• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.8
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• pp.735-744
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• 2000

In order to define the heat transfer characteristics in a spray column direct contact heat exchanger, the development of a multidimensional numerical model and computational algorithm is essential to analyze the inherent multidimensional characteristics of a direct contact heat exchanger. In the present study, it has been carried out numerical calculations using a two-dimensional model for operation of a direct contact heat exchanger. Such operational and system parameters as the injection velocity, void fraction, aspect ratio and injection temperature of each fluid are examined thoroughly to assess their influence on the performance of a spray column. Analyzed results has shown that our two-dimensional model predicts the heat transfer phenomena well in a spray column.

• Journal of Mechanical Science and Technology
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• v.16 no.3
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• pp.344-353
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• 2002

A reliable computational heat transfer model has been investigated to define the heat transfer characteristics of a spray column direct contact heat exchanger, which is often utilized in the process involving counterflows for heat and mass transfer operations. Most of the previous studies investigated are one-dimensional unsteady solutions based on rather fragmentary experimental data. Development of a multidimensional numerical model and a computational algorithm are essential to analyze the inherent multidimensional characteristics of a direct contact heat exchanger. The present study has been carried out numerically and establishes a solid simulation algorithm for the operation of a direct contact heat exchanger. Operational and system parameters such as the speed and direction of working fluid droplets at the injection point, and the effects of aspect ratio and void fraction of continuous fluid are examined thoroughly as well to assess their influence on the performance of a spray column.

• Journal of ILASS-Korea
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• v.14 no.3
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• pp.97-102
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• 2009

The spray characteristics of the high speed rotating fuel injection system were studied. The five variants of rotating fuel nozzle were used by spray test. The diameter of single column injection orifices are varied from 1 mm, 2 mm, 3 mm, 4 mm and 5 mm. We constructed high speed rotating test rig and measured droplet size by PDPA (Phase Doppler Particle Analyzer) system. Also spray was visualized by using high speed camera. In the test results, we could understand that length of liquid column from the injection orifice is mainly controlled by the rotational speeds. SMD is decreased with increasing injection orifice diameter and rotational speeds. Furthermore, from the comparison to the theoritical calculation, we confirmed that SMD is influenced by the liquid film thickness which is formed inner surface of injection orifice.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.1
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• pp.1-10
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• 1991

The purpose of this study is to lay groundwork for a complete analysis of two component flow by analyzing a single component flow made of continuous fluid without dispersed phase. In order to achieve uniform velocity distributions which are desirable in designing an optimum spray column direct contact heat exchanger, the influence of injection nozzle orientation has been investigated for axial and radial injections. The results that radial injection ensures more uniform velocity distributions compared to the axial case. The flow characteristics in a spray column have been investigated with various L/D values and inlet velocities, the most uniform internal velocity distributions have been obtained for the case of L/D=10 and 0.1m/sec. In the present investigation, it is shown that radial injection method for the continuous flow is advantageous in obtaining desirable uniform velocity distributions in a spray column. It is also found that as the value of L/D increases and the inlet velocity decreases, the flow improves to be better uniform velocity distributions.

• Journal of ILASS-Korea
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• v.10 no.1
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• pp.35-42
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• 2005

The present study has numerically and experimentally investigated the spray behavior of liquid jet injected in subsonic cross-flow. The corresponding spray characteristics are correlated with jet operating parameters. The spray dynamics are known to be distinctly different in the three regimes: the column, the ligament and the droplet regimes. The behaviors of column, penetration and breakup of liquid jet have been studied. Numerical and physical models are base on a modified KIVA code. The primary atomization is represented by a wave model base on the KH(Kelvin-Helmholtz) instability that is generated by a high interface relative velocity between the liquid and gas flows. In odor to capture the spray trajectory, CCD camera has been utilized. Numerical and experimental results indicate that the breakup point is delayed by increasing gas momentum ratio and the penetration decreases by increasing Weber number.

