http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
엔진 사이클 시뮬레이션에 의한 직분식 디젤기관의 NO 배출물에 미치는 흡기충전 조건의 영향에 관한 연구
함윤영 한국마린엔지니어링학회 2002 한국마린엔지니어링학회지 Vol.26 No.6
In this study, a cycle simulation using a two-zone model is carried out to investigate the effect of intake charging conditions such as oxygen concentration, temperature and pressure on NO emissions in a DI diesel engine. The model is validated against measurements in terms of cylinder pressure, torque, BSFC and NOx emissions with 2902 cc DI diesel engine. Calculated results can be summarized as follows. The oxygen concentration in the intake charge is decreased with increasing of EGR rate and equivalence ratio. As the intake oxygen concentration is reduced, the combustion pressure and the burned gas temperature decrease and, as a result, NO formation decreases. Also, the results show that as the intake pressure increases and the intake temperature decreases, NO emissions are effectively reduced.
비지배 정렬 유전 알고리즘(NSGA-II)을 이용한 이중연료 RCCI 엔진의 연소성능 최적화에 대한 수치적 연구
함윤영(Yun-Young Ham),장효정(Xiaojing Zhang) 한국산학기술학회 2023 한국산학기술학회논문지 Vol.24 No.10
디젤엔진의 열효율을 높이면서 NOx와 PM을 효과적으로 저감시키기 위해 저온연소(LTC: Low Temperature Combustion)전략이 개발되어 왔다. 최근 이중 연료를 사용하는 반응성 제어 압축착화(RCCI ; Reactivity Controlled Compression Ignition) 방식에 대한 연구가 꾸준히 진행되고 있다. RCCI방식은 HCCI나 PCCI방식보다 연소 제어에유리하기 때문에 보다 넓은 작동영역에서 운전이 가능한 것으로 알려져 있으나 두 개의 연료를 사용하기 때문에 연료분사와 관련된 제어인자가 많아 전체 운전 영역에서 최적의 운전조건을 설정하는 매핑작업에 많은 시간과 비용이 소요되는 문제가 있다. 본 연구에서는 저반응성 연료로는 가솔린을 사용하고 고반응성 연료로는 디젤을 사용하는 RCCI 엔진에서 비지배 정렬 유전 알고리즘(NSGA-II)을 도입하여 연소성능 최적화를 위한 수치해석을 수행하였다. 수치해석 결과, NSGA-II를 이용한 방법이 RCCI엔진의 연소성능 최적화에 효과적으로 사용될 수 있음을 확인하였으며, 1300rpm, 6bar 조건에서 저반응성연료비율은 0.68, 이단 분사 시 첫 번째 연료분사시기는 -56°ATDC, 두 번째 연료분사시기는 -26°ATDC, 이단 분사 시 첫 번째 분사량 비율은 0.4의 조건으로 운전 시 열효율 0.47, NOx는 0.054g/kWh, soot는 0.00072g/kWh의 결과를 얻었다. 최적화 시뮬레이션 과정을 통해 실제 엔진 매핑 시험 시간 및 비용을 크게 절감할 수 있을 것으로 기대된다. Low-temperature combustion (LTC) strategies have been developed to effectively reduce NOx and PM while increasing the thermal efficiency of diesel engines. Recently, reactivity controlled compression ignition (RCCI) using dual fuel has been studied. The RCCI method is known to be able to operate in a wider operating area than HCCI or PCCI because it has an advantage in combustion control. But because it uses two fuels, there are many control factors related to fuel injection, and mapping work to set optimal operating conditions in the entire operating area is time-consuming and costly. In this study, the non-dominated sorting genetic algorithm (NSGA-II) was introduced to optimize the combustion performance of an RCCI engine using gasoline as a low-reactivity fuel and diesel as a high-reactivity fuel. A numerical analysis was performed, and the results confirm that the method using NSGA-II can be effectively used to optimize the combustion performance. A thermal efficiency of 0.47, NOx level of 0.054 g/kWh, and soot level of 0.00072 g/kWh were obtained when the ratio of low-reactive fuel was 0.68, the first fuel injection timing was -56° ATDC, the second fuel injection timing was -26° ATDC, and the first injection fuel ratio was 0.4 for two-stage injection at 1300 rpm and 6 bar. The optimization simulation process is expected to significantly reduce the time and cost of engine mapping tests.
Urea-SCR 시스템의 NH₃ 흡 · 탈착 특성 및 모델기반 제어 연구
함윤영(Yunyoung Ham),박수열(Suyeol Park) 한국자동차공학회 2016 한국 자동차공학회논문집 Vol.24 No.3
Urea-SCR system is currently regarded as promising NOx reduction technology for diesel engines. SCR system has to achieve maximal NOx conversion in combination with minimal NH₃ slip. In this study, model based open loop control for urea injection was developed and assessed in the European Transient Cycle (ETC) for heavy duty diesel engine. On the basis of the transient modeling, the kinetic parameters of the NH₃ adsorption and desorption are calibrated with the experimental results performed over the zeolite based catalyst. NH₃ storage or surface coverage of SCR catalyst can not be measured directly and has to be calculated, which is taken into account as a control parameter in this model. In order to reduce NH₃ slip while maintaining NOx reduction, NH₃ storage control algorithm was applied to correct the basic urea quantity. If the actual NH₃ surface coverage is higher than the maximal NH₃ surface coverage, the urea injection quantity is significantly reduced in the ETC cycle. By applying this logic, the resulting NH₃ slip peak can be avoided effectively. With optimizing the kinetic parameters based on standard SCR reaction, it suggests that a simplified, less accurate model can be effective to evaluate the capability of model based control in the ETC cycle.
