• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.227-232
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• 1998

The purpose of this study is to develop a numerical method for analyzing the transient heat transfer and evaluating the residual stress. The analysis of heat transfer and thermal stress are carried out by three-dimensional finite element method. Thermal spraying is one of the most common surface coating techniques to be used for many applications. In order to improve the mechanical properties of flame-sprayed ceramic coating layer, the accurate and effective analysis of heat transfer and thermal stress is essentially required.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.29-36
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• 2003

Exhaust manifolds suffer from serious temperature variation during the thermal fatigue test. The spatial distribution of temperature changes at each moment. Because transient flow can not be simulated during the long period of temperature change, the simulation can not be performed by conjugate heat transfer analysis. In this study, a new procedure for transient thermal analysis is established by decoupling fluid-solid analysis. The procedure consists of (1) transient CFD calculation (2 cycles), (2) mapping heat transfer coefficient to the inner surface of solid mesh as a boundary condition of heat conduction analysis and (3) transient heat conduction analysis in the long period (30 min). The realistic temperature change can be predicted by this procedure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.39-43
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• 2002

A new model for heat transfer and thermal deformation analysis according to strip mm in coiling process has been proposed. Finite difference analyses for heat transfer of cold rolled coil have been carried out under various coiling tensions and strip crown using the equivalent thermal conductivity for the radial direction of cold rolled coil which is a function of strip thickness, surface characteristics and compressive pressure. The compressive pressure is calculated from a equation expressed as a function of hoop stress and coil tension considering strip mm obtained by experiment. Finite element method for thermal deformation of cold rolled coil has been performed to investigate the effects of the strip crown, the coil tension and temperature. From these analyses, it is found that the axial inhomogeneity of thermal deformation is increased as the strip crown, compressive pressure, and temperature drop in cold coiled strip increase.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.167-170
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• 2008

A numerical and experimental studies are carried out to investigate the transient heat transfer characteristics of 5kWth dish type solar air receiver. Measured solar radiation and temperatures at several different locations are used as boundary conditions for numerical simulation. Many parameters' effects (reflectivity of the reflector, the thermal conductivity of the receiver body, transmissivity of the quartz window, etc.) on the thermal performance are investigated. Discrete Transfer Method is used to calculate the radiation heat exchange in the receiver. A transient heat transfer model is developed and the rate of radiation, convection and conduction heat transfer are calculated. Comparing the experimental and numerical results, good agreement is obtained. Using the numerical model, the transient heat transfer characteristics of volumetric air receiver for dish type solar thermal systems are known and the transient thermal performance of the receiver can be estimated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.8
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• pp.305-310
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• 2016

A thermal storage systems was designed to correspond to the temporal or quantitative variation in the thermal energy demand, and most of its heat is stored using the latent and sensible heat of the heat storage material. The heat storage method using latent heat has a very complex phenomenon for heat transfer and thermal behavior because it is accompanied by a phase change in the course of heating/cooling of the heat storage material. Therefore, many studies have been conducted to produce an experimentally accessible as well as numerical approach to confirm the heat transfer and thermal behavior of phase change materials. The purpose of this study was to investigate the problems encountered during the actual heat transfer from an internal storage tank through simulation of the process of storing and utilizing thermal energy from the thermal storage tank containing charged PCM. This study used analysis methods to investigate the heat transfer characteristics of the PCM with simultaneous heating/cooling conditions in the rectangular space simulating the thermal storage tank. A numerical analysis was carried out in a state considering natural convection using the ANSYS FLUENT(R) program. The result indicates that the slope of the liquid-solid interface in the analysis field changed according to the temperature difference between the heating surface and cooling surface.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2082-2087
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• 2008

The heat transfer process from steam to web through the cylinder drum consists of the thermal resistance by condensate thickness. thickness of shell, and the contact resistance between cylinder and web. The most thermal resistance in conventional cylinder drum dryer is generated by condensate, which is increased by the increase on revolution per minute(RPM). Therefore, the increase of RPM for the production enhancement results in the more thermal resistance, and eventually RPM is restricted. In this study, the theoretical analysis on the characteristics of heat transfer in cylinder drum for paper dryer was performed in the stationary state of steam in drum. The overall heat transfer coefficient, steam quantity and heat transfer quantity were predicted by diameter and length of drum, condensate thickness, revolution per minute and steam temperature for experimental apparatus design.

• Transactions of Materials Processing
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• v.13 no.4
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• pp.319-325
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• 2004

Continuous casting machine has been experienced a rapid development to increase productivity with high casting speed and to meet consumer's strict demands for high quality. However, because most of defects and cracks are initially formed in mold and grown into surface cracks during the post process, more specific and clear investigations upon heat transfer mechanism between mold and solidified shell are necessarily needed. In this study heat transfer coefficients which shows the characteristic of heat transfer mechanism are calculated with temperatures measured in bloom mold using optimal algorithm, and thermal analysis are investigated using the calculated heat transfer coefficients. Finally uniformity of solidified shell is investigated for high carbon steel, 0.187%C from thermal analysis.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.12 no.1
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• pp.45-53
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• 2006

Thermal insulation is used in a variety of applications to protect temperature sensitive products from thermal damage. Several factors affect the performance of insulation packages. Among these factors, the thermal resistance of the insulating wall is the most important factor to determine the performance of the insulating package. In many cases, insulating wall consists of multi-layered structure and the heat transfer through this structure is a very complex process. In this study, an one-dimensional mathematical model, which includes all of the heat transfer principles covering conduction, convection and radiation in multi-layered structure, were developed. Based on this model, several heat transfer phenomena occurred in the air space between the layer of the insulating wall were investigated. From the simulation results, it was observed that the heat transfer through the air space between the layer were dominated by conduction and radiation and the low emissivity of the surface of each solid layer of the wall can dramatically increase the thermal resistance of the wall. For practical use, an equation was derived for the calculation of the thermal resistance of a multi-layered wall.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.165-168
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• 2008

A numerical analysis was conducted to predict the heat transfer characteristics of a solar receiver which is subject to very high heat fluxes and temperatures for solar thermal applications. The concentration ratio of the solar receiver ranges 1000 and the concentrated heat is required to be transported to a certain distance for specific applications. This study deals with a solar receiver according to internal geometry variation incorporating high-temperature heat pipe. The isothermal characteristics in the receiver section is of major concern. The diameter of the solar thermal receiver was 120 mm and the length was 400 mm and the angle of receiver end wall set $90^{\circ},\;60^{\circ},\;45^{\circ},\;30^{\circ}$. And the diameter of the heat pipe was 12.7 mm, 48 axial channels of the same dimensions were attached to the outer wall of the receiver with even spacing in the circumferential direction. The channels are changed to high-temperature sodium heat pipes. Commercial softwares were employed to deal with the radiative heat transfer inside the receiver cavity and the convection heat transfer along the channels. The numerical results are compared and analyzed from the view point of high-temperature solar receiver.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.238-244
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• 2008

A numerical and experimental studies are carried out to investigate the heat transfer characteristics of 5kWth dish-type solar air receiver. Measured solar radiation and temperatures at several different locations are used as boundary conditions for numerical simulation. Many parameters' effects (reflectivity of the reflector, the thermal conductivity of the receiver body, transmissivity of the quartz window, etc.) on the thermal performance are investigated. Discrete Transfer Method is used to calculate the radiation heat exchange in the receiver. A heat transfer model is developed and the rate of radiation, convection and conduction heat transfer are calculated. Using the numerical model, the heat transfer characteristics of volumetric air receiver for dish-type solar thermal systems are known and the thermal performance of the receiver can be estimated.