• KSBB Journal
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• v.8 no.1
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• pp.83-88
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• 1993

Lipase was separated using reverse mlcelles in a spray column. The 50 mM AOT-Isooctane solution was used as reverse micellar solution for the extraction of lipase (crude containing 25% Protein). Ionic strength was controlled by KCl(0.1M KCl for extraction, 0.5M KCl for back exlractlon). Acetate buffer and phosphate buffer were used for control of pH. The efficiencies of extraction and stripping were 30% and 50%. An increase of circulation did not change the efficiency of extraction in forward extraction. The optimum flow rate was around 0.10ml/sec.

• Journal of ILASS-Korea
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• v.9 no.2
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• pp.34-40
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• 2004

In a liquid-fueled ramjet engine, the insufficient mixing and evaporation result in the low combustion efficiency and combustion instability. Improving its characteristics and devising a means of fuel droplets with air may compensate these disadvantages of liquid fuel ramjet engine. The jet penetrations of various fuel injectors were measured to investigate the spray characteristics of a liquid-fueled ramjet engine under high pressure air-stream conditions. The penetrations in high pressure conditions are smaller than the values calculated from Inamura's or Lee's equations, and the jet penetrations in the high pressure conditions have a similar tendency. In the dual orifice injectors, the jet penetrations of rare orifice is rapidly increased due to the reduction of the drag, which is created by the jet column of front orifice. The jet penetration of rare orifice is increased because of the drag reduction created by the jet column of the front orifice. Because of the drag reduction formed by the column of jet, the jet penetration in the rear orifice of dual orifice injector is much larger than the jet penetrations of single orifice injector. As the distances of the orifice are increased, the jet penetrations of the rear orifice decrease.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.56-62
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• 1999

The disintegration of transient diesel spray in early was investigated at different opening pressure and chamber pressure by measns of shadowgraph method using nanolite and still camera. Diesel spary was injected into the spray chamber which was charged with high pressure nitrogen gas. Atthe begining of injection, a liquid column that was almost the same diameter as the nozzle hole was observed . Spray tip penetration and spray angle were always increased with an increase in opening pressure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.749-752
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• 2004

In a liquid-fueled ramjet engine, the insufficient mixing and evaporation result in the low combustion efficiency and combustion instability. Improving its spray characteristics and devising a means of mixing fuel droplets with air may compensate these disadvantages of liquid fuel ramjet engine. The jet penetrations of various fuel injectors were measured to investigate the spray characteristics of a liquid-fueled ramjet engine under high pressure air-stream conditions. The penetrations in high pressure conditions are smaller than the values calculated from Inamura's or Lee's equations, and, in the high pressure conditions, the jet penetrations are similar each other. In the dual hole injectors, the jet penetrations of rear orifice is rapidly increased due to the reduction of the drag, which is created by the jet column of front orifice. The jet penetration of rear orifice is increased because of the drag reduction created by the jet column of the front orifice. And, because of the drag reduction formed by the column of jet, the jet penetration in the rear orifice of dual hole injector is much larger than the jet penetration of single hole injector. As the distances of the orifice are increased, the jet penetrations of the rear orifice decrease.

• Journal of ILASS-Korea
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• v.8 no.4
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• pp.1-8
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• 2003

The objective of this study is to investigate experimentally atomization characteristics for differently made an ultrasonic twin-fluid nozzle. A spray system, an ultrasonic system, and three different type(Nozzle type, Tube type, Conventional type)are made and tested by applied with ultrasonic energy. In this investigation, the measurement and calculation of spray droplet are to analyze the effects of ultrasonic energy on the agricultural atomization system. Through the measurement of suray angle, spray column using, high speed camera and PDA, it is found that nozzle type is highest efficiency than that of tube type and conventional type. It was found that the ultrasonic energy increased the atomization efficiency of spray droplets about 9% respectively and spray angle was wide spray.