• International Journal of Air-Conditioning and Refrigeration
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• 제17권2호
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• pp.52-60
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• 2009

The purpose of this research is to develop high efficiency plastic plate heat exchangers which can be substituted for conventional aluminum plate heat exchangers. Four simulation models of plastic plate heat exchangers are designed and simulated: that is, flat plate type, turbulent promoter type, corrugate type and dimple type heat exchanger. The flat plate type is designed as the reference model in order to evaluate how much thermal performance increases. The turbulent promoter type is fabricated with cylindrical-type vortex generators and rib-type turbulent promoters. The corrugate type is obtained from the conventional stainless steel compact heat exchangers, which are called the herringbone-type compact heat exchangers. The dimple type has a number of dimples on its surface. In this study, the flow and heat transfer characteristics of the plastic plate heat exchanger are investigated using numerical simulation and compared with experimental results. Numerical simulation is carried out using the FLUENT code. The flows are assumed as a three-dimensional, incompressible and turbulent model. The computational analysis and experimental results both show that the friction coefficient and Nu number is highest in the corrugate type. The tendency of numerical simulation results is in good agreement with that of the experimental results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.1876-1881
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• 2007

The micro plated heat exchangers were designed to transfer more heat/volume or mass than previous heat exchangers within the context of the design constraints specified. The increase of the surface-to-volume ratio results in an increase of the interfacial area. This enhances considerably the performance of a heat exchanger. This can be an important component in a wide range of applications fuel cell, aerospace, automotive, electronic system and home heating, etc). In this study, the performance evaluation of micro plated heat exchangers under the counter flows with straight and S-shaped channel are carried out. The pressure drop as well as inlet and outlet fluid temperature were measured at steady state under various operating conditions and the total heat transfer rate were also calculated.

• 한국산학기술학회논문지
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• 제12권3호
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• pp.1111-1116
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• 2011

열교환기는 자동차, 공조시스템 및 기타 다양한 산업시설에 이용되고 있어 그 수요가 매우 넓다. 보통 고효율의 루버핀 열교환기는 비오염 환경에 많이 사용되고 파형핀 열교환기는 건설 현장 등 오염이 문제가 되는 곳에 사용된다. 본 논문에서는 공기측과 오일측에 각기 다른 형태의 격자를 사용할 수 있는 듀얼셀 모델을 이용하여 오일쿨러나 연료쿨러에 쓰이는 전형적인 열교환기에 대한 방열 성능을 수치해석하였다. 먼저 풍동 실험을 통한 열교환기 방열성능 실험을 수행하여 1차원 방열성능 데이터를 확보하였다. 다음으로 3차원 수치해석 듀얼셀 열교환기 모델을 이용하여 통과 풍량에 따른 열교환량을 예측하였다. 이러한 모델은 통과 풍속의 불균일도에 따른 열교환량을 예측할 수 있어 방열설계 정확성 향상에 크게 기여할 수 있다.

• 대한기계학회논문집B
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• 제25권11호
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• pp.1492-1499
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• 2001

In order to develop the compact and flexible heat exchangers, we made the helically coiled heat exchangers. They can be manufactured with small diameter copper tubes without the need for fins; inner diameter=1.0 mm, straight tube length=1.5 m. The experiments were carried out with the following conditions; evaporation pressure=0.6 MPa, air velocity=0.7 ∼ 1.7 m/s, and working fluid=R-22. Pressure drop and heat transfer coefficient of heat exchangers were experimented according to the air velocity. The results of heat transfer coefficient show a 35% beneficial increase fur these heat exchangers over the other covered fin-tube heat exchangers. A cooling capacity of about 3 kW was obtained with an air velocity of 1.5 m/s. The distribution header has also been designed fur efficient distribution of refrigerant flow.

• 동력기계공학회지
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• 제17권6호
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• pp.54-62
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• 2013

A numerical analysis is performed to evaluate mass flow balance in the heat exchanger for the dehumidifier. To improve the mass flow balance for maximum heat transfer performance, inlet, outlet and baffle are changed. Mass flow balance is evaluated by non-uniformity of flow which is the same concept with the standard deviation. Usually, there will occur many paths between the inlet and the outlet, however, it will follow shortest and low resistance ways. The uniform distribution of flow is numerically analyzed for several types of heat exchangers. Making the shortest way between the inlet and the outlet is most important factor. Two types of heat exchangers are installed in the dehumidifier and 4 cases of Type A heat exchangers and 3 cases of Type B heat exchangers are evaluated and optimized. The result of this research is applied to design heat exchanger for commercial dehumidifiers.

