• 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.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.3
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• pp.90-98
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• 2006

The Heated Tube Facility(HIF) was fabricated to identify the forced convective heat transfer and the cooling characteristic for the hydrocarbon fuel(Jet A-1), which is used for the coolant of the regenerative cooling system. The forced convective heat transfer coefficient was calculated from the measured coolant and tube surface temperature. In case of using the Jet A-1, the maximum heat flux which the coolant can absorb was identified by determining the critical wall temperature generating the burnout on the fixed flow condition. The inlet bulk-temperature of the coolant has a direct influence on the forced convective heat transfer characteristic.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1629-1636
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• 2004

The continuous casting is primarily a heat-extraction process in which the heat transfer at various cooling zones profoundly influences quality of products. So development of numerical model is necessarily needed for more specific and clear investigations upon heat transfer mechanism at mold and secondary cooling zones. In this study, heat transfer coefficients which show the characteristic of heat transfer mechanism in mold are calculated for more exact analysis with temperature measured in bloom mold using optimal algorithm, and finally the validity of cooling conditions at secondary cooling zone actually used at field fur 30 Ton bloom type continuous casting of 0.187%C is investigated. From the results of solidification analysis, the characteristic of bloom mold shows a similar tendency with that of previous studies, and optimized cooling conditions for 0.187%C are presented.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.5
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• pp.337-345
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• 2003

In the case of heat exchangers operating under frosting condition, the growth of frost layer causes the heat exchanger to increase the thermal resistance and pressure loss of the air flow. In this paper, a transient characteristic prediction model of the heat transfer for multi inverter heat pump with frosting on its surface was presented taking into account the change of the fin efficiency due to the growth of the frost layer. In this dynamic simulation program, which was peformed for a basic air conditioning system model, such as evaporator, condenser, compressor, linear electronic expansion valve (LEV) and bypass circuit. The theoretical model was driven from the obtained heat transfer coefficient and mass transfer coefficient, independently. And we consider heat transfer performance was only affected by a decrease of the wind flow area. The calculated results were compared with some cases of experiments for frosting conditions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.275-281
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• 2007

For a cooling performance research of the combustor operated in a extreme environment of a high temperature and high pressure, we accomplished a cooling performance analysis. Generally a heat transfer characteristic in cooling passage is known well experimentally and theoretically, however heat flux in the combustion chamber isn't. In this study, fluid flow combined with heat transfer analysis is accomplished about a combustor nozzle. We tried to analyze the cooling performance with a heat transfer characteristic of a gas and coolant side in the view point of quantity on the mass flow rate to be supplied to the cooling channel. And finally, evaluation on the thermal safety of nozzle wall material was accomplished.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.3
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• pp.54-60
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• 2013

Numerical analysis of the radiant heat characteristic around heatsink according to arrangement and shape of fin on 60W-LED lamp is conducted in this study. In the case of top blow blowing from upper side on LED lamp, there is just little difference in cooling characteristics according to the height of fin. On the other hand, the fin arranged side by side has the advantage of heat transfer enhancement by comparing with zig-zag type because it leads to more loss of flow. In case of making fin round to increase the amount of heat transfer, designing arrangement with the minimized loss of flow has the advantage of characteristic.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.51-54
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• 2003

The continuous casting is primarily a heat-extraction process in which the heat transfer at various cooling zones profoundly influences quality of products. So development of numerical model is necessarily needed for more specific and clear investigations upon heat transfer mechanism at mold and secondary cooling zones. In this study, heat transfer coefficients which shows the characteristic of heat transfer mechanism in mold are calculated for more exact analysis with temperatures measured in bloom mold using optimal algorithm, and finally the validity of cooling conditions at secondary cooling zone which is actually used at field for 30 Ton bloom type continuous casting of 0.187%C is investigated. From the results of solidification analysis, the characteristic of bloom mold shows good agreements with that of previously studies by other authors and optimized cooling conditions for 0.187%C are presented.

• Transactions of Materials Processing
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• v.22 no.2
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• pp.101-107
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• 2013

The heat transfer characteristics between die and sheet and die and coolant are important parameters in hot press forming process. The determination of the quenching time that guarantees full martensitic transformation requires proper understanding of these heat transfer characteristics. The contact area changes drastically during the quenching process due to volume changes of both die and sheet by temperature drop as well as phase transformation. Several types of modeling techniques are tested in order to select the most suitable. The effect of quenching time as well as die heat conductivity on martensitic transformation is investigated and predictions are compared to experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.126-131
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• 2001

One of the major obstacles in testing or evaluating precisely the thermal behavior of a machine tool is the difficulty in measuring the heat transfer coefficients on the surfaces by a conventional method. This paper presents a new approach based on the inverse method to identify the values of heat transfer coefficients by using temperature changes measured on the surfaces of a machine tool during a short period in its operating. In the present method, a machine tool structure is modeled by the finite element method and the characteristic curves of the temperature change at several points on machine tool surfaces are theoretically derived in the form that they contain the heat transfer coefficient as an unfixed heat source are approximated so that the theoretical characteristic curves of temperature change fit the measured ones as closely as possible.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.5
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• pp.502-510
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• 2000

Evaporation heat transfer characteristics were studied in a horizontal tube using R22/R114 non-azotropic refrigerant mixture. the heat transfer coefficient was high in the upper part for pure refrigerants, and heat transfer coefficient was low in the lower part for refrigerant mixtures. In the low quality region where nucleate boiling was dominant, the average heat transfer coefficient was low. In the region where forced convection was dominant, heat transfer coefficient was high. Results show that the heat transfer coefficient for pure refrigerants obtained by experiments were lower than those of Yoshida et al. but agreed well with Jung et al., and Chen et al. data. But the heat transfer coefficients for refrigerant mixtures were lower about 20% than those predicted by the equation for pure refrigerant.