• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.323-327
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• 2008

본 연구는 판형 핀-관 열교환기의 열전달 특성을 상용 CFD 코드인 SC/Tetra를 사용하여 해석한 내용에 관한 것이다. 해석조건은 입구속도 0.63 m/s, 튜브온도 $44.5^{\circ}C$이다. 해석 열교환기는 총6가지로 검토하였으며 각각의 온도분포와 유동패턴을 해석하고 판형 핀-관 열교환기의 열전달 특성을 비교 검토하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.279-285
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• 1997

본 연구에서는 나선형과 판형의 핀을 가진 원자력 발전소용 직교류 핀-관 열교환기의 열량을 ARI Standard-410에 따라 실험적으로 측정하여 풍속과 냉수속에 따른 열저항 및 압력 손실을 도출하는 것을 목적으로 하였으며, 이러한 시도를 통해서 실제 열교환기의 성능 평가시 필요한 기술적 자료를 축적하고자 하였다. 실험에서는 나선형 6fin/in, 8fin/1n, 10fin/in 열교환기와 판형 8fin/in 열교환기를 사용하였으며, 풍속을 0.486m/s와 2.214m/s로, 수속을 1m/s～4m/s로 하여 실험을 행하였다. 실험 결과를 통하여, 원자력 발전소의 격납 용기내의 공기조화를 위하여 사용되어 지는 열교환기의 성능 평가 방법 및 실증 능력을 확보하였으며, 풍속 증가에 따라 총괄 열전달 계수는 전체적으로 비례 증가하는 경향을 보였다. 판형이 나선형 보다 열전달 계수가 작게 나타났으며, 나선형 열교환기의 경우 fin수에 따른 변화는 크지 않았으나, 열전달 면적을 고려한 경우에는 나선형 10fin/in 열교환기가 가장 뛰어난 열교환 성능을 발휘함을 알 수 있었다. 또한, 공기측의 압력 손실은 전체적으로 전연 풍속 증가에 따라서 속도 제곱에 비례하여 증가하는 경향을 보였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4802-4808
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• 2014

A plate-fin tube type heat exchanger has a lighter weight, approximately 30%, than the conventional circular-fin type condenser of household refrigerator. Because the low weight means low cost, it can have significant effects on the growth of related businesses if similar performance can be guaranteed. To check the possibility of the use of such a plate fin-tube condenser, experimental evaluations were performed in this study. Four different condensers including a conventional circular fin-tube condenser were used for the test. A well designed refrigerant supply system was used to supply similar conditions with a refrigerator, and the heat transfer rate and pressure drops of air side were measured precisely. As a result, the plate fin-tube type condensers showed a lower heat transfer rate of more than 13% than the conventional circular fin-tube type condenser, but the air side pressure drop was reduced and the heat transfer per unit weight was increased. Therefore, it shows the possibility of the use of a plate fin-tube type condenser after optimizing the air flow path and increasing the air flow to make a similar heat transfer rate.

• 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.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.639-647
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• 2014

Due to global warming and depletion of fossil fuels, technologies reducing $CO_2$ emission and increasing fuel efficiency simultaneously are required. An exhaust gas heat recovery system is a technology to satisfy both issues. This study analyses three types of heat exchanger installed on an exhaust pipe. In case of plate type heat exchanger, back pressure rapidly increased and maximum cylinder pressure reduced in high speed and maximum load, and back pressure increased over twice and specific fuel consumption also increased up to 2% which were the highest increasing rate. In case of fin tube type, the amounts of exhaust emissions and specific fuel consumption rate were less than the other two types. The effect of shell and tube was in the middle. Making a decision by only the effect on engine performance, a fin tube type is the best for exhaust heat recovery systems.

