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Flow structure of natural dehumidification over a horizontal finned-tube

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Abstract

In the present study, structure of water drops formation, growth, coalescence and departure over a horizontal finned-tube during natural dehumidification is investigated experimentally. Starting time of repelling the drops as well as heat transfer rate and the rate of dripping condensates in quasi-steady-state conditions are presented. Furthermore, cold airflow pattern around the horizontal finned-tube is visualized by using smoke generation scheme during natural dehumidification process. The finned-tube has a length of 300 mm, and inner and outer fin diameters, fin thickness and fin spacing are 25.4, 56, 0.4 and 2 mm, respectively. The tests are conducted in an insulated control room with dimensions of 5.8 m × 3 m × 4 m. Ambient air temperature, relative humidity and fin base temperature are selected from 25 to 35 °C, from 40 to 70 % and from 4 to 8 °C, respectively. Observations show that natural condensation from humid air over the test case is completely dropwise. Droplets only form on the edge of the fin and lateral fin surfaces remain almost dry. Dehumidification process over the tested finned-tube is divided into four stages; nucleation, formation, growth and departure of drops. It is also observed that the condensate inundation leaves the tube bottom in the form of droplets. Smoke visualization depicts that humid airflows downward around the cold finned-tube surface without noticeable turbulence and separation in the initial stages of dehumidification process. But the airflow has some disturbances in the intermediate stage and especially during drop departure on the edge of the fins.

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Abbreviations

A :

Total surface area (m2)

A i :

Inner surface area (m2)

A o :

Outer surface area (m2)

d :

Tube outer diameter (mm)

D :

Fin outer diameter (mm)

g :

Acceleration of gravity (m/s2)

\(\bar{h}\) :

Average heat transfer coefficient (W/m2 K)

\(\bar{h}_{\text{m}}\) :

Average mass transfer coefficient (m/s)

\(\dot{m}\) :

Rate of dripping condensates (kg/s)

n :

Number of fins

\(\dot{Q}\) :

Heat transfer rate (W)

R :

Thermal resistance (K/W)

\(Ra^{*}\) :

Elenbaas Rayleigh number \(\left( {g \cdot \beta \cdot \Delta T \cdot s^{4} /\nu \cdot \alpha \cdot D} \right)\)

s :

Fin spacing (mm)

t :

Time (min)

\(t^{*}\) :

Starting time of dripping (min)

T :

Temperature (°C)

ΔT :

Temperature difference (T a − T fb)

α :

Thermal diffusivity (m2/s)

β :

Volumetric thermal expansion coefficient (1/K)

δ :

Fin thickness (mm)

ν :

Kinematic viscosity (m2/s)

ρ :

Density (kg/m3)

ϕ :

Relative humidity (%)

ω :

Humidity ratio (kgwater/kgair)

a:

Ambient air

f:

Film

fb:

Fin base

sat:

Saturation

References

  1. Faghri A, Zhang Y (2006) Condensation. Transport phenomena in multiphase systems, 1st edn. Academic Press, New York, pp 581–667

    Google Scholar 

  2. Gstöhl D (2004) Heat transfer and flow visualization of falling film condensation on tube arrays with plain and enhanced surfaces. PhD diss. No. 3015, École Polytechnique Fédérale de Lausanne (Swiss Federal Institute of Technology in Lausanne)

  3. Katz D, Hope R, Datska S (1946) Liquid retention on integral-finned tubes. Department of Engineering Research, University of Michigan

  4. Beatty KO, Katz DL (1948) Condensation of vapors on outside of finned tubes. Chem Eng Prog 44:55–70

    Google Scholar 

  5. Rudy T, Webb R (1985) An analytical model to predict condensate retention on horizontal integral-fin tubes. J Heat Transf 107:361–368

    Article  Google Scholar 

  6. Honda H, Nozu S, Mitsumori K (1983) Augmentation of condensation on horizontal finned tubes by attaching a porous drainage plate. Proc ASME-JSME Therm Eng Jt Conf 3:289–296

    Google Scholar 

  7. Masuda H, Rose J (1987) Static configuration of liquid films on horizontal tubes with low radial fins: implications for condensation heat transfer. Proc R Soc Lond A Math Phys Sci 410:125–139

