scope Submit manuscript

Abstract

This study intended to verify the cooling heat transfer characteristics of supercritical gas for refrigerating and air-conditioning devices that use CO2, a natural refrigerant, as the operating fluid. Experiments were performed with a gas cooler, which was the test part. The gas cooler was a heat exchanger made of a micro-fin tube with an inner diameter of 4.6 mm and an outer diameter of 5.0 mm. The experiment results are summarized as follows. The heat transfer coefficient, according to the mass flux, peaked at the low cooling pressure of 8.0 MPa in the gas cooler, and reached its minimum at the high pressure of 10.0 MPa. Furthermore, when the mass flux of the refrigerant increased, the coefficient increased faster with the lower cooling pressure in the gas cooler. The heat transfer coefficient, according to the shape of the heat transfer tube, showed that the maximum values of the CO2 cooling heat transfer coefficients of the smooth tube and the micro-fin tube were found at 44.7 °C, which were the pseudo-critical temperatures for the entrance pressures. It was found that the cooling heat transfer coefficient of the micro-fin tube increased by 12–39 % more than that of the smooth tube. The experiment results for the CO2 heat transfer coefficients of the smooth tube and the micro-fin tube were compared with the results estimated from previous correlations. It was found that the experiment values generally significantly differed from and the experiment values greater than the estimated values. The differences were especially greater in the vicinity of the critical temperature points. Based on these results, a new correlation was suggested that includes the density ratio and the specific heat ratio.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12

Similar content being viewed by others

Abbreviations

A:

Area (m2)

Cp :

Specific heat at constant pressure (kJ kg−1 K−1)

d:

Diameter (m)

G:

Mass flux (kg m−2 s−1)

h:

Heat transfer coefficient (kW m−2 K−1)

i:

Enthalpy (kJ kg−1)

k:

Thermal conductivity (kW m−1 K−1)

M:

Mass flow rate (kg h−1)

N:

Number

n:

Number of local tube

P:

Pressure, (Pa)

Q:

Heat capacity (W)

q:

Heat flux (W m−2)

T:

Temperature (K)

z:

Tube length (m)

Δ:

Difference

ρ:

Density (kg m−3)

σ:

Deviation

Nu:

Nusselt number (h d κ−1)

Pr:

Prandtl number (cp μ κ−1)

Re:

Reynolds number (G di μ−1)

abs:

Absolute

avg:

Average

b:

Bulk

bottom:

Bottom

cal:

Calculated

cs:

Source water of gas cooler

exp:

Experimental

gc:

As cooler, refrigerant

i:

Inner

in:

Inlet

loc:

Local

o:

Outer

out:

Outlet

pc:

Pseudo-critical point

side:

Side

sub:

Sub

top:

Top

w:

Wall

References

  1. Bodinus WS (1999) The rise and fall of carbon dioxide system. In: Will HM (ed) The first century of air conditioning. ASHRAE, Atlanta, GA, pp 29–34

  2. Donaldson B, Nagengast B (1994) Heat and cold: mastering the great indoors. ASHRAE, Atlanta, GA

    Google Scholar 

  3. Ebner T, Halozan H (1994) Testing the aviable alternative—an examination of R-134a, R-152a and R-290. IEA HPC Newsletter 12(1), Sittard, The Netherlands

  4. Dang C, Hihara E (2002) Effect of tube diameter on heat transfer coefficient of supercritical carbon dioxide. In: Proceedings of the Asian conference on refrigeration and air conditioning, December 4, Kobe, Japan, pp 60–66

  5. Gao L, Honda T (2002) Experimental on heat transfer characteristics of heat exchanger for CO2 heat pump system. In: Proceedings of the Asian conference on refrigeration and air conditioning, December 4, Kobe, Japan, pp 75–80

  6. Lorentzen G, Pettersen J (1993) A new, efficient and environmentally benign system for car air-conditioning. Int J Refrig 16(1):4–12

    Article  Google Scholar 

  7. Oh HK, Son CH (2010) New correlation to predict the heat transfer coefficient in-tube cooling of supercritical CO2 in horizontal macro-tubes. Exp Thermal Fluid Sci 34:1230–1241

    Article  Google Scholar 

  8. Yoon SH (2002) Studies on the characteristics of evaporation and supercritical gas cooling heat transfer of carbon dioxide. The degree of doctor of Seoul National University

