• 한국지열·수열에너지학회논문집
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• 제7권2호
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• pp.23-29
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• 2011

The objectives of this paper are to study the characteristics of heat transfer and pressure drop of the plate heat exchanger with corrugation height by numerical analysis. Plate heat exchanger of three types was designed, which was corrugation height 3.1mm, 2.8mm and 2.5mm. The plate heat exchanger was numerically investigated for Reynolds number in a range of 950~3,380. The temperatures of the hot side were performed at $14.5^{\circ}C$ while that of the cold side was conducted at $4.5^{\circ}C$. The results show that the performance of heat transfer coefficient for corrugation height 2.5mm increases about 9.5~17.1% compared to that of corrugation height 3.1mm. On the other hand, the performance of pressure drop for corrugation height 2.5mm is remarkably higher than that of corrugation height 3.1mm, about 65.7~86.0%.

• 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.

• 동력기계공학회지
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• 제11권2호
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• pp.20-25
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• 2007

The performance of air-to-air heat exchanger has been investigated with rotating porous plates newly developed in this study. With an equal interval of 18 mm, the rotating porous plates are installed inside the heat exchanger where the hot and cold airs enter at opposite ends. When flowing in opposite directions by the separating plate installed in the center of the rotating porous plates, the airs give and receive the heat each other. Dry bulb temperature is set by adjusting heat supply at heater. In order to measure the temperature distribution of the hot air side inside heat exchanger, the thermocouples are inserted between the plates. The first location of thermocouple is 10mm downstream from the inlet of heat exchanger, and succeeding ten locations are aligned at an equal interval of 18mm. From the experiment of air-to-air heat exchanger with the rotating porous plates, the heat transfer rate increased as both air flow rate and RPM of the rotating porous plate increased. It was found that the overall heat transfer coefficient increased with the increase in RPM of porous plate at the conditions of the same air flow rate.

• 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.

• 대한기계학회논문집B
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• 제32권9호
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• pp.676-682
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• 2008

Numerical analysis was carried out to examine the heat transfer and pressure drop characteristics of plate heat exchangers for absorption application using Computational Fluid Dynamics(CFD) technique. A commercial CFD software package, FLUENT was used to predict the characteristics of heat transfer, pressure drop and flow distribution within plate heat exchangers. In this paper, a welded plate heat exchanger with the plate of chevron embossing type was numerically analyzed by controlling mass flow rate, solution concentration, and inlet temperatures. The working fluid is $H_2O$/LiBr solution with the LiBr concentration of 50-60% in mass. The numerical simulation shows reasonably good agreement with the experimental results. Also, the numerical results show that plate of the chevron shape gives better results than plate of the elliptical shape from the view points of heat transfer and pressure drop. These results provide a guideline to apply the welded PHE for the solution heat exchanger of absorption systems.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.419-424
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• 2008

Heat transfer and pressure drop characteristics of welded plate heat exchanger are studied to apply it for the solution heat exchanger of 210RT absorption system. This study quantifies the effect of mass flow rate and strong solution concentration on the heat transfer coefficient and pressure drop in the plate heat exchanger. The concentration of weak solution is fixed at 55% and the strong solution varies 55%, 57%, and 59% in mass. The results show that the overall heat transfer coefficient and pressure drop increase linearly with increasing Reynolds number. It is also found that the heat transfer coefficient of hot side increases with increasing the concentration of strong solution while the strong solution concentration has no effect on heat transfer coefficient of cold side.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.91-100
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• 2004

Plate heat exchangers (PHE) have been widely used in different industrial applications, because of high heat transfer efficiency per unit volume. Basic study is performed for PHE to the application of intercooler in automobile. In order to understand the flow phenomena in the plate heat exchanger, a channel which was formed by the upper and lower plate in single plate was considered as calculation domains. Because chevrons attached on the upper plate are brazed with chevrons attached on the lower plate, the flow channel has very complex configuration. This complex geometry was analyzed by Fluent. In order to validate this methodology the proper experimental and theoretical data are collected and compared with numerical results. Finally, due to the lack of experimental values for PHE to the application of intercooler, various chevron angles and air velocities at inlet were tested in terms of physical phenomena. From this point of view, results of velocity vector, path lines, static pressure, heat flux, heat transfer coefficient, and Nusselt number are physically reasonable and accepted for the solutions. From these results, the correlations for pressure drop and Nusselt number with respect to chevron angle and Reynolds number in specific PHE are obtained for the design purpose. Thus, the methodology of the flow analysis in the full geometry of the channel was established for the predictions of performance in plate heat exchanger.

• 설비공학논문집
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• 제18권8호
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• pp.627-634
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• 2006

Evaporation heat transfer characteristics by pulsating flow in a plate heat exchanger have been investigated experimentally in this study. R-l34a is evaporated by receiving heat from the hot water in the plate heat exchanger. The pulsating frequency in refrigerant side of the plate heat exchanger is varied in the range of 5-25 Hz. The operating pressure of R-l34a and mass flux of hot water are also varied 0.6-0.9 MPa and $45-105 kg/m^2s$, respectively. The experimental results indicate that evaporation heat transfer coefficient of pulsating flow is improved up to 6.3% compared with that of the steady flow at 10 Hz and $G_w=45 kg/m^2s$. It is also found that the evaporation heat transfer enhancement ratio is decreased with an increase in mass flux of hot water, and the evaporation heat transfer enhancement is little influenced by operating pressure of R-l34a.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.189-194
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• 2009

In a gas engine based cogeneration system, heat is recovered from two parts, which are jacket water and exhaust gas. The heat from the jacket water is often recovered by a plate type heat exchanger and used for the room heating and/or hot water supply. Depending on the operating conditions of engine and heat recovery system, there should be imbalance in the flow rate and supply pressure between engine and heat recovery side of the heat exchanger. The imbalance cause the deformation of the plate, which affects the pressure drop characteristics. In the present study, the pressure drop inside the heat exchanger has been investigated in a 1/5 scaled test rig and compare with the experimental correlations, which are used for the design.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2363-2368
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• 2008

The objectives of this paper are to measure the heat transfer and pressure drop of the plate heat exchangers for absorption system applications. Three types of plate heat exchangers with different chevron angles are tested in the present experiment. Heat transfer and pressure drop performance of plate heat exchangers are measured in various operating conditions, and compared each other. The results show that the heat transfer rate of high theta ($120^{\circ}$) and mixed theta plate heat exchanger increases about 118% and 98% at the solution flow rate 350 kg/h compared to that of low theta ($60^{\circ}$), respectively. The effectiveness of high theta was evaluated about $0.70{\sim}0.83$ in this experimental range.