• 동력기계공학회지
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• 제14권1호
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• pp.22-26
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• 2010

Generally, it is a method to remove the fouling cleaning the plate heat exchanger with chemicals or polishing with a brush or cloth after stopping the equipment and disassembling heat exchanger. However, the equipment must be stopped and taken apart when using this method, which causes an unnecessary work to assemble again after cleaning it. In this study, it has developed and tested the equipment which can automatically clean the fouling on plate heat exchanger at regular intervals with air bubbles. It indicated that the overall heat transfer coefficient had decreased without significant differences similar to that calculated without air bubbles until after 72 hours when making air bubbles to remove fouling ingredient on the surface of heat transfer area every 10 minutes per 2 hours. However, it showed that there was a 10% higher of heat transfer effect compared to the case without air bubbles of after 192 hours.

• 설비공학논문집
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• 제16권9호
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• pp.855-862
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• 2004

This study reports pressure drops during evaporation for R-l34a, R-407C (a mixture of 23 wt% R-32, 25 wt% R-125, and 52 wt% R-l34A) and R-410A (a mixture of 50 wt% R-32 and 50 wt% R-125) in the oblong shell and Plate heat exchanger. The effects of the mass fluxes, heat fluxes, refrigerant saturation temperatures and vapor quality of refrigerants on the measured data were explored in detail. The present data showed that pressure drops of all refrigerants increase with the vapor quality. At a higher mass flux, pressure drops are higher for the entire range of the vapor quality A rise in the heat flux doesn't show significant effects on the pressure drops. Finally, at a higher saturation temperature the pressure drops are found to be lower. The pressure drops for R-407C were approximately 20% lower than those of R-l34a. R-410A had 33% lower pressure drops than R-l34a. Correlation is also provided for the measured pressure drops in terms of the friction factor.

• 한국결정성장학회지
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• 제30권6호
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• pp.237-243
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• 2020

본 연구에서는 STS-316 플레이트와 구리(Cu) 브레이징으로 구성된 접합 판형 열교환기(BPHE, Brazed Plate Heat Exchanger)의 내식성과 열효율 성능 향상을 위해 실란계 코팅을 적용하고자 하였다. 코팅 재료에 따른 부식 및 접촉각을 평가하여 선정된 코팅재료를 열교환기에 적용하였으나, 전열 성능 평가 결과 코팅하지 않은 열교환기에 비해 열효율이 떨어지는 결과가 나타났다. 이는 접합 판형 열교환기 내부의 유로에 코팅제의 고착화 및 표면의 잔여 코팅제가 열저항으로 작용하여 열전달을 방해는 것으로 분석되었다. 이는 내부에 미세한 유로가 존재하는 판형 열교환기의 구조적인 특성에 기인한 것으로, 판형 열교환기 제작 공정에서 사전에 유로 표면에 코팅 후 제작하는 것이 전열성능을 향상 시킬 수 있을 것으로 판단된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1046-1051
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• 2004

A plate-fin-tube heat exchanger used for a $SF_{6}$ gas-insulated transformer is extremely important since the dissipation of the heat generated from inside coils has a significant effect on the performance as well as the durability of the transformer. The heat exchanger consists of corrugated plate fins and staggered array tube bundles for coolant. In order to find out heat transfer and pressure drop characteristics, series of numerical analyses for plate fins with enhanced surface geometries were conducted. Based on the results of the numerical analyses, an improved model of the plate fin has been proposed.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.172-177
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• 2005

The object of this experiment is comparing heat transfer performance and pressure drop characteristics by baffle cut rate, fluid velocity and heating temperature. Experiments were carried out in cross flow heat exchanger with water as a working fluid. In this experiment, baffle cut rate is 30%, 40%, 50%, velocity is 0.5m/s, 1.0m/s, 1.5m/s, and heating temperature is $30^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$. An experimental device to measure the heat transfer coefficient was constructed. The experimental result were obtained for the fully developed turbulent flow of water in tube on the condition of uniform heat flux.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2292-2297
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• 2008

Recently, a study on condensers for refrigerators has focused on new model which will cost less and will be more efficient. Some widely used condensers for domestic refrigerators are wire-and-tube type condenser, hot-wall type condenser, and spiral type condenser. Some companies which use the spiral type condenser at the moment try to develop a new type condenser which will cost less and will be as efficient as the spiral type. The new type condenser consists of a steel tube, steel plates and louver fins attached to the tube. The tube and the plate are bent into a single-passage serpentine shape.

