• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.510-518
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• 1996

The study presents experimental and theoretical analysis focusing on the infulence of a noncondensable gas upon the absorption enhancement that is obtained by Marangoni convection generated by the addition of the surfactant. The shadowgraph method is adopted in this visualization. As a result of absorption phenomena with shadowgraph photos, the different patterns of Marangoni convection cells are observed in accordance with the various amounts of noncondensable gas. Furthermore, non dimensional number K(Ma/Ra) is introduced to calculate the value of surface tension difference theoretically for the comparison with the various amount of non condensable gas in absorber.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.2
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• pp.85-93
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• 1985

An experimental investigation on condensing heat transfer for the Refrigerant-11 superheated vapor during condensation on the 40 mm O.D by 75 mm long horizontal tube is carried out under the various conditions of air contents as noncondensable gas, condensing pressure, and coolant temperature. The data span a refrigerant flow range from 23 to 63 kg/h and weight fractions of noncondensable gas range from 0 to $15\%$. The comparisons are made using data obtained by the authors and further data obtained from other sources. The characteristics of the condensing heat transfer of refrigerant superheated vapor with and without noncondensable gas flowing horizontally are revealed experimentally, and on the basis of the data obtained, correlations for predicting heat transfer coefficient during condensation on the tube are proposed.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.23.2-23.2
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• 2005

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.1
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• pp.25-30
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• 2000

In present paper, mass transfer over a flat plate with film condensation including noncondesable gas is analyzed with the help of similarity methods. Couette flow was assumed in liquid film and boundary-layer approximation was used in the ambient flow. Governing equations were transformed into the ordinary differential equtions by the similarity methods. Runge-Kutta and shooting method were used in order to fine the effect of mass transfer on the velocity and concentrations at the liquid-vapor interface.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.152-152
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• 1999

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.67-74
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• 2012

A numerical analysis was carried out to estimate the effect of the gap size ratio on the performance of condensers under noncondensable gas ventilation using the porous medium approach (PMA). In the PMA, the details of the tube bundle in the condenser are considered to be those of a porous medium, and the flow resistance term is added in the momentum equation. Three-dimensional analysis of the condensation for a McAllister condenser was conducted with the PMA using Fluent and user-defined functions (UDFs). The gap size effect on the condensation was negligible under pure steam conditions. However, the gap size effect was dominant in condensation with noncondensable gas and external venting. As the gap size decreased, the condensation rate increased for noncondensable gas in an external venting system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.5
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• pp.337-349
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• 1991

Heat and mass transfer rates to spray water droplets for spray transients in a high pressure vessel have been predicted by two different droplet models: the complete mixing model and the non-mixing model. In this process, the ambient fluid surrounding the droplets is a real-gas mixture composed of saturated steam and noncondensable hydrogen gas at high pressure. The physical properties of the mixture are estimated by applying the concept of compressibility factor and using appropriate correlations. A computer program, DROPHMT, to calculate the heat and mass transfer rates for two different droplet models has been developed. As an illustrative application of the computer program to engineering practices, heat and mass transfer rates to spray water droplets for spray transients in a Pressurized Water Reactor (PWR) pressurizer have been calculated, and the typical results have been provided.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.6
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• pp.514-523
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• 2001

The thermal performance characteristics of gas-loaded heat pipe(GLHP) were investigated by using transient diffuse-front model. Numerical evaluation of the GLHP is made with water as a working fluid and Nitrogen as control gas in the stainless steel tube. The transient vapor temperature and wall temperature were obtained. It is found that the temperature profiles and gas mole fraction distribution have been mainly influence by the diffusion between working fluid and noncondensable control gas in the condenser of GLHP. It is also found that he large power input make the diffusion region smaller.

• Nuclear Engineering and Technology
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• v.47 no.5
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• pp.567-578
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• 2015

In a nuclear reactor containment, wall condensation forms with noncondensable gases and their accumulation near the condensate film leads to a significant reduction in heat transfer. In the framework of nuclear reactor safety, the film condensation in the presence of noncondensable gases is of high relevance with regards to safety concerns as it is closely associated with peak pressure predictions for containment integrity and the performance of components installed for containment cooling in accident conditions. In the present study, CUPID code, which has been developed by KAERI for the analysis of transient two-phase flows in nuclear reactor components, is improved for simulating film condensation in the presence of noncondensable gases. In order to evaluate the condensate heat transfer accurately in a large system using the two-fluid model, a mass diffusion model, a liquid film model, and a wall film condensation model were implemented into CUPID. For the condensation simulation, a wall function approach with a heat/mass transfer analogy was applied in order to save computational time without considerable refinement for the boundary layer. This paper presents the implemented wall film condensation model, and then introduces the simulation result using the improved CUPID for a conceptual condensation problem in a large system.

• Nuclear Engineering and Technology
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• v.31 no.5
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• pp.465-475
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• 1999

The objective of the present work is to assess the analysis capability of two wall film condensation models, the default and the alternative models, of RELAP5/MOD3.2 on condensation experiments in the presence of noncondensable gas in a vertical tube of PCCS of CP-1300. In the calculation of a base case the default model of RELAP5/MOD3.2 under-predicts the heat transfer coefficients, and Its alternative model over-predicts them throughout the condensing tube, Also, both models over-predict the void fractions. The nodalization study shows that the variation of the node number does not change both modeling results of RELAP5/MOD3.2 Sensitivity study for varying input parameters shows that the inlet steam-air mixture flow rate, the inlet air mass fraction, and the inlet saturated steam temperature give significant changes of their heat transfer coefficients Run statistics show that the grind time of the default model is always higher than that of the alternative model by about 23%.