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Viewing 1 to 30 of 59
2011-04-12
Technical Paper
2011-01-1389
Kihyun Kim, Sangwook Han, Choongsik Bae
Mode transition between low temperature combustion and conventional combustion was investigated in a direct injection diesel engine. Low temperature diesel combustion was realized by means of high exhaust gas recirculation rate (69~73%) and early injection timing (-28~ -16 crank angle degree after top dead center) compared with those (20% exhaust gas recirculation rate and -8 crank angle degree after top dead center) of conventional combustion. Tests were carried out at different engine speeds and injection pressures. Exhaust gas recirculation rate was changed transiently by controlling each throttle angle for fresh air and exhaust gas recirculation to implement mode transition. Various durations for throttle transition were applied to investigate the effect of speed change of exhaust gas recirculation rate on the characteristics of mode transition.
2009-06-15
Technical Paper
2009-01-1847
Jinyoung Jang, Kiseon Yang, Choongsik Bae
Dimethyl ether (DME) as a high cetane number fuel and liquefied petroleum gas (LPG) as a high octane number fuel were supplied together to evaluate the controllability of combustion phase and improvement of power and exhaust emission in homogeneous charge compression ignition (HCCI) engine. Each fuel was injected at the intake port and in the cylinder separately during the same cycle, i.e., DME in the cylinder and LPG at the intake port, or vice versa. Direct injection timing was varied from 200 to 340 crank angle degree (CAD) while port injection timing was fixed at 20 CAD. In general, the experimental results showed that DME direct injection with LPG port injection was the better way to increase the IMEP and reduce emissions. The direct injection timing of high cetane number fuel was important to control the auto-ignition timing because the auto-ignition was occurred at proper area, where the air and high cetane number fuel were well mixed.
2011-08-30
Technical Paper
2011-01-1823
Youngsoo Park, Choongsik Bae
The effect of pilot injection and exhaust gas recirculation (EGR) on premixed charge compression ignition (PCCI) combustion was investigated in a single-cylinder direct-injection diesel engine with low engine speed and low load. The injection timing of PCCI combustion was fixed at 25 ~ 30 crank angle degree before top dead center (°CA BTDC) based on the ignition delay and power output. The level of oxides of nitrogen (NOx) emissions of PCCI combustion was 68% lower than that of conventional diesel combustion owing to the reduction of near-stoichiometric region which is well known as the main source of NOx formation. However, the indicated mean effective pressure (IMEP), hydrocarbon (HC), particulate matter (PM) and carbon monoxide (CO) emissions deteriorated compared with conventional diesel combustion because of early injection, advanced combustion phase and lowered combustion temperature. EGR has been applied to PCCI combustion.
2011-04-12
Technical Paper
2011-01-1357
Yongjin Jung, Choongsik Bae, Jinyoung Jang, Duksang Kim
Premixed compression ignition (PCI) combustion was implemented using advanced injection strategy and exhaust gas recirculation in a direct-injection single-cylinder diesel engine. The injection timing swept experiment using a baseline injector, which had an injection angle of 146° and 8 nozzle holes, obtained three types of combustion regime: conventional diesel combustion for an injection timing of 10° CA (crank angle) BTDC (before top dead center), PCI combustion for an injection timing of 40° CA BTDC and homogeneous charge compression ignition (HCCI) combustion for an injection timing of 80° CA BTDC. PCI combustion can be verified by burn duration analysis. The burn duration, which was defined as the period from 10% to 90% of the accumulated heat release, was very short in PCI combustion but not in the others. PCI combustion with an injection timing of 40° CA BTDC was achieved in a range of an exhaust gas recirculation (EGR) rate from 0% to around 40%.
2013-10-14
Technical Paper
2013-01-2662
Joonsik Hwang, Donghui Qi, Yongjin Jung, Choongsik Bae
An experimental study was conducted to investigate the impact of injection parameters on the combustion and emission characteristics in a compression ignition engine fuelled with neat waste cooking oil (WCO) biodiesel. A single-cylinder diesel engine equipped with common-rail system was used in this research. The test was performed over two engine loads at an engine speed of 800 r/min. Injection timing was varied from −25 to 0 crank angle degree (CAD) after top dead center (aTDC) at two different injection pressures (80 and 160 MPa). Based on in-cylinder pressure, heat release rate was calculated to analyze the combustion characteristics. Carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOx) and smoke were measured to examine the emission characteristics. The results showed that the indicated specific fuel consumption (ISFC) of WCO biodiesel was higher than that of diesel. The ISFC was increased as the injection timing was advanced and injection pressure was increased.
2013-09-08
Journal Article
2013-24-0058
Sangwook Han, Hyunchul Kim, Choongsik Bae
Mode transition between low temperature combustion (LTC) and conventional combustion was performed by changing the exhaust gas recirculation (EGR) rate from 60% to 0% or vice versa in a light duty diesel engine. The indicated mean effective pressure (IMEP) before mode transition was set at 0.45 MPa, representing the maximum load of LTC in this research engine. Various engine operating parameters (rate of EGR change, EGR path length, and residual gas) were considered in order to investigate their influence on the combustion mode transition. The characteristics of combustion mode transition were analyzed based on the in-cylinder pressure and hydrocarbon (HC) emission of each cycle. The general results showed that drastic changes of power output, combustion noise, and HC emission occurred during the combustion mode transition due to the improper injection conditions for each combustion mode.
