• Journal of Korean Society for Atmospheric Environment
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• v.27 no.3
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• pp.272-280
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• 2011

A novel particle removal system for air handling unit (AHU) of subway station was evaluated experimentally. The novel system was designed in order to minimize the maintenance cost by applying axial-flow cyclones. The system consists of multiple cyclone units and dust trap. Based on our previous numerical study, it was found to be effective for removal $1\sim10{\mu}m$ sized dust particles. In this study, we manufactured the mock-up model and evaluated the model experimentally. Liquid and solid test particles were generated for evaluating collection efficiency of the system and the pressure drop was monitored. The collection efficiency was varied from 41.2% to 85.9% with increasing the sizes of particle from 1 to $6.5{\mu}m$ by particle count ratio of inlet and outlet. The pressure drop was maintained constant less than $20mmH_2O$. In addition, the collection efficiency was estimated by total mass for solid test particles. It was found that the collection efficiency was 65.7% by particle mass ratio of inlet and outlet. It shows that present system can replace current pre-filters used in subway HVAC system for removing particulate matters with minimal operational cost.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.7
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• pp.585-592
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• 2015

Effects of opening distance on liquid-gas spray of pintle injector were experimentally investigated under atmospheric condition by using water and air as simulants of propellants. Discharge coefficients($C_d$) and mass flow rates were calculated with various injection conditions; 0.1 bar - 1.0 bar for water pressures and 0.2 mm - 1.0 mm for the pintle opening distances. Spray angles were measured from the spray images that were obtained by a shadowgraphy method. When opening distance is 0.2 mm, liquid sheet is not formed properly and it show non-uniform spray. than it can result in combustion instability. it has a weak correlation between the momentum flux ratio and the spray angle, while it has a strong correlation between the momentum ratio and spray angle. Finally the spray angles reduced exponentially when the momentum ratio increased and the spray angles converged to about 40 degrees.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.449-457
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• 1996

The main purpose of this study was to investigate sulfur dioxide removal performance of flue gas desulfurization system utilizing a Spray Absorption/Drying Reactor. In this system, the size of droplets was considered the most significant factor and tested using a PDA system. Lime slurry flow rate, operating temperature, calcium/sulfur (Ca/S) ratio and applied air pressure were selected as major operation variables and tested/analyzed in terms of system performance. The results are as follows. 1. The $SO_2$ removal efficiencies were 49%, 74%, 85% for Ca$(OH)_2$ slurry flow rate of 10, 20, 30 ml/min, which implies that the increase of slurry flow rate improves removal efficiency. The optimum slurry flow rate in this study was, however, considered 20 ml/min because of constraints of system troubles and absorbent utilization. 2. As Ca/S ratio increased, $SO_2$ removal efficiency was observed to increase. 3. As air pressure, at the atomizing nozzole, increased from 3 to 5 $kg/cm^2, SO_2$ removal efficiency increased from 74% to 80%, because of droplet size reduction due to pressure increase during atomizing process and the increase of surface area, helping mass transfer between gas and liquid phase.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.53-60
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• 2020

In liquid-fuel spray combustion, an experimental study was conducted to observe the effect of ultrasonic excitation on the ultrasonically-atomized liquid fuel flame by controlling pressure field through an ultrasonic standing wave. Flame of the ultrasonically-atomized kerosene aerosol was visualized by using a high speed camera, DSLR, and Schlieren photography. The amount of fuel consumed was obtained by a precise flow-rate measurement technique during combustion, through which the ratio of carrier gas (air) to fuel mass was able to be obtained, too. As a result, it could be found that the combustion reaction-rate of the liquid-fuel aerosol was increased by applying an ultrasonic standing wave to the secondary flame zone of the flame.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.39-45
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• 2004

Experiments were performed in a two-phase swirling spray facility that has been described elsewhere. Measurements of spray transport and drop size distribution are analyzed over wide ranges of air to liquid mass flow ratios, utilizing four different internal mixing pneumatic nozzles. The spatial distributions of mean velocities. fluctuating velocities, and velocity-diameter correlation were quantitatively analyzed. Also, the exponential correlation curves were obtained with ALR along the spray centerline, which indicated an approximately identical formulation regardless of ALR. It indicated that the atomization characteristics were remarkably superior in the case of 30o of swirl angle with higher ALR. Among other things. nozzle configuration is one of the significant parameters affecting spray phenomena from an internal mixing nozzle. Turbulence intensities are increasingly degenerated with an increase of nozzle configuration, allowing a rapid increment of drop size distribution.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.8
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• pp.535-542
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• 2011

