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Dong Han,Huanyu Guang,Zheng Yang,XingCai Lu,Zhen Huang 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.8
The effects of fuel/air equivalence ratio and CO2 concentration in fuel/air charge on the ignition process of gasoline and diesel-like fuel (n-heptane) blends on a rapid compression machine are investigated in this study. Results showed that the effects of equivalence ratio on ignition delays of two ignition stages are varied. As equivalence ratio increases from 0.3 to 0.5, the first stage ignition delay slightly increases because the increased equivalence ratio improves the mixture heat capacity, reducing the in-cylinder temperature and weakening the low-temperature heat release process of the fuel. The second stage ignition delay is shortened with the increased equivalence ratio because increased fuel concentration facilitates mixture reactivity. CO2 addition to the cylinder charge can effectively reduce the peak cylinder pressure and the two stage pressure rise rates, as well as extend the durations of ignition delays of two ignition stages.
배기 재순환 조건에서 n-heptane/n-butnaol 혼합연료의 혼합비율 변화에 따른 착화지연에 관한 연구
송재혁(JaeHyeok Song),강기중(Kijoong Kang),Zheng Yang,XingCai Lu,최경민(GyungMin Choi),김덕줄(DuckJool Kim) 한국자동차공학회 2013 한국자동차공학회 지부 학술대회 논문집 Vol.2013 No.4
This study was conducted to observe the ignition delay time using a rapid compression machine (RCM). It also adapted high exhaust gas recirculation (EGR) rate by 9-10% O2 condition which is expected to lead low temperature combustion that result in decreasing NOx and soot emission. The experiments were performed using binary fuel of n-heptane and n-butanol so that the combustion characteristics of binary fuel were observed with changing the blending ratio. In addition, simulation of the ignition delay time was performed using CHEMKIN code to validate the experimental results and predict the chemical species after combustion process. Experiments showed that the ignition delay increased with increasing the n-butanol ratio in the mixture due to a decrease of oxidation of n-heptane at the low temperature. Moreover, all of the binary fuel mixtures indicated clear cool flame behavior at low temperature and negative-temperature -coefficient (NTC) behavior which is a characteristics of n-heptane as well.
저온연소조건에서 급속압축기를 이용한 n-heptane/n-butanol 혼합연료의 착화지연에 관한 연구
송재혁(Jae Hyeok Song),강기중(Ki Joong Kang),Zheng Yang,XingCai Lu,최경민(Gyung Min Choi),김덕줄(Duck Jool Kim) 한국연소학회 2013 한국연소학회지 Vol.18 No.2
This study presents both experimental and numerical investigation of ignition delay time of n-heptane and n-butanol binary fuel. The O2 concentration in the mixture was set to 9-10% to make high exhaust gas recirculation(EGR) rate condition which leads low NOx and soot emission. Experiments were performed using a rapid compression machine(RCM) at compressed pressure 20bar, several compressed temperature and three equivalence ratios(0.4, 1.0, 1.5). In addition, a numerical study on the ignition delay time was performed using CHEMKIN codes to validate experimental results and predict chemical species in the combustion process. The results showed that the ignition delay time increased with increasing the n-butanol fraction due to a decrease of oxidation of n-heptane at the low temperature. Moreover, all of the binary fuel mixtures showed the combustion characteristics of n-heptane such as cool flame mode at low temperature and negative-temperature-coefficient(NTC) behavior. Due to the effect of high EGR rate condition, the operating region is reduced at lean condition and the ignition delay time sharply increased compared with no EGR condition.
혼합비율 및 압력 변화가 바이오매스 합성가스의 점화지연 시간에 미치는 영향
심태영(Tae Young Shim),강기중(Ki Joong Kang),Xingcai Lu,최경민(Gyung Min Choi),김덕줄(Duck Jool Kim) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.12
본 연구에서는 바이오매스 합성가스를 모사하여 합성가스의 주요성분에 따른 자착화 특성을 실험 및 수치적으로 고찰하였으며, 온도, 혼합물의 조성, 압력의 변화가 자착화 특성에 미치는 영향을 분석하였다. 충격파관(Shock Tube)을 이용하여 모사 합성가스의 점화지연 시간을 측정하였고, 수치해석은 실험결과 검증과 연소과정 중 중간화학종 분석을 위해 상용프로그램인 CHEMKIN-PRO를 사용하였다. 모든 온도 조건에서 혼합물 내의 수소의 몰 비율이 증가함에 따라 점화지연 시간이 감소하는 현상을 확인할 수 있었다. 1150K 이상의 온도 조건에서 압력이 증가함에 따라 점화지연 시간이 감소하는 현상을 확인할 수 있었다. 하지만 1150K 이하의 온도 조건에서는 압력이 증가함에 따라 점화지연 시간이 증가하는 현상을 확인할 수 있었다. The autoignition characteristics of biosyngas were investigated both numerically and experimentally. The effects of the temperature, gas composition, and pressure on the autoignition characteristics were evaluated. A shock tube was employed to measure the ignition delay times of the biosyngas. The numerical study on the ignition delay time was performed using the CHEMKIN-PRO software to validate the experimental results and predict the chemical species in the combustion process. The results revealed that the ignition delay time increased with an increase in the hydrogen fraction in the mixture. Under most temperature conditions, the ignition delay time decreased with a pressure increase. However, the ignition delay time increased with an increase in pressure under relatively low temperature conditions.