• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.639-644
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• 2009

This study presents the new idea of liquid desiccant system with extended surface to reduce the system size. The extended surface is inserted between vertical cooling/heating tubes to increase the mass transfer area, and the liquid desiccant flows through the tube wall and the extended surface. Mathematical models for heat and mass transfer between liquid desiccant and air stream at tube wall and extended surface are provided. Dimensionless design parameters governing heat and mass transfer phenomena around the tube and the extended surface are identifier, and dimensionless operating parameters depicting system operating condition including flow rate ratio between dehumidification/regeneration processes, and mass flow rate ratio between air stream and liquid desiccant are explained. The effects of the parameters on system performance are summarized.

• 한국분무공학회지
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• 제1권1호
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• pp.21-27
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• 1996

This experimental study was to investigate spray angles and drop sizes in an external mixed twin-fluid swirl jet nozzle. Twin-fluid swirl jet nozzle with swirlers designed four swirl angles such as $0^{\circ},\;22.5^{\circ},\;45^{\circ},\;64.2^{\circ}$ was employed. A PDA system was utilized for the measurement of drop size and mean velocity. Water and air were used as the working fluids in this experiment. The mass flow rate of water was fixed as 0.03 kg/min, and air flow rates were controlled to have the air/liquid mass ratio from 1.0 to 6.0. As a result, swirl angle controlled to spray angles and drop sizes. It was found that swirl angle was increased with spray angle and with decreased SMD. However, the effect of swirl angle was reduced at large air/liquid mass ratio(Mr=6.0).

• 대한기계학회논문집
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• 제12권6호
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• pp.1390-1398
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• 1988

본 연구에서는 액주가 가장 긴 평활류 조건하에서 여기에 동축수직하방으로 공기를 흘렸을 경우, 액주분열에 영향을 미친다고 생각되는 제 인자 즉, 액체유속, 공 기유속, 액체노즐과 공기 오리피스 직경의 비, 노즐의 형상, 기액 접촉개시 위치등을 변화시켜 분열과정 및 분열기구를 규명하고, 이류체 분사노즐의 설계기준을 제공하는 것을 그 목적으로 한다.

• 설비공학논문집
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• 제29권7호
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• pp.385-389
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• 2017

Generally, refrigerant temperature out of the receiver is assumed to be saturated. This may be true for horizontal or vertical receivers having small aspect ratio. However, this assumption needs verification for vertical receiver having large aspect ratio. No study has reported information on this issue. The objective of this study was to determine the effect of liquid level and mass flow rate on liquid subcooling of a long vertical receiver using R-410A. During the test, inlet subcooling was maintained at $5^{\circ}C$ while saturation temperature was maintained at $10^{\circ}C$. Results showed that subcooling was maintained for the long vertical receiver. Subcooling preservation ratio (ratio of exit to inlet subcooling) was increased as mass flow rate or liquid level was increased. As a whole, 50 to 70% subcooling preservation was possible for the present receiver. Further investigations are needed to enhance information on this issue using receivers having different aspect ratios.

• 한국분무공학회지
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• 제5권3호
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• pp.27-36
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• 2000

In this study, spray characteristics of a dual airblast atomizer are addressed. Three dimensional characteristics of a dual airblast atomizer with air swirl are measured to provide the significant data. The liquid flow rate was fixed at 0.06 kg/min, and atomizing air was controlled at the liquid-air mass ratio of 4.0. The performance of the spray with co-swirl and counter-swirl flow was investigated at each point in the developed spray region using a three-component phase Doppler particle analyzer. This instrument was also used to evaluate the concentration profiles. The three dimensional mean velocity were investigated of present flow characteristics of the dual airblast atomizer. In addition, drop size distributions, mean droplet size profile, and droplet concentration were analyzed to understand atomization characteristics. This experimental results can be conveniently utilized for the preliminary design of gas turbine engines for aircraft.

