Simple Model of Boiling Heat Transfer on Tubes in Large Pools

1997 ◽  
Vol 119 (2) ◽  
pp. 376-379 ◽  
Author(s):  
Y. Parlatan ◽  
U. S. Rohatgi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Heat Exchanger ◽  
Atmospheric Pressure ◽  
Boiling Heat Transfer ◽  
Saturation Temperature ◽  
Flow Dynamics ◽  
Simple Method ◽  
Vertical Tubes

A simple method has been developed to model boiling heat transfer from a heat exchanger to pools using the experimental data available in the literature without modeling the flow dynamics of the pool. In this approach the heat flux outside vertical tubes is expressed as a function of outside wall temperature of the tubes and saturation temperature of the pool at or near atmospheric pressure.

The Characteristics of Boiling Heat Transfer of R-600a-oil Mixture in a Circular Tube with Porous Inserts

2014 ◽  
Vol 610 ◽  
pp. 106-110
Author(s):  
Mao Yu Wen ◽  
Kang Jang Jang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Circular Tube ◽  
Saturation Temperature ◽  
Circular Pipe ◽  
Oil Mixtures ◽  
Oil Concentration

This investigation was carried out to study the characteristics of boiling heat transfer for hydrocarbon refrigerant R600a (isobutane)/oil mixtures flowing in a circular pipe within dispersed-copper porous inserts. The oil was the EMKARATE RL 32H with a viscosity 150 SUS. The test was conducted at a saturation temperature of 10 , vapor qualities from 0.076 to 0.87, inlet oil concentration from 0 to 3 mass% oil, mass flux of 120 1100 and heat flux of 12-65 . The effects of the concentration of the refrigerant/oil mixtures, and the sizes of inserts on the heat transfer of R-600a for present study were presented.

Nucleate Pool Boiling Heat Transfer of R134a and R134a-PVE Lubricant Mixtures on Smooth and Five Enhanced Tubes

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Wen-Tao Ji ◽  
Ding-Cai Zhang ◽  
Nan Feng ◽  
Jian-Fei Guo ◽  
Mitsuharu Numata ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Saturation Temperature ◽  
Transfer Coefficients ◽  
Pool Boiling Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Enhanced Tubes ◽  
Mass Fractions

Pool boiling heat transfer coefficients of R134a with different lubricant mass fractions for one smooth tube and five enhanced tubes were tested at a saturation temperature of 6°C. The lubricant used was polyvinyl ether. The lubrication mass fractions were 0.25%, 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 7.0%, and 10.0%, respectively. Within the tested heat flux range, from 9000 W/m2 to 90,000 W/m2, the lubricant generally has a different influence on pool boiling heat transfer of these six tubes.

Numerical and Experimental Investigation of Boiling Heat Transfer for Subcooled Water Flowing in a Small-Diameter Tube

2019 ◽  
Author(s):  
Makoto Shibahara ◽  
Qiusheng Liu ◽  
Koichi Hata ◽  
Katsuya Fukuda
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Flux ◽  
Exponential Function ◽  
Boiling Heat Transfer ◽  
Small Diameter ◽  
Uniform Heat Flux ◽  
Inlet Temperature ◽  
Simple Method ◽  
Subcooled Water

Abstract Numerical simulation of boiling heat transfer for subcooled water flowing in a small-diameter tube was conducted using the commercial computational fluid dynamics (CFD) code, PHOENICS ver. 2013. A small-diameter tube (d = 1.0–2.0 mm) was modeled in the simulation. A uniform heat flux with an exponential function was given at the inner tube wall as the boundary conditions. The inner wall boundary condition was set to a non-slip. The inlet temperature ranged from 302 to 312 K. The flow velocities of d = 1.0 mm and d = 2.0 mm are 9.29 m/s and 2.34 m/s, respectively. The transient analysis was carried out from the non-boiling region since the heat flux increased with time in the author’s experiments. The governing equations including the energy equation were discretized using the finite volume method in the PHOENICS code. The SIMPLE method was applied for the numerical simulation. For modeling boiling phenomena in the tube, the Eulerian-Eulerian two-fluid model was adopted using the interphase slip algorithm of PHOENICS code. In the experiment, a platinum tube was used as the experimental tube (d = 1.0–2.0 mm) to conduct joule heating by direct current. The distilled and deionized water was pressured by the pressurizer. The heat generation rate of the tube was controlled with the exponential function to obtain the transient heat transfer characteristics from the non-boiling region. The surface superheat increased as the heat flux increased in the experiment. The numerical simulation predicted the experimental data well. When the heat flux of the experiment was reached to the CHF point, the predicted value of heat transfer coefficient was approximately 3.5 % lower than that of the experiment.

