• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.732-734
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• 2002

The rotor thermal analysis consists of determining the heat load to the rotor, sizing the cryogenic system, and ensuring that the HTS rotor will operate at the design goal of 30 K. The heat load to the rotor is due to heat conduction through the torque tubes, current leads, instrumentation. and radiation from the thermal shield and the end caps. Coil operating temperature is determined from the coil losses and the heat transport to the coolant. An FEM thermal conductivity model is developed to allow calculation of heat transport in HTS field coil according to the heat exchanger shape and coolant feeding method. The losses determine the size of the cryocooler.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2273-2278
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• 2007

Brazed Plate Heat Exchanger (BPHE) is a type of compact plate heat exchanger with parallel corrugated plates which are brazed together in series. Each plate hascorrugation called herringbone pattern. Inside a BPHE, hot fluid and cold fluid alternate its flow direction to establish counter current flow configuration. Two-phase flow heat transfer and pressure drop of R-22 in BPHE were experimentally measured in this study. In the present experiments, single-phase region and two-phase region coexist in a BPHE. Therefore, the inside of a BPHE have to be divided into single phase region and two phase region and analyzed accordingly. The results from the single phase flow analysis are then extended to the two phase flow analysis to correlate the condensation and evaporation heat transfer and pressure drop for the refrigerant R-22 in the BPHEs. Previous models for two- phase friction factor have been compared with the present experimental results.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1472-1475
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• 2004

Current processor power consumption has dramatically increased and already reached 115 Watts. Therefore, Heat sink design needs more high accuracy in 1U server. The target performance of heat sink is very dependent of fin geometry and it is also seriously affected by design conditions such as fan type, air duct shape and heatsink design parameters. The present paper investigates the behavior of heat sink performance under various conditions. The present work addresses pressurized type plane fin heat sinks having dimension of 40 mm by 40 mm by 56 mm fan.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.672-675
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• 2007

Experimental data are presented which describe heat losses of cavity type receiver in wind tunnel. Experiments are conducted at various conditions such as the heater temperature in cavity changes from 300, 400, and 500 oC, wind speed in tunnel from 2 to 8 m/s, and four different tilt angle of 30, 50, 70, 90o. The power consumption including temperature, voltage and current for each experimental conditions are measured and stored in data logger at everyone second interval. The experimental results show that heat losses increase with increasing wind speed and with tilt angle. However, heat losses for the tilt angle of 70 and 90o is almost same at each heater temperature. In addition, the effects of natural convection in combined convection heat losses vary in according to the tilt angle.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.93-96
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• 2006

The heat transfer enhancement by pulsatile flow in the plate heat exchanger has been investigated numerically in the present study. The numerical study was performed in the range of the mass flux from 0.04 to 0.12 kg/s. The results showed that the pulsatile flow produces resonating vortex shedding at the groove sharp edges and a strong transient vortex rotation within the grooved channels. As a result, the mixing between the trapped volume in the grooved cavity and the main stream was enhanced. Good agreements between the predictions and measured data are obtained in steady flow. And the heat transfer of pulsatile flow is about 2.4 times than steady flow when frequency is 10 Hz and the mass flux of cold side is 0.04 kg/s.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.30-33
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• 2004

In order to analyze the heat transfer phenomena in the plasma flames, a mathematical model describing heat and fluid How in an electric arc has been developed and used to predict heat transfer from the arc to the steel bath in a DC Electric Arc Furnace. The arc model takes the separate contributions to the heat transfer from each involved mechanism into account, i.e. radiation, convection and energy transported by electrons. The finite volume method and a SIMPLE algorithm are used for solving the governing MHD equations, i.e., conservation equations of mass, momentum, and energy together with the equations describing a standard $k-\varepsilon$ model for turbulence. The model predicts heat transfer for different currents and arc lengths. Finally these calculation results can be used as a useful insight into plasma phenomena of the industrial-scale electric arc furnace. from these results, it can be concluded that higher arc current and longer arc length give high heat transfer.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.424-428
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• 2007

In the current most tool using heat and mass balance in a coal gasifier is dependent on commercial code such as STANJAN, CHEMKIN. However, in order to keep the self-reliance technology, it is necessary to develop the original design tool available for comprehension and analysis on the spot. So in this study, its own heat and mass balance program is developed on the assumption that the process in a coal gasifier is adiabatic and quasi-equilibrium. The mass balance is calculated by using the chemical equilibrium principle. Also the heat and mass balance according to main operating factors such as temperature, pressure and O2/Coal ratio, was carried in this tool. This heat and mass balance was verified on the basis of the results simulated in STANJAN, commercial codes using similar logic.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1251-1257
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• 2004

In order to analyze the heat transfer phenomena in the plasma flames, a mathematical model describing heat and fluid flow in an electric arc has been developed and used to predict heat transfer from the arc to the steel bath in a DC Electric Arc Furnace. The arc model takes the separate contributions to the heat transfer from each involved mechanism onto account, that is radiation, convection and energy transported by electrons. The finite volume method and a SIMPLE algorithm are used for solving the governing MHD equations, that are conservation equations of mass, momentum and energy together with the equations describing a standard k-${\varepsilon}$ model for turbulence. The model predicts heat transfer for different currents and arc lengths. Finally these calculation results can be used as a useful insight into plasma phenomena of the industrial-scale electric arc furnace. From these results, it can be concluded that higher arc current and longer arc length give high heat transfer

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.9-16
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• 2012

Currently due to increasing integration of various electronic devices and need of multi-functions, more and more heat is produced and for electronic devices to achieve maximum performance with optimum life time, heat dissipation is critical. A solution to such problems is use of high heat dissipative insulating sheet. In this paper status of current products are introduced and several technology aspects to meet the demand of increased heat dissipation needs is introduced.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.1
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• pp.162-170
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• 2001

In torch weaving in arc welding on V groove, the heat input distribution on groove surface is a main factor determining the bead shape and the weld quality with and without the weld defects such as undercut, overlap, etc. In this study, we calculate the heat input varying with the welding current, arc voltage, welding speed and the touch weaving condition using numerical method. And we investigate the heat input distribution on groove surface while applying the various grooves having 2 dimensional heat sources.