• 동력기계공학회지
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• 제18권5호
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• pp.88-93
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• 2014

In this paper, the performance analysis of condensation and evaporation capacity, turbine work and efficiency of the OTEC power system using vapor-liquid Ejector is presented to offer the basic design data for the operating parameters of the system. The working fluid used in this system is $CO_2$. The operating parameters considered in this study include the vapor quality at heat exchanger outlet, pressure ratio of ejector and inlet pressure of low turbine, mass flow ratio of separator at condenser outlet. The main results were summarized as follows. The efficiency of the OTEC power cycle has an enormous effect on the mass flow ratio of separator at condenser outlet. With a thorough grasp of these effects, it is possible to design the OTEC power cycle proposed in this study.

• 한국분무공학회지
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• 제5권3호
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• pp.9-16
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• 2000

In a SI engine, three-way catalyst converter has the best efficiency when A/F ratio is near the stoichiometry. The feedback control using oxygen sensors in the commercial engine has limits caused by the system delays. So it is necessary to control fuel quantity in accordance with intake air amount in order to reduce exhaust emission and improve the specific fuel consumption. Precise A/F ratio control requires measurement of air amount with respect to the cylinder and injection fuel according to the air amount In this paper, we applied nonlinear fuel injection model and developed the algorithm of A/F ratio control. This algorithm includes the methods of measurement of transient air mass flowing into each cylinder, of calculation of injection pulse width for measured air mass, and the method of feedback and engine control by using lambda sensor. Also we developed control program for IBM-PC by using C++ Builder, and tested it in the commercial engine.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제29회 추계학술대회논문집
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• pp.159-162
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• 2007

아음속 유동 내에 수직으로 분사된 액체제트의 액적분열 분포 특성을 알아보기 위해 이유체 노즐을 사용하여 실험적으로 연구하였다. 노즐은 L/d=3의 외부혼합형으로 공기와 액체의 비를 0 ${\sim}$ 59.4%까지 변화시키면서 분사하였다. 분무형상의 변화를 이미지화 하였으며 분무의 궤적과 액주의 형상을 관찰하였다. 액체제트 분열의 단면분포 특성을 PDPA를 사용하여 측정하였며 SMD, 액적속도, 그리고 체적유속을 측정하였다. 그 결과 노즐로 공급되는 공기의 양이 많아질수록 Y/d방향의 관통거리는 증가하였고 액적의 미립화는 가속화되는 것을 관찰할 수 있었다.

• Korean Chemical Engineering Research
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• 제53권4호
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• pp.482-488
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• 2015

생물학적 방법에 의한 대기오염물질 처리는 기존의 처리방법을 대체할 수 있는 방법으로 각광을 받고 있다. 생물학적 처리방법은 유기화합물 또는 악취가 포함된 저농도 고유량의 공기를 처리하는데 효과적이다. 생물살수여과법을 이용한 대기오염물질 제거에서 물질전달 연구는 공정 최적화를 위해 매우 중요한 부분이다. 본 연구에서는 3상의 물질전달이 이루어지는 생물살수여과법에서 기체/액체(살수액), 기체/고체(미생물), 액체/고체 물질전달 실험방법 개발과 물질전달 현상을 고찰하였다. 또한 본 연구에서는 각 상간에서 물질전달에 영향을 미치는 인자로 동적적체량, 기/액 유량비, 반응기내 미생물량, 살수액 순환량 등에 대해 고찰하였다.

• 한국자동차공학회논문집
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• 제8권4호
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• pp.42-50
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• 2000

Drop size distribution of an air-assisted fuel injector(AAFI) was investigated. Influence of parameters such as ambient air density supply pressure and air-liquid mass ratio(ALR) was examined through both measurement and analysis. The Sauter mean diameter$D_{32}$ varied from 9 to 25$\mu$m throughout all experimental conditions. An empirical correlation for droplet size was obtained. Analytical correlations for predicting $D_{32}$ with respect to operating conditions were also derived through energy consideration and introduction of a simplified model of the from the empirical fitting was adapted to the original equation the proposed correlation in this study matched more closely with measured results. The current correlation exhibited a favorable study matched more closely with measured results. The current correlation exhibited a favorable prediction for $D_{32}$ compared to that by the empirical correlation at selected experimental conditions so that it may be used to predict atomization performance of the AAFI at operating conditions which was not covered in the measurements. After validation the analytical equation was applied to survey the feasible operating conditions for gasoline direct injection application.