    Article  Google Scholar 

  8. Coney J, Kazeminejad H, Sheppard C (1989) Dehumidification of turbulent air flow over a thick fin: an experimental study. Proc Inst Mech Eng Part C J Mech Eng Sci 203:177–188

    Article  Google Scholar 

  9. Eckert E, Drake RM (1959) Heat and mass transfer. McGraw-Hill Inc., New York

    MATH  Google Scholar 

  10. Kazeminejad H (1995) Analysis of one-dimensional fin assembly heat transfer with dehumidification. Int J Heat Mass Transf 38:455–462

    Article  Google Scholar 

  11. Nabovati B, Yaghoubi M, Avara A (2012) Experimental study of free convection heat transfer and condensation of vapor of humid air over an inclined cold tube. Heat Transf—Asian Res 41:565–579

    Article  Google Scholar 

  12. Yaghoubi M, Mahdavi M (2013) An investigation of natural convection heat transfer from a horizontal cooled finned tube. Exp Heat Transf 26:343–359

    Article  Google Scholar 

  13. Fujii T, Uehara H (1973) Condensation heat transfer. Advance of heat transfer, Yokendo, Tokyo

    Google Scholar 

  14. Fujii T (1981) Vapor shear and condensate inundation: an overview. In: Marto PJ, Nunn RH (eds) Power condenser heat transfer technology, 1st edn. Hemisphere Publ., New York, pp 193–223

    Google Scholar 

  15. Marto P (1984) Heat transfer and two-phase flow during shell-side condensation. Heat Transf Eng 5:31–61

    Article  Google Scholar 

  16. Honda H (1997) Tube banks, condensation heat transfer. In: International encyclopedia of heat and mass transfer, 1st edn. CRC Press, Florida, pp 1177–1181

    Google Scholar 

  17. Gebauer T, Al-Badri AR, Gotterbarm A, Hajal JE, Leipertz A, Fröba AP (2013) Condensation heat transfer on single horizontal smooth and finned tubes and tube bundles for R134a and propane. Int J Heat Mass Transf 56:516–524

    Article  Google Scholar 

  18. Hirbodi K, Yaghoubi M (2014) Experimental investigation of natural dehumidification over an annular finned-tube. Exp Therm Fluid Sci 57:128–144

    Article  Google Scholar 

  19. Hirbodi K, Yaghoubi M (2013) Experimental study of dehumidification from humid air over a finned-tube by free convection. Iran J Mech Eng Trans ISME (Persian Ed) 31:64–79

    Google Scholar 

  20. Chen HT, Hsu WL (2007) Estimation of heat transfer coefficient on the fin of annular-finned tube heat exchangers in natural convection for various fin spacings. Int J Heat Mass Transf 50:1750–1761

    Article  MATH  Google Scholar 

  21. Elenbaas W (1942) Heat dissipation of parallel plates by free convection. Physica 9:1–28

    Article  MATH  Google Scholar 

  22. Wang C-S, Yovanovich M, Culham J (1999) Modeling natural convection from horizontal isothermal annular heat sinks. J Electron Packag 121:44–49

    Article  Google Scholar 

  23. Kirkup L, Frenkel RB (2006) An introduction to uncertainty in measurement: using the GUM (guide to the expression of uncertainty in measurement). Cambridge University Press, New York

    Book  MATH  Google Scholar 

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Acknowledgments

The authors are grateful to the financial support from Iran’s National Elites Foundation and also to Mr. K. Azodi Ghajar for his assistance in the construction of the experimental setup.

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Authors and Affiliations

  1. School of Mechanical Engineering, Shiraz University, Shiraz, P.O. Box 71348-51154, Iran

    Kamran Hirbodi & Mahmood Yaghoubi

  2. The Academy of Sciences of IR Iran, Tehran, P.O. Box 19735-167, Iran

    Mahmood Yaghoubi

Authors
  1. Kamran Hirbodi
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  2. Mahmood Yaghoubi
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Correspondence to Mahmood Yaghoubi.

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Hirbodi, K., Yaghoubi, M. Flow structure of natural dehumidification over a horizontal finned-tube. Heat Mass Transfer 52, 1455–1468 (2016). https://doi.org/10.1007/s00231-015-1659-3

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