• Journal of the Korean Society of Safety
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• v.39 no.1
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• pp.1-8
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• 2024

Commercial gas stoves feed primary air to the burner and burn the fuel-air mixture in a partially premixed combustion. This mechanism produces carbon monoxide during combustion. In this study, design parameters of a commercial gas stove were optimized by considering the carbon monoxide emission. Gas consumption rate, carbon monoxide emission, and water boiling temperature as a heating performance were determined. Carbon monoxide emission was measured using a Korean Industrial Standards standard collector. Water boiling temperature was measured by first soaking the pot in water for approximately 10 min and then heating the pot filled with water. A thermocouple was installed inside the pot. Carbon monoxide increased as the nozzle diameter was increased and the burner-pot height was decreased. This result was due to the insufficient mixing between the fuel and air. Heating performance was enhanced when the nozzle diameter was increased and the burner-pot height was decreased. However, the heating performance deteriorated when the nozzle diameter was 1.8 mm and the burner-pot height was reduced to 50 mm. This phenomenon was due to the formation of a flame on the side of the pot. A merit factor was defined to find the optimal design parameters to satisfy gas consumption rate, carbon monoxide emission, and heating performance. Optimal design values were established to be a nozzle diameter of 1.5 mm and a burner-pot height of 60 mm.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.933-942
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• 1992

The effects of the folwrate on the dropsize from the two-phase coaxial nozzle are investigated by using the direct photographic method and the empirical equation is obtained. For the photography, the light source which the life time is the order of 100ns is fabricated and the lens is the zoom lens which has the MICRO function with a teleconvertor. The distillated water and the compressed air of the surrounding temperature are injected and atomized. For the purpose of the exact adjustment and measurement of the flowrates, the two rotameters are used. As a result of this study, the sauter mean diameter of droplets has a tendency for a logarithmic function with air flowrate and for a exponential function with water flowrate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.4
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• pp.295-302
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• 1990

The purpose of this study is augmentation of heat transfer without additional power in two-dimensional impinging air jet. The technique of heat transfer augmentation used in this experiment is to place rod bundles in front of the flat heated surface. The effects of rod diameter, nozzle-to-target plate distance and the nozzle exit velocity on heat transfer have been investigated. The main conclusions obtained from this experiment are as follows. High heat transfer augmentation is achieved by means of flow acceleration and thinning of boundary layer by placing rod bundles in front of the flat plate. Average heat transfer coefficient becomes maximum in the case of H/B=10,D=4mm. For H/B=2,D=4mm, maximum heat transfer augmentation has been determined to be about 1.5 times larger than that of the flat plate. Heat transfer augmentation by placing the rod bundles at 12m/s is to be about 2 times more than increasing nozzle exit velocity from 12m/s to 18m/s.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.801-806
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• 2000

This experimental study is to investigate the intermittent spray characteristics of a multi-hole nozzle in a heavy-duty DI diesel engine. Multi 8 hole$(d_n=0.25mm)$, Multi 3 hole$(d_n=0.42)$ and Sing hole nozzle$(d_n=0.25mm)$ were used in this experiment. By using the 2-D PDPA(phase Doppler particle analyzer), the droplet diameter and the velocity of a diesel spray injected intermittently from the multi and the single-hole nozzle into a still ambient were measured. In order to calculate the mean values such as mean velocity, SMD, AMD etc. and to analyze the intermittent characteristics, the time-window of 0.15ms were applied. In the spray, the small droplet$(D<10{\mu}m)$ was regarded as an air flow, and the correlation between the fuel droplet$(10{\mu}m and the air (low was examined. The normalized axial droplet-air relative velocity of the 8 hole, the 3 hole and the single hole nozzle was evaluated as 0.081, 0.067, 0.06 and in case of the radial droplet-air relative velocity, the normalized. value is 0.014, 0.013 and 0.008 respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.353-358
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• 1995

The emission characteristics of a semi-Bunsen type burner for gas boilers were studied experimentally. The experimental results reveal that nitric oxide emission increases with fuel flow rate. It is linearly proportional to total fue flow rate at a small amount of fuel up to 0.4 liters per minute. It does not change significantly within the range of fuel flow rate from 0.4 to 1.2 liters per minute per nozzle and increases at large fuel flow rate. The carbon monoxide emission reveals to be dependent upon the fuel flow rate per each nozzle and the number of fuel injection nozzles. Diameter of an injection nozzle could have an effect on the emission characteristics of this type of burners. However, there is no marked change in the nitric oxide emission if the total fuel flow rate is same with different nozzle sizes.

