Heat and Mass Transfer

, Volume 55, Issue 1, pp 41–57 | Cite as

Effects of geometry and fluid properties during condensation in minichannels: experiments and simulations

  • Paolo Toninelli
  • Stefano Bortolin
  • Marco Azzolin
  • Davide Del ColEmail author


The present paper aims at investigating the condensation process inside minichannels, at low mass fluxes, where bigger discrepancies from conventional channels can be expected. At high mass flux, the condensation in minichannels is expected to be shear stress dominated. Therefore, models originally developed for conventional channels could still do a good job in predicting the heat transfer coefficient. When the mass flow rate decreases, the condensation process in minichannels starts to display differences with the same process in macro-channels. With the purpose of investigating condensation at these operating conditions, new experimental data are here reported and compared with data already published in the literature. In particular, heat transfer coefficients have been measured during R134a and R1234ze(E) condensation inside circular and square cross section minichannels at mass flux ranging between 65 and 200 kg m−2 s−1. These new data are compared with those of R32, R717, R290, R152a to show the effect of channel shape and fluid properties and to assess the applicability of correlations developed for macroscale condensation. For this purpose, a new criterion based on the Weber number is presented to decide when the macroscale condensation correlation can be applied. The present experimental data are also compared against three-dimensional Volume of Fluid (VOF) simulations of condensation in minichannels with circular and square cross section. This comparison allows to get an insight into the process and evaluate the main heat transfer mechanisms.


Bo [−]

Bond number, Bo = [(ρL- ρV)gDh2]/σ

Bocr [−]

Critical Bond number, Bocr = [ρL/(ρL- ρV)-π/4]−1

Dh [m]

Hydraulic diameter

ep [%]

Percentage deviation, ep = 100·(HTCCALC- HTCEXP)/ HTCEXP

eR [%]

Average deviation, eR = (1/Np)∑ep

g [m s−2]

Acceleration due to gravity

G [kg m−2 s−1]

Mass flux

HTC [W m−2 K−1]

Cross-sectional average heat transfer coefficient

JV [−]

Dimensionless gas velocity, JV = xG/[gDhρV(ρLV)]0.5

k [m2 s−2]

Turbulent kinetic energy

Np [−]

Number of data points

p [bar]


R [m]

Channel radius

T [K]


t [m]

Average liquid film thickness

t + [−]

Dimensionless average liquid film thickness, t+ = t/y*

UVS [m s−1]

Superficial velocity of vapour phase, UVS = xG/ρV

ULS [m s−1]

Superficial velocity of liquid phase, ULS = (1-x)G/ρL

We [−]

Weber number, We = ρV(UVS-ULS)2Dh/σ

x [−]

Vapor quality

Xtt [−]

Martinelli parameter, Xtt = (μL/μV)0.1V/ ρL)0.5[(1-x)/x]0.9

y [m]

y - coordinate

y* [m]

Length scale, y* = μLW/ ρL)-0.5/ ρL

Greek symbols

αt+ [−]

Dimensionless turbulent eddy diffusivity for heat

ΔT [K]

Temperature difference

λ [W m−1 K−1]

Thermal conductivity

μ [Pa s]

Dynamic viscosity

νt+ [−]

Dimensionless turbulent eddy diffusivity for momentum

ρ [kg m−3]


σ [N m−1]

Surface tension

σN [%]

Standard deviation, σN = {[∑(ep-eR)2]/(Np-1)}0.5

τW [Pa]

Wall shear stress

ω [s−1]

Specific dissipation rate of turbulent kinetic energy


















The authors acknowledge the financial support of MIUR (Ministero dell’Istruzione, dell’Università e della Ricerca) through the program PRIN 2015 (Grant Number 2015M8S2PA) and the support of the European Space Agency through the MAP Condensation program ENCOM-3 (AO 2004-096).

Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.


