• Proceedings of the KSME Conference
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• 2000.11b
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• pp.291-296
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• 2000

Usually the contact between fin collar and tube surface for fin-tube heat exchanger is secured by mechanical expansion of the tubes. The objective of the present study is to develop a method of measuring the thermal contact resistance between fin collar and tube surface for fin-tube heat exchanger. Also an experimental work has been performed to evaluate the thermal contact resistance, and a rigorous numerical analysis has been employed to calculate the contact resistance from the measured data. The experiments have been conducted fur the fin-tube heat exchangers with the tube of outer diameters 7 and 9.52 mm.

• Journal of the Korean Society of Visualization
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• v.10 no.3
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• pp.37-41
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• 2012

Plate-fin heat exchanger is a kind of compact heat exchangers with a good performance in heat transfer. It is widely used in various engineering fields such as aerospace, chemical and biomedical industries. Quantitative and qualitative flow visualization study were performed using the water model of commercial plate-fin heat exchanger with header angles of $30^{\circ}$. The Reynolds number was 100. Conventional digital particle image velocimetry was used to measure the instantaneous velocity fields of the header region and the flow visualization using dye injection and hydrogen bubble method were applied to capture the qualitative flow characteristics. The results showed the existence of separation flow region at the junction area and the bottom wall of the exit region.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.3
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• pp.292-300
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• 1999

Fin conduction not only enhances heat transfer to the ambient air but also increases tube-to-tube conduction. The latter is known to deteriorate the heat exchanger performance. Heat conduction between neighboring tubes thorough the fin is numerically investigated for accurate performance analysis of plate finned-tube heat exchangers. Governing equations for arbitrary plate fin are solved and the temperature distribution is obtained using the principle of superposition. Analysis is made using finite element method by changing the shapes of fin, the arrangements of tubes and the fin parameter mD. It is found that tube-to-tube conduction is significant when mD is small or the distance between neighboring tubes is small.

• Journal of computational fluids engineering
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• v.14 no.4
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• pp.7-12
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• 2009

The purpose of the present study is to investigate the convective heat transfer characteristics and the validity of fin efficiency of the circular finned-tube heat exchanger by using commercial CFD code. The heat transfer coefficient obtained by using the laminar model was 22% overestimated to the experimental data. The fin surface temperature compared with the experimental data measured by the liquid crystal method. The fin efficiency by the present numerical experiment, defined as normalized and averaged fin surface temperature, was greater than the theoretical fin efficiency and the difference is increased at high value of the factor $mr{\phi}$.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.4
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• pp.1-7
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• 2016

This paper presents a design method for the horizontal straight ground heat exchanger (GHE) based on the Kavanaugh design method. In order to examine suitability of the suggested design method, a horizontal line type GHE was installed in a steel box of which the size was $5m{\times}1m{\times}1m$ filled with dried Joomunjin standard, and a thermal response test (TRT) was conducted for 21 hours. A numerical analysis was performed for a simulation of a peak month operation and for its verification by finite element method (FEM). According to the simulation results, it was concluded that the suggested design method for a horizontal straight GHE is reliable for the estimation of a design length.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.4
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• pp.330-335
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• 2012

A characteristic behavior of the thermal storage tank for varying thermal load in heat pump water heater was studied. The control method was suggested and applied. By measuring the temperature within the storage tank, the heat pump was ON/OFF controlled. The appropriate measuring position and the size of heat exchanger gives the minimized power consumption of heat pump. As the length of heat exchanger increases, the temperature measuring position goes down of the storage tank and the power consumption increases.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2358-2372
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• 1993

In this study, the computer modeling for prediction of the performance of fin-tube heat exchanger using alternative refrigerant, HFC-134a was developed and the computer program for calculating the various properties of HFC-134a and the existing refrigerant CFC-12 and HCFC-22 was made. The heat exchanger modeling is based on a tube-by-tube approach, which is capable of analysis for the complex coil array. Performance of each tube is analyzed separately by considering the cross-flow heat transfer with external airstream and the appropriate heat and mass transfer relationships. A performance comparison according to the different refrigerants is provided using this developed model. As the result of this study, total heat transfer rate of evaporator and condenser using HFC-134a were found higher than that of using CFC-12 for the same operating conditions. When the mass flow rate of HFC-134a was less than CFC-12 about 18. 16%, the cooling capacities of evaporator were found to be the same.

• Journal of Chest Surgery
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• v.15 no.2
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• pp.259-265
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• 1982

We have designed a new type of bubble oxygenator (KOREA-KIM VENOTHERM OXYGENATOR) made of PVC sheet and deforming mesh incorporated in the heat exchanger, and evaluated in experimental animal for the analysis of it`s efficiency. The Oxygenator has low priming volume with high flow rate up to 6 L/rain, and efficiency of heat exchanger was excellent as 1-$1.5^{\circ}C.$ using total cardiopulmonary bypass method under moderate to deep hypothermia. Average priming volume of 1317 ml with 30% hemodilution method was perfused with an average of 1.1-3.0 L/min.$M^2$of arterial blood and pure oxygen at a rate of 2-3.4 L/min for 49.6 minutes continuously in average. During total cardiopulmonary bypass, average $PaO_2$ was $159.8{\pm}60$mmHg, $PaCO_2$ $41.0{\pm}3$mmHg respectively under $SaO_2$ over 96% with systolic arterial pressure of 70 mmHg and CVP of 5-10 cm$H_2O$. Plasma free Hemoglobin was $7.0{\pm}4$ mg/dl with 25% drop of hemoglobin and hematocrit at the end of cardiopulmonary bypass. This KKV Oxygenator was observed to have excellent capabillty of oxygen and carbon dioxide gas transfer with small amount of blood trauma, and the efficiency of heat exchanger was satisfactory during cooling and rewarming of the bubbled blood. Disadvantages have included the somewhat poor deforming effect due to loose PVC fiber mesh, the extracompact character of Teflon filters, and the rough inner surface of the heat exchanger copper pipes.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.4
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• pp.377-383
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• 2024

In this paper, the flow uniformity improvement and flow characteristic of the sensor condenser for a heat exchanger cleaning system were studied using response surface method and computational-fluid-dynamics. The design variable was defined as a shape for controllable sensor condenser area. The objective functions were defined as the improvement of flow uniformity in heat exchanger cleaning system tubes. The flow uniformity improvement and flow characteristic of optimum model was verified by numerical analysis and the reliability of the model was retained by comparison of numerical analysis and comparative analysis with the reference model.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.4
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• pp.155-159
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• 2004

Numerical analysis which is based on finite element techniques, implicit Euler method and frontal solving algorithm was performed to study the effects of the crucible shape on the temperature of sapphire crystal and the shape of the melt/crystal interface in heat exchanger method. The computer simulation described here and effective to solving the heat transport phenomena with the transition of the interface shape from hemispherical to planar. In the work, various crucibles with differently shaped corners at their bottom are considered to improve the deflection of the melt/crystal interface. The shape of the crucible should be considered as one of the variables for the process optimization.