• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.311-312
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• 2002

In this paper a systematic design approach to determine the optimum size (height) of circulating fluidized bed heat exchanger for exhaust gas heat recovery is prososed. Unlike the convensional heat exchangers where the length of the heat exchanger section is not very much emphasized, the vertical length of heat exchanger tube in the case of fluidized bed heat exchangers is important because this length determines the time interval during which particles reside and transfer heat in the heat exchanger section. For particles initial conditions are nearly stationary, accelerating particles motion should be considered rather than simply assuming fully developed condition. A way to estimate optimum tube length at different fluid velocity and particle sizes is suggested based on the required conditioning time for heat transfer from the flue gas to solid particles.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 춘계 학술대회논문집
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• pp.149-152
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• 2007

The numerical simulations on the heat transfer and flow field were carried out for the improvement of the performance of the shell and tube heat exchanger. The steady incompressible 3-D Navier-Stokes solution is obtained with the actual operational condition and geometry of the heat exchanger. The present geometry of the heat exchanger causes poor heat transfer since the air inside shell dose not flow through the tube bundle, but around it. The enhancement of the heat transfer can be achieved by the variation of the design factor like the sealing strip located on the top/bottom and middle of the baffle.

• 대한기계학회논문집B
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• 제24권5호
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• pp.640-651
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• 2000

For the heat and fluid flow analyses of a parallel flow heat exchanger, an improved model considering the effect of flat tube with micro-channels is proposed. The effect of flow distribution on the thermal performance of a heat exchanger is numerically investigated. The flow distribution is examined by varying geometrical parameters, i.e., the position of the separators and the inlet/outlet, and the aspect ratio of micro-channels of the heat exchanger. The flow nonuniformities along the paths of the heat exchanger are proposed and observed to evaluate the thermal performance of the heat exchanger. The optimization using ALM method has been accomplished by minimizing the flow nonuniformity. It is found that the heat transfer rate of the optimized model is increased by 6.0% of that of the reference heat exchanger model, and the pressure drop by 0.4%

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.2105-2110
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• 2004

Plate-fin type recuperators for the gas turbine/fuel cell hybrid power generating system were designed using commercial design software, MUSE. Heat transfer efficiency and total pressure drop in the recuperator were calculated to confirm required recuperator performance. Both counter flow and cross flow type plate-fin recuperators were designed. Results show that the counter flow type has higher efficiency and short core length, but the cross flow type is simpler to construct because the cross flow type does not need additional distributors. Two or three headers for the each recuperator core will be designed and tested to evaluate best header design. The designed recuperators and headers which will be designed later will be constructed, tested, and used in gas turbine/fuel cell hybrid power generating system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.423-428
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• 2007

This study was performed to construct a geothermal data base about thermal conductivity of ground heat exchanger and thermal properties of grouting material which used to refill the borehole. We have acquired geothermal data sets from 39 sites over wide area of South Korea except to Jeju island. From data analysis, the range of thermal conductivity is 1.5$\sim$4.0 W/mK. It means that thermal conductivity varies with grouting material as well as regional geology and ground water system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.633-638
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• 2006

This study presents the air side heat transfer and friction characteristics of fin-tube heat exchangers with various fin types. A total of 8 samples of heat exchangers are tested. Fin patterns tested are slit, louver and plate fins. Each fin type has three cases of number of tube rows(N=1, 2, 3) and two different fin pitches. The results are plotted in terms of Colburn j-factor and friction factor f with respect to Reynolds number in the range of 200 to 510.

• 한국가시화정보학회지
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• 제17권1호
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• pp.26-33
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• 2019

The rapid increase in the usage of energy in the fast-changing industries has led to resource depletion and environmental conflicts. Many types of research are available on heat exchangers that undergo simple energy conversion processes. The impingement rods discussed in this study improves the durability of the heat exchanger and ensure the stability of the operation. However, it is uncertain about selecting the installation location of the impingement rods. The commercially available CFD code, ANSYS CFX, is used for the impingement rods installation.

• 한국지열·수열에너지학회논문집
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• 제15권2호
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• pp.1-9
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• 2019

In a ground-source heat pump (GSHP) system, a vertical ground heat exchanger (GHE) is widely accepted due to a higher thermal performance. In the vertical GHE, grout (also called grouting material) plays an important role in the heat transfer performance and the initial installation cost of the GHE. Bentonite-based grout has been used in practice because of its high swelling potential and low hydraulic conductivity. This study evaluated the thermo-physical properties of the bentonite-based grouts through lab-scale measurements. In addition, we conducted performance simulation to analyze the effect of mixed ratio of grouts on the design length and thermal performance of the vertical GHE. The simulation results show that thermally-enhanced grouts improve the heat transfer performance of the vertical GHE and thus reduce the design length of GHE pipe.

• 대한기계학회논문집B
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• 제40권9호
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• pp.557-567
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• 2016

태양열 가열을 도입한 해양온도차발전용 열교환기(증발기와 응축기)설계 최적화가 수행되었다. 출력은 100kW이고 작동유체는 R134a이며 고성능 상용튜브를 사용하였다. 열전달면적과 압력강하는 관수의 증가와 관통로수의 감소에 따라 서로 상반되는 경향이 존재하므로 이를 해결하기 위하여, 설비투자비에 관련되는 열전달면적과 압력강하에 관련되는 운전비용 최소화를 고려한 두 목적함수를 갖는 유전자 알고리즘(GA)을 이용하여 다목적설계최적화를 수행하였다. 설계최적화 결과, 구현 가능한 최적의 열전달면적 및 압력강하의 조합들이 적정한 관수 및 관통로 수에 대하여 존재하였다. 도출된 증발기와 응축기의 Pareto 선들은 설계자들에게 재정적인 면을 고려하여 선택할 수 있도록 넓은 범위의 최적해를 제공하였다. 또한, 총열전달면적 중 응축기의 열전달면적이 증발기 쪽보다 크게 나타났다.

• 에너지공학
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• 제10권2호
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• pp.105-113
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• 2001

지구환경문제와 에너지문제를 해소하는 한 방법으로서 Vuilleumier 사이클 기관(VM)을 이용한 공조기형 열구동형 히트펌프시스템(VMHP)이 각광을 받고 있다. VMHP의 제작에 있어서는 VM의 각 부분의 이론적 검토 및 최적설계를 위한 해석프로그램의 개발이 필수적이고 최적설계를 위한 설계 기본서의 도출 및 설계자료의 확보가 필요하다. VMHP의 상세한 성능해석이나 설계에 활용 가능한 성능해석프로그램을 개발하였다. 해석은 VM의 시스템의 각 부분을 11개 부분으로 나누어 단열모델해석으로 수행하였다. 열교환기에서의 열전달 성능과 재생기손실, 열전도손실, 셔틀손실, 유동에 의한 압력손실과 열압축측과 열펌프측 사이의 마찰손실, 피스턴실 및 로드실의 마찰손실을 고려한 해석을 수행하였다. 해석에 의한 계산치의 정확성을 본 해석결과를 이용하여 제작한 시험기에 의해 비교하였다. 계산치와 시험기에 의한 전체성능을 비교하였고 또한 각각의 손실에서 고유한 파라미터를 추출하여 그 파라미터의 변화에 따른 열손실 전체의 변화 정도를 파악하여 실험치와 계산치의 정상적인 비교로부터 성능해석의 정도를 비교하였다. 비교결과에 의해 난방능력은 8%, 냉방능력은 19%의 최대오차로서 본 해석결과가 VMHP의 설계를 위해 유용한 수단으로 사용될 수 있음을 확인하였다.