  1. 1.
    Kew PA, Reay DA (2011) Compact/micro-heat exchangers - Their role in heat pumping equipment. Appl Therm Eng 31:594–601CrossRefGoogle Scholar
  2. 2.
    Nema G, Garimella S, Fronk BM (2014) Flow regime transitions during condensation in microchannels. Int J Refrig 40:227–240CrossRefGoogle Scholar
  3. 3.
    Coleman JW, Garimella S (2003) Two-phase flow regimes in round, square and rectangular tubes during condensation of refrigerant R134a. Int J Refrig 26:117–128CrossRefGoogle Scholar
  4. 4.
    Cavallini A, Del Col D, Doretti L, Matkovic M, Rossetto L, Zilio C, Censi G (2006) Condensation in horizontal smooth tubes: a new heat transfer model for heat exchanger design. Heat Transfer Eng 27:31–38CrossRefGoogle Scholar
  5. 5.
    Cavallini A, Bortolin S, Del Col D, Matkovic M, Rossetto L (2011) Condensation heat transfer and pressure losses of high- and low-pressure refrigerants flowing in a single circular minichannel. Heat Transfer Eng 32:90–98CrossRefGoogle Scholar
  6. 6.
    Del Col D, Bortolin S, Cavallini A, Matkovic M (2011) Effect of cross sectional shape during condensation in a single square minichannel. Int J Heat Mass Transf 54:3909–3920CrossRefzbMATHGoogle Scholar
  7. 7.
    Del Col D, Bortolato M, Azzolin M, Bortolin S (2015) Condensation heat transfer and two-phase frictional pressure drop in a single minichannel with R1234ze(E) and other refrigerants. Int J Refrig 50:87–103CrossRefGoogle Scholar
  8. 8.
    Bandhauer TM, Agarwal A, Garimella S (2006) Measurement and modeling of condensation heat transfer coefficients in circular microchannels. Trans ASME J Heat Transf 128(10):1050–1059CrossRefGoogle Scholar
  9. 9.
    Matkovic M, Cavallini A, Del Col D, Rossetto L (2009) Experimental study on condensation heat transfer inside a single circular minichannel. Int J Heat Mass Transf 52:2311–2323CrossRefGoogle Scholar
  10. 10.
    Liu N, Li JM, Sun J, Wang HS (2013) Heat transfer and pressure drop during condensation of R152a in circular and square microchannels. Exp Thermal Fluid Sci 47:60–67CrossRefGoogle Scholar
  11. 11.
    Sakamatapan K, Kaew-On J, Dalkilic AS, Mahian O, Wongwises S (2013) Condensation heat transfer characteristics of R-134a flowing inside the multiport minichannels. Int J Heat Mass Transf 64:976–985CrossRefGoogle Scholar
  12. 12.
    Bortolin S, Da Riva E, Del Col D (2014) Condensation in a square minichannel: application of the VOF method. Heat Transfer Eng 35:193–203CrossRefGoogle Scholar
  13. 13.
    Del Col D, Bortolato M, Azzolin M, Bortolin S (2014) Effect of inclination during condensation inside a square cross section minichannel. Int J Heat Mass Transf 78:760–777CrossRefGoogle Scholar
  14. 14.
    Da Riva E, Del Col D (2011) Effect of gravity during condensation of R134a in a circular minichannel. Microgravity Sci Technol 23(Suppl. 1):87–97CrossRefGoogle Scholar
  15. 15.
    Marchuk I, Lyulin Y, Kabov O (2013) Theoretical and experimental study of convective condensation inside a circular tube. Interfacial Phenom Heat Transf 1(2):153–171CrossRefGoogle Scholar
  16. 16.
    Garimella S, Fronk BM, Milkie JA, Keinath B (2014) Versatile models for condensation of fluids with widely varying properties from the micro to macroscale. In: Proceedings of the 15th international heat transfer conf., IHTC-15, p 10516Google Scholar
  17. 17.