2006-04-03
Technical Paper
2006-01-0197
Sanghoon Kook, Choongsik Bae, Paul C. Miles, Dae Choi, Michael Bergin, Rolf D. Reitz
Engine-out CO emission and fuel conversion efficiency were measured in a highly-dilute, low-temperature diesel combustion regime over a swirl ratio range of 1.44-7.12 and a wide range of injection timing. At fixed injection timing, an optimal swirl ratio for minimum CO emission and fuel consumption was found. At fixed swirl ratio, CO emission and fuel consumption generally decreased as injection timing was advanced. Moreover, a sudden decrease in CO emission was observed at early injection timings. Multi-dimensional numerical simulations, pressure-based measurements of ignition delay and apparent heat release, estimates of peak flame temperature, imaging of natural combustion luminosity and spray/wall interactions, and Laser Doppler Velocimeter (LDV) measurements of in-cylinder turbulence levels are employed to clarify the sources of the observed behavior.
2015-04-14
Journal Article
2015-01-0809
Joonsik Hwang, Yongjin Jung, Choongsik Bae
Abstract The effect of biodiesel produced from waste cooking oil (WCO) on the soot particles in a compression ignition engine was investigated and compared with conventional diesel fuel. The indicated mean effective pressure of approximately 0.65 MPa was tested under an engine speed of 1200 revolutions per minute. The fuels were injected at an injection timing of −5 crank angle degree after top dead center with injection pressures of 80 MPa. Detailed characteristics of particulate matters were analyzed in terms of transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and elemental analysis. Soot aggregates were collected on TEM grid by thermophoretic sampling device installed in the exhaust pipe of the engine. High-resolution TEM images revealed that the WCO biodiesel soot was composed of smaller primary particle than diesel soot. The mean primary particle diameter was measured as 19.9 nm for WCO biodiesel and 23.7 nm for diesel, respectively.
2015-04-14
Technical Paper
2015-01-0836
Behzad Rohani, Stephen Sungsan Park, Choongsik Bae
Abstract Low Temperature Combustion (LTC) is known to be feasible only in lower load ranges so in real world application of LTC, engine operation mode should frequently change back and forth between LTC mode in lower loads and conventional mode in higher loads. In this research, effect of injection strategy on smoothness and emissions during mode transition in a single cylinder heavy duty diesel engine is studied. The Exhaust Gas Recirculation (EGR) line was controlled by a servo-valve capable of opening or closing the EGR loop within only one engine cycle. Ten cycles after the EGR valve closure were taken as the transition period during which injection timing and quantity were shifted in various ways (i.e. injection strategies) and the effect on Indicated Mean Effective Pressure (IMEP) stability and emissions was studied.
2010-04-12
Technical Paper
2010-01-0336
Changhoon Oh, Jinyoung Jang, Choongsik Bae
The effect of the composition of propane (C₃H₈) and butane (C₄H₁₀) in liquefied petroleum gas (LPG) was investigated in a dual-fuel HCCI engine fueled with di-methyl ether (DME) and LPG. The composition of LPG affects DME-LPG dual fuel HCCI combustion due to the difference in the physical properties of propane that and butane such as octane number, auto-ignition temperature and heat of vaporization. DME was injected directly into the cylinder at various injection timing from 160 to 350 crank angle degrees (CAD). LPG was injected at the intake port with a fixed injection timing at 20 CAD. It was found that power output was increased with propane ratio. This gain in power output resulted from increased expansion work due to the better anti-knock properties of propane. However, higher propane ratio made combustion efficiency decrease because of the suppression in low temperature reaction of DME which determines heat release amount of high temperature reaction.
2009-09-13
Technical Paper
2009-24-0104
Hyeonsook Yoon, Jeeyeon Jeon, Choongsik Bae
Two-stage injection strategy was studied in dimethyl-ether homogeneous charge compression ignition engine combustion. An early direct injection, main injection, was applied to form a premixed charge followed by the second injection after the start of heat release. Experiments were carried out in a single-cylinder direct-injection diesel engine equipped with a common-rail injection system, and the combustion performance and exhaust emissions were tested with the various second injection timings and quantities. Engine speed was 1200 rpm, and the load was fixed at 0.2 MPa IMEP. Main injection timing for homogeneous mixture was fixed at −80 CAD, and the fuel quantity was adjusted to the fixed load. Second injection quantity was varied from 1 to 5 mg, and the timing was selected according to the heat release rate of the HCCI combustion without second injection.