스파크 점화 기관의 실린더 블록 진동 신호를 이용한 노킹 제어
함윤영(Y. Y. Ham),전광민(K. M. Chun) 한국자동차공학회 1997 한국 자동차공학회논문집 Vol.5 No.1
The objective of this study is to develope knock control algorithms which can increase engine power without causing frequent knock occurrence. A four cylinder spark-ignition engine is used for the experiments to develope knock control algorithms which use block vibration signals. Knock occurrence is detected accurately by using knock threshold values which consider the difference of transmission path of each cylinder.<br/> Spark timing is controlled both simultaneously and individually. With the simultaneous contol, torque gain is achieved by retarding the spark timing on knock occurrence in propotion to the knock intensity. The individual knock control algorithm results in higher torque gain than the si-multaneous knock con-trol algorithm. The knock occurrence frequency of the individual knock control algorithm is about twice the value of the simultaneous knock control algorithm results. Both control algorithms give similar torque gain of about 3 % when they are optimized.
직분식 디젤엔진에서 엔진 매개변수들이 NO 및 soot 배출에 미치는 영향에 대한 수치해석 연구
함윤영(Yun young Ham),전광민(Kwang Min Chun) 한국자동차공학회 2002 한국 자동차공학회논문집 Vol.10 No.5
Engine cycle simulation using a two-zone model was performed to investigate the effect of the engine parameters on NO and soot emissions in a DI diesel engine. The present model was validated against measurements in terms of cylinder pressure, BMEP, NO emission data with a 2902cc turbocharger/intercooler DI diesel engine. Calculations were made for a wide range of the engine parameters, such as injection timing, ignition delay, intake air pressure, inlet air temperature, compression ratio, EGR. This parametric study indicated that NO and soot emissions were effectively decreased by increasing intake air pressure, decreasing inlet air temperature and increasing compression ratio. By retarding injection timing, increasing ignition delay and applying EGR, NO emission was effectively reduced, but the soot emission was increased.<br/>
직분식 디젤엔진에서 EGR이 연소특성 및 배출가스에 미치는 영향에 대한 시뮬레이션 연구
함윤영(Yun Young Ham),전광민(Kwang Min Chun) 한국자동차공학회 2002 한국 자동차공학회논문집 Vol.10 No.4
In this study, cycle simulation was performed to investigate the effect of EGR on combustion characteristics and emissions including NO and soot using a two-zone model in a DI diesel engine. The NO formation was well predicted for different EGR rate and temperature using a two-zone model. The oxygen in the inlet charge was replaced by CO₂and H₂O with EGR. The reduction in the inlet charge oxygen resulted in very large reduction in NO level at the same inlet charge temperature. The effect of EGR was to reduce the burned gas temperature. When EGR was increased from 0% to 15%, the peak flame temperature was decreased by 50℃ and it caused about 57% NO reduction. EGR caused increase of the overall inlet charge temperature which offset some of benefit of lower flame temperature resulting from 0₂displacement. Cooling the EGR was confirmed to provide additional benefits by lowering NO emission. It also reduced soot emission.
전기히터방식 매연여과장치의 PM 산화 특성에 관한 연구
함윤영(Yunyoung Ham),김대하(Daeha Kim),김경운(Kyungwoon Kim) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.1
For continuously regenerative PM collecting system which adopted thermally stable SiC DPF and electrical heater which was placed upstream of the filter and driven by well constructed control logic, PM oxidation characteristics were investigated varying air flow rate, amounts of PM accumulated on the DPF and filter inlet temperature in order to get optimized PM regeneration performance. This study showed that the operating condition of air flow rate 70 lpm, high PM loading around 30g and filter inlet temperature 700℃ with heat insulation was effective in achieving high regeneration efficiency. Also, in this condition, we could decrease the electric energy consumption by reducing the regeneration time.
Urea-SCR 시스템의 DeNox 특성에 관한 실험적 연구
함윤영(Yunyoung Ham),이성호(Seongho Lee),정홍석(Hongseok Jung),신동현(Donghyun Shin) 한국자동차공학회 2009 한국 자동차공학회논문집 Vol.17 No.2
To meet the NOx limit without a penalty of fuel consumption, urea SCR system is currently regarded as promising NOx reduction technology for diesel engines. SCR system has to achieve maximal NOx conversion in combination with minimal NH₃ slip. In this study, as a basic research to develop an algorithm for urea injection control, the characteristics of engine out NOx emission and behavior of NOx reduction during steady-state and transient conditions were investigated using 2L DI diesel engine. Test results show that on increasing the catalyst temperature the variations in the outlet NOx concentration are faster and maximal allowable NH₃ storage exponentially decreases. For change from a low to high engine load, it can be seen that a few seconds after load-step is required to reach full NOx conversion and the adsorbed amount of NH₃ at lower temperature desorb during the next temperature increase, causing NH₃ slip. Engine out NOx emission needs to be corrected because NOx emissions just after step load is lower than that of steay state condition.