• 한국수소및신에너지학회논문집
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• 제32권3호
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• pp.180-188
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• 2021

This paper conducted a study on the ortho-para hydrogen conversion in the cryogenic heat exchanger filled with catalysts for hydrogen liquefaction by utilizing the numerical model of plate-fin heat exchanger considering catalytic reaction of ortho-para hydrogen conversion, heat and mass transfer phenomena and fluid dynamics in a porous medium. Various numerical analyzes were performed to investigate the characteristics of ortho-para hydrogen conversion, the effects of space velocity and activated catalyst performance.

• 대한기계학회논문집B
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• 제28권12호
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• pp.1535-1548
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• 2004

Condensation heat transfer experiments were conducted with the oblong shell and plate heat exchanger without oil in a refrigerant loop using R-l34a, R-407C and R-410A. An experimental refrigerant loop has been developed to measure the condensation heat transfer coefficient h$_{r}$ and frictional pressure drop $\Delta$p$_{f}$ of the various refrigerants in a vertical oblong shell and plate heat exchanger. The effects of the refrigerant mass flux(40∼80kg/$m^2$s), average heat flux(4∼8kW/$m^2$), refrigerant saturation temperature(30∼4$0^{\circ}C$) and vapor quality of refrigerants on the measured data were explored in detail. Similar to the case of a plate heat exchanger, even at a very low Reynolds number, the flow in the oblong shell and plate heat exchanger remains turbulent. A comparison of the performance of the various refrigerants revealed that R-410A had the highest heat transfer performance followed by R-l34a, and R-407C had the lowest performance of the refrigerants tested. The pressure drops were also reported in this paper. The pressure drops for R-410A were approximately 45% lower than those of R-l34a. R-407C had 30% lower pressure drops than R-l34a. Experimental results were compared with several correlations which predicted condensation heat transfer coefficients and frictional pressure drops. Comparison with the experimental data showed that the previously proposed correlations gave unsatisfactory results. Based on the present data, empirical correlations of the condensation heat transfer coefficient and the friction factor were proposed.tor were proposed.sed.

• 설비공학논문집
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• 제16권9호
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• pp.845-854
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• 2004

The evaporation heat transfer coefficient for R-l34a, R-407C (a mixture of 23wt% R-32, 25 wt% R-125, and 52 wt% R-l34a) and R-410A (a mixture of 50 wt% R-32 and 50 wt% R-125) flowing in the oblong shell and plate heat exchanger were investigated experimentally in this study. Four vertical counterflow channels were formed in the exchanger by four plates of commercial geometry with a corrugated sinusoid shape of a chevron angle of 45 degree. The effects of the mean vapor quality, mass flux, heat flux, and saturation temperature of different refrigerants on the evaporation heat transfer were explored in detail. Similar to the case of a Plate heat exchanger, even at a very low Reynolds number, the flow in the oblong shell and plate heat exchanger remains turbulent. It is found that the evaporation heat transfer coefficient in the plates is much higher than that in circular pipes. The present data show that the evaporation heat transfer coefficients of all refrigerants increase with the vapor quality. At a higher mass flux h, is higher than for the entire range of the vapor quality. Raising the imposed wall heat flux was found to slightly improve h$_{r}$, while h$_{r}$ is found to be lower at a higher refrigerant saturation temperature. A comparison of the performance of the various refrigerants reveals that R-410A has the highest heat transfer performance followed by R-l34a, and R-407C had the lowest performance of the refrigerants tested. Based on the present data, empirical correlations of the evaporation heat transfer coefficient were proposed.sed.

• 한국수소및신에너지학회논문집
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• 제15권3호
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• pp.194-200
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• 2004

Thermal energy performance of a brazed plate heat exchanger has been evaluated experimentally. The effects of plate pitch as well as chevron angle of a plate heat exchanger on the heat transfer rate and pressure drop have been investigated in the wide range as mass flow rates in detail. This problem is of particular interest in the design of a plate heat exchanger. The results obtained indicate that both heat transfer rate and pressure drop are increased as mass flow rate is increased, as expected. It is also found that the heat transfer rate is increased with a decrease in the plate pitch while the heat transfer is decreased with a decrease in the chevron angle. Friction factor correlations are suggested based on the measured pressure drop and effectiveness of plate heat exchangers are also compared.