• 한국자동차공학회논문집
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• 제20권5호
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• pp.36-43
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• 2012

In this work the mixing and flow characteristics of a vane-type static mixer were investigated numerically for the reduction of NOx in the SCR-system of the diesel engines. The mixer was located in the 57 times pipe diameter away from the inlet. The analysis were performed by changing such various parameters as vane shape, angles, blockage ratio and location of the vane. The flow structure through the mixer was characterized by uniformity index and pressure drop. The results show that uniformity index and pressure coefficient are substantially influenced by the vane shape, angle, blockage ratio and position of the vane of the mixer.

• 한국해양공학회지
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• 제20권4호
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• pp.64-69
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• 2006

A numerical analysis is made to investigate the wave absorption efficiency of a OWC-type wave power generator. Energy absorption by an OWC(Oscillating Water Column) air-chamber is computed in regular waves, taking account of the oscillating surface-pressure, due to pressure drop, across the duct of the air chamber. The problem is formulated in the scope of potential theory and solved by the Localized Finite Element Method(LFEM), based on the classical variational principle. The efficiency of energy absorption is investigated by. changing wave conditions, sea-bottom slope and pressure drop coefficient.

• 설비공학논문집
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• 제14권1호
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• pp.83-90
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• 2002

An experimental study on the performance evaluation of a brazed plate heat exchanger with 10USRT of normal cooling capacity has been carried out. In the present study, a brazed plate heat exchanger was tested at a chevron angle $25^{\circ}$with refrigerant R-22. Refrigerant mass flux was ranged from 23 to 58 kg/$m^2$s in condensation, and from 22 to 53 kg/$m^2$s in evaporation. The heat transfer coefficients and pressure drops are increased as the mass flux increases. The water side pressure drop is increased as the cooling water flow rate and chilled water flow rate increase, while mass flux has little effect. It is also shown that the system performance can be improved by enlarging condensation heat transfer area.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권1호
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• pp.24-31
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• 2003

A new fluidized bed heat exchanger for exhaust gas heat recovery is do-veloped. Compared to the existing ones, the present heat exchanger system is featured by the particle fluidization method which does not depend on conventionally used baffle plate with holes and by the multiple downcomer tubes to extract heat energy from hot particles during the time particles moves down to be fed again to the hot gas line. Particles are introduced to the main hot gas stream alongside the pipe circumference. The heat exchanger performance and pressure drop are evaluated through experiments for the present gas-to-water heat exchanger system.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.279-282
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• 2007

When ground disturbance takes place due to vertical drain construction through mandrel penetration, that affects excess pore water pressure dissipation time because of soft clay coefficient of permeability decreasing. Eventually, consolidation time is influenced. In this research, we measure process of excess pore water pressure dissipation before and after each other different shape's mandrel penetration through model test, and calculates range of smear zone, coefficient of permeability and horizontal coefficient of consolidation after model test. Using of test result, we grasp a degree of drainage ability drop resulting from vertical drain construction.

• 대한기계학회논문집
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• 제16권4호
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• pp.795-802
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• 1992

본 연구에서는 일정한 각도의 분사를 갖는 평씨일(plain seal)에 대하여 각 인자들이 누수성능에 미치는 영향을 수치적으로 조사하였다. 인자들로는 축방향 레 이놀즈수, 축회전속도, 분사의 유입속도, 간극비, 분사의 위치 및 유입각 등이 고려되 었다.

• 동력기계공학회지
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• 제18권5호
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• pp.22-27
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• 2014

The objectives of this paper are to obtain an empirical equations regarding the correlations between heat transfer and pressure drop of oval fin-tube heat exchanger having large diameter using wilson plot method. It was difficult to find any recommendable heat transfer and friction factor correlation available for our large diameter experimental cases. Overall heat transfer coefficients are composed of the heat transfer coefficients both inside and outside tubes. The resulting empirical correlations for the Nui and f-factor are given as $Nu_i=0.0146Re^{0.809}Pr^{0.3}$ and $f=4.366Re^{-0.64}$, respectively. The empirical correlations of the Nui and f-factors were developed for the large diameter oval finned-tube heat exchanger as a function of the Reynolds number. As the EG(Ethylene glycol) and air flow rate increases, the heat transfer rate and pressure drop is increased largely.

• 대한기계학회논문집B
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• 제22권11호
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• pp.1555-1563
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• 1998

Heat transfer and pressure drop for ${\phi}10.07$ dry surface fin-tube heat exchanger with wave and wave-slit fins were measured for different fin spacings and number of tube rows. Longitudinal and transverse tube spacings of the heat exchangers are 21.65mm and 25mm respectively, and wave depth of wave fin is 1.5mm. The experiments were performed for 4 different fin spacings, 1.3, 1.5, 1.7 and 2.0mm, and the number of tube rows were 1,2 and 3 rows. The present results were compared with the previous results for the wave depth of 2mm. Also hydrophilic coated and bare fins were tested. Correlations for Colburn j-factor and friction factor were developed.

• 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%.

• 동력기계공학회지
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• 제4권1호
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• pp.26-32
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• 2000

Single-phase heat transfer performance and pressure drop for internally grooved tubes with angles were studied. Experiments were carried out in a counter flow heat exchanger with water as a working fluid. Two commercially available internally grooved tubes and smooth tube were tested. The internal diameter of the smooth tube was 16.5mm and the internal diameters of grooved tubes were 15.4mm, 14.9mm, 15.0mm, 16.7mm, respectively. Grooved angles in the tubes were $37^{\circ},\;43^{\circ},\;45^{\circ},\;50^{\circ}$, respectively. An experimental device to measure the friction factor and heat transfer coefficient was constructed. The experimental results were obtained for the fully developed turbulent flow of water in tube on the condition of uniform heat flux. As the increase of flow rate, Reynolds number, numbers of groove and grooved angle led to the increase of pressure drop. Also this paper showed that heat transfer rate increased with increasing numbers of groove and grooved angle. An empirical relation taken from this study represented most of the data within ${\pm}25%$.