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정적분위기에서 디젤대체연료의 연소 특성에 관한 수치해석적 연구
배재옥(Jaeok Bae),최민수(Minsu Choi),전충환(Chunghwan Jeon) 한국자동차공학회 2013 한국자동차공학회 지부 학술대회 논문집 Vol.2013 No.4
The objective of this numerical research is to analyze characteristics of combustion on various diesel alternative fuels in constant volume combustion chamber by using AVL-FIRE. Therefore, it is available to predict the results of application in the real engine. Numerical condition is chosen in considering TDC conditions of the real engine. As a result numerical study, ignition delay was shorten because of rapid atomization. However pressure and temperature were decreased. Biodiesel has plain characteristics between diesel and DME. Consequently, Diesel alternative fuels need to increase amount of injection for same power with diesel because its heating value is lower than diesel.
배재옥(Jaeok Bae),최낙원(Nakwon Choi),최민수(Minsu Choi),한동식(Dongsik Han),전충환(Chunghwan Jeon) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
The object of this research is to analyze characteristics of diesel combustion on various O₂ fraction on numerical investigation with AVL-FIRE. It is the most important to understand characteristics of spray and combustion on various ambient gas composition in CVCC(constant volume combustion chamber) in the study of low temperature combustion of diesel engine. Gas compositions in CVCC for simulation each contain [O₂_21%], [O₂_16%, CO₂_5%], [O₂_11%, CO₂_10%] and fixed fraction [N₂_79%]. Numerical results are as follows : ignition delay time was decreased and flame temperature was increased when O₂ fraction was increased. Also grade on the curve of heat release rate was decreased when O₂fraction was decreased. The mass production of NO is reduced and that of Soot is increased definitely in condition of lower O₂ fraction.
배재옥(Jaeok Bae),최민수(Minsu Choi),서현욱(Hyunuk Suh),한동식(Dongsik Han),전충환(Chunghwan Jeon) 한국자동차공학회 2012 한국자동차공학회 지부 학술대회 논문집 Vol.2012 No.5-1
The objective of this numerical investigation is to analyze characteristics of combustion and emission on various fuel ratio and injection strategy in RCCI(reactivity controlled compression ignition) with AVL-FIRE. RCCI operated by using the different firing characteristic of gasoline and that of diesel can achieve combustion with homogeneous flame. Combustion characteristic of RCCI is studied according to multiple-injection and fuel ratio of gasoline injected for premixed in advance and diesel injected for ignition. Peak pressure with premixed 70% gasoline and diesel multiple injection is higher than that of result with 100% diesel single injection. NOx emissions in RCCI tend to increase compared to that of diesel combustion. Especially, while diesel combustion produces large quantities of Soot, RCCI combustion produces almost zero quantities of Soot that show lower emission.
배재옥(Jaeok Bae),최민수(Minsu Choi),서현욱(Hyunuk Suh),한동식(Dongsik Han),전충환(Chunghwan Jeon) 한국자동차공학회 2012 한국자동차공학회 지부 학술대회 논문집 Vol.2012 No.11
This paper describes the numerical results of combustion and emission characteristics in gasoline with hydrogen on various equivalent ratio and rate of hydrogen addition by AVL-FIRE. GDI(Gasolin Direct Injection) which is a kind of gasoline combustion has a advantage to achieve high performance and fuel-efficiency by accurate control of combustion through direct injection of gasoline in a cylinder, but produce large amount of Soot. In this study, we try to solve the problem by adding hydrogen. We made the initial gas composition of CVCC(Constant Volume Combustion Chamber) to homogeneous mixture of air and hydrogen(24%, 48%) and let equivalence ratio to three conditions(0.5, 0.8, 1.0). The numerical results indicate that there is a ID(Ignition Delay) and reduction of exhaust emission including Soot according to a increase of hydrogen addition. Especially, COx and NOx emission are reduced by decreasing initial amount of gasoline and air in CVCC.
