• Journal of the Korean Solar Energy Society
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• v.31 no.3
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• pp.23-28
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• 2011

In this study, the ejector design was modeled using Fluent 6.3 of FVM(Finite Volume Method) CFD(Computational Fluid Dynamics) techniques to resolve the flow dynamics in the ejector. A vacuum system with the ejector has been widely used because of its simple construction and easy maintenance. Ejector is the main part of the desalination system, of which designs determine the efficiency of system. The effects of the ejector was investigated geometry and the operating conditions in the hydraulic characteristics. The ejector consists mainly of a nozzle, suction chamber, mixing tube (throat), diffuser and draft tube. Liquid is supplied to the ejector nozzle, the fast liquid jet produced by the nozzle entrains and the non condensable gas was sucked into the mixing tube. The multiphase CFD modeling was carried out to determine the hydrodynamic characteristics of seawater-air ejector. Condition of the simulation was varied in entrance mass flow rate (1kg/s, 1.5kg/s, 2kg/s, 2.5kg/s, 3kg/s), and position of driving nozzle was located from the central axis of the suction at -10mm, 0mm, 10mm, 20mm, 30mm.. Asaresult, suction flow velocity has the highest value in central axis of the suction.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.646-651
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• 2001

The present study is an experimental work of the sonic/supersonic air ejector-diffuser system. The pressure-time dependence in the secondary chamber of this ejector system is measured to investigate the steady operation of the ejector system. Six different primary nozzles of two sonic nozzles, two supersonic nozzles, petal nozzle, and lobed nozzle are employed to drive the ejector system at the conditions of different operating pressure ratios. Static pressures on the ejector-diffuser walls are to analyze the complicated flows occurring inside the system. The volume of the secondary chamber is changed to investigate the effect on the steady operation. the results obtained show that the volume of the secondary chamber does not affect the steady operation of the ejector-diffuser system but the time-dependent pressure in the secondary chamber is a strong function of the volume of the secondary chamber.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.19-22
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• 2003

Ejector-diffuser system is one of fluid machinery which can entrain the fluid in low pressure part and transport it to the higher pressure part. The conventional ejector-diffuser system has been pointed out that its overall efficiency is quite low compared with other fluid machinery since it is derived by only the pure shear stresses. In the present study, 4, 6, and 8 lobed petal nozzles with a design Mach number of 1.7 are adopted as a primary nozzle to improve the performance, and are compared with a conventional circular nozzle.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3191-3196
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• 2007

The present study addresses a method to operate a fuel-cell system effectively using a recirculation ejector which recycles wasted hydrogen gas. Configuration of a recirculation ejector is changed to investigate the flow behavior through it under varying operating conditions, and how such conditions affect the fuel-cell hydrogen cycle. The numerical simulations are based on a fully implicit finite volume scheme of the axisymmetric, compressible, Reynolds-Averaged, Navier-Stokes equations for hydrogen gas, and are compared with available experimental data for validation. The results show that a hydrogen recirculation ratio is effectively controlled by a configurational alteration within the operational region in which the recirculation passage doesn't plugged by a sonic line.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.648-651
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• 2004

A vacuum system with ejector has been widely used because of its simple construction and easy maintenance. Ejectors are the main part of the vacuum system, of which designs determine the efficiency of vacuum system. The ejector with the capacity of 1.5 ton/hr steam consumption was designed and tested. The results showed that the tested values are satisfied with the designed specifications. Comparing with other ejectors designed by overseas specialist makers, it seems to have a good performance.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2589-2593
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• 2008

In a fuel cell vehicle using polymer electrolyte membrane fuel cell(PEMFC), hydrogen is over-supplied to gain higher stack efficiency. So it is needed considering fuel efficiency to re-circulate hydrogen which is not reacted in stack. And to re-circulate hydrogen, a blower or an ejector is used. Ejector re-circulation system has several merits compared with blower system, for example no parasite energy, simple structure and no lubrication system. But the secondary flow of an ejector in fuel cell vehicle, has high humidity because of crossover problem in stack. Therefore in this paper, ejector is designed by 1-D modeling and CFD with the primary and secondary flow of hydrogen. And the ejector which has the primary and secondary flow of air, is designed to have the same Reynolds number and Mach number at the nozzle exit as the hydrogen ejector's. And this air ejector is tested while the humidity of the secondary flow is varied.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.7 no.2
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• pp.73-79
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• 1978

This paper presents the experimental study on the design conditions of pressure between booster ejector and air ejector in the steam-jet water-vapour refrigeration system. In this experiment, the motive steam of booster ejector and ai. ejector was dry saturated from 6 ata to 8 ata and flash chamber pressure were about $10\∼540mmHg$ higher than mixing section in booster ejector. The investigation of air on the pressure of booster ejector was performed by changing the condenser pressure. The experimental results show that flash chamber vacuum and condenser pressure of steam-jet refrigeration cycle increased in accordance with the increase of motive steam Pressure. Among the several nozzle sires tested, No.4 nozzle were best in term of evaporator vacuum under the constant operating conditions of air ejector in condenser.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.847-854
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• 2013

The objective of this study is to experimentally investigate the mixed flow and oxygen transfer characteristics of a horizontally injected aeration process using an annular nozzle ejector. The flow rate ratio, pressure ratio and ejector efficiency are calculated using the measured flow rate and pressure with the experimental parameters of the ejector pitch and primary flow rate. The visualization images of mixed flow issuing from the ejector are analyzed qualitatively, and the volumetric oxygen transfer coefficients are calculated using the measured dissolved oxygen concentration. The mixed flow behaves like a buoyancy jet or horizontal jet owing to the momentum of primary flow and air bubble size. The buoyancy force of the air bubble and the penetration of mixed flow are found to be important parameters for the oxygen transfer rate owing to the contact area and time of two phases.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.135-138
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• 2002

High-speed ejection of burnt gases from the resonator cavity is essential for performance optimization of the chemical laser system. Additionally, to maintain the population of lasing species at a level for maximum optical power, the pressure within the cavity must be of order of 10 torr. In the present study, a small-scale ejector was designed and built for parametric study of its performance. High-pressure air was used as a motive gas. Measurements include schlieren visualization and pressure distribution trace near the ejector nozzle and along the diffuser downstream of the ejector. preliminary tests showed performance of the ejector is a function of parameters including mass flow rate and stagnation pressure of the motive gas, ejector nozzle area ratio, throat area of the diffuser downstream of the ejector.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.42.2-42.2
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• 2005