The performance of a plate heat exchanger for using liquid solution in the absorption chiller-heater was analyzed. The model was developed by using the various performance prediction correlations. The performance characteristics of the plate heat exchanger with the mass flow rate ratio was verified by using experimental data. To investigate performance of plate heat exchanger with geometry variables, the chevron angle, corrugated wave length, and corrugation depth were changed. As a result, the capacity of Kim and Martin correlation models was similar with the experimental data, and the capacity difference was less than 2%. Besides, the pressure drop of Marin correlation model showed a similar variation with experimental data, and the difference of pressure drop was less than 1.5 kPa.

• International Journal of Automotive Technology
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• v.1 no.2
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• pp.95-100
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• 2000

The droplet and the turbulent characteristics of a counterflowing internal mixing pneumatic nozzle mainly focused. The measurements were made using a Phase Doppler Particle Analyzer under the different air pressures. The nozzle with tangential-drilled holes at an angle of 30 to the central axis has been designed. The spatial distributions of velocities, fluctuating velocities, droplet diameters and SMD were quantitatively and qualitatively fluctuating velocities were substantially higher than the radial and the tangential ones. This implies that the disintegration process is enhanced with the higher air pressure. The larger droplets were detected near the spray centerline at the upstream while the smaller ones were generated at the downstream. This was attributed to the lower rates of spherical particles which were not subject to instantaneous breakup. However, substantial increases in SMD from the central part tower spray periphery were predictable in downstream regions.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.268-277
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• 2012

The thermal decomposition characteristic of waste PVC wires has been studied by using TGA and fixed-bed reactor. The experimental conditions of decomposition temperatures, air flow rates and weight ratio of CaO/PVC were considered in this work. To verify the effectiveness of CaO addition to remove HCl and toxic gases generated from thermal decomposition of PVC wire, the gaseous products obtained from the thermal decomposition of PVC were analyzed by GC/MS(Gas Chromatograph and Mass Spectrometry). To investigate the effect of CaO in thermal decomposition of PVC, liquid products were also analyzed by GC/MS. And the effect of decomposition temperature, air flow rate and CaO/ PVC weight ratio on the yield of liquid, gas and residue fraction have been also studied. From this work, it was found that the removal amount of HCl generated from thermal decomposition of PVC increased with increase of CaO addition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.6
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• pp.485-496
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• 2015

The present study presents experimental results on the characteristics of emission spectra of kerosene/air swirl flames. The aviation fuel Jet A-1, which is used for the liquid rocket engines of the Korea Space Launch Vehicle, is used with three different swirlers to investigate the swirl strength effects. The emission spectra from the flames are measured with a spectrometer as the swirl strength and combustion air temperature are varied. Chemiluminescence intensities of $OH^*$, $CH^*$ and $C_2{^*}$ are identified from the spectra. The chemiluminescence intensities from the kerosene flames show sensitivity to the swirl strength and are affected by changes in the combustion air temperature. Among the three radicals of interest, $C_2{^*}$ show the most significant changes in chemiluminescence intensity with the swirl strength and equivalence ratio. The intensity ratios $I_{OH^*}/I_{CH^*}$ and $I_{C_2{^*}}/I_{CH^*}$ are adequate for indicating changes in the equivalence ratio with the air and fuel mass flow rates, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.399-405
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• 1994

Beacuse of the energy resources exhaustion, the aggravating environmental air pollution and the smoke phenomena etc., the importance of clean gas fuel compared with liquid fuel is highly considered in recent years. The combustion system which consists of porous media is actively studied as a new method for solving above problems. Therefore, excess enthalpy combustion using porous media was interested by many researchers and investigated through numerical and experimental analysis. In this study, the simplified combustor has the unique combustion characteristics of mixture gas preheated effect using radiative and convective heat energy by changing the flow passage of unburned gas with solenoid valves and has the intensive excess enthalpy phenomena As the result of according to reduce equivalence ratio, flame temperature was remarkably higher than adiabatic flame temperature. This show the ability of super-lean combustion.