• Journal of Environmental Science International
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• v.27 no.3
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• pp.219-225
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• 2018

This study was conducted to investigate the possibility of utilizing various types of nozzles and gas-liquid mixers to increase the dissolution rate of plasma gas containing ozone generated in a dielectric barrier plasma reactor. After selecting the air atomizing nozzle with the highest gas dissolution rate among the 13 types of test equipment, we investigated the influence of the operating factors on the air atomizing nozzle to determine the optimal plasma gas dissolution method. The gas dissolution rate was measured by a simple and indirect method, specifically, the measurement of KLa instead of direct measurement of ozone concentration, which requires a longer analysis time. The results showed that the KLa value of the simple mix of air and water was $0.372min^{-1}$, Which is 1.44 times higher than that ($0.258min^{-1}$) of gas emitted from a normal diffuser. Among the nozzles of the same type, the KLa value was highest for the nozzle having the smallest orifice diameter. Among the 13 types of devices tested, the nozzle with highest KLa value was the M22M nozzle, which is a gas-liquid spray nozzle. The relationship between water circulation flow rate and KLa value in the experimental range was linear. The air supply flow rate and KLa value showed a parabolic-type correlation, while the optimum air supply flow rate for the water circulation flow rate of 1.8 L / min is 1.38 times.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.35-44
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• 2000

It was numerically studied that NOx emission characteristics of confined $CH_{4}$ jet flames with the variation of the diameter of inner fuel nozzle, the flow rate of $CH_{4}$ and equivalence ratio. Parabolic type equations were adopted in the calculation and GRI-2.1I mechanism was used for the chemical reaction. NOx emission index (EINOx) was introduced to evaluate NOx emission quantitatively in parametrically varied flames and the contribution of Thermal and Prompt NO mechanism was discussed. The results showed that Total EINOx varied sensitively with the variation of the flow rate of$CH_{4}$ but it was not sensitive to the variation of the diameter of inner fuel nozzle. Thermal EINOx showed the similar tendency to total EINOx and Prompt EINOx showed insensitivity to the variation of the diameter of inner fuel nozzle and the flow rate of $CH_{4}$.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.514-519
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• 2003

A computational study is performed to clarify the characteristics of supersonic moist air jet issuing from a simple sonic nozzle. The effects of the initial supersaturation on the Mach disk diameter and location, the barrel shock wave and jet boundary structures are investigated in details. The axisymmetric, compressible, Navier-Stokes equations, coupled with droplet growth equation, are solved using a third-order MUSCL type TVD finite-difference scheme. It is found that the Mach disk diameter increases with an increase in relative humidity of moist air. while its location is not significantly dependent on the relative humidity. As the relative humidity increases, the barrel shock wave and jet boundary are more expanded due to the local static pressure rise of nonequilibrium condensation.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.562-567
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• 2003

A computational study is performed to clarify the characteristics of supersonic moist air jet issuing from a simple sonic nozzle. The effects of the initial supersaturation on the Mach disk diameter and location, the barrel shock wave and jet boundary structures are investigated in details. The axisymmetric, compressible, Navier-Stokes equations, coupled with droplet growth equation, are solved using a third-order MUSCL type TVD finite-difference scheme. It is found that the Mach disk diameter increases with an increase in relative humidity of moist air. while its location is not significantly dependent on the relative humidity. As the relative humidity increases, the barrel shock wave and jet boundary are more expanded due to the local static pressure rise of nonequilibrium condensation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.3
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• pp.209-216
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• 2001

A numerical study is peformed to investigate the effect of circumferential velocity generated by the guide vane on the nozzle flow of a jet fan, s a way of increasing the penetration force of jet fan with nozzle of 175mm diameter. For the validation of numerical results. the velocity is measured by a 5-hole pitot tube and flow visualization is conducted by the tuft method. Under the inlet condition that the maximum circumferential velocity in the stator outlet of the present jet fan is 1.8m/s, the axial velocity in the nozzle outlet has the feature that the velocity at the axis is low and the velocity near the wall high. Therefore, to increase the throw length of the jet fan, the configuration of the fairing and nozzle needs to be developed and the precise revise of the stator angle is required, In addition, the bigger the circumferential velocity, the smaller the axial velocity at the axis and the bigger non-uniformity of the flow distribution.