In this study, an effervescent atomizer capable of mixing and spraying vegetable oil and kerosene at the same time was proposed to examine the usefulness of vegetable oil and kerosene in terms of recycling of renewable energy and waste resources. The effect of nozzle exit diameter variation on the atomization characteristics such as spray angle, droplet size distribution, cumulative volume distribution, and SMD was investigated using LDPA. The results of this study showed that the spray angles decreased with increasing ALR at the same nozzle exit diameter and increased with increasing nozzle exit diameter under the same ALR condition. SMD was decreased with increasing ALR at all nozzle exit diameters, and SMD was decreased with decreasing nozzle exit diameter even under the same ALR conditions. Also, the droplet was more finely atomized when the nozzle exit diameter is reduced under the same ALR conditions and when the ALR is increased at the same nozzle exit diameter, but the uniformity of the droplets was lowered because the droplet with a larger diameter existed.

In order to apply rotary atomizer to agricultural spraying system, the motor direct coupled rotary atomizer was proposed. The effect of operating conditions such as atomizing air flow rate, working fluid flow rate, and rotation speed of spinning cup on the atomization performance was investigated for the proposed direct coupled rotary atomizer. The motor speed was controlled in the range of 6,000 to 12,000 rpm using an alternating current transformer, and the atomizing air was supplied by the compressor. In this study, LDPA was used to analyze the spray characteristics of the rotary atomizer. The representative particle diameters of D10, SMD, MMD, D90, and DMax tended to decrease as the atomizing air flow rate and the motor speed increased, but increased as the working fluid flow rate increased. Also, SMD was found to be influenced by order of atomizing air flow rate> motor speed> working fluid flow rate, and DMax was influenced by order of operating fluid supply> motor speed> atomizing air flow rate.

An experimental study was conducted to investigate the atomization characteristics of spray from the effervescent atomizer, which has separated two aerator tubes. The atomization characteristics were examined through the influence of ALR and the changes of atomizer geometry such as nozzle orifice diameter, diffusion angle, mixing chamber volume. PDPA(Phase Doppler Particle Analyzer) was used to evaluate the atomization characteristics. During the experiments, the mass flow rate of liquid was kept constant at 2.8g/s and the mass flow rate of atomizing air was changed from 0.2 to 0.6g/s. Experimental results showed that SMD was not a linear function of ALR. While SMD is very sensitive to the changes of ALR, the changes of atomizer geometry had little effect on droplet mean diameter. As the effervescent atomizer with separated two aerator tubes is insensitive to the changes of atomizer geometry, it is expected that the effervescent atomizer with separated two aerator tubes is capable of requirements of many applications, without the drawbacks of atomization characteristics.

An update and the latest results on molten metal atomization using a Pressure-Gas-Atomizer will be given. This atomizer combines a swirl-pressure atomizer, to generate a liquid hollow cone film and a gas atomizer to atomize the film and/or the fragments of the film. The paper is focused on powder production, but this atomization system is also applicable for deposition purposes. Different alloys (Sn, SnCu) were atomized to study the characteristics of the Pressure-Gas-Atomizer.

MgO based nanocomposite powder including ferromagnetic iron particle dispersions, which can be available for the magnetic and catalytic applications, was fabricated by the spray pyrolysis process using ultra-sonic atomizer and reduction processes. Liquid source was prepared from iron (Fe)-nitrate, as a source of Fe nano-dispersion, and magnesium (Mg)-nitrate, as a source of MgO materials, with pure water solvent. After the chamber were heated to given temperatures (500~), the mist of liquid droplets generated by ultrasonic atomizer carried into the chamber by a carrier gas of air, and the ist was decomposed into Fe-oxide and MgO nano-powder. The obtained powders were reduced by hydrogen atmosphere at 600~. The reduction behavior was investigated by thermal gravity and hygrometry. After reduction, the aggregated sub-micron Fe/MgO powders were obtained, and each aggregated powder composed of nano-sized Fe/MgO materials. By the difference of the chamber temperature, the particle size of Fe and MgO was changed in a few 10 nm levels. Also, the nano-porous Fe-MgO sub-micron powders were obtained. Through this preparation process and the evaluation of phase and microstructure, it was concluded that the Fe/MgO nanocomposite powders with high surface area and the higher coercive force were successfully fabricated.

Flow and heat transfer characteristics of gas, and trajectories and cooling characteristics of droplets/particles in a gas atomizer were investigated by a numerical simulation using FLUENT code. Among several kinds of solution method, the k- turbulent model, power-law scheme, SIMPLE algorithm is adopted in this study. Momentum and heat exchange between a continuous phase(gas) and a dispersed phase(particle) were taken into account. Particle trajectories are simulated using the Lagrangian method, and Rosin-Rammler formula is used for the particle size distribution. Streamlines, velocities and pressures of gas, and trajectories, velocities and cooling rates of particles have been investigated for the various gas inlet conditions. Small but very intensive recirculation is found just below the melt orifice, and this recirculation seems to cause the liquid metal to spread radially. Particle trajectory depends on the particle size, the location of particle formation and the turbulent motion of gas. Small particle cools down rapidly, while large diameter particles solidify slowly, and this is mainly due to the differences in thermal inertia.

The behavior of the flow about gas atomizers with a supersonic nozzle containing an under-expanded or over-expanded jet is very important with respect to performance and stability characteristics. Since detailed experiments are expensive, computational fluid mechanics have been applied recently to various relating flow field. In this study, a higher order upwind method with the 3rd order MUSCL type TVD scheme is used to solve the full Reynolds Wavier-Stokes equations. To delineate the purely exhaust jet effects, the melt flow is not considered. Comparison is made with some experimental data in terms of density fields. The influence of the exhaust-jet-to freestream pressure ratio and the effect of the protrusion length of the melt orifice are studied. The present study leads us to believe that the computational fluid mechanics should be considered as powerful tool in predicting the gas atomizer flows.