• Journal of Korean Society of Steel Construction
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• v.18 no.4
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• pp.437-446
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• 2006

Open-steel-plate-girder(OSPG) bridges are one of the most prevalent bridge types among Korean railway bridges. They account for about 40% of all Korean railway bridges. However, the line-type bearings used for OSPG bridges generate several problems with respect to the bridges' dynamic behavior and maintenance. The replacement of the existing bearings with polyurethane disk bearings could be a possible solution to this problem. This type of disk bearing is an elastic bearing using a polyurethane disk. This study estimated the variations in the natural frequency of a bridge when disk bearings were installed and the bridge's dynamic behavior with a running locomotive and running trains. The first natural frequency of the bridge was 3% lower than that of the as-built bridge after the installation of the disk lower, respectively. Also, the second and third frequencies were 7 and 15% lower, respectively. The disk bearings increased the vertical displacement of the bridge, but the pure displacement, excluding the disk deformation, did not vary. The vertical acceleration did not increase when the disk bearing was installed, with trains running. The shear pin in the disk bearing reduced the lateral displacement and the acceleration of the bridge.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.5
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• pp.494-501
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• 2000

Effectiveness of a 3-pass plate finned-tube heat exchanger is calculated using heat exchangelet method by changing the shape of fin and the arrangement of tubes. The alternative refrigerant R134a is taken in this study. Conduction between neighboring tubes along the fin is taken into account in addition to convection between the fin and the surrounding air. Governing equations are obtained by using energy balance in a small control volume containing a tube and fins. They are numerically solved following the tube. Effect of tube-to-tube conduction is investigated in single-phase and two-phase flows with various fin shapes and arrangements of tubes. Improvement of effectiveness by fin perforation is studied too. The results shows that perforating fins, increasing the number of tubes, and increasing the distance between neighboring tubes at the same fin area enhance the effectiveness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.46-51
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• 2009

In this work, the experimental investigation was carried out to evaluate the heat transfer performance on the shell side of shell-and-plate finned tube heat exchanger with three different tube numbers(9, 13 and 19). Oil flowing on the shell side was cooled by cold water flowing inside the tubes. A shell-and-tube heat exchanger of an oil cooler consisted of one shell pass and two tube passes with the inner tube diameter of 8.82 mm and the tube length of 575 mm. Mass flow rate was varied from 1.2 to $6.0\;m^3/h$ for oil and from 0.6 to $3.0\;m^3/h$ for cold water, respectively. From the experiment of shell-and-plate finned tube heat exchanger, the overall heat transfer coefficient of heat exchanger with 9 tubes was compared with that of 13 and 19 tubes. It was found that the heat transfer coefficients in shell side of heat exchanger with 9 plate finned tubes showed averagely 1.8 times and 2.3 times higher than those of 13 and 19 tubes, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.5
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• pp.171-177
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• 2016

Plate heat exchangers have been widely used in various fields because of their high heat transfer coefficients, small area of installation, and ease of maintenance compared to other heat exchangers. However, when plate heat exchanger is used for a long time, leak can occur due to inner crack. Therefore, it is important to understand the inner flow characteristics in plate heat exchangers. In this study, the inner flow characteristics and flow rate of plate heat exchanger were evaluated using various flow directions, pin-hole sizes, and Reynolds numbers. In downflow, initially most water flowed to the opposite of the inlet due to distribution region. Then it gradually had a uniform distribution due to chevron configuration. In upflow, it had a uniform flow consistently due to the dominant gravity effect. As the Reynolds number increased, the leak rate was decreased due to the inertia effect regardless of the flow direction.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.89-90
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• 2007

Electrowetting 현상을 contact angle의 변화가 아닌 전자기 체적력의 관점으로 고찰한다. 정수역학의 방정식과 Kelvin 식, 표면장력 공식을 도입하고, 체표면의 모든 곳에서의 압력이 일정하다는 원리를 이용하여 유체 표면의 형상을 고찰한다. 액적의 초기 형상은 반원, 반지름은 1mm이다. 절연 처리한 판형태의 도체위에 액적을 올려놓고 그 액적에 핀을 꽃은 형태로 전계를 인가한다.