• Research Article

    Early Diagnosis of Combustion Instability Using Statistical Methods

    통계적 기법을 활용한 연소불안정 조기진단

    Seungkyu Choi, Jaemin Baek and Daesik Kim

    최승규, 백재민, 김대식

    Various statistical approaches have been recently proposed to detect combustion instabilities in a short time through a fast data processing on dynamic … + READ MORE
    Various statistical approaches have been recently proposed to detect combustion instabilities in a short time through a fast data processing on dynamic pressure of time domain measured in a gas turbine combustor. In the current study, four methods, PE(permutation entropy), TK(temporal kurtosis), ZCR(zero crossing rate), and STFT(short time Fourier transform), were applied and compared with the conventional instability onset-detection method, RMS(root mean square), using the same dynamic pressure data measured in a lab-scale gas turbine combustor. As a result of the comparison, it was found that PE, TK, and ZCR can detect combustion vibration earlier than the instability onset time determined by RMS. On the other hand, STFT did not show relatively good early detection characteristics. - COLLAPSE
    30 September 2022
  • Research Article

    Effect of DC Electric Field on Propane Premixed Flame

    프로판 예혼합 화염에 대한 DC 전기장 효과

    Junyoung Choi, MinSeok Kim and Hyemin Kim

    최준영, 김민석, 김혜민

    In this study, the effects of electric field on the propane premixed flame were experimentally investigated. The experiment was conducted by observing … + READ MORE
    In this study, the effects of electric field on the propane premixed flame were experimentally investigated. The experiment was conducted by observing the chemiluminescence of radicals, measuring the temperature of the flow field and the NOx emission of exhaust gas. The regions of OH, and CH radicals expanded toward the radial direction in negative electric field, and it moved toward burner under the positive electric field. The temperature Distribution of flow field was changed with the radical position in each electric field condition. The temperature of flow field unified when negative electric field applied, and NOx reduced to maximally about 6.8%. On the other hand, it increased to maximally about 19% in positive electric field because the flame contracted toward the center. - COLLAPSE
    30 September 2022
  • Research Article

    Control of Self-excited Instabilities and Emissions using Radial Fuel Staging in a Mesoscale Multinozzle Array

    반경 방향 연료 스테이징을 통한 메조스케일 다중노즐 연소불안정 및 배기가스 제어

    Hyebin Kang and Kyu Tae Kim

    강혜빈, 김규태

    The effect of radial fuel staging on combustion instabilities and NOx/CO emissions characteristics was investigated in a mesoscale multinozzle array consisting of … + READ MORE
    The effect of radial fuel staging on combustion instabilities and NOx/CO emissions characteristics was investigated in a mesoscale multinozzle array consisting of sixty swirl injectors. We observe that inner fuel staging effectively mitigates high-amplitude oscillations by controlling the collective motion of the small-scale flames. The production of thermal NOx and CO emissions, however, tends to increase due to the presence of high-temperature region in the center flames. This result means that combustion dynamics and exhaust emissions need to be compromised when radial fuel staging scheme is used in gas turbine combustor environments. - COLLAPSE
    30 September 2022
  • Research Article

    Effect of Pulsation Characteristics of Fuel Flow on Local Equivalence Ratio, Combustion, and NOx Emission in a Nozzle-Mixed Burner

    연료유량 제어밸브의 작동특성에 따른 로컬 당량비 변화와 연소 및 질소산화물 발생의 관계

    Hookyung Lee, Jonghyun Kim, Jungsoo Park and Young Tae Guahk

    이후경, 김종현, 박정수, 곽영태

    The present work investigated the NOx reduction effect that can be obtained by periodically changing the local equivalence ratio by repeatedly … + READ MORE
    The present work investigated the NOx reduction effect that can be obtained by periodically changing the local equivalence ratio by repeatedly controlling the fuel flow. When there was no pressure pulsation of the fuel, the NOx emission was 30.3 ppm (O2 vol.11%), and the NOx emission was reduced from 4% to 30% according to the pulsation variables. Since it is difficult to directly measure the instantaneous mass and volumetric flow rate during a periodic change on a 103-millisecond scale in an industrial-scale experiment, the measured pressure was used to calculate the mass and volumetric flow rate. The fuel and air supply pressure was fixed at 700 mmH2O, and when flow pulsation occurred in the fuel pipe, the pressure was changed within the range of 150 to 694 mmH2O. As a result of calculation through the one-dimensional model, it had a local equivalence ratio range of 0.108 to 0.776. In the chemical equilibrium domain of methane, the relationship between the local equivalence ratio change and combustion products according to the operating characteristics of the fuel-flow pulsation valve was discussed. - COLLAPSE
    30 September 2022
  • Research Article

    Experimental Study of Combustion Characteristics of a Diesel Engine Fueled with Diesel/1-Decanol Blends

    경유/1-데칸올 혼합유의 디젤엔진 연소 특성 연구

    Cheol-oh Park, Jeonghyeon Yang, Beomsoo Kim and Jaesung Kwon

    박철오, 양정현, 김범수, 권재성

    There have been many studies on the combustion characteristics of lower alcohols in diesel engines, but information on higher alcohols is relatively … + READ MORE
    There have been many studies on the combustion characteristics of lower alcohols in diesel engines, but information on higher alcohols is relatively scarce. In this study, diesel/1-decanol blends were prepared to investigate the combustion and emission characteristics of a single-cylinder 4-stroke diesel engine. The concentration of 1-decanol in the fuel blends was 10%, 15%, and 20% by volume. Experiments were conducted by varying the engine torque from 4 Nm to 12 Nm at the same engine speed of 2000 rpm. Results show that the thermal efficiency and smoke opacity decreased while the brake specific fuel consumption increased with blended fuels. The concentration of NOx in the exhaust gas generally reduced, while it increased for some conditions with 20% 1-decanol as the load increased. CO emissions increased for relatively high loads when the 1-decanol ratio is 15% and 20% due to the reduction in the air-fuel ratio. - COLLAPSE
    30 September 2022
  • Technical Notes

    Reduction Technology on White Smoke of Decrepit Construction Vehicles with Plasma Burner

    플라즈마 버너를 활용한 노후건설기계의 백연(white smoke) 배출 저감 기술

    Young-Hoon Song, Dae Hoon Lee, Hongjae Kang, Kwangchul Oh, Chunbeom Lee and Kwangok Choi

    송영훈, 이대훈, 강홍재, 오광철, 최광옥, 최광옥

    White smoke emission from decrepit construction vehicles is one of the main causes of fine dust production. In particular, despite the fact … + READ MORE
    White smoke emission from decrepit construction vehicles is one of the main causes of fine dust production. In particular, despite the fact that a large amount of white smoke is occurring in the vehicles such as decrepit construction machinery equipped with DPF (Diesel Particulate Filter), no technical solution has been found yet. This study aims to analyze the causes of white smoke emission that occurs in DPF system and propose technical solutions to resolve the issues. The performance and operational characteristics of the burner mounted to thermally manage the DPF performance are the main causes of the occurrence of white smoke. The fundamental ignition mechanism of the diesel burners was investigated depending on the types of ignition sources; the rotating gliding arc for plasma burner and glow plug for conventional diesel burner. It was verified that plasma burner can be applied to drastically reduce the occurrence of white smoke. - COLLAPSE
    30 September 2022