• Korean Journal of Materials Research
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• v.23 no.2
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• pp.81-88
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• 2013

In this study, using a tin chloride solution as the raw material, a nano-sized tin oxide powder with an average particle size below 50 nm is generated by a spray pyrolysis process. The properties of the tin oxide powder according to the nozzle tip size are examined. Along with an increase in the nozzle tip size from 1 mm to 5 mm, the generated particles that appear in the shape of droplets maintain an average particle size of 30 nm. When the nozzle tip size increases from 1 mm to 2 mm, the average size of the generated particles is around 80-100 nm, and the ratio of the independent particles with a compact surface structure increases significantly. When the nozzle tip size is at 3 mm, the majority of the generated particles maintain the droplet shape, the average size of the droplet-shaped particles increases remarkably compared to the cases of other nozzle tip sizes, and the particle size distribution also becomes extremely irregular. When the nozzle tip size is at 5 mm, the ratio of droplet-shaped particles decreases significantly and most of the generated particles are independent ones with incompact surface structures. Along with an increase in the nozzle tip size from 1 mm to 3 mm, the XRD peak intensity increases, whereas the specific surface area decreases greatly. When the nozzle tip size increases up to 5 mm, the XRD peak intensity decreases significantly, while the specific surface area increases remarkably.

• Resources Recycling
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• v.25 no.6
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• pp.41-49
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• 2016

The present study was intended to prepare cobalt oxide ($Co_3O_4$) powder of average particle size 50 nm or less by spray pyrolysis reaction using the raw cobalt chloride ($CoCl_2$) solution, in order to identify the change in the nature of the particles according to the change in the nozzle tip size. When the nozzle tip was 1 mm, it turned out that most of the droplets were spherical and the surface showed very tight structure. The average particle size of the finally formed particles was 20-30 nm. When the nozzle tip size was 2 mm, some of the droplets formed were spherical, but a considerable part of them showed severely disrupted form. particles formed showed an average particle size of 30 - 40 nm. For the nozzle tip size of 5 mm, spherical droplets were almost non-existent and most were in badly fragmented state. The tightness of surface structure of the droplets has greatly been reduced compared with other nozzle tip sizes. Average size of the formed particles was about 25 nm. As the nozzle tip size increased from 1 mm to 2 mm and 3 mm, the intensities of the XRD peaks have changed little, but significantly been reduced when the nozzle tip size increased to 5mm. As the nozzle tip size increased from 1 mm to 2 mm, the specific surface area of the particles decreased, but the nozzle tip size increased to 5mm, the specific surface area remarkably increased.

• Journal of Powder Materials
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• v.10 no.4
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• pp.262-269
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• 2003

Nano-sized Ni-ferrite powder was fabricated by spray pyrolysis process using the waste solution resulting from shadow mask processing. The average particle size of the powder was below 100 nm. The effects of the concentration of raw material solution, the nozzle tip size and air pressure on the properties of powder were studied. As the concentration increased, the average particle size of the powder gradually increased and its specific surface area decreased, but size distribution was much wider and the fraction of the Ni-ferrite phase greatly increased as the concentration increasing. As the nozzle tip size increased from 1 mm to 2 mm, the average particle size of the powder decreased. In case of 3 mm nozzle tip size, the average particle size of the powder increased slightly. On the other hand, in case of 5 mm nozzle tip size, average particle size of the powder decreased. Size distribution of the powder was unhomogeneous, and the fraction of the Ni-ferrite phase decreased as the nozzle tip size increasing. As air pressure increased up to 1 kg/$cm^2$, the average particle size of the powder decreased slightly, on the other hand, the fraction of the Ni-ferrite phase was almost constant. In case of 3kg/$cm^2$ air pressure, average particle size of the powder and the fraction of the Ni-ferrite phase remarkably decreased, but size distribution was narrow.

• Korean Journal of Materials Research
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• v.23 no.9
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• pp.489-494
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• 2013

In this study, by using nickel chloride solution as a raw material, a nano-sized nickel oxide powder with an average particle size below 50 nm was produced by spray pyrolysis reaction. A spray pyrolysis system was specially designed and built for this study. The influence of nozzle tip size on the properties of the produced powder was examined. When the nozzle tip size was 1 mm, the particle size distribution was more uniform than when other nozzle tip sizes were used and the average particle size of the powder was about 15 nm. When the nozzle tip size increases to 2 mm, the average particle size increases to roughly 20 nm, and the particle size distribution becomes more uneven. When the tip size increases to 3 mm, particles with an average size of 25 nm and equal to or less than 10 nm coexist and the particle size distribution becomes much more uneven. When the tip size increases to 5 mm, large particles with average size of 50 nm partially exist, mostly consisting of minute particles with average sizes in the range of 15~25 nm. When the tip size increases from 1 mm to 2 mm, the XRD peak intensities greatly increase while the specific surface area decreases. When the tip size increases to 3 mm, the XRD peak intensities decrease while the specific surface area increases. When the tip size increases to 5 mm, the XRD peak intensities increase again while the specific surface area decreases.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.2
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• pp.3758-3762
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• 1975