    Wang HS, Rose JW (2005) A theory of film condensation in horizontal non-circular section microchannels. Trans ASME J Heat Transf 127(10):1096–1105CrossRefGoogle Scholar
  18. 18.
    Wang HS, Rose JW (2009) Film condensation in horizontal circular-section microchannels. Int J Eng Syst Model Simul 1:115–121Google Scholar
  19. 19.
    Wang HS, Rose JW (2011) Theory of heat transfer during condensation in microchannels. Int J Heat Mass Transf 54:2525–2534CrossRefzbMATHGoogle Scholar
  20. 20.
    Nebuloni S, Thome JR (2010) Numerical modeling of laminar annular film condensation for different channel shapes. Int J Heat Mass Transf 53:2615–2627CrossRefzbMATHGoogle Scholar
  21. 21.
    Ganapathy H, Shooshtari A, Choo K, Dessiatoun S, Alshehhi M, Ohadi M (2013) Volume of fluid-based numerical modeling of condensation heat transfer and fluid flow characteristics in microchannels. Int J Heat Mass Transf 65:62–72CrossRefGoogle Scholar
  22. 22.
    Shah MM (2009) An improved and extended general correlation for heat transfer during condensation in plain tubes. HVAC&R Res 15(5):889–913CrossRefGoogle Scholar
  23. 23.
    El Mghari H, Asbik M, Louahlia-Gualous H, Voicu I (2014) Condensation heat transfer enhancement in a horizontal non-circular microchannel. Appl Therm Eng 64:358–370CrossRefGoogle Scholar
  24. 24.
    Antonsen N, Thome JR (2014) Numerical simulation of condensing and evaporating annular flows in microchannels with laminar and turbulent liquid films. In: Proceedings of the 15th int. heat trans. conf., IHTC-15, p 9798Google Scholar
  25. 25.
    Cioncolini A, Thome JR (2011) Algebraic turbulence modeling in adiabatic and evaporating annular two-phase flow. Int J Heat Fluid Flow 32:805–817CrossRefGoogle Scholar
  26. 26.
    Fronk MB, Garimella S (2012) Heat transfer and pressure drop during condensation of ammonia in microchannels. In: Proceedings of the 3rd micro/nanoscale heat and mass transfer int. conf., MNHMT, pp 399–409Google Scholar
  27. 27.
    Del Col D, Bortolato M, Bortolin S (2014) Comprehensive experimental investigation of two-phase heat transfer and pressure drop with propane in a minichannel. Int J Refrig 47:66–84CrossRefGoogle Scholar
  28. 28.
    Lemmon EW, Huber ML, McLinden MO (2010) NIST standard reference database 23: reference fluid thermodynamic and transport properties-REFPROP, version 9.0. National Institute of Standards and Technology, Standard Reference Data Program, GaithersburgGoogle Scholar
  29. 29.
    Moser KW, Webb RL, Na B (1998) A new equivalent Reynolds number model for condensation in smooth tubes. J Heat Transf 120:410–417CrossRefGoogle Scholar
  30. 30.
    Wilcox DC (1998) Turbulence Modeling for CFD, second edn. DCW Industries, Inc., La CañadaGoogle Scholar
  31. 31.
    Menter FR (1994) Two-equation eddy-viscosity turbulence models for engineering applications. AIAA J 32:1598–1605CrossRefGoogle Scholar
  32. 32.
    Da Riva E, Del Col D, Garimella SV, Cavallini A (2012) The importance of turbulence during condensation in a horizontal circular minichannel. Int J Heat Mass Transf 55:470–3481CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2017

Authors and Affiliations

  • Paolo Toninelli
    • 1
  • Stefano Bortolin
    • 1
  • Marco Azzolin
    • 1
  • Davide Del Col
    • 1
    Email author
  1. 1.Dipartimento di Ingegneria IndustrialeUniversità degli Studi di PadovaPadovaItaly

Personalised recommendations