• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.3
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• pp.381-387
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• 1994

In this paper, we found the improved SPICE heat transfer modeling of impulsed magnetizing fixture system and investigated temperature characteristics using the proposed model. As the detailed thermal characteristics of magnetizing fixture can be obtained, the efficient design of the impulsed magnetizing fixture which produce desired magnet will be possible using our heat transfer modeling. The knowledge of the temperature of the magnetizing fixture is very important of forecast the characteristics of the magnetizing fixture which produce desired magnet will be possible using our heat transfer modeling. The knowledge of the temperature of the magnetizing fixture is very important to forecast the characteristics of the magnetizing circuits under different conditions. The capacitor voltage was not raised above 810[V] to protect the magnetizing fixture from excessive heating. The purpose of this work is to compute the temperature increasing for different magnetizing conditions. The method uses multi-lumped model with equivalent thermal resistance and thermal capacitance. The reliable results are obtained by using iron core fixture (stator magnet of air cleaner DC motor) coupled to a low-voltage magnetizer(charging voltage : 1000[V], capacitor : 3825[$\mu$F]. The modeling and experimental results are in close aggrement.

• Nuclear Engineering and Technology
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• v.33 no.2
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• pp.241-253
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• 2001

Under severe accidents, the pressure and temperature response has an important role for the integrity of a nuclear power plant containment. The history of the pressure and temperature is characterized by the amount and state of steam/air mixture in a containment. Recently, the heat transfer rate to the structure surface is supposed to be increased by the wavy interface formed on condensate film. However, in the calculation by using CONTAIN code, the condensation heat transfer on a containment wall is calculated by assuming the smooth interface and has a tendency to be underestimated for safety. In order to obtain the best- estimate heat transfer calculation, we investigated the condensation heat transfer model in CONTAIN 1.2 code and adopted the new forced convection correlation which is considering wavy interface. By using the film tracking model in CONTAIN 1.2 code, the condensate film is treated to consider the effect of wavy interface. And also, it was carried out to investigate the effect of the different cell modelings - 5-cell and 10-cell modeling - for KNGR(Korean Next Generation Reactor) containment phenomena during a severe accident. The effect of wavy interface on condensate film appears to cause the decrease of peak temperature and pressure response . In order to obtain more adequate results, the proper cell modeling was required to consider the proper flow of steam/air mixture.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.154-159
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• 2012

For numerical analysis of the plate heat exchanger, a lot of time are required in modeling work and calculation. Whereas, this paper was purposed to identify characteristic of the plate heat exchanger through simplification of modeling by interpreting the numerical analysis proximity with the actual model. This study was also examined temperature difference between inlet side and outlet side, inner pressure drop, heat transfer area of plate and change of heat transfer coefficient on the plate depending on the inner corrugation angle and corrugation pitch of a herring bon pattern of the plate heat exchanger among chevron types of the plate exchanger.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.1
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• pp.53-58
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• 2016

Modeling of engine coolant temperature was conducted for a series hybrid powertrain system. The purpose of this modeling was a simplification of complex heat transfer process inside a engine cooling system in order to apply it to the vehicle powertrain simulation software. A basic modeling concept is based on the energy conservation equation within engine coolant circuit and are composed of heat rejection from engine to coolant, convection heat transfer from an engine surface and a radiator to ambient air. At the final stage, the coolant temperature was summarized as a simple differential equation. Unknown heat transfer coefficients and heat rejection term were defined by theoretical and experimental methods. The calculation result from this modeling showed a reasonable prediction by comparison with the experimental data.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.9
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• pp.768-778
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• 2003

Numerical analysis has been carried out to investigate laminar convective heat transfer in a tube for supercritical water near the thermodynamic critical point. Fluid flow and heat transfer are strongly coupled due to large variations of thermodynamic and transport properties such as density, specific heat, viscosity, and thermal conductivity near the critical point. Heat transfer characteristics in the developing region of the tube show transition behavior between liquid-like and gas-like phases with a peak in heat transfer coefficient distribution near the pseudocritical point. The peak of the heat transfer coefficient depends on pressure and wall heat flux rather than inlet temperature and Reynolds number, Results of the modeling provide convective heat transfer characteristics including velocity vectors, temperature, and the properties as well as the heat transfer coefficient. The effect of proximity to the critical point is considered and a heat transfer correlation is suggested for the peak of Nusselt number in the tube.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.4
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• pp.206-216
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• 2005

Numerical analysis has been carried out to investigate laminar convective heat transfer at zero gravity in a tube for supercritical water near the thermodynamic critical point. Fluid flow and heat transfer are strongly coupled due to large variation of thermodynamic and transport properties such as density, specific heat, viscosity, and thermal conductivity near the critical point. Heat transfer characteristics in the developing region of the tube show transition behavior between liquid-like and gas-like phases with a peak in heat transfer coefficient distribution near the pseudo critical point. The peak of the heat transfer coefficient depends on pressure and wall heat flux rather than inlet temperature and Reynolds number. Results of the modeling provide convective heat transfer characteristics including velocity vectors, temperature, and the properties as well as the heat transfer coefficient. The effect of proximity on the critical point is considered and a heat transfer correlation is suggested for the peak of Nusselt number in the tube.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1457-1462
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• 2017

Unsteady thermal processes in storage containers with spent nuclear fuel were modeled. The daily fluctuations of outer ambient temperatures were taken into account. The modeling approach, which is based on the solving of conjugate and inverse heat transfer problems, was verified by comparison of measured and calculated temperatures in outer channels. The time delays in the reaching of maximal temperatures for each spent fuel assembly were calculated. Results of numerical investigations show that daily fluctuation of outer temperatures does not have a large influence on the maximal temperatures of stored spent fuel, so that fluctuation can be neglected and only daily average temperature should be considered for safety estimation using the "best estimation" approach.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.53-54
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• 2012

In an IGCC plant, one of the most important issues on fuel flexibility in the lean premixed combustor is combustion instabilities. They are characterized by large amplitude pressure oscillations which are caused by unsteady heat release from the flames. The relationship between the unsteady heat release and flow oscillation can be qualitatively and quantitatively explained by flame transfer function. This paper introduces combustion instability modeling methods based on the flame transfer function approach.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.243-246
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• 2008

This paper is to consider analytical thermodynamic modeling of bipropellant propulsion system. The objective of thermodynamic modeling is to predict thermodynamic conditions such as pressures, temperatures and densities in the pressurant tank and the propellant tank in which heat and mass transfer occur. In this paper also it shows analytic equations that calculate the evolution of ullage volume and interface areas. Since the ullage interface areas are time-varying,(the liquid propellant volume decreases as the rocket engine is firing; the change of ullage volume correspond to the change of liquid propellant volume) for a numerical convenience non-dimensionalized correlations are commonly used in most literatures with limitations; a few percentages of inherent error. The analytic equations are derived from analytic geometry, subsequently without inherent error. Those equations are important to calculate the heat transfer areas in the heat transfer equations. It presents the comparison result of both analytic equations and correlation method.

• Advances in aircraft and spacecraft science
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• v.9 no.6
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• pp.493-506
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• 2022

The study presents the results of the research of heat and heat exchange processes on the heat-stressed elements of the structure of an advanced TsAGI descent vehicle. The studies were carried out using a mathematical model based on solving discrete analogs of continuum mechanics equations. Conclusions were drawn about the correctness of the model and the dependence of the intensity of heat and mass transfer processes on the most heat-stressed sections of the apparatus surface on its geometry and the catalytic activity of the surface.