• 한국산학기술학회논문지
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• 제16권5호
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• pp.3014-3021
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• 2015

셀-튜브 열교환기는 다양한 크기와 유동형태로 쉽게 제작이 용이함으로 산업분야에 널리 이용된다. 본 연구에서는 열교환기의 열전달성능을 도모하고자 배플의 컷 방향, 배플의 경사각 및 배플의 회전각 등을 변경하여 ANSYS FLUENT v.14를 사용한 SST $k-{\omega}$ 난류모델을 적용하여 쉘 내부의 열전달률 및 압력강하 특성을 해석하였다. 그 해석결과로 배플의 컷 방향은 수평형 모델 A보다 수직형 모델 B 및 각도 $45^{\circ}$형 모델 C가 이 열전달성능이 향상되는 것으로 나타났다. 또한 배플의 경사각을 $10^{\circ}$로 적용한 경우와 배플의 회전각을 $0^{\circ}-90^{\circ}-180^{\circ}-270^{\circ}$로 배치한 모델 D의 경우가 열전달률 및 압력강하 특성이 우수한 결과를 나타냈다.

• 설비공학논문집
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• 제13권5호
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• pp.368-376
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• 2001

Performance of heat exchanger was evaluated to heat exchanger using oscillating heat pipe for waste heat recovery of low temperature. Oscillating heat pipe used in this study was formed to the closed loop of serpentine shapes using copper tubes. Heat exchanger was formed to shell and tube type and composed of low finned tube. R-22 and R-141b were used to the working fluids of tube side and their charging ratio was 40%. And, water was used to the working fluid of shell side. As the experimental parameters, the inlet temperature difference of heating and cooling part of secondary fluid and the mass velocity of secondary fluid were used. The mass velocity of secondary fluid was changed from 90 kg/$m^2s\; to\;190 kg/m^2$s from the experimental results, heat recovery rate was linearly increased to the increment of the mass velocity of secondary fluid and the inlet temperature difference of secondary fluid. Finally, the performance of heat exchanger was evaluated by using $\varepsilon$-NTU method. It was found that NTU was about 1.5 when effectiveness was decided to 80%.

• Journal of Mechanical Science and Technology
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• 제20권2호
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• pp.212-226
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• 2006

This paper is a continuation of the authors' previous work on spiral coil heat exchangers. In the present study, the heat transfer characteristics and the performance of a spirally coiled finned tube heat exchanger under wet-surface conditions are theoretically and experimentally investigated. The test section is a spiral-coil heat exchanger which consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled finned tubes. Each tube is fabricated by bending a 9.6 mm diameter straight copper tube into a spiral-coil of four turns. The innermost and outermost diameters of each spiral-coil are 145.0 and 350.4 mm, respectively. Aluminium crimped spiral fins with thickness of 0.6 mm and outer diameter of 28.4 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Air and water are used as working fluids in shell side and tube side, respectively. The experiments are done under dehumidifying conditions. A mathematical model based on the conservation of mass and energy is developed to simulate the flow and heat transfer characteristics of working fluids flowing through the heat exchanger. The results obtained from the present model show reasonable agreement with the experimental data.

• 한국자동차공학회논문집
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• 제1권2호
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• pp.42-48
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• 1993

In this paper, dynamic collapse behavior of the rectangular tube under impact loading is anlayzed using nonlinear finite element method of shell element. In case of shell element formulation using corotational element coordinates system, dynamic collapse behavior is analyzed without initial imperfection, and with initial imperfection. This paper reveals that the collapse of a rectangular tue without initial imperfection is caused by an error of transformation of the corotational coordinates system.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2018년도 공동국제학술발표회
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• pp.198-198
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• 2018

• 한국막학회:학술대회논문집
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• 한국막학회 1992년도 추계 총회 및 학술발표회
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• pp.43-44
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• 1992

