An Experimental Investigation of Steam Condensation in the Presence of Non-Condensable Gases for Nuclear Plant Containment

2014 ◽  
Author(s):  
Jiqiang Su ◽  
Zhongning Sun ◽  
Yanmin Zhou ◽  
Chaoxing Yan ◽  
Guangzhan Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Fraction ◽  
Cooling System ◽  
Nuclear Reactors ◽  
Condensation Heat Transfer ◽  
Steam Condensation ◽  
Air Mass

The condensation heat transfer occurring in containment atmospheres during the loss of coolant accident (LOCA), is one of the most important areas in research related to the safety of nuclear reactors. In the advanced Generation III and III+ nuclear reactors, decay heat is removed by passive containment cooling system (PCCS). For the system, the study of condensation of steam in the presence of non-condensable gases is prior to be investigated because when LOCA happens steam flashes into the containment which contains air and other non-condensable gases (helium, argon, etc.). An experimental investigation has been conducted to evaluate the steam heat removal capacity over a vertical tube external surface with air. Condensation heat transfer coefficients have been obtained under the total pressure ranging from 0.4MPa to 0.6MPa, the wall subcooling ranging from 13 to 25°C and air mass fraction ranging from 0.07 to 0.52. The influence of the wall subcooling on the steam condensation heat transfer with the fixed pressure and air mass fraction have been researched. The effect of wall subcooling on condensation heat transfer coefficient with air is negative. The developed empirical correlation for the heat transfer coefficient covered all data points within 15%.

scholarly journals PREDICTING OF STEAM CONDENSATION HEAT TRANSFER COEFFICIENT IN HORIZONTAL FLATTENED TUBE

2020 ◽  
Vol 24 (06) ◽  
pp. 115-126
Author(s):  
Mohammed Ghazi M. Kamil ◽  
◽  
Muna Sabah Kassim ◽  
Louay Abd Alazez Mahdi ◽  
◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Uniform Heat Flux ◽  
Steam Condensation ◽  
The Heat Transfer Coefficient ◽  
Condensation Heat Transfer Coefficient

The heat transfer coefficient of steam condensation has a significant role in the performance of air-cooled heat exchangers. The purpose of this work is to predict the local/average local steam condensation heat transfer coefficient inside the horizontal flattened tube under vacuum conditions using numerous correlations that were developed by some researches which have been conducted under specified conditions. The results from these correlations have been compared with experimental data of Davies, therefore more investigate for the values are necessary to improve or/and validate the existing correlations. The effect of such parameters like the uniform heat flux and saturation temperature also have been studied on the local steam condensation heat transfer coefficient as the results show that the heat transfer coefficient decrease as the heat flux increase, while it increases as the steam saturated temperature increase.

Influence of Wall Sub-Cooling on Local Heat Transfer for Forced Convection Condensation of Steam/Air in a Horizontal Tube

2016 ◽  
Author(s):  
Huiqiang Xu ◽  
Qiunan Sun ◽  
Haifeng Gu ◽  
Xiaofan Hou ◽  
Zhongning Sun
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Fraction ◽  
Local Heat Transfer ◽  
Horizontal Tube ◽  
Local Heat ◽  
Condensation Heat Transfer ◽  
Fraction Mixture ◽  
Condensation Heat Transfer Coefficient

For the purpose of analyzing the influence of wall sub-cooling on condensation heat transfer characteristic in the presence of noncondensable gases inside a horizontal tube, experiments for air-cooling and water-cooling at the secondary side outside the condenser tube have been conducted. By comparing the experimental data of different inlet air mass fraction, mixture gases velocity and coolant volume flow rate, the variation of local heat transfer coefficient with wall sub-cooling was obtained. The results show that for annular and wavy flow, the condensation heat transfer coefficient increases with increasing wall sub-cooling but decreases for stratified flow. For annular and wavy flow, the positive influence of wall sub-cooling on condensation heat transfer coefficient is enhanced by the rise of inlet noncondensable gas mass fraction, mixture gases velocity and pressure.

Experimental Investigation of Evaporation and Condensation in Herringbone, Smooth and EHT Tubes

2015 ◽  
Author(s):  
Xiao-peng Zhou ◽  
Jian-jun Sun ◽  
Si-pu Guo ◽  
Sun Zhichuan ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Smooth Tube ◽  
Evaporation And Condensation ◽  
Condensation Heat Transfer Coefficient

An experimental investigation was performed for evaporation and condensation characteristics inside smooth tube, herringbone tube and EHT tube with the same outer diameter 12.7 mm, refrigerant are R22 and R410a. Mass flux are 60–140 kg/m2s, 81–178.5 kg/m2s, for evaporation and condensation respectively. The evaporation saturation temperature is 6°C, with inlet and outlet vapor qualities of 0.1 and 0.9, respectively. The condensation saturation temperature is 47°C, with inlet and outlet vapor qualities of 0.8 and 0.2, respectively. EHT tube has best evaporating performance for both R22 and R410a. Herringbone tube is also batter than smooth tube. Evaporation heat transfer coefficient increases with mass flux increasing obviously. Pressure drop of R22 evaporation in EHT tube is the highest, herringbone tube is a little higher than in smooth tube. Herringbone tube has highest condensation heat transfer coefficient, about 3 and 2.3 times that of smooth tube for R22 and R410a respectively. EHT tube has heat transfer coefficient about 2 and 1.8 times that of smooth tube for R22 and R410a respectively. Condensation heat transfer coefficient increases with increasing of mass flux, but very slowly, R410a flow in micro-fin tube even decreases with mass flux increasing.

