Critical heat flux on a flat plate heater located at the middle of a duct in forced flow of pressurized He II

Cryogenics ◽  
2004 ◽  
Vol 44 (9) ◽  
pp. 603-609
Author(s):  
T Okamura ◽  
M Saeki ◽  
K Hata ◽  
K Hama ◽  
Y Shirai ◽  
...  
Keyword(s):  
Heat Flux ◽  
Flat Plate ◽  
Critical Heat Flux ◽  
Forced Flow ◽  
Plate Heater

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.

Critical Heat Fluxes and Flow Patterns in High-Pressure Boiling Water Flows

1964 ◽  
Vol 86 (1) ◽  
pp. 12-22 ◽  
Author(s):  
F. E. Tippets
Keyword(s):  
Heat Flux ◽  
High Pressure ◽  
Critical Heat Flux ◽  
Rectangular Channel ◽  
Motion Pictures ◽  
Flow Patterns ◽  
Heat Fluxes ◽  
Boiling Water ◽  
Forced Flow ◽  
Flux Level

High-speed motion pictures (4300 pictures/sec) of boiling water flow patterns in conditions of forced flow at 1000 psia pressure in a vertical heated rectangular channel were taken over the range of mass velocities from 50 to 400 lb/sec-ft2, fluid states from bulk subcooled liquid flow to bulk boiling flow at 0.66 steam quality, and heat fluxes up to and including the critical heat flux level. Eighty critical heat flux determinations were made in the course of the experiment at 1000 psia in conditions of bulk boiling. The motion pictures provide photographic evidence of the general arrangement of the flow in conditions of bulk boiling at high pressure with heat fluxes near and including the critical heat flux level.

Ultra High Critical Heat Flux During Forced Flow Boiling Heat Transfer With an Impinging Jet

2003 ◽  
Vol 125 (6) ◽  
pp. 1038-1045 ◽  
Author(s):  
Yuichi Mitsutake ◽  
Masanori Monde
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Flow Boiling ◽  
Heated Surface ◽  
Forced Flow ◽  
Maximum Heat ◽  
Subcooled Liquid ◽  
System Pressure ◽  
Maximum Heat Flux ◽  
Flow Boiling Heat Transfer

An ultra high critical heat flux (CHF) was attempted using a highly subcooled liquid jet impinging on a small rectangular heated surface of length 5∼10mm and width 4 mm. Experiments were carried out at jet velocities of 5∼60m/s, a jet temperature of 20°C and system pressures of 0.1∼1.3MPa. The degree of subcooling was varied from 80 to 170 K with increasing system pressure. The general correlation for CHF is shown to be applicable for such a small heated surface under a certain range of conditions. The maximum CHF achieved in these experiments was 211.9 MW/m2, recorded at system pressure of 0.7 MPa, jet velocity of 35 m/s and jet subcooling of 151 K, and corresponds to 48% of the theoretical maximum heat flux proposed by Gambill and Lienhard.

Experimental Evaluation of Critical Heat Flux in Downward-Facing Boiling on SS304 L Flat Plate Relevant to In-Calandria Retention in PHWRs

2020 ◽  
Vol 6 (3) ◽  
Author(s):  
Sumit V. Prasad ◽  
A. K. Nayak
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Natural Convection ◽  
Flat Plate ◽  
Critical Heat Flux ◽  
Outer Surface ◽  
Flat Surface ◽  
Large Diameter ◽  
Convection Heat Transfer ◽  
Heat Removal

Abstract Retention of corium inside the calandria vessel (CV) by externally cooling it by calandria vault water is essential to mitigate severe accidents in pressurized heavy water reactor (PHWR). The thermal failure of CV can be prevented by effective decay heat removal on the outer surface of CV using vault water, which depends on the heat transfer behavior from the outer surface of CV to the vault water. Determination of limiting heat removal capability of vault subcooled water through outer surface of CV is very important. Since the CV has a very large diameter and length, the bottom most part of the CV almost behaves as a flat plate with downward natural convection boiling heat transfer. The natural convection heat transfer is lesser on the flat surface as compared to the curved surface of the CV. Thus, the critical heat flux (CHF) on the flat surface under downward boiling condition is the limiting CHF of the CV under external surface boiling scenario. In order to estimate CHF in this configuration with local boiling, experiments were carried out on a downward facing SS304 L flat plate simulating the conditions of CV of 700 MWel Indian PHWR. The pool boiling CHF obtained in this study is also compared with other earlier works.

Critical heat flux on a flat plate in pressurized He II

Cryogenics ◽  
2001 ◽  
Vol 41 (1) ◽  
pp. 35-38 ◽  
Author(s):  
H. Tatsumoto ◽  
K. Hata ◽  
K. Hama ◽  
Y. Shirai ◽  
M. Shiotsu
Keyword(s):  
Heat Flux ◽  
Flat Plate ◽  
Critical Heat Flux

Critical Heat Flux Measurements in a 16-Rod Simulation of a BWR Fuel Assembly

1969 ◽  
Vol 91 (3) ◽  
pp. 355-361 ◽  
Author(s):  
S. Israel ◽  
J. Casterline ◽  
B. Matzner
Keyword(s):  
Heat Flux ◽  
Fuel Assembly ◽  
Critical Heat Flux ◽  
Power Distribution ◽  
Test Section ◽  
Flow Boiling ◽  
Forced Flow ◽  
Flux Data ◽  
Flux Measurements ◽  
Square Array

Critical heat flux data were obtained for forced flow boiling in a 16-rod test section arranged in a square array. The tests were performed at 1000 psia and used a radial power distribution which represented the region about the hot corner in a BWR fuel assembly. The results are lower than data obtained in a 9-rod square array, having a uniform power distribution, based on the average bundle exit quality. These two sets of data are in fair agreement when compared on the basis of the highest subchannel exit quality. Comparisons of different sets of data show the effects of different rod spacers and bundle misalignment on the critical heat flux.

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