• Journal of ILASS-Korea
• /
• v.2 no.2
• /
• pp.35-42
• /
• 1997

An innovating technique of atomizer has been proposed to supply and to atomise molten materials. Both of a simple geometry of nozzle and an improved nozzle have been fabricated in the present study. With these nozzles, characteristics of the suction and disintegration have been empirically investigated. The important conclusions are as follows; In the case of a simple nozzle: 1) Although the sucking up and supplying of molten materials are available, the applications of powder metallurgy are limited. 2) It is concluded that the more air flow rate, $W_A$ or the shorter the height of air nozzle from the surface of supplied water, $L_h$, the more the atomizing mass of liquids, $W_L$. In the case of an improved nozzle: 3) The stable liquids can be supplied due to cut off the passage of surrounding air entrainment by air jets. 4) The atomizing mass of liquids, $W_L$ has affected not so much on the height of nozzle from the surface of supplied water, $L_h$ as that from the orifice, hc.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.12
• /
• pp.3377-3385
• /
• 1994

This paper introduces empirical correlations to obtain the gas/liquid flow rates and the spray drop size of low viscosity liquid injected by Y-jet twin-fluid atomizers. The gas flow rate is well correlated with the gas injection pressure and the mixing point pressure, based on the compressible flow theory. Similarly, the liquid flow rate is determined by the liquid injection pressure and the mixing point pressure, and a simple correlation for the liquid discharge coefficient at the liquid port was deduced from the experimental results. The mixing point pressure, which is one of the essential parameters, was expressed in terms of the gas/liquid flow rate ratio and the mixing port length. Disintegration and atomization mechanisms both within the mixing port and outside the atomizer were carefully re-examined, and a "basic" correlation form representing the mean diameter of drops was proposed. The "basic" correlation was expressed in terms of the mean gas density within the mixing port, gas/liquid mass flow rate ratio and the Weber number. Though the correlation is somewhat complicated, it represents the experimental data within an accuracy of ${\pm}15%$.EX>${\pm}15%$.

• Proceedings of the KSME Conference
• /
• 2001.06e
• /
• pp.125-130
• /
• 2001

Experimental and analytical researches have been conducted on the twin-fluid atomizers for better droplet breakup during the past decades. But, the studies on the disintegration mechanism still present a great challenge to understand the drop behavior and breakup structure. In an effort to describe the aerodynamic behavior of the sprays issuing from the internal mixing counter-swirling nozzle, the spatial distribution of axial (U) radial (V) and tangential (W) components of droplet velocities are investigated across the radial distance at several axial locations of Z=30, 50, 80, 120 and 170mm, respectively. Experiments were conducted for the liquid flow rates which was kept constant at 7.95 g/s and the air injection pressures were varied from 20 kPa to 140 kPa. Counter-swirling internal mixing nozzles manufactured at angles of $15^{\circ},\;30^{\circ},\;45^{\circ}$ and $60^{\circ}$ the central axis with axi-symmetric tangential-drilled holes was considered. The distributions of velocities and turbulence intensities are comparatively analyzed. PDPA is installed to specify spray flows, which have been conducted along the axial downstream distance from the nozzle exit. Ten thousand of sampling data was collected at each point with time limits of 30 second. 3-D automatic traversing system is used to control the exact measurement. It is observed that the sprays with all swirl angle have the maximum SMD for on air injection pressure of 20 kPa and 140 kPa with centerline, respectively. The nozzle with swirl angle of $60^{\circ}$ has vest performance.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.3
• /
• pp.325-333
• /
• 2012

An experimental study was carried out to determine the correlation between the internal flow in a circular nozzle and elliptical nozzles with the external flow. The flow rate, spray angle and drop size were measured under various conditions of the injection pressure. Numerical simulations were attempted to investigate the internal flow structure in the elliptical nozzles, because the experimental study was limited in its measurements of flow velocity and pressure distributions in the relatively small orifice. In the case of the elliptical nozzles, the disintegration characteristics of the liquid jet were significantly different from those of the circular nozzle. Surface breakup was observed at the jet issued from the elliptical nozzles with injection pressure. This is due to the internal flow structure, which is reattached to the orifice wall at the minor axis plane of the elliptical nozzle, unlike that observed with the circular nozzle.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.7
• /
• pp.2267-2276
• /
• 1996

Twin-fluid atomization has been widely used in combustors and process industries because of its high performance and simple structure. Flow visualization and pressure measurements were conducted to investigate the effects of gas flow in twin-fluid atomization. Schlieren photographs showed that changes in atomizing gas pressure, altered the wave patterns, and the lengths of both recitrculating toroid (impinging stangnation point) nad supersonic flow region in the jet. A longer supersonic wave pattern like net-shape wqas observed as atomizing gas pressure increased. The disintegration phenomenon of liquid delivery tube. The variation of spray angles with gas pressures were obtained by visualization using laser sheet beam. Suction pressuresat the nozzle orifice exit and recirculating region are shown to be used to estimate the stable atomization condition of a twin-fluid atomizer.

• Journal of Life Science
• /
• v.27 no.7
• /
• pp.754-759
• /
• 2017

The 100 l culture system was made on the basis of LED light, and Nannochloropsis oculata was cultured in f/2 medium at light intensity ($100{\mu}mol/m^2/s$), culture temperature ($20^{\circ}C{\pm}1^{\circ}C$) and LD cycle (12hr). As a result, the maximum biomass of 1.07 g/l was cultured as a result of 100 l mass culture at $100{\mu}mol/m^2/s$ and 24 mg/l nitrate concentration in LED blue (475 nm). The extraction was carried out using sonicator, homogenizer and chemical method 0.5M HCl shredding method. The contents of chlorophyll a, chlorophyll b and carotenoid were 1.6, 0.5 and 0.3 mg/g cell. When using homogenizer, it was measured at 1.0, 0.6 and 0.2 mg/g cell. The chemical breakdown method of 0.5M HCl, chlorophyll a, b, and carotenoid contents were measured as 0.9, 0.8, 0 mg/g cell. The highest amount of biomass during the distruption time was measured at 3.6 mg/g cell at 15 min disintegration and acetone, 3.6 mg/g cell of acetone, methanol, and ethanol were measured as effective solvents. Concentration was measured by using microfilter, disk type continuous centrifuge and tubular type continuous centrifuge were 16.0, 1.1 and 0.5 g/l, respectively. Four kinds of equipment such as hot air dryer, vacuum dryer, spray dryer and freeze dryer were tested to optimize the drying process. As a result, the recovery rates of spray dryer and freeze dryer were 80% and 60%.