Vertical tube length calculation based on available heat transfer coefficient expressions for the subcooled flow boiling region

2008 ◽  
Vol 28 (5-6) ◽  
pp. 499-513 ◽  
Author(s):  
Jose Zambrana ◽  
Teresa J. Leo ◽  
Pedro Perez-del-Notario
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Boiling ◽  
Vertical Tube ◽  
Tube Length ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

Experimental investigation and comparison of subcooled flow boiling of TiO2 nanofluid in a vertical and horizontal tube

2012 ◽  
Vol 227 (8) ◽  
pp. 1742-1753 ◽  
Author(s):  
E Abedini ◽  
A Behzadmehr ◽  
H Rajabnia ◽  
SMH Sarvari ◽  
SH Mansouri
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Turbulent Flows ◽  
Base Fluid ◽  
Volume Fraction ◽  
Flow Boiling ◽  
Horizontal Tube ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

In this study, variations of local heat transfer coefficient are obtained in subcooled flow boiling conditions for water/TiO2 nanofluid in a vertical and horizontal tube. The results for the base fluid are compared with the predictions of the well known Shah correlation and Gnielinski formula for laminar and turbulent flows for single-phase forced convection and also with Chen correlation for subcooled flow boiling. A good agreement between the results is realized. At the subcooled regime, heat transfer coefficient of nanofluid is less than that of the base fluid and it decreases by increasing nanoparticle concentration for both of the channels; however, addition of the nanopraticles into the fluid causes that the vapor volume fraction increases.

scholarly journals Experimental investigation of subcooled flow boiling of water/TiO2 nanofluid in a horizontal tube

2016 ◽  
Vol 20 (1) ◽  
pp. 99-108 ◽  
Author(s):  
Hossein Rajabnia ◽  
Ehsan Abedini ◽  
Ali Tahmasebi ◽  
Amin Behzadmehr
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Single Phase ◽  
Flow Boiling ◽  
Horizontal Tube ◽  
Subcooled Flow Boiling ◽  
Boiling Regime ◽  
Subcooled Flow ◽  
Experimental Apparatus

Subcooled flow boiling heat transfer of water/TiO2 nanofluid in a horizontal tube is experimentally investigated. To validate the experimental apparatus as well as the experimental procedure, data for distilled water were compared with the available results on the literature in both single phase and subcooled flow boiling regime. Experimental investigations were carried out at three nanoparticles volumetric concentrations of 0.01%, 0.1%, and 5%. It was found that the nanofluid heat transfer coefficient in single-phase flow regime augments with the nanoparticle concentration. However, in the case of subcooled flow boiling regime the heat transfer coefficient decreases with the nanoparticle volume fractions.

scholarly journals Experimental Study on Heat Transfer and Flow Characteristics in Subcooled Flow Boiling in a Microchannel

2020 ◽  
Vol 26 (9) ◽  
pp. 173-190
Author(s):  
Suha A. Mohammed ◽  
Ekhlas M. Fayyadh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Flow Boiling ◽  
Phase Region ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Boiling Heat Transfer Coefficient ◽  
Experimental Pressure

The current study presents an experimental investigation of heat transfer and flow characteristic for subcooled flow boiling of deionized water in the microchannel heat sink. The test section consisted of a single microchannel having 300μm wide nominal dimensions and 300μm height (hydraulic diameter of 300μm). The test section formed of oxygen-free copper with 72mm length and 12mm width. Experimental operation conditions spanned the heat flux (78-800) kW/m2, mass flux (1700 and 2100) kg/m2.s at 31˚C subcooled inlet temperature. The boiling heat transfer coefficient is measured and compared with existing correlations. Also, the experimental pressure drop is measured and compared with microscale pressure drop correlations. The results showed that higher mass flux leads to higher boiling heat transfer coefficient, and the dominant mechanism is convective boiling. Also, the experimental pressure drop decrease with increasing heat flux in a single-phase region while it increases in a two-phase region. Comparing the experimental results in the experimental condition range, showed that an existing correlation provides a satisfactory prediction of heat transfer coefficient and pressure drop.

