Critical Heat Flux Modeling in Forced Convection Boiling During Power Transients

1990 ◽  
Vol 112 (4) ◽  
pp. 1058-1062 ◽  
Author(s):  
K. O. Pasamehmetoglu ◽  
R. A. Nelson ◽  
F. S. Gunnerson
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Theoretical Prediction ◽  
Forced Convection ◽  
Critical Heat Flux ◽  
Nucleate Boiling ◽  
Convective Boiling ◽  
New Model ◽  
Semi Empirical

In this paper, a theoretical prediction of critical heat flux (CHF) during power transients in forced convective boiling is presented. The analysis is restricted to departure from nucleate boiling (DNB) type of CHF at low qualities. The developed theory is compared with the experimental data available in the literature. The agreement is exceptionally good. The new model also is compared with the semi-empirical transient CHF model in the literature.

Empirical Correlation of Factors Influencing Departure From Nucleate Boiling in Steam-Water Mixtures Flowing in Vertical Round Tubes

1966 ◽  
Vol 88 (4) ◽  
pp. 367-373 ◽  
Author(s):  
D. Pasint ◽  
R. H. Pai
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Forced Convection ◽  
Mass Flow ◽  
Nucleate Boiling ◽  
Vertical Tube ◽  
Empirical Correlation ◽  
Factors Influencing ◽  
Vertical Tubes ◽  
Heated Length

An empirical correlation of forced convection DNB for steam-water mixtures between 500 and 3000 psia in uniformly heated vertical tubes is proposed. DNB quality is expressed in terms of pressure, mass flow, inlet enthalpy, heated length from inlet to DNB point, and tube dia. The experimental data of the authors at 2000–3000 psia, 250,000–1,000,000 lb/hr sq ft2 mass flow, and 40,000–180,000 Btu/hr sq ft heat flux, obtained from a 6 ft long, 3/4-in-ID electrically heated vertical tube, are correlated with other published results ranging from 500 to 2000 psia.

Critical Heat Flux of Steady Boiling for Subcooled Water Jet Impingement on the Flat Stagnation Zone

2004 ◽  
Vol 126 (2) ◽  
pp. 179-183 ◽  
Author(s):  
Zhen-Hua Liu ◽  
Tie-Feng Tong ◽  
Yu-Hao Qiu
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Jet Impingement ◽  
Nucleate Boiling ◽  
Water Jet ◽  
Stagnation Zone ◽  
Subcooled Water ◽  
Nozzle Size ◽  
Jet Nozzle

An experimental investigation was carried out for predicting the critical heat flux (CHF) of steady boiling for a round subcooled water jet impingement on the flat stagnation zone. The experimental data were measured in a steady nucleate boiling state. Three main influencing parameters, i.e., subcooling, impact velocity and jet nozzle size were widely changed and their effects on the critical heat flux were systemically studied. An empirical correlation was obtained using the experimental data over a wide experimental range for predicting the critical heat flux of steady boiling for a round subcooled water jet impingement on the flat stagnation zone.

Prediction of Critical Heat Flux for Convective Boiling of Saturated Water Jet Impinging on the Stagnation Zone

2002 ◽  
Vol 124 (6) ◽  
pp. 1125-1130 ◽  
Author(s):  
Zhen-Hua Liu ◽  
Qun-Zhi Zhu
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Experimental Investigation ◽  
Critical Heat Flux ◽  
Correlation Factor ◽  
Water Jet ◽  
Stagnation Zone ◽  
Helmholtz Instability ◽  
Convective Boiling ◽  
Saturated Water

A theoretical analysis and an experimental investigation were carried out for predicting the critical heat flux (CHF) of convective boiling for a round saturated water jet impinging on the jet stagnation zone. The model of the maximum liquid subfilm thickness based on the Helmholtz instability is used to derive a semi-theoretical equation and the correlation factor was determined from the experimental data. Finally, a semi-theoretical correlation was proposed for predicting CHF of convective boiling for saturated water jet impinging on the jet stagnation zone.

THE CALCULATION OF CRITICAL HEAT FLUX IN FORCED CONVECTION BOILING

1974 ◽  
Author(s):  
P. B. Whalley ◽  
P. Hutchinson ◽  
Geoffrey F. Hewitt
Keyword(s):  
Heat Flux ◽  
Forced Convection ◽  
Critical Heat Flux

Boiling Heat Transfer and Critical Heat Flux Enhancement of Upward- and Downward-Facing Heater in Nanofluids

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Muhamad Zuhairi Sulaiman ◽  
Masahiro Takamura ◽  
Kazuki Nakahashi ◽  
Tomio Okawa
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Flux Enhancement ◽  
Optimum Configuration ◽  
Wall Superheat ◽  
Nucleate Boiling Heat Transfer

Boiling heat transfer (BHT) and critical heat flux (CHF) performance were experimentally studied for saturated pool boiling of water-based nanofluids. In present experimental works, copper heaters of 20 mm diameter with titanium-oxide (TiO2) nanocoated surface were produced in pool boiling of nanofluid. Experiments were performed in both upward and downward facing nanofluid coated heater surface. TiO2 nanoparticle was used with concentration ranging from 0.004 until 0.4 kg/m3 and boiling time of tb = 1, 3, 10, 20, 40, and 60 mins. Distilled water was used to observed BHT and CHF performance of different nanofluids boiling time and concentration configurations. Nucleate boiling heat transfer observed to deteriorate in upward facing heater, however; in contrast effect of enhancement for downward. Maximum enhancements of CHF for upward- and downward-facing heater are 2.1 and 1.9 times, respectively. Reduction of mean contact angle demonstrate enhancement on the critical heat flux for both upward-facing and downward-facing heater configuration. However, nucleate boiling heat transfer shows inconsistency in similar concentration with sequence of boiling time. For both downward- and upward-facing nanocoated heater's BHT and CHF, the optimum configuration denotes by C = 400 kg/m3 with tb = 1 min which shows the best increment of boiling curve trend with lowest wall superheat ΔT = 25 K and critical heat flux enhancement of 2.02 times.

Study on Subcooled-Forced Flow Boiling Heat Transfer and Critical Heat Flux of Solid-Water Two-Phase Mixture

1999 ◽  
Author(s):  
Yasuo Koizumi ◽  
Hiroyasu Ohtake ◽  
Manabu Mochizuki
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Liquid Layer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Forced Flow ◽  
Superheated Liquid ◽  
Flow Boiling Heat Transfer

Abstract The effect of solid particle introduction on subcooled-forced flow boiling heat transfer and a critical heat flux was examined experimentally. In the experiment, glass beads of 0.6 mm diameter were mixed in subcooled water. Experiments were conducted in a range of the subcooling of 40 K, a velocity of 0.17–6.7 m/s, a volumetric particle ratio of 0–17%. When particles were introduced, the growth of a superheated liquid layer near a heat trasnsfer surface seemed to be suppressed and the onset of nucleate boiling was delayed. The particles promoted the condensation of bubbles on the heat transfer surface, which shifted the initiation of a net vapor generation to a high heat flux region. Boiling heat trasnfer was augmented by the particle introduction. The suppression of the growth of the superheated liquid layer and the promotion of bubble condensation and dissipation by the particles seemed to contribute that heat transfer augmentation. The wall superheat at the critical heat flux was elevated by the particle introduction and the critical heat flux itself was also enhanced. However, the degree of the critical heat flux improvement was not drastic.

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