Experimental Investigation to Boiling Heat Transfer on a Heated Surface with Multiple Impinging Jets

2013 ◽  
Vol 663 ◽  
pp. 477-482
Author(s):  
Bin Ni ◽  
Jie Wen ◽  
Jun Liao ◽  
Hong Wu Deng
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Flux ◽  
Atmospheric Pressure ◽  
Boiling Heat Transfer ◽  
Heated Surface ◽  
Impinging Jets ◽  
Boiling Regime ◽  
Multiple Jets ◽  
Jet Velocity

On the condition of water multiple jet impingements, a steady-state experimental study had been conducted for boiling heat transfer in an atmospheric pressure. The jet velocity was 0.95~1.59m/s and the sub-cooling degrees of jet fluid were 30~83°C.The results revealed that increasing either jet velocity or sub-cooling degrees would promote the heat flux through heated surface, and the effect was more pronounced in partial boiling regime than fully-developed boiling regime. The heat transfer with multiple jets is enhanced due to disturbance of different impingements. With modification of the factor which related to flow distance of fluid on heated surface, correlation which is applicable to one single impinging jet boiling, can also be used to calculate critical heat flux(CHF) in boiling heat transfer with multiple impinging jets.

Effects of Heat Exchanger Tube Parameters on Nucleate Pool Boiling Heat Transfer

1998 ◽  
Vol 120 (2) ◽  
pp. 468-476 ◽  
Author(s):  
Moon-Hyun Chun ◽  
Myeong-Gie Kang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Roughness ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Tube Diameter ◽  
Nucleate Pool Boiling ◽  
Pool Boiling Heat Transfer ◽  
Horizontal Tubes ◽  
Vertical Tubes

In an effort to determine the combined effects of major parameters of heat exchanger tubes on the nucleate pool boiling heat transfer in the scaled in-containment refueling water storage tank (IRWST) of advanced light water reactors (ALWRs), a total of 1966 data points for q″ versus ΔT have been obtained using various combinations of tube diameters, surface roughness, and tube orientations. The experimental results show that: (1) increased surface roughness increases the heat transfer coefficient for both horizontal and vertical tubes, and the effect of surface roughness is more pronounced for the vertical tubes compared to the horizontal tubes, (2) the two heat transfer mechanisms, i.e., increased heat transfer due to liquid agitation by bubbles generated and reduced heat transfer by the formation of large vapor slugs and bubble coalescence, are different in two regions of low heat flux (q″ ≤ 50 kW/m2) and high heat flux (q″ > 50 kW/m2) depending on the orientation of tubes and the degree of surface roughness, and (3) the heat transfer rate decreases as the tube diameter is increased for both horizontal and vertical tubes, but the effect of tube diameter on the nucleate pool boiling heat transfer for vertical tubes is greater than that for horizontal tubes. Two empirical heat transfer correlations for q″, one for horizontal tubes and the other for vertical tubes, are obtained in terms of surface roughness (ε) and tube diameter (D). In addition, a simple empirical correlation for nucleate pool boiling heat transfer coefficient (hb) is obtained as a function of heat flux (q″) only.