Experimental Investigation of Heat Transfer Coefficient and Correlation Development for Subcooled Flow Boiling of Water–Ethanol Mixture in Conventional Channel

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
B. G. Suhas ◽  
A. Sathyabhama
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Boiling ◽  
Inlet Temperature ◽  
Subcooled Flow Boiling ◽  
Ethanol Mixture ◽  
Subcooled Flow

In this present work, bubble dynamics of subcooled flow boiling in water–ethanol mixture is investigated through visualization using a high-speed camera in horizontal rectangular channels. The heat transfer coefficient of water–ethanol mixture during subcooled flow boiling is determined for various parameters like heat flux, mass flux, and channel inlet temperature. The effect of bubble departure diameter on heat transfer coefficient is discussed. A correlation is developed for subcooled flow boiling Nusselt number of water–ethanol mixture. The parameters considered for correlation are grouped as dimensionless numbers by Buckingham π-theorem. The present correlation is compared with the experimental data. The mean absolute error (MAE) of Nusselt number of water–ethanol mixture calculated from the experimental data and those predicted from the present correlation is 10.39%. The present correlation is also compared with the available literature correlations developed for water. The MAE of Nusselt number of water predicted from the present correlation and those predicted with Papel, Badiuzzaman, Moles–Shaw, and Baburajan correlations is 41%, 19.61%, 29.9%, and 43.1%, respectively.

Enhanced Subcooled Flow Boiling Heat Transfer in Microchannel With Piranha Pin Fin

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
X. Yu ◽  
C. Woodcock ◽  
Y. Wang ◽  
J. Plawsky ◽  
Y. Peles
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Flow Boiling Heat Transfer

An experimental study on subcooled flow boiling with engineering fluid HFE-7000 in a microchannel fitted with piranha pin fins (PPFs) is presented. Heat fluxes of up to 735 W/cm2 were achieved and mass fluxes ranged from 618 kg/m2s to 2569 kg/m2 s. It was found that the flow boiling heat transfer was significantly enhanced with PPFs. The heat transfer coefficient with flow boiling was double the corresponding single-phase flow. Correlations for two-phase heat transfer coefficient and pressure drop in the nucleate flow boiling regime were developed based on the boiling, Weber, and Jakob numbers. The onset of nucleate boiling (ONB) and the critical heat flux (CHF) conditions were determined through visualization and was typically initiated from the last row of fins where temperatures were highest and flow rates lowest.

scholarly journals Investigation of Forced Convective and Subcooled Flow Boiling Heat Transfer Coefficients of Water-Ethanol Mixture: Numerical Study

2021 ◽  
Vol 39 (2) ◽  
pp. 512-520
Author(s):  
Suhas Badakere Gopalakrishna ◽  
Ravi Lakkanna ◽  
Satyabhama Alangar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Subcooled Flow Boiling ◽  
Ethanol Mixture ◽  
Subcooled Flow ◽  
Flow Boiling Heat Transfer ◽  
Boiling Heat Transfer Coefficient

The subcooled flow boiling is related to the operation of electronic devices, Hybrid electric vehicle (HEV) Battery module and small catalytic reactors. It is well known that the operational temperature must be maintained to avoid any malfunction of these heat dissipative devices. In this paper the forced convective and subcooled flow boiling heat transfer coefficients of water-ethanol mixture is determined numerically by Volume of fluid analysis (VOF). The interaction between liquid and local vapour is analysed by solving the bubble volume of fraction in the numerical study. Crank Nicolson implicit scheme is used for discretizing the scalar convection equation for bubble void fraction and transforming into algebraic equation. Thomas Algorithm is used to solve the algebraic equations of bubble void fraction. The corrector predictor equation method is used to solve for bubble void fraction when the value obtained is less than 0 or exceeds 1. The thermodynamic and Thermophysical properties are substituted in the x-momentum and energy equation to determine the values of pressure drop, velocity and temperature of the fluid. From the temperature values, the subcooled flow boiling heat transfer coefficient is obtained. It is found that the addition of ethanol to water decreases the forced convective and subcooled flow boiling heat transfer coefficient of the water-ethanol mixture. The numerically determined heat transfer coefficient of water ethanol mixture is compared with that of the experimental results. The average deviation between the experimentally determined and numerically determined subcooled flow boiling heat transfer coefficient of water ethanol-mixture is found to be 24.13%.