In order to find out the optimum size of nozzle of the power sprayer in the paddy field, four different sized hole of nozzles were tested on its discharge volume per unit time and its effective covering distance. 1. The discharge rate of each nozzle is proportional to square root of the transmitted internal pressure of liquid, and the discharge coefficient ranges from 0.82 to 0.86 at the pressure of 20 to 30 kg/$\textrm{cm}^2$. 2. The effective covering distance is increased as the size of the hole is larded and also the pressure is increased under under the limited pressure. Generally, the effective covering distance is not greatly increased at the pressure of above 25kg/$\textrm{cm}^2$. The distance from the nozzle to the spot where the largest amount of droplets are dropped is about 14.5m for 3.05mm nozzle and 16m for 4.05mm nozzle in the pressure range from 20 to 25kg/$\textrm{cm}^2$. 3. From the above results it is concluded that the 3mm nozzle with the power sprayers, which are now being supplied to the farmers, can be used for disease and insect control on the paddy field of which block size is 30m${\times}$100m, and operators need not to enter the field for spraying. For the 40m${\times}$100m block, 4mm nozzle should be used with large size of pump which discharge capacity is 60l/min or more.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.6
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• pp.479-487
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• 2015

In a reflected shock tunnel, stagnation conditions of a nozzle are determined by the flow behind a reflected shock. When calculating the flow behind the reflected shock, unlike a shock tube, the flow leakage through the nozzle is to be considered. The analytical studies were done to find out the characteristics of the stagnation conditions of the nozzle with various nozzle throat size. Experiments and numerical simulations were also carried out for further understanding of the flow leakage effects. It was found that the nozzle stagnation pressure was diminished by the increase of the size of the nozzle throat. It was also found that the steady pressure in the stagnation were maintained well at the area ratio of the driven tube to the nozzle throat is 4.5.

• Fire Science and Engineering
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• v.30 no.2
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• pp.62-67
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• 2016

In this study, the optical depth is analyzed with the effects of droplet size distribution of the water curtain nozzle to attenuate the radiative heat transfer. The HELOS/VARIO equipment is used for the measurement of the droplet size distributions. The spray characteristics are quantified by the investigation of Deirmenjian's modified gamma distribution function. The distribution constant of the nozzle can be obtained as ${\alpha}=1$ and ${\gamma}=5.2$. The generalized equation of the optical depth related with the droplet size distribution is introduced. These results will be applicable to the analysis of the design condition of the water curtain nozzle.

• Journal of Biosystems Engineering
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• v.20 no.3
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• pp.236-244
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• 1995

Droplet size is one of the important factors in the deposition and drift of agrichemical application. In this study, droplet size and its distribution of the three different sizes of ceramic hollow cone nozzles being used in the air carrier sprayer for apple production were investigated at the various nozzle pressures and the three air velocities. The Malvern particle size analyzer were used for the measurement of droplet size and its distribution. The important results emerged from th is study can be summarized as follows. 1. Discharged rate was increase with the increase of the nozzle diameter and pressure, amount of the difference was remarkable between the nozzle diameter of 1.0, 1.2 and 1.5 mm, but no difference were found between the diameter of 1.0 and 1.2 mm in the same nozzle pressure. 2. Mass median diameter were varied as 40~160 ${mu}m$ at the air velocity of 0 m/s, 70~140 ${mu}m$ of 15 m/s and 100~160 ${mu}m$ of 20 m/s 3. It appeared that the air velocity range of 15~20 m/s was desirable for both drift and deposition control in the given experimental conditions.

• Journal of the Semiconductor & Display Technology
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• v.4 no.1 s.10
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• pp.35-41
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• 2005

An air levitation type wafer transfer system is composed of control and transfer track. Wafer transfer speed is mainly affected by air velocity of propulsion nozzle. In this study, the propulsion force coefficient was evaluated experimentally for the nozzle with 0.5mm, 0.8mm, and 1.0mm diameter. As a result, the propulsion force was largest in the smallest size of nozzle at same air velocity. The propulsion force coefficient of nozzle increases with reducing diameter of nozzle. This increment of propulsion force coefficient was enlarged remarkably at the 0.5mm diameter of nozzle.

• Journal of ILASS-Korea
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• v.10 no.2
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• pp.18-31
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• 2005

This study was performed to explore the liquid breakup and atomization characteristics for the classification of drop formation mode and background of uniform droplets generation in electrohydrodynmaic atomization according to the change of experimental parameters such as nozzle material (stainless steel. teflon). fluid flow rate, applied electrical field and intensity, and frequency. In results, from the classification map of drop formation modes according to the variation of applied AC voltage and frequency at a stainless nozzle, the droplet size was smaller than the outer diameter of the nozzle tip relatively in the spindle mode. The transition points became clearly to be moved toward the high applied voltage by rising the applied AC frequency beyond 450Hz. Also the droplet radius can be observed quite small in the frequency bandwidth of $350{\sim}450Hz$. The droplet radiuses decrease as the applied voltage increases for a fixed applied AC frequency within the range from 50Hz to 400Hz Over 400Hz, the relation between the power intensity and the droplet size was not consistent with a continuous mechanism of liquid breakup. Thus, it is showed that the droplet size distribution using the teflon nozzle was analogous to the results of stainless steel, but the droplet size was bigger than that of stainless steel relatively in case of a teflon nozzle.