촉매막반응기란 반응기와 분리막이 동시에 하나의 과정으로 결합된 unit로, 촉매막반응기를 사용할 경우 가역 반응에서 막을 통한 생성물의 선택적 제거는 화학 평형이동을 유발시켜 열역학적으로 얻을수 있는 평형 전환율보다 높은 전환유을 얻을 수 있다. 본 연구는 이러한 촉매막반응기의 성능에 대한 실험적 연구로, 산 촉매하에서 일어나는 MTBE 분해반응을 12-텅스토인산 촉매상에서 수행하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 춘계 학술대회논문집
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• pp.49-55
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• 2004

This paper addresses a numerical simulation of the flow and heat transfer in a simplified model of helically coiled tube steam generator using a general purpose computational fluid dynamic analysis computer code. The steam generator model is comprised of a cylindrical shell and helically coiled tubes. A cold feed water entered the tubes is heated up, evaporates. and finally become a superheated steam with a large amount of heat transferred continuously from the hot compressed water at higher pressure flowing counter-currently through the shell side. For the calculation of tube side two-phase flow field formed by boiling, inhomogeneous two-fluid model is used. Both the internal and external turbulent flows are simulated using the standard k-e model. The conjugate heat transfer analysis method is employed to calculate the conduction in the tube wall with finite thickness and the convections in the internal and external fluids simultaneously so as to match the fluid-wall-fluid interface conditions properly. The numerical calculations are peformed for helically coiled tubes of steam generator at an integral type pressurized water reactor under normal operation. The effects of tube-side inlet flow velocity are discussed in details. The results of present numerical simulation are considered to be physically plausible based on the data and knowledge from previous experimental and numerical studies where available.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1233-1243
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• 2023

Shell-and-tube heat exchanger (STHX) is widely used by virtue of its simple structure and high reliability, especially in a space-constrained surface ship. For the STHX of the surface ship, roll, pitch and other motion of the ship will affect the heat transfer performance, resistance characteristics and structural strength of the heat exchanger. Therefore, it is urgent to carry out numerical simulation research on three-dimensional thermal hydraulic characteristics of surface ship STHX under the marine conditions. In this paper, the numerical simulation of marine shell and tube heat exchanger of surface ship was carried out using the porous media model. Firstly, the mathematical physical model and numerical method are validated based on the experimental data of a marine engine cooling water shell and tube heat exchanger. The simulation results are in good agreement with the experimental results. The prediction errors of pressure drop and heat transfer are less than 10% and 1% respectively. The effect of marine conditions on the heat transfer characteristics of the heat exchanger is investigated by introducing the additional force model of marine condition to evaluate the effect of different motion parameters on the heat transfer performance of the heat exchanger. This study could provide a reference for the optimization of marine heat exchanger design.

• 대한기계학회논문집 C: 기술과 교육
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• 제3권1호
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• pp.23-28
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• 2015

본 논문은 GHP 에 사용되고 있는 이중 쉘-튜브형 배기가스 열교환기의 설계 변수의 변화에 따라 열전달 및 마찰특성 변화를 알아보기 위해 CFD 와 RSM 을 이용하여 최적화를 수행하였다. CFD 해석은 복잡한 형상의 열교환기 해석에 유용한 도구이나, 해석결과를 얻기까지 많은 시간이 소요된다. 이러한 해석시간을 줄이고, 유용한 결과를 얻기 위해 RSM 과 병행하여 최적화 설계를 진행하였다. 시뮬레이션 결과를 이용한 RSM 해석결과, 배플 6 개, 튜브 25 개에서 최적화되었으며, 기존 보다 차압 및 열전달 성능이 약 12.2% 개선되었다. 이러한 CFD 와 RSM 을 이용한 최적화 기법은 다양하고 복잡한 형상의 열교환기 해석에 유용함을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.875-880
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• 2002

It is necessary to determine the vibration source and its transmission paths in order to develop a low-noise compressor. Through the use of multiple-input/single-output(MISO) mode1, the transmission paths of vibration within a reciprocating compressor have been investigated. In order to identify the transmission path, we measure the accelerations of the block and transverse vibrations of the line discharge tube. As outputs, vibrations of compressor shell were measured at three positions; cylinder head, one near the suction line, and the top of upper shell. The partial coherence function and transfer function are obtained ken the measured data, and the results are observed in order to determine vibration source and its influence on the shell vibration.