Roll Wave Effects on Annular Condensing Heat Transfer in Horizontal PCCS Condenser Tube

2002 ◽  
Author(s):  
Masaya Kondo ◽  
Hideo Nakamura ◽  
Yoshinari Anoda ◽  
Sadanori Saishu ◽  
Hiroyuki Obata ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Annular Flow ◽  
Cooling System ◽  
Condensation Heat Transfer ◽  
Transfer Model ◽  
Condenser Tube ◽  
Condensing Heat Transfer ◽  
Condensation Heat Transfer Coefficient

A horizontal in-tube condensation heat exchanger is under investigation to be used for a passive containment cooling system (PCCS) of a next generation-type BWR. The flow conditions in the horizontal condenser tube were observed both visually and by local void fraction fluctuation. The observed flow regimes at a rated condition were annular flow at the tube inlet, and turned gradually into wavy flow and smooth stratified flow along the length of the tube. It was found further that frequency of the roll waves that appear on the liquid film in the annular flow is closely related to the measured local condensation heat transfer coefficient. Based on the flow observation, the roll wave frequency and measured condensation heat transfer coefficient, a model is proposed which predicts the condensation heat transfer coefficient particularly for annular flows around the tube inlet region. The proposed heat transfer model predicts well the influences of pressure, local gas-phase velocity and film thickness.

scholarly journals Experimental investigation on effect of helical grooves on condensation heat transfer performance of vertically oriented copper tubes

2019 ◽  
Vol 128 ◽  
pp. 06001
Author(s):  
Jyothish Abraham ◽  
Venugopal G ◽  
Rajkumar M R
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Condensation Heat Transfer ◽  
Transfer Performance ◽  
Helical Groove ◽  
Helical Grooves ◽  
Condensation Heat Transfer Coefficient

An experimental investigation was conducted to study the influence of pitch of helical grooves on condensation heat transfer performance on vertically oriented copper tubes. The condensation heat transfer coefficient of bare as well as grooved copper tubes of various pitches ranging from 2.54 mm to 22.4mm were studied. The investigation revealed that copper tube with groove pitch ≤ 6.35 mm has an adverse effecton the heat transfer performance in comparison to bare copper. The helical groove with pitch > 6.35 mm showed improvement in heat transfer coefficient. The helical groove with pitch 8.47 mm showed a maximum enhancement of 68.4% in condensation heat transfer coefficient at ∆T = 40°C.

scholarly journals The Investigation on Heat Transfer Characteristics of Steam Condensation in Presence of Noncondensable Gas under Natural Convection

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xizhen Ma ◽  
Jiang Ma ◽  
Heng Tong ◽  
Haijun Jia
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Transfer Coefficient ◽  
Molar Fraction ◽  
Condensation Heat Transfer ◽  
Heat Transfer Characteristics ◽  
Steam Condensation ◽  
Noncondensable Gas ◽  
Condensation Heat Transfer Coefficient

The NHR-200 reactor in China adopts the noncondensable gas self-stabilizing control and the noncondensable gas used for pressure stabilization control can weaken steam condensation heat transfer in the integrated steam-gas pressurizer. A condensation experimental system was established and the heat transfer characteristics of steam-nitrogen and steam-argon condensation under natural convection had been investigated. The pressure ranged from 0.516 to 5.10 MPa. The distributions of nitrogen and argon in the steam/gas mixture were obtained in the experiments, and the results showed that nitrogen and argon were evenly distributed in the steam under different pressure, respectively. The effects of heat transfer temperature difference had also been investigated and it is found that the total heat transfer coefficient difference had little influence on the total condensation heat transfer coefficient. However, the steam condensation heat transfer coefficient decreased with the increase of the degree of supercooling of the wall. The condensation heat transfer coefficient was reduced by approximately 0.11 kW/(m2·K) as the degree of supercooling of the wall changed from 14°C to 36°C. The condensation heat transfer coefficient also decreased with the mass/molar fraction of noncondensable gas increasing and a certain difference between the effect of the mass fraction of noncondensable gas and the effect of the molar fraction of noncondensable gas was discussed in this paper.

Experimental Study of Pure Steam and Steam-Air Mixture Condensation on a Vertical Chrome-Plated Tube

2020 ◽  
Author(s):  
Zesheng Niu ◽  
Guangming Fan ◽  
Jie Cheng ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Coating Thickness ◽  
Total Pressure ◽  
Mass Fraction ◽  
Air Mass ◽  
Chrome Coating ◽  
Pure Steam ◽  
Condensation Heat Transfer Coefficient

Abstract To investigate the heat transfer characteristics of the chrome-plated tube and hope it could be used on the internal heat exchanger of passive containment cooling system (PCS), an experimental investigation has been conducted. In this experiment, a series of steam condensation experiments are performed under pure steam and steam-air mixed conditions over chrome-plated tube for a variety of chromium coating thickness (1μm and 10μm), total pressure, air mass fraction and wall subcooling. Condensation heat transfer coefficient was obtained for the total pressure ranging from 0.2 MPa to 0.4 MPa, air mass fraction ranging from 0.10 to 0.71, and wall subcooling from 10°C to 70°C. Moreover, the designed visualization experimental device makes the experimental phenomenon can be directly observed through the observation window. Under the pure steam condition, the results show that droplet condensation and filmwise condensation is co-existed on both two kinds of chrome-plated tubes, the chrome coating thickness of 10μm tube shows better heat transfer ability. Under the steam-air mixed condition, the condensation heat transfer coefficient of both two kinds of tubes increases with total pressure, and decrease with the air mass fraction and wall subcooling, while the influence of chrome coating thickness on heat transfer is no longer noticeable. The results also indicate that the thickness of the chromium coating will affect the surface microstructure of the chrome-plated tube and then affect the heat transfer ability of the chrome-plated tube.

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