• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.405-420
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• 2012

A number of existing and emerging concepts for formulating solution algorithms applicable to multidisciplinary inverse problems involving aerodynamics, heat conduction, elasticity, and material properties of arbitrary three-dimensional objects are briefly surveyed. Certain unique features of these algorithms and their advantages are sketched for use with boundary element and finite element methods.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.3
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• pp.57-65
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• 1991

The quenching of steels by water is one of the important problems in engineering for the applications of heat treatment or continuous casting process, but the fundamental researches by the theoretical approaches have not been satisfactorily improved yet. The very rapid cooling problems by the thermal conduction including the latent heat of phase transformation in steel and the transient boiling heat transfer of water on the surface of the steel covering from $850^{\circ}C$ to $20^{\circ}C$ are the key problems of heat treatment. The present quenching experiments are performed for the cylindrical specimens of carbon steel, S45C of diameters (12-30). Nonlinear transient heat conduction and transient boiling heat transfer problem of water on the surface of specimens is analyzed by the numerical method of inverse heat conduction problem. The conditions for the calculation are that the initial temperature of specimens is $820^{\circ}C$ and the cooling water in bath are $20^{\circ}C$,$40^{\circ}C$,$60^{\circ}C$,$80^{\circ}C$,$95^{\circ}C$ with no agitation.

• Journal of Korea Foundry Society
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• v.15 no.2
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• pp.156-163
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• 1995

Solidification of aluminum alloys under moderate pressures has been investigated. Interfacial heat transfer coefficient at the casting/mold interface varies with time after pouring the molten metal into the die cavity, and therefore plays an important role in determining solidification sequence. The heat transfer coefficients were evaluated by using an inverse problem method, based on the measured temperature distribution. The calculated heat transfer coefficients were used for solidification simulation in the squeeze casting process. The effects of applied pressure and positions of insulation in the mold have also been investigated on solidification microstructures and on the formation of macrosegregation of Al-4.5wt.%Cu alloys.

• 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.16 no.2
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• pp.391-399
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• 1992

The analysis of the evaporative heat transfer in the inclined porous layer (0.deg.<.theta.<90.deg.) is made by using capillary model. The length of the evaporation zone is obtained numerically by integrating the differential equation using a Runge-Kutta algorithm. As a result, the length of the evaporation zone is inverse proportional to the dimensionless number, E(=Re*.phi./cos.theta.) representing the evaporation intensity, and the relationship of these parameters shows linear in the log graph.

• The KSFM Journal of Fluid Machinery
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• v.12 no.4
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• pp.7-13
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• 2009

The purposes of present work are to analyze the convective heat transfer with three-dimensional Reynolds-averaged Navier-Stokes analysis, and to optimize shape of the mixing vane using the analysis results. Response surface method is employed as an optimization technique. The objective function is defined as a combination of inverse of heat transfer rate and friction loss. Two bend angles of mixing vane are selected as design variables. Thermal-hydraulic performances have been discussed and optimum shape has been obtained as a function of weighting factor in the objective function. The results show that the optimized geometry improves the heat transfer performance far downstream of the mixing vane.

• Journal of computational fluids engineering
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• v.14 no.2
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• pp.1-8
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• 2009

The purposes of present work are to analyze the convective heat transfer with three-dimensional Reynolds-averaged Navier-Stokes analysis, and to optimize shape of the mixing vane taken tolerance into consideration by using the analysis results. Response surface method is employed as an optimization technique. The objective function is defined as a combination of heat transfer rate and inverse of pressure drop. Two bend angles of mixing vane are selected as design variables. Thermal-hydraulic performances have been discussed and optimum shape has been obtained as a function of weighting factor in the objective function. The results show that the optimized geometry improves the heat transfer performance far downstream of the mixing vane.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.2
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• pp.20-26
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• 1995

The very rapid cooling problem from $820^{\circ}$C to $20^{\circ}$C on the surface of the steel by thermal conduction including the latent heat of phase transformation of steel and by transient boiling heat transfer of water are considered to principal problem in quenching. The transient boiling process of water at the surface of specimen during the quenching process were experimentally analyzed. Then the heat flux was numerically calculated by the numerical method of inverse heat condition problem. In this report, the simulation program to calculate the cooling curves for large rolls was made using the subcooled transient boiling curve as a boundary condition. By this simulation program, the cooling curves of rolls from D=50mm to D=200mm were calculated and the effects of agitation of circulation of water also investigated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1529-1540
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• 1993

The quenching of steels by water is one of the imprtant problems in the applications of heat treatment, but the fundamental researches by way of theoretical approaches have not been satisfactorily improbed yet. This study aimed at measuring the exact subcooled transient boiling curve for cylindrical specimens and at conducting the analytical researches into the prediction of cooling curves, including the latent heat of phase transformation of steel. Experiments of quenching were made with cylindrical specimens of carbon steel S45C of diameters from 12 to 30 mm and with Cu specimens of 12 mm diameter respectively. The internal temperature of specimens during the quenching process was measured by C-A sheathed thermocouple. The heat fluxes were numerically calculated by the numerical method of inverse heat conduction problem, using the measured inner temperature of specimen as a boundary condition. In case of ${\Delta}T_{sub}=80K$, $q_{s}$ is as follows $q_{s}=2.02{\times}10^{5}{\Delta}T_{set}^{0.05}:{\Delta}T_{set}\le500K.$ And the numerical analysis of unsteady heat conduction during the quenching process was made and the cooling curves were calculated by TDMA method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.5
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• pp.231-238
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• 2017

HFO refrigerants have recently come to be regarded as promising alternatives to R134a for use in turbo chillers. This study provides results from experiments evaluating the film condensation heat transfer characteristics of HFO refrigerants R1234ze(E) and R1233zd(E) on smooth horizontal laboratory tubes. The experiments were conducted at a saturation vapor temperature of $38.0^{\circ}C$ with surface sub-cooling temperatures in the range of $3{\sim}15^{\circ}C$. We observe that the film condensation heat transfer coefficient decreases as surface sub-cooling temperatures increase. In the case of laboratory tubes with a diameter of 19.05 mm, the film condensation heat transfer coefficients of R1234ze(E) and R1233zd(E) were approximately 11% and 20% lower than those of R134a, respectively. Furthermore, our investigation of the effect of tube diameter on film condensation heat transfer coefficients, demonstrates an inverse relationship where the film condensation heat transfer coefficient increases as laboratory tube diameter decreases. We propose experimental correlations of Nusselt number for R1234ze(E) and R1233zd(E), which yield a ${\pm}20%$ error band.