Critical Heat Flux and Minimum Heat Flux of Film Boiling of Binary Mixtures Flowing Upwards in a Vertical Tube

2019 ◽  
pp. 213-218
Author(s):  
Hein Auracher ◽  
Andreas Marroquin
Keyword(s):  
Heat Flux ◽  
Binary Mixtures ◽  
Critical Heat Flux ◽  
Vertical Tube ◽  
Film Boiling ◽  
Minimum Heat

On the Role of Marangoni Effects on the Critical Heat Flux for Pool Boiling of Binary Mixtures

1996 ◽  
Vol 118 (1) ◽  
pp. 103-109 ◽  
Author(s):  
W. R. McGillis ◽  
V. P. Carey
Keyword(s):  
Surface Tension ◽  
Heat Flux ◽  
Binary Mixtures ◽  
Critical Heat Flux ◽  
Full Range ◽  
Pool Boiling ◽  
Marangoni Effect ◽  
Restoring Force ◽  
Marangoni Effects

The Marangoni effect on the critical heat flux (CHF) condition in pool boiling of binary mixtures has been identified and its effect has been quantitatively estimated with a modified model derived from hydrodynamics. The physical process of CHF in binary mixtures, and models used to describe it, are examined in the light of recent experimental evidence, accurate mixture properties, and phase equilibrium revealing a correlation to surface tension gradients and volatility. A correlation is developed from a heuristic model including the additional liquid restoring force caused by surface tension gradients. The CHF condition was determined experimentally for saturated methanol/water, 2-propanol/water, and ethylene glycol/water mixtures, over the full range of concentrations, and compared to the model. The evidence in this study demonstrates that in a mixture with large differences in surface tension, there is an additional hydrodynamic restoring force affecting the CHF condition.

scholarly journals Characteristics of Flow Boiling Heat Transfer and Critical Heat Flux in a Vertical Tube with a Wire Coil.

2001 ◽  
Vol 67 (653) ◽  
pp. 128-134
Author(s):  
Keishi TAKESHIMA ◽  
Terushige FUJII ◽  
Nobuyuki tAKENAKA ◽  
Hitoshi ASANO ◽  
Takamitsu KONDO
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Vertical Tube ◽  
Flow Boiling Heat Transfer ◽  
Wire Coil

Subcooled Boiling Heat Transfer for Turbulent Flow of Water in a Short Vertical Tube

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Koichi Hata ◽  
Suguru Masuzaki
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Turbulent Flow ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Vertical Tube ◽  
Test Tube ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Infrared Thermal Imaging

The subcooled boiling heat transfer and the critical heat flux (CHF) due to exponentially increasing heat inputs with various periods (Q=Q0 exp(t/τ), τ=22.52 ms–26.31 s) were systematically measured by an experimental water loop flow and observed by an infrared thermal imaging camera. Measurements were made on a 3 mm inner diameter, a 66.5 mm heated length, and a 0.5 mm thickness of platinum test tube, which was divided into three sections (upper, mid, and lower positions). The axial variations of the inner surface temperature, the heat flux, and the heat transfer coefficient from nonboiling to critical heat flux were clarified. The results were compared with other correlations for the subcooled boiling heat transfer and authors’ transient CHF correlations. The influence of exponential period (τ) and flow velocity on the subcooled boiling heat transfer and the CHF was investigated and the predictable correlation of the subcooled boiling heat transfer for turbulent flow of water in a short vertical tube was derived based on the experimental data. In this work, the correlation gave 15% difference for subcooled boiling heat transfer coefficients. Most of the CHF data (101 points) were within 15% and −30 to +20% differences of the authors’ transient CHF correlations against inlet and outlet subcoolings, respectively.

Influence of Test Tube Material on Subcooled Flow Boiling Critical Heat Flux in Short Vertical Tube

2006 ◽  
Author(s):  
Koichi Hata ◽  
Masahiro Shiotsu ◽  
Nobuaki Noda
Keyword(s):  
Heat Flux ◽  
Steady State ◽  
Critical Heat Flux ◽  
Flow Boiling ◽  
Vertical Tube ◽  
Test Tube ◽  
304 Stainless Steel ◽  
Tube Material ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

The steady state subcooled flow boiling critical heat flux (CHF) for the flow velocities (u = 4.0 to 13.3 m/s), the inlet subcoolings (ΔTsub,in = 48.6 to 154.7 K), the inlet pressure (Pin = 735.2 to 969.0 kPa) and the increasing heat input (Q0exp(t/τ), τ = 10, 20 and 33.3 s) are systematically measured with the experimental water loop. The 304 Stainless Steel (SUS304) test tubes of inner diameters (d = 6 mm), heated lengths (L = 66 mm) and L/d = 11 with the inner surface of rough finished (Surface roughness, Ra = 3.18 μm), the Cupro Nickel (Cu-Ni 30%) test tubes of d = 6 mm, L = 60 mm and L/d = 10 with Ra = 0.18 μm and the Platinum (Pt) test tubes of d = 3 and 6 mm, L = 66.5 and 69.6 mm, and L/d = 22.2 and 11.6 respectively with Ra = 0.45 μm are used in this work. The CHF data for the SUS304, Cu-Ni 30% and Pt test tubes were compared with SUS304 ones for the wide ranges of d and L/d previously obtained and the values calculated by the authors’ published steady state CHF correlations against outlet and inlet subcoolings. The influence of the test tube material on CHF is investigated into details and the dominant mechanism of subcooled flow boiling critical heat flux is discussed.

Hybrid Electrophoretic Deposition with Anodization Process for Superhydrophilic Surfaces to Enhance Critical Heat Flux

2012 ◽  
Vol 507 ◽  
pp. 9-13 ◽  
Author(s):  
Young Soo Joung ◽  
Cullen R. Buie
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Electrophoretic Deposition ◽  
Film Boiling ◽  
The Novel ◽  
Nucleation Sites ◽  
Anodization Process ◽  
Titanium Surfaces ◽  
Titanium Substrates ◽  
Superhydrophilic Surfaces

Superhydrophilic surfaces with hydrophobic layers were successfully produced in order to enhance critical heat flux (CHF) and reduce boiling inception temperatures (BIT). The novel surfaces were fabricated by a hybrid electrophoretic deposition (EPD) method coupled with a break down anodization (BDA) process. With the BDA process, microporous superhydrophilic surfaces were created on titanium substrates. Subsequently, nanoporous hydrophobic layers were deposited with EPD on the superhydrophilic surfaces. The hydrophobic layers provide numerous nucleation sites, lowering BIT while the superhydrophilic layers prevent film boiling, resulting in increased CHF. The resulting surfaces exhibit higher CHF with lower BIT than untreated titanium surfaces .

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