• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.12
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• pp.931-937
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• 2008

A high motive pressure thermal vapor compressor(TVC) for a commercial multi-effect desalination(MED) plant is designed to have a high entraining performance and its robustness is also considered in the respect of operating stability at the abrupt change of the operating pressures like the motive and suction steam pressure which can be easily fluctuated by the external disturbance. The TVC having a good entraining performance of more than entrainment ratio 6.0 is designed through the iterative CFD analysis for the various primary nozzle diameter, mixing tube diameter and mixing tube length. And then for a couple of TVC having a similar entrainment ratio, the changes of the entrainment ratio are checked along the motive and suction pressure change. The system stability is diagnosed through the analyzing the changing pattern of the entrainment ratio.

• Journal of the Korean Society of Combustion
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• v.18 no.2
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• pp.8-16
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• 2013

The flameless combustion has been considered as one of the promising combustion technology for high thermal efficiency, reducing NOx and CO emissions. In this paper, the effect of air and fuel injection condition on formation of flameless combustion was analyzed using three dimensional numerical simulation. The results show that the high temperature region and the average temperature was decreased due to increase of recirculation ratio when air velocity is increased. The average temperature was also affected by entrainment length. Generally mixing effect was enhanced at low entrainment length and dilution was dominated at high entrainment length. This entrainment length was greatly affected by air and fuel injection velocity and distance between air and fuel. It is also found that the recirculation ratio and dilution effect were generally increased by entrainment length and the recirculation ratio, mixing and dilution effect are the significant factor for design of flameless combustion system.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.47-49
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• 2013

Entrainment length and recirculation ratio that are important factors of flameless combustion systems were analyzed by injection conditions using three dimensional numerical simulation. As a result, the entrainment length increased with an increase of momentum ratio and distance of between nozzle. Also, in case of increasing in momentum of oxidation, recirculation ratio was increased and the average temperature was decreased.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.3
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• pp.206-213
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• 2002

In this paper, the flow characteristics of an axial fan spraying isothermal compact jet in a confined space were investigated by the experimental methods, the numerical method, and the free jet theory According to the results, the numerical result and the experimental result are agreed well qualitatively and different quantitatively within $\pm1.0%$ for the centerline velocity, the entrainment ratio, and the maximum throw. However, the free jet theory can reasonably predict the centerline velocity except the entrainment ratio and the maximum throw. In other words, the entrainment ratio and the maximum throw by 1.he free jet theory are hard to estimate the characteristics of jet because of restriction of c confined space.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.414-417
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• 2004

A cone cylinder is used to obtain variable operation conditions for the sonic ejector-diffuser system. The cone cylinder is designed to be shifted upstream and downstream to change the ejector throat area ratio, thus obtaining variable mass flow rates. The present study investigates the effects of ejector throat area ratio and operating pressure ratio on the entrainment of secondary stream for the variable sonic ejector system. The study is carried out experimentally. The ejector throat area is varied at the range from Ψ= 11.88 to 66.69, and the operating pressure ratio is changed from $P_{op}$ / $P_{a}$=1.25 to 9.0. The results show that the variable sonic ejector system can be operated to obtain specific entrainment ratio of secondary stream by altering the ejector throat area ratio and operating pressure ratio.o.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.526-531
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• 2003

A cone cylinder is used to obtain variable operation conditions of a sonic ejector-diffuser system. The cone cylinder is movable to change the ejector area ratio, thus obtaining variable mass flow rates. The present study investigates the effects of ejector throat area ratio and operating pressure ratio on the entrainment of secondary stream. The numerical simulations are based on a fully implicit finite volume scheme of the compressible, Reynolds-Averaged, Navier-Stokes equations. The ejector throat area is varied between 3.94 and 8.05, and the operating pressure ratio is changed from 3.0 to 9.0. The results show that the entrainment ratio and mass flux ratio become more dependent on the ejector throat area ratio, when the pressure operating ratio is low. The total pressure losses produced in the present ejector system increase with the operating pressure ratio and the ejector area ratio, but for a given operating pressure ratio, the losses are not significantly dependent on the ejector area ratio when it is larger than about 5.0.

• Journal of Power System Engineering
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• v.20 no.6
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• pp.87-92
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• 2016

This research dealt with performance characteristics of OTEC system applying an ejector and additional pump. Each system using five kinds of working fluids was analyzed, and primary parameters with respect to entrainment ratio were examined: Turbine gross power, evaporation capacity, pump work, efficiency and volume flow ratio. The primary results were as following. The efficiency of ejector-pump OTEC system was dependent on entrainment of the ejector. The degree of efficiency change was different from applied working fluid, and amount of pump work was turned out to be primary factor affected system efficiency. Meanwhile, optimized entrainment ratio was different from applied working fluid since their different vapor density. System efficiency at optimized entrainmet ratio of each working fluid was around 5%, showing minor difference each other.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.2035-2040
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• 2004

A cone cylinder is used to obtain variable operation conditions for the sonic ejector-diffuser system. The cone cylinder is designed to move upstream and downstream to change the ejector throat area ratio, thus obtaining variable mass flow rates. The present study investigates the effects of ejector throat area ratio and operating pressure ratio on the entrainment of secondary stream for the variable sonic ejector system. In experiment, the ejector throat area is varied in the range from ${\psi}=11.88$ to 66.69, and the operating pressure ratio from $p_{0p}/p_a=1.25$ to 9.0. The results show that the variable sonic ejector system is suitable for a required entrainment ratio of secondary stream by altering the ejector throat area ratio and operating pressure ratio.

• Tribology and Lubricants
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• v.14 no.4
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• pp.58-63
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• 1998

This paper presents a study of the elastohydrodynamic lubrication of elliptical contacts where lubricant entrainment coincides with the major axis of the Hertzian contact ellipse. A finite difference method and the Newton-Raphson method are applied to analyze the problem. Film contours and pressure distributions are compared with the results for lubricant entrainment coincides with the minor axis. Variations of the minimum and central film thicknesses with the radius ratio are also examined. The results showed that the present numerical scheme can be used generally in the analysis of the EHL of elliptical contacts where the lubricant entraining vector did not coincide with either of the principal axis of the conjunction.

• Journal of Industrial Technology
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• v.17
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• pp.227-232
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• 1997

This study was conducted to evaluate durability of concrete which are increasingly demanded recently. Concrete durability properties incorporating waste foundry sand was performed with the variable of W/C ratio, Sand/Waste foundry sand ratio and Air entrainment-Non air entrainment. Cylinder specimens were made and subjected to freezing and thawing cycle at $-18^{\circ}C$ and $4^{\circ}C$. Dynamic modulus of elasticity were evaluated as F/T cycle increase. The results show that decreasing W/C ratio and AE concrete makes improved resistance of freezing and thawing improved. Especially, resistance of freezing and thawing is improved by Fine aggregate/Waste foundry sand ratio which is 50%, 25%, 0% in a row.