• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.33-42
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• 1999

The effects of wan thermal boundary condition were investigated for a uniform wall temperature, a uniform wall heat flux, and for coupled heat conduction In the channel wall with transverse rectangular ribs. Numerical investigations for steady laminar flow show behavior similar to that observed experimentally in the separated flow region for flow over a cylinder. Conjugate heat transfer with a low solid-fluid thermal conductivity ratio does not lead to the same results as for the uniform heat flux boundary condition, and heat transfer reversal is found on the back sides of the ribs.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.1
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• pp.36-46
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• 2001

Finite element analyses of the ceramic drying process are performed. The heat and moisture movements in green ceramics caused by temperature gradient, moisture gradient, conduction, convection and evaporation are considered. The finite element formulation for solving the temperature and moisture distributions which not only change the volume but also induce the hygro-thermal stress is carried out. In order to verify the formulation, the drying process of a ceramic electric insulator is simulated. Temperature distribution, moisture distribution, and hygro-thermal stress are compared with those of other researcher. Good agreements are achieved.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.347-352
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• 2000

In the present study, DOM and FVM have been used to analyze the radiative heat transfer in an axisymmetric cylindrical enclosure with obstacles. Heat flux distributions on the wall of enclosure form DOM and FVM are compared to those from simplified zone analysis for a nonparticipating medium. The comparison of DOM and FVM is also presented. Results show that there is a good agreement between FVM and simplified zone analysis. In addition, the effect of the thickness of the obstacle on the results is considered. Heat flux distribution on the surface of the obstacle is also presented.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.304-308
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• 2000

This paper presents a numerical optimization method to design geometric shape of streamwise periodic ribs mounted on one of the principal walls to enhance turbulent heat transfer in a rectangular channel flow. The golden section method is used for the one dimensional search. The optimization is based on Wavier-Stokes analysis of turbulent forced convection with $k-{\varepsilon}$ turbulence model. The width-to-height ratio of a rib is chosen as a design variable. The object function is defined as an inverse of average Nusselt number. An optimum shape of the rib has been obtained with reasonable computing time.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.5
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• pp.505-515
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• 1984

동일한 물리적인 인자와 경계조건하에서, 서로 다른 두 개 이상의 유동이나 열전달이 발생되는 다중정상상태에 대한 현상은 최근 자연과학이나 공업분야에서 매우 중요시 되어지고 있다. 그 한 예로서 -0.1988<.betha.<0 영역에서 쐐기면에 따른 유동현상이 다중정상상태가 됨을 Stewrtson에 의해 밝혀진 바 있다. 이 영역에서 주위유체가 공기(Pr=0.72)이고, 쐐기 면이 여러 가지 열유속을 가지는 경우에 대해서 강제대유열전달을 multiple shooting방법으로 현론해석하 였다. 그 결과, 상이한 두 개의 열전달매개변수 즉 다중해가 얻어져서 다중정상상태의 강제대류 열전달이 일어남을 알았다.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.191-198
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• 2001

A numerical analysis of the heat and mass transfer and pressure drop characteristics in modular shell and tube bundle heat exchanger was carried out. Finite Concept Method based on FVM and $k-\varepsilon$ turbulent model were used for this analysis. Condensation heat transfer enhanced total heat transfer rate $4\sim8%$ higher than that of dry heat exchanger. With increasing humid air inlet velocity, temperature and relative humidity, and with decreasing heat exchanger aspect ratio and cooling water velocity, total heat and mass transfer rate could be increased. Cooling water inlet velocity had little effect on total heat transfer.

• Journal of computational fluids engineering
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• v.19 no.2
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• pp.1-7
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• 2014

This study is to analyze the local convective heat transfer for a circular cylinder with annular fins. The relation between wall heat transfer and three-dimensional flow is investigated for different distances of annular fins. Depending on the fin spacing, the flow structure is strongly changed by the variation of horseshoe vortices. As the fin spacing increases, the heat transfer rate is maximized at a certain condition. This is clearly obtained as the Reynolds number increases, and it is closely related to the development of horseshoe vortices.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.172-179
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• 1996

For mechanical systems operating at high tempertature, thermal fatigue phenomenon has been recognized as a major cause of mechanical component failures. To evaluate cumulative fatigue damage as a conesquence of thermal fatugue on real time, the stress tranfer function(Green's function) approach is popularly used. The objective of this paper is to investigate the effect of thermophsical properties on the stress tranfer function. For this purpose a modified Green's function approach considering temperature-dependent thermophysical properties is proposed. Two case studies were performed and the proposed approach agrees well with full finite element analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1351-1359
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• 2003

This study presents a numerical procedure to optimize shape of streamwise periodic ribs mounted on both of the principal walls to enhance turbulent heat transfer in a rectangular channel flow. The response surface method is used as an optimization technique. The optimization is based on Navier-Stokes analysis of flow and heat transfer with $k-{\varepsilon}$ turbulence model. The width-to-height ratio of a rib, rib height-to-channel height ratio and rib pitch to rib height ratio are chosen as design variables. The object function is defined as a function of heat transfer coefficient and friction drag coefficient with weighting factor. Optimum shapes of the rib have been obtained for the range of 0.02 to 0.1 of weighting factor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1756-1765
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• 2001

The heat and mass transfer process between the falling liquid desiccant(TEG) film and the air in counter flow at the dehumidifier of desiccant cooling system were investigated. The governing equations with appropriate boundary and interfacial conditions describing the physical problems were solved by numerical analysis. As a result, the effects of the design parameters and the outside air conditions on the rates of dehumidification and sensible cooling were discussed. The results of the dehumidification and sensible cooling rates were compared with those of the cross flow at the same conditions.