  9. Yun L, Kim YC, Kim MS (2003) Two-phase flow patterns of CO2 in a narrow rectangular channel. In: International congress of refrigeration, Washington D. C., pp 1–7

  10. Cavallini A, Del Col D, Doretti L, Longo GA, Rossetto L (2000) Heat transfer and pressure drop during condensation of refrigerants inside horizontal enhanced tubes. Int J Refrig 23:4–25

    Article  Google Scholar 

  11. Kim JH (2001) An experimental study on heat transfer characteristics during gas cooling process of carbon dioxide. The degree of master of Seoul National University

  12. Dang C (2003) Cooling heat transfer of supercritical carbon dioxide. The degree of doctor of Tokyo school of engineering department

  13. Mori K, Onishi J, Shimaoka H, Nakanishi S, Kimoto H (2002) Cooling heat transfer characteristics of CO2 Oil mixture at supercritical pressure conditions. In: Proceedings of the Asian conference on refrigeration and air conditioning, Kobe, Japan, pp 81–86

  14. Dang C, Iino K, Hihara E (2010) Effect of PAG-type lubricating oil on heat transfer characteristics of supercritical carbon dioxide cooled inside a small internally grooved tube. Int J Refrig 33:558–565

    Article  Google Scholar 

  15. McLinden MO, Klein SA, Lemmon EW, Peskin AP (1998) NIST thermodynamic properties and refrigerant mixtures database (REFPROP), Version 8.01. National Institute of Standards and Technology, Gaithersburg, MD

  16. Moffat RJ (1985) Using uncertainty analysis in the planning of an experiment. J Fluid Eng 107:173–182

    Article  Google Scholar 

  17. Holman JP (1989) Experimental methods for engineers, 5th edn. McGraw-Hill, New York

    Google Scholar 

  18. Yoon SH, Kim JH, Kim MS (2004) Experimental studies on heat transfer and pressure drop characteristics during gas cooling process of carbon dioxide in the supercritical region. Int J Air Cond Refrig 16(6):538–545

    Google Scholar 

  19. Petukhov BS, Krasnoshchekov EA, Protopopov VS (1961) An investigation of heat transfer to fluids flowing in pipes under supercritical conditions. ASME Int Dev Heat Transf 3:569–578

    Google Scholar 

  20. Petrov NE, Popov VN (1985) Heat transfer and resistance of carbon being cooled in the supercritical region. Therm Eng 32(3):131–134

    Google Scholar 

  21. Gnielinski V (1994) Wärmeübergang bei der Strömung durch Rohre, VDI-Wärmeatlas, edition 7. VDI-Verlag, Düsseldorf

    Google Scholar 

  22. Pitla SS, Robinson DM, Groll EA, Ramadhyani S (1998) Heat transfer from supercritical carbon dioxide in tube flow: a critical review. HVAC&R Res 4(4):281–301

    Article  Google Scholar 

  23. Fang X, Bullard CW, Hrnjak PS (2000) Heat transfer and pressure drop of gas coolers. ASHRAE Trans 107(1):255–266

    Google Scholar 

  24. Krasonshchekov EA, Protopopov VS (1966) Experimental study of heat exchange in carbon dioxide in the supercritical range at high temperature drops. Teplofiz Vys Temp 4(3):389–398

    Google Scholar 

  25. Baskov VL, Kuraeva IV, Protopopov VS (1977) Heat transfer with the turbulent flow of a liquid at supercritical pressure in tubes under cooling conditions. Teplofiz Vysok Temp 15(1):96–102

    Google Scholar 

  26. Dittus FW, Boelter LMK (1930) Publications on engineering. University of California, Berkeley, vol 2, p 443

Download references

Acknowledgments

This work was financially supported by the National R&D project of “Development of Energy Utilization of Deep Ocean Water” supported by the Korean Ministry of Land, Traffic and Maritime Affairs.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Chang-Hyo Son.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Lee, HS., Kim, HJ., Yoon, JI. et al. The cooling heat transfer characteristics of the supercritical CO2 in micro-fin tube. Heat Mass Transfer 49, 173–184 (2013). https://doi.org/10.1007/s00231-012-1070-2

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00231-012-1070-2

Keywords

Navigation