수소 예혼합 가솔린 직분사 엔진의 연소특성에 관한 수치해석 연구
배재옥(Jaeok Bae),최민수(Minsu Choi),서현욱(Hyunuk Suh),김규보(Gyubo Kim),전충환(Chunghwan Jeon) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
The objective of this study is to improve fuel consumption and to decrease COx emissions by reducing amount of injected gasoline as a result of hydrogen addition during intake period of GDI engine that is available to lean burn. Amount of carbon mole in cylinder before combustion gets lower because of reducing amount of gasoline injection, thus it can reduce COx emissions generated after burning. Also, production by hydrogen addition is H₂O which is no harmful to the environment. amount of injected gasoline fitted by hydrogen fraction to addition, oxigen and nitrogen fraction, density and fixed equivalent ratio were decided by a little bit complexed calculation. Ignition delay is shortend and production of Soot and CO₂ is decreased in accordance with increasing of hydrogen addition. On the other hand, amount of NO production tends to accelate because of increasing max temperature except for cases of hydrogen percent 11%, 15%.
정적 연소기 내 LNG-Diesel 혼소 특성에 관한 수치해석적 연구
서현욱(Hyunuk Suh),배재옥(Jaeok Bae),최민수(Minsu Choi),전충환(Chunghwan Jeon) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
The objective of this numerical study is to investigate the dual-fuel combustion characteristics and emissions including NO, Soot in Diesel with LNG. Simulations are performed in CVCC mesh structure of which initial conditions are including LNG mass fraction. As a result of LNG addition, pressure rises rapidly because of premixed gas combustion of LNG and NO emission production becomes lower due to fast combustion. Soot emission becomes lower until α=0.45, but higher to 170% comparison with diesel combustion over that fraction. CO emission looks likely to follow the soot emission tendency. This may mean that incomplete combustion caused by high LNG fraction accelerates the soot production. COx emission including CO and CO2 gets lower by reason of lower carbon content of LNG as compared that of diesel.
점화 모델에 따른 발전용 디젤 엔진의 연소 특성에 관한 수치적 연구
서현욱(Hyunuk Suh),배재옥(Jaeok Bae),이병화(Byeonghwa Lee),한동식(Dongsik Han),전충환(Chunghwan Jeon) 한국자동차공학회 2013 한국자동차공학회 지부 학술대회 논문집 Vol.2013 No.4
The objective of this numerical study is to evaluate the results of the simulation of which ignition models are diesel and shell. Power generation diesel engine used for this study has bore of 160mm, stroke of 240mm and compression ratio of 15.2. This study contains experimental result and numerical result calculated by STAR-CD and AVL-Fire. Pressure data of AVL-Fire has a 15~20bar maximum error compared with experimental pressure data in peak pressure range. Especially, Shell ignition model has a different shape of pressure and heat release rate curve increased and decreased rapidly. NO and Soot emissions in diesel ignition model are lower than those in shell ignition model which may be due to fast combustion. Finally, replacement of ignition model causes quite different numerical results and diesel ignition model may be appropriate for diesel combustion in AVL-Fire.
서현욱(Hyunuk Suh),배재옥(Jaeok Bae),최민수(Minsu Choi),전충환(Chunghwan Jeon) 한국자동차공학회 2013 한국자동차공학회 지부 학술대회 논문집 Vol.2013 No.11
Diesel engine has a advantage to obtain a high thermal efficiency and high power output, but emissions such as PM has become a problem caused by diffusion flame. In order to solve this problem, dual fuel engine using diesel fuel and gas has been developed, for which research is not enough. Therefore, the objective of this study is to investigate the characteristics of the diesel spray by injecting diesel into the Constant Volume Combustion Chamber of which ambient condition is premixed with methane gas 5%, 10%. As a result, spray tip penetration increase and spray cone angle decrease due to decline of internal gas density according to growth of methane gas fraction.