• 한국산학기술학회논문지
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• 제10권2호
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• pp.222-229
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• 2009

본 논문에서는 루버형 핀 형상을 가진 핀-튜브 열교환기와 알루미늄 평행류 열교환기의 에어컨 응축기 조건에서의 열전달 성능과 공기측 압력강하 특성을 비교하였다. 모든 실험은 ASHRAE 표준에 근거해 제작된 공기엔탈피형 칼로리미터를 사용하여 수행하였다. 관외 측 공기 속도는 0.7-1.6 m/s까지 0.3 m/s 간격으로 변화시켰으며 건구온도는 $20^{\circ}C$, 상대습도는 60%로 유지하였다. 관내 측 물의 입구온도는 $70^{\circ}C$, 유량은 10 LPM로 고정하였다. 알루미늄 열교환기의 열전달 성능은 루버 핀-튜브 열교환기보다 단위체적당, 단위질량당, 단위열전달면적당 약 17-163%정도 높게 나타나는 연구결과를 보였으며 반면에 공기측 압력강하는 핀-튜브 열교환기에 비해 약 19-81% 정도 낮게 나타났다.

• 대한기계학회논문집B
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• 제33권1호
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• pp.53-59
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• 2009

The objectives of this paper are to study the characteristics of heat transfer and pressure drop of the micro channel heat exchangers using diffusion bonding technology. Four types of heat exchangers are designed and manufactured, which are straight type, long dot type, splited wavy type and straight double side type. Heat transfer and pressure drop performance of each heat exchangers are measured in various operating conditions, and compared each other. The results show that the $(j/f)^{1/3}$ performance of splited wavy type and long dot type increases about 10.3% and 6.1% at the Reynolds number 470 compared to that of straight type, respectively. On the other hand, $(j/f)^{1/3}$ performance of straight double side type decreases 19.7%.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2304-2309
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• 2008

The objectives of this paper are to study the characteristics of heat transfer and pressure drop of the micro channel heat exchangers using diffusion bonding technology. Four types of heat exchangers are designed and manufactured, which are straight type, long dot type, splited wavy type and straight double side type. Heat transfer and pressure drop performance of each heat exchangers are measured in various operating conditions, and compared each other. The results show that the $(j/f)^{1/3}$ performance of splited wavy type and long dot type increases about 10.3% and 6.1% at the Reynolds number 470 compared to that of straight type, respectively. On the other hand, $(j/f)^{1/3}$ performance of straight double side type decreases 19.7%.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.51-58
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• 2020

Despite the recent growth of interest in molten salt reactor technology and the crucial role which heat transfer plays in the design of power reactors, specific studies on the design of heat exchangers for the Molten Salt Fast Reactor have not yet been performed. In this work we deliver a preliminary but quantitative analysis of the intermediate heat exchangers, based on reference design data from the SAMOFAR H2020-Euratom project. Two different promising reference technologies are selected for study thanks to their compactness features, the Printed Circuit and the Helical Coil heat exchangers. We present preliminary design results for each technology, based on simplified design tools. Results highlight the limiting effects of the compactness constraints imposed on the fuel salt inventory and the allowed size. Large pressure drops on both flow sides are to be expected, with negative consequences on pumping power and natural circulation capabilities. The small size required for the flow channels also represents possible fabrication issues and safety concerns regarding channel blockage.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.627-632
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• 2006

An experimental study is conducted to investigate the effect of the tube row and fin spacing on the air-side heat transfer and friction characteristics of fin-tube heat exchangers with slit fin pattern. A total of twelve samples of fin-tube heat exchangers with the nominal tube diameter of 7 mm, transverse tube pitch of 19 mm and longitudinal tube pitch of 12.5 mm are tested. The thermal fluid measurements are made using a psychometric calorimeter. The raw data are reduced to the desired heat transfer coefficient in terms of j-factor and friction factor of f for various frontal air velocities, fin pitches and number of tube rows.