EGR을 이용한 천연가스차량(NGV)의 배출물 저감에 관한 연구

홍명석 조선대학교 환경공해연구소 1999 環境公害硏究 Vol.15 No.2

CNG(compressed natural gas) is becoming the alternative fuel that appears to offer the most promise of success. NGVs are available as bifuel conversions and uses a high compression ratio to take advantage of the very high octane rating of CNG. The goal of this study was to develop a natural gas conversion technique that has superior performances in comparison to the gasoline version of this vehicle while producing low emission. But the difficulty is the emission control, especially for NOx. The solution to this problem is to use a high rate of EGR to control the peak temperature and a three-way catalyst for additional control of the emitted pollutants. This EGR system can be applied to any NGV that has been designed to control exact air/fuel ratio and adequate EGR rate.

이온 프로브법에 의한 예혼합 난류화염의 전파기구에 관한 연구

홍명석,하옥남,정낙규 조선대학교 동력자원연구소 1995 動力資源硏究所誌 Vol.17 No.1

A method using an ion probe to detect a flame by its plasma potential signal has been developed. The spatial resolution of the probe is demonstrated to be well improved over that of the conventional one. The plasma potential signal obtained by this method from a premixed propagating turbulent flamelet in the reaction zone of the flame. Based on this consideration, the propagating speed, the thickness of the reaction zone and number of flamelets in the zone, the separation distance between two adjacent flamelets, etc. of the flame, were then obtained. Results of this experiment suggest the existence of "reactant islands" in the reaction zone, and show that the averaged number of flamelets in the zone increases in the turbulence intensity and /or a decrease in the Damko¨hler number.

스파크 점화 엔진의 냉간시동 중 탄화수소 배출의 시간분해 측정

홍명석 조선대학교 환경연구소 1999 環境硏究 Vol.15 No.1

The effects of ignition timing and idle speed on the required starting enrichment, hydrocarbon emissions and exhaust temperature are explored. The measurements are focused upon the first 20 seconds of operation after starting with the engine and coolant initially at ambient temperature because this period has a major effect on HC emissions, decreasing cold start enrichment and decreasing the time to catalyst light-off are desirable. Increasing the idle speed is interest as a means to improve in-cylinder oxidation. Speciated HC emissions from the exhaust system of a production engine have been obtained with 3 second time resolution during cold start using two control strategies for the conventional cold start, the emissions were initially enriched in light fuel alkanes and depleted in heavy aromatic species. The light alkanes fell rapidly while the lower vapor pressure aromatics increased over a period of 50sec. These results indicate early retention of low vapor pressure fuel components in the atmospheric reactivity of the exhaust HC emissions for photochemical smog formation increases as the engine warms.

정전탐침과 레이저 단층 촬영에 의한 예혼합 난류화염의 구조

홍명석,박용태 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1

The structure of premixed turbulent flames in a constant-volume vessel was investigated by using the electrostatic-probe method and the laser tomography. The eletrostatic-probe method, which perceives a flamelet by detecting its flame potential signal was used to measure the flame propagation speed, the thickness of flame zone and the number of existing flamelets. And the laser tomography was used to visualize the deeper structure of flames, where the laminar burning velocity and the turbulence intensity where varied independently. A laser sheet, 200 micrometers and 2.2cm wide, was passed through the turbulent flame, then 2-D cross section of the flame front was obtained by the intensity variation of the scattered light corresponding to the change in the gas density. As a result, at least on the 2-D cross section, reactant islands were found in a strong turbulence field.

직접분사 성층 연소방식에서 수소의 첨가에 의한 연소성능의 개선

홍명석,하옥남 조선대학교 생산기술연구소 1995 生産技術硏究 Vol.17 No.1

The direct injection stratified charge (DISC) engine is considered to be an alternative to the conventional spark ignition engines. Its actual utilization is, however, prevented by high emission levels of unburned hydrocarbons during light load operation. Over-lean mixtures due to the long combustion duration and wall quenching due to these lean mixtures will be the main causes of unburned hydrocarbons in the DISC system. In order to solve this problem, small amount of hydrogen was added to the charging air or injected fuel. When hydrogen was added to the charge of air, the combustion pressure was increased and the unburned hydrocarbons was reduced with increasing the amount of hydrogen addition. In the case hydrogen was added to the fuel, the combustion pressure was more increased than the case that the same amount of hydrogen was added to the charge.

정적 용기내의 직접분사식 스파크 점화 성층 연소에 관한 연구

홍명석(M. S. Hong),김경석(K. S. Kim) 한국자동차공학회 1994 한국 자동차공학회논문집 Vol.2 No.5

直接噴射式 成層燃燒方式에서 未燃炭化水素의 低減

洪明錫,張完植 조선대학교 동력자원연구소 1993 動力資源硏究所誌 Vol.15 No.2

The direct-injection stratified-charge engine is considered to be a promising alternative to conventional spark-ignition engines. It has, however, an unfavourable feature of high unburned hydrocarbon emission levels, especially during light-load operations. In crjer to conquer this problem, the effects of intensification of local premixing of fuel with air on combustion process were investigated using a pancake type constant volume bomb. Considerable improvements in the maximum combustion pressure, combustion duration and the amount of unburned hydrocarbons were obtained in this study.

메탄가스를 이용한 직접분사식 성층연소에 관한 연구

홍명석 조선대학교 동력자원연구소 1994 動力資源硏究所誌 Vol.16 No.1

The direct-injection stratified-charge (DISC) engine is considered to be a promising alternative to conventional spark ignition engines, It has, however, an unfavorable feature of high unburned hydrocarbon emission levels, especially during light operations. In this paper, the effect of swirl on radial and tangential fuel injection in the DISC system, was investigated using methane gas and pancake type constant volume bomb. The stratification and mixing process of fuel jet and combustuon process were observed by schlieren photography. Then, locally homogenized and premixed direct-injection stratified-charge combustion system were examined for the purpose of reducing unburned hydrocarbon emission and obtaining the maximum combustion pressure.

4행정 SI엔진의 연소효율에 대한 준평형 모델

홍명석,안철봉 조선대학교 동력자원연구소 1996 動力資源硏究所誌 Vol.18 No.2

A simple but accurate model for the combustion efficiency of 4-stroke homogemeous charge spark ignition engines has been developed based upon thermochemical equilibrium arguments. This model assumes that the combustion efficiency is a function of only the fuel-air equivalence ratio for hydrocarbon fules with a hydrogen-to-carbon ratio similar to that of iso-octane. This model was shown to accurately predict experimental data for ranges of compression ratio, load, ignition timing, and speed typical of the normal engine design and operation. The model slightly overpredicts the data for high than typical engine speeds and is not applicable to engines operating near the partial burn, ignition, or lean misfire limits. An example of the potential usefulness of this model is also briefly discussed.

스파크 점화에 직접분사식 스파크 점화 성층 연소에 관한 연구

洪明錫,張完植 조선대학교 환경연구소 1993 環境公害硏究 Vol.10 No.-

The direct injection stratified charge engine is considered to be a alternative to conventional spark ignition engines. It has the favourable features of high thermal efficiency, low carbon monoxide and nitric oxide emission levels as well as multifuel capability. It has, however, the unfavourable feature of a high unburned hydrocarbon emission level, especially during light load operations. In this paper, fundamental studies on this system were carried out using a pancake type constant volume bomb. The effects of intensification of local premixing by tangential and radial fuel injection were examined experimentally. Unburned hydrocarbon emission levels with radial fuel injection were shown to be lower than those of tangential fuel injection cases. The stratification and mixing process of fuel jet and combustion process were observed by Schlieren photography.