• 유기물자원화
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• 제30권4호
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• pp.15-25
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• 2022

수본 연구에서는 Bio-drying 공법 활용한 공기 송풍량 및 예열에 따른 음식물류 폐기물의 수분 및 유기물의 처리 효율에 대해 분석하였으며, 음식물류 폐기물 처리 시 온도, CO2의 평가를 통해 공기 송풍량 및 공기 예열이 Bio-drying 공법의 미치는 영향에 대해 평가하였다. 그 결과 공기 송풍량의 증가는 수분 제거율 및 제거 속도가 증가하는 결과를 미쳤지만, Bio-drying 내부 온도를 저하 시켜 미생물 활성도의 감소를 야기시켰다. 미생물의 활성도 유지를 위해서는 음식물류 폐기물의 성상에 따른 적정 공기 송풍량을 주입하는 것이 필요할 것으로 판단되었으며, 본 연구에서는 15L/min으로 주입하였을 때가 최적이었다. 공기 예열 유무에 따른 유기물 및 수분 제거율을 평가한 결과 공기 예열을 하였을 때가 하지 않았을 때에 비해 유기물 제거율 및 수분 제거율이 3~5% 가량 증가하는 결과를 보였다. 또한 Bio-drying 내부에 응축수 발생에 의한 내부 뭉침 현상도 발견되지 않았다. 따라서, 음식물류 폐기물의 효과적인 Bio-drying을 위해서는 미생물 활성도 유지를 위한 적정 송풍량을 유지 해야 하며, 공기 예열을 통한 주입이 필요할 것으로 사료된다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.86-87
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• 2005

The combustion characteristics of the D.I. diesel engine are largely dependent on the air-fuel ratio and the gas exchange process. The main factors are the shape of combustion chamber, fuel injection system, air flow inside the cylinder, intake air mass flow rate and so forth. Because these factors affect the combustion in a mutual and combined manner, it is very important to clearly understand the correlation of these factors in order to provide the combustion improvement plans. In this paper, we studied the performance and the gas exchange process of marine four-stroke engine using the engine cycle simulation. Also, we predicted briefly turbocharger engine matching.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.149-157
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• 2004

In the present paper we studied experimentally fundamental optimization of oxygen enriched pyrolysis melting incinerator, Characteristics of this system was confirmed dealing with the gas flow and combustion properties for the inside secondary air injection. The experiment setup has a disposal rate of 30kg/hr which was measured by the inside temperature and gas. Along with above experiments, the three-dimensional computation was employed to analyse the combustion fluid dynamics and gas residence time. Equations for turbulence and heat - transmission as well as chemical reactions were solved by using common codes. The experimental combustion chamber was composed of staged combustion types structure for reducing NOx. Finally, it was verified that the control of the secondary air and air ratio of thermo stack were important. In the computational analysis, it showed reasonable agreement with the experimental results regarding the temperature and discharged gas concentration.

• 한국화재소방학회논문지
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• 제24권4호
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• pp.109-115
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• 2010

중앙코어형 80층 초고층건물에서 평상시 동절기 연돌효과에 따른 최대차압은 약 75Pa로 외부 풍속이 없을 시에는 별 문제가 되지 않았으며, 화재로 계단실 단독 급기가압 시에는 급기가압 팬의 위치에 따라 급기 초기에 최대 약 225pa의 차압이 발생할 수 있으며 이를 해소하기 위한 적절한 과압배출장치나 대책이 필요하였다. 급기 송풍기의 위치에 따른 단독하부급기 방식이 최대차압의 크기와 분포 특성 및 최소설계차압 유지를 위한 소요풍량 면에서 가장 유리하였으며, 단독 상부급기방식은 소요급기풍량이나 차압분포 특성을 고려할 때 우리나라 특성에는 가장 적합하지 않는 것으로 나타났다. 차가운 외기 급기로 인해 계단실의 온도가 점차 하강하게 되면 계단실 연돌효과의 감소로 인해 소요풍량이 줄어들었으며 고층부에서의 차압은 줄어드는 반면 저층부에서의 차압이 크게 증가하는 양상으로 변화하는 것으로 나타났다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권4호
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• pp.427-438
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• 2018

The reduction of $CO_2$ emissions has been a key target in the marine industry since the IMO's MEPC published its findings in 2009. Air lubrication method is one of the mature technologies for commercialization to reduce the frictional resistance and enhance fuel efficiency of ships. Air layer is formed by the coalescence of the injected air bubbles beyond a certain air flow rate. In this study, a model ship (${\lambda}=33.33$) of a 50,000 ton medium range tanker is equipped with an air lubrication system. The experiments were conducted in the 100 m long towing tank facility at the Pusan National University. By selecting optimal air injector configuration and distribution ratio between two injectors, the total resistance of model $R_{TM}$ was able to be reduced down to 18.1% in the model scale. Key issue was found to suppress the sideway leakage of injected air by appropriate injection parameters.