Experimental study of the subcooled flow boiling heat transfer of magnetic nanofluid in a vertical tube under magnetic field

2019 ◽  
Vol 140 (6) ◽  
pp. 2805-2816 ◽  
Author(s):  
Sajjad Ahangar Zonouzi ◽  
Rahmatollah Khodabandeh ◽  
Habibollah Safarzadeh ◽  
Habib Aminfar ◽  
Mousa Mohammadpourfard ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Experimental Study ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Vertical Tube ◽  
Subcooled Flow Boiling ◽  
Magnetic Nanofluid ◽  
Subcooled Flow ◽  
Flow Boiling Heat Transfer

Subcooled Flow Boiling Critical Heat Flux in Short Vertical Tube: Influence of Inner Surface Roughness

2004 ◽  
Author(s):  
Koichi Hata ◽  
Masahiro Shiotsu ◽  
Nobuaki Noda
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Flow Boiling ◽  
Vertical Tube ◽  
Heat Transfer Characteristics ◽  
Subcooled Flow Boiling ◽  
Transfer Characteristics ◽  
Subcooled Flow ◽  
Wide Range ◽  
Inner Surface

The subcooled flow boiling CHF and the heat transfer characteristics for the flow velocities (u=4.0 to 13.3 m/s), the inlet subcoolings (ΔTsub,in=137.49 to 153.87 K), the inlet pressure (Pin=740.67 to 975.78 kPa) and the dissolved oxygen concentration (O=8.63 to 0.0288 ppm) are systematically measured by the experimental water loop installed the pressurizer. The SUS304 tubes of d=3 mm and L=66.5 mm (L/d=22.17) with the inner surfaces of smooth and mirror finished are mainly used in this work. Heat transfer characteristics and CHF data are compared with those for the rough finished inner surface (RF) previously obtained and the CHFs are compared with the values calculated by the CHF correlations against outlet and inlet subcoolings based on the experimental data for the rough finished inner surface under the N2 gas pressure. The influence of inner surface roughness on the heat transfer characteristics and the CHFs for wide range of dissolved gas concentration are investigated in detail.

scholarly journals Subcooled flow boiling heat transfer of ethanol aqueous solutions in vertical annulus space

2012 ◽  
Vol 18 (2) ◽  
pp. 315-327 ◽  
Author(s):  
M.M. Sarafraz ◽  
S.M. Peyghambarzadeh ◽  
N. Vaeli
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Water Solution ◽  
Nucleate Boiling ◽  
Subcooled Flow Boiling ◽  
Nucleate Boiling Heat Transfer ◽  
Vertical Annulus

The subcooled flow boiling heat-transfer characteristics of water and ethanol solutions in a vertical annulus have been investigated up to heat flux 132kW/m2. The variations in the effects of heat flux and fluid velocity, and concentration of ethanol on the observed heat-transfer coefficients over a range of ethanol concentrations implied an enhanced contribution of nucleate boiling heat transfer in flow boiling, where both forced convection and nucleate boiling heat transfer occurred. Increasing the ethanol concentration led to a significant deterioration in the observed heat-transfer coefficient because of a mixture effect, that resulted in a local rise in the saturation temperature of ethanol/water solution at the vapor-liquid interface. The reduction in the heat-transfer coefficient with increasing ethanol concentration is also attributed to changes in the fluid properties (for example, viscosity and heat capacity) of tested solutions with different ethanol content. The experimental data were compared with some well-established existing correlations. Results of comparisons indicate existing correlations are unable to obtain the acceptable values. Therefore a modified correlation based on Gnielinski correlation has been proposed that predicts the heat transfer coefficient for ethanol/water solution with uncertainty about 8% that is the least in comparison to other well-known existing correlations.

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