Effect of saturation temperature and vapor quality on the boiling heat transfer and critical heat flux in a microchannel

2020 ◽  
Vol 117 ◽  
pp. 104768
Author(s):  
Ahmet Selim Dalkılıç ◽  
Ali Celen ◽  
Murat Erdoğan ◽  
Kittipong Sakamatapan ◽  
Kazi Salim Newaz ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Saturation Temperature ◽  
Vapor Quality

Experiment and CFD Simulation of Boiling Heat Transfer Coefficient of R410A in Minichannels

2015 ◽  
Vol 23 (04) ◽  
pp. 1550032 ◽  
Author(s):  
Nguyen Ba Chien ◽  
Kwang-Il Choi ◽  
Jong-Taek Oh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Saturation Temperature ◽  
Boiling Heat Transfer Coefficient

This study performed a comparison between experimental and computational fluid dynamic (CFD) simulation results of boiling heat transfer coefficient of R410A in a small tube. The experimental data were obtained in the horizontal circular tubes of 3.0[Formula: see text]mm inner diameter, the length of 3000[Formula: see text]mm including: mass flux and heat flux in a range from 300[Formula: see text]kg/m2s to 600[Formula: see text]kg/m2s and from 5[Formula: see text]kW/m2 to 10[Formula: see text]kW/m2, respectively, and the saturation temperature constantly kept at 20[Formula: see text]C. In the simulation procedure, the Eulerian multiphase with wall boiling were obtained. The effects of mass flux and heat flux on the heat transfer coefficient of R410A were analyzed. The comparative data between CFD and experiment was also illustrated.

Investigation of Boiling Heat Transfer and Critical Heat Flux Enhancement for SiC and Graphene Layers on ITO Surfaces

2013 ◽  
Author(s):  
Han Seo ◽  
Seok Bin Seo ◽  
Sung Bo Moon ◽  
Soon-Yong Kwon ◽  
Ji Hyun Kim ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Indium Tin Oxide ◽  
Atmospheric Pressure ◽  
Boiling Heat Transfer ◽  
Graphene Layer ◽  
Temperature Fields ◽  
Working Fluid ◽  
Graphene Layers

This paper presents a study on the enhancement in the boiling heat transfer (BHT) and critical heat flux (CHF) with a bare indium tin oxide (ITO) surface, few-graphene layer deposited on an ITO surface, and silicon carbide (SiC) particles deposited on an ITO surface. The experiment was conducted in atmospheric pressure using FC-72 refrigerant at saturation. Infrared (IR) thermometry was used to determine the temperature fields of the heater surfaces and CHF. The values of CHF for the graphene layer on the ITO surface and SiC deposited on the ITO heater were increased by 9% and 42%, compared to the bare ITO heater, respectively. All the heater surfaces showed hydrophilic condition with the working fluid (FC-72 refrigerant). The enhancement in the BHT coefficient and CHF was attributed to surface modifications such as the formation of microporous structures and the material properties.

Forced Convective Boiling Heat Transfer and Pressure Drop Characteristics of Two-Phase Flow Inside a Small Horizontal Helically Coiled Tubing Once-Through Steam Generator

2003 ◽  
Author(s):  
Liang Zhao ◽  
Liejin Guo ◽  
Bofeng Bai ◽  
Yucheng Hou ◽  
Ximin Zhang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Pressure Drop ◽  
Boiling Heat Transfer ◽  
Phase Flow ◽  
Two Phase ◽  
Convective Boiling ◽  
Coiled Tube ◽  
Helically Coiled Tube

The pressure drop and boiling heat transfer of steam water two-phase flow were studied in a small horizontal helically coiled tube once-through steam generator of 9-mm inside diameter with 292-mm coil diameter and 30-mm pitch. Experiments were performed at a range of qualities up to 0.95, a system pressure range of 0.5∼3.5MPa, a mass flux range of 236∼943kg/m2s and a heat flux range of 0∼900kW/m2. Based on the experimental results, a new two-phase frictional pressure drop correlation was developed on the basis of Chisholm’s B-coefficient method. In the present experimental range, boiling heat transfer was found to be dependent not only on mass flux but also on heat flux. This result implies that both the nucleation mechanism and the convection mechanism have the same importance to forced convective boiling heat transfer in small horizontal helically coiled tube over the full range of qualities (pre-critical heat flux qualities of 0.1∼0.9) which is contrary to situations in larger helically coiled tube where the convection mechanism dominates at qualities typically > 0.1. Traditional single parameter Lockhart-Martinelli type correlations failed to satisfactorily predict present experimental data and in this paper a new flow boiling heat transfer correlation was put forward to better predict the experimental data of the present study.

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