• 한국대기환경학회지
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• 제19권4호
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• pp.437-449
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• 2003

A multi-functional indoor smog chamber was designed and evaluated to investigate photochemical or water vapor reaction mechanisms of air pollutants. Various smog chamber experiments could be conducted using ambient air or purified air in this smog chamber. The smog chamber consisted of a housing, a Teflon bag, blacklights, injection ports, sampling ports, and utility facilities. The characteristics of light source, the wall losses of air pollutants, and the quality of purified air were experimentally investigated. The maximum NO$_2$ photolysis rate was 1.10 min$^{-1}$ . In a 2.5-m$^3$ Teflon bag, the wall losses of ambient $O_3$, NO, and NO$_2$ were 1.2~2.4$\times$10$^{-3}$ min$^{-1}$ , 0.7~2.0$\times$10$^{-3}$ min$^{-1}$ , and 0.4~2.0$\times$10$^{-3}$ min$^{-1}$ , respectively. The wall loss of ambient particles ranging 0.05 to 0.2 ${\mu}{\textrm}{m}$ was 1.8~5.4$\times$10$^{-3}$ min$^{-1}$ , which was slightly higher than those of ambient gaseous species. The purified air supply system provided high quality of air with NO$_{x}$ < 1 ppb, and total hydrocarbons < 5 ppb.b.

• 한국자동차공학회논문집
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• 제7권9호
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• pp.36-47
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• 1999

Three-way catalyst converter, cleaning up the exhaust gas contamination of SI engine, has the best efficiency when A/F ratio is near the stoichiometry . The feedback control using oxygen sensors in the exhaust manifold has limits caused by the system delays. So the accurate measurement of air flow rate to an engine is essential to control the fuel injection rate especially on transient condition like the rapid throttle opening and closing. To measure the rapid change of flow rates. the air flow meter for the engine requires quick response, flow reversal detection, and linearity . Tjhe proposed integration type air flow meter (IFM), composed of an ultrasonic flow meter with an integration circuit, has significantly improved the measurement accuracy of air mass inducted through the throttle body. The proposed control method estimated the air mass at the cylinder port using the measured air mass at the throttle . For the fuel dynamic model, the two constant fuel model is introduced . The control parameters from air and fuel dynamics are tuned to minimize the excursion of the air fuel ratio. As a result A/F ratio excursion can be reduced within 5% when throttle rapidly opens and closes at the various engine conditions.

• 한국자동차공학회논문집
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• 제6권6호
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• pp.142-154
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• 1998

The effects of recirculated exhaust gas on the characteristic of soot emissions have been investigated by using an eight-cylinder, four-stroke, direct injection and water-cooled diesel engine operating at several loads and speeds. The experiments in this study are carried out at the fixed fuel injection timing of $38^{\circ}$ BTDC regardless of experimental conditions. The intake oxygen concentration and the mean equivalence ratio calculated by the intake air flow and fuel consumption rate are used to analyze and discuss the influences of EGR rate on soot emissions. Results of this study indicate that soot emissions increase owing to the drop of intake oxygen concentration and the rise of equivalence ratio as the EGR rate increases at a given engine load and speed, especially the high load.

• 대한기계학회논문집
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• 제17권9호
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• pp.2339-2358
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• 1993

Since the rate and completeness of combustion in direct injection engines were controlled by the characteristics of gas flow fields and sprays, an understanding of those was essential to the design of the direct injection engines. In this study the numerical simulations of injection pressure effects on the characteristics of gas flow fields and sprays were preformed using the spray model that could predict the interactions between gas fields and spray droplets. The governing equations were discretized by the finite volume method and the modified k-.epsilon. model which included the compressibility effects due to the compression/expansion of piston was used. The results of the numerical calculation of the spray characteristics in the quiescent environment were compared with the experimental data. There were good agreements between the results of calculation and the experimental data, except in the early stages of the spray. In the motoring condition, the results showed that a substantial air entrainment into the spray volume was emerged and hence the squish motion was relatively unimportant during the fuel injection periods. It was found that as the injection pressure increased, the evaporation rate of droplets was decreased due to the narrow width of spray and the increased number of droplets impinged on the bottom of the piston bowl.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.60-65
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• 2004

Numerical simulations and experiments have been carried out to investigate the effect of fuel injection nozzles on the combustion and NOx formation processes in a medium-speed marine diesel engine. Spray visualization experiment was performed in the constant-volume high-pressure chamber to verify the numerical results on the spray characteristics such as spray angle and spray tip penetration. Time-resolved spray behaviors were captured by high-speed digital camera and analyzed to extract the information on the spray parameters. Spray and combustion phenomena were examined numerically using FIRE code. Wave breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation processes. Numerical results were verified with experimental data such as cylinder pressure, heat release rate and NOx emission. Finally, the effects of fuel injection nozzles on the engine performance were investigated numerically to find the optimum nozzle parameters such as fuel injection angle, nozzle hole diameter and number of nozzle holes. From this study, the optimum fuel injection nozzle (nozzle hole diameter, 0.32 mm, number of nozzle holes, 8 and fuel injection angle, $148^{\circ}$) was selected to reduce both the fuel consumption and NOx emission. The reason for this selection could be explained from the highest fuel-air mixing in the early phase of injection due to the longest spray tip penetration and the highest heat release rate after $19^{\circ}$ ATDC due to the increased injection duration.