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RISS 인기검색어
- 검색키워드
- 저자 : 염정국(Jungkuk Yeum) (검색결과 5 건)
- 무료
- 기관 내 무료
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CVC에서 CNG 직접분사에 의한 부실소기에 관한 연구
유희은(Heeeun Yu),박종상(Jongsang Park),강병무(Byungmu Kang),염정국(Jongyul Ha),하종률(Jungkuk Yeum),정성식(Sungsik Chung) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_1
An experimental study was carried out to acquire the data about the effects of radical ignition on lean burn using CVC(constant volume combustor) and a real engine. A CVC is divided into the sub-chamber and the main chamber and numerous narrow passage holes are arranged among the main chamber and the sub-chamber. The products including radicals generated by spark ignition in the sub-chamber derives the simultaneous multi-point ignition in the main chamber. We examined the effects of the ratio between the sub-chamber volume and the sectional area of passage holes. In a CVC, the overall burning time including the ignition delay became very short and the maximum burning pressure was slightly increased by the radical ignition(RI) method in comparison with those by the conventional spark ignition(SI) method. It was proved that the optimum Ah/Vs ratio exists with the equivalence ratio. Also, conventional diesel engine was remodeled to a spark ignition engine, and that is finally converted to a radical engine with sub-chamber. It was proved that the residual gas in the sub-chamber brings severe cycle variation in a real RI engine. Therefore a new system using CNG and solenoid type of fuel injector was adopted to solve scavenging problem and fundamental experiments were performed for CVC prior to engine operation. As a result, the effects of residual gas were very great and the more detailed analysis is required on residual gas.
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RI 방식 CNG 엔진의 분사시기가 연소특성에 미치는 영향
박종상(Jongsang Park),진종무(Jongmoo Jin),하동흔(Dongheun Ha),염정국(Jungkuk Yeum),이중순(Joongsoon Lee),정성식(Sungsik Chung) 한국자동차공학회 2007 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
The prior study for RI(radical ignition) method was carried out in the experimental ways using a CVC(constant volume combustor) and applying the basic results from the CVC to a real engine. The rapid combustion and the expansion of the combustible lean limit of RI method were realized by the 0.45% sub-chamber volume of the overall combustion chamber in the CVC. But the gasoline fueled RI engine showed the severe problem of high cycle variation due to the difficulty of the residual gas scavenge in the sub-chamber from the former cycle. To solve this problem, CNG fuel was directly supplied into the sub-chamber instead of the port fuel injection. A DI Diesel Engine with the same specifications used in a previous study was modified to a RI-CNG Engine, and injection pressure was constantly kept at 6㎫ by a regulator. This study was performed to investigate the effects of injection timings on the combustion and performances of the RI-CNG Engine. The excess air ratio was varied from 1.0 to the lean limit at the condition of 50% throttle open rate and 1700rpm. The combustion characteristics of the RI-CNG engine such as in-cylinder pressure, indicated thermal efficiency, cycle-by-cycle variation, combustion duration and emissions were investigated.
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하동흔(Dongheun Ha),김민철(Mincheol Kim),박종상(Jongsang Park),염정국(Jungkuk Yeum),하종률(Jongyul Ha),정성식(Sungsik Chung) 한국자동차공학회 2008 한국자동차공학회 지부 학술대회 논문집 Vol.2008 No.11
This study was carried out to investigate the availability of using CNG fuel in a commercial two-cylinder gasoline engine and to derive the optimum performance of the engine. The results of this study is used to determine the optimized injection quantity at the time of dual injection and to improve the engine efficiency through comparing and investigating the performance of a PFI(Port Fuel Injection) and a sub-chamber DI(Direct Injection) type engine in order to establish the base of using PFI and sub-chamber DI type together in a multi-cylinder engine. A gasoline engine was adapted for this study, and air excess ratio was controlled using Lambda sensor and handle accelerator, and spark timing and injection timing were controlled using the ECU that was made personally. Combustion characteristics in accordance with air excess ratio and injection timing were investigated by multi-point injection using CNG fuel. On the basis of PFI type, the standard of fuel injection duration is obtained and it is applied to DI type. According to the air excess ratio, in-cylinder pressure, rate of heat release, IME(Indicated Mean Effective pressure), mass fraction burned, COVimep(Coefficient Of Variation), and so on are derived. As a result, the engine operation in PFI type is the safest at stoichiometric ratio and the engine operation in sub-chamber DI type is the safest at lean mixture ratio. This result is applied to the next study in order to obtain the optimized injection quantity and to improve the efficiency.
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