2013-10-14
Technical Paper
2013-01-2547
Kihyun Kim, Choongsik Bae, Bengt Johansson
Spray and combustion of gasoline and diesel were visualized under different ambient conditions in terms of pressure, temperature and density in a constant volume chamber. Three different ambient conditions were selected to simulate the three combustion regimes of homogeneous charge compression ignition, premixed charge compression ignition and conventional combustion. Ambient density was varied from 3.74 to 23.39 kg/m3. Ambient temperature at the spray injection were controlled to the range from 474 to 925 K. Intake oxygen concentration was also modulated from 15 % to 21 % in order to investigate the effects of intake oxygen concentrations on combustion characteristics. The injection pressure of gasoline and diesel were modulated from 50 to 150 MPa to analyze the effect of injection pressure on the spray development and combustion characteristics. Liquid penetration length and vapor penetration length were measured based on the methods of Mie-scattering and Schileren, respectively.
2013-10-14
Journal Article
2013-01-2499
Jinyoung Jung, Heechang Oh, Choongsik Bae
Steady and transient tests in a downsizing Gasoline Direct Injection (GDI) in-line 4 cylinders 2.0 liter engine were carried out to investigate characteristics of turbocharger with Titanium aluminide (TiAl) turbine wheel. The density of TiAl material is lower than Inconel 718 (Inconel) which is raw material for conventional turbine wheel. The objective of this study was to investigate the effect of light rotational inertia of turbine wheel on engine performance. Performance of TiAl turbine wheel turbocharger itself was also compared to that of Inconel turbine wheel turbocharger. Except for the turbine wheels, all experimental conditions were matched to be the same load and engine speed conditions. The compressor total-to-total pressure ratio of TiAl turbocharger was higher under part load condition due to higher turbocharger speed of TiAl turbocharger, which was led by lower rotational inertia of TiAl turbine wheel, while the engine performance was not much improved.
2013-04-08
Technical Paper
2013-01-0906
Stephen Sungsan Park, Yongjin Jung, Choongsik Bae
In this study, premixed charge compression ignition (PCCI) combustion was implemented using an injector that had a narrow injection angle of 70° and a moderately early injection timing of -40° crank angle after top dead center (CA ATDC). In-cylinder pressure measurements and high-speed direct imaging of the flame were performed in an optically accessible single-cylinder diesel engine. Frequency analysis of the acquired in-cylinder pressure data was carried out to obtain the frequency range of diesel knock. Meanwhile, image segmentation and a tracking algorithm based on YCbCr color space were implemented to determine the frequency range of diesel knock from the obtained high-speed image. The results show that the frequency of diesel knock was dominated by the range from 13 kHz to 15 kHz. Still, frequency with low power existed down until 7 kHz. The frequencies of the area movement were shown to be 13 kHz and, in some cases, 8.67 kHz.
2013-10-14
Technical Paper
2013-01-2572
Yongjin Jung, Donghui Qi, Choongsik Bae
The characteristics of soot particles in an exhaust gas for low temperature diesel combustion (LTC) compared with conventional combustion in a compression ignition engine were experimentally investigated by the elemental and thermogravimetric analysis (TGA). Morphology of soot particles was also studied by the transmission electron microscopy (TEM). From the result of the TGA, the water can be evaporated until about 150°C for both combustion regimes. The soot particles for LTC contained more volatile hydrocarbons, which can be easily evaporated from 200°C to 420°C compared with conventional diesel combustion. The soot oxidation for conventional combustion occurs up to 600°C, on the other hand the particles for LTC is oxidized below 520°C. Elemental analysis showed higher oxygen weight fraction resulted from the oxygenated hydrocarbon for the soot particles in LTC. TEM has shown primary particles to be in a diameter range of 20 to 50 nm for conventional diesel combustion.
2010-10-25
Journal Article
2010-01-2152
Heechang Oh, Choongsik Bae, Kyoungdoug Min
An experimental study was performed to evaluate the effects of ethanol blending on to gasoline spray and combustion characteristics in a spray-guided direct-injection spark-ignition engine under lean stratified operation. The spray characteristics, including local homogeneity and phase distribution, were investigated by the planar laser-induced fluorescence and the planar Mie scattering method in a constant volume chamber. Therefore, the single cylinder engine was operated with pure gasoline, 85 %vol, 50 %vol and 25vol % ethanol blended with gasoline (E85, E50, E25) to investigate the combustion and exhaust emission characteristics. Ethanol was identified to have the potential of generating a more appropriate spray for internal combustion due to a higher vapor pressure at high temperature conditions. The planar laser-induced fluorescence image demonstrated that ethanol spray has a faster diffusion velocity and an enhanced local homogeneity.
2012-09-10
Technical Paper
2012-01-1721
Sangwook Han, Choongsik Bae
The influence of fuel injection pressure and intake pressure on conventional and low temperature diesel combustion was investigated in a light duty diesel engine. The in-cylinder pressure and exhaust emissions were measured and analyzed in each operating condition. The two combustion regimes were classified in terms of intake oxygen concentrations, which were adjusted by varying the amount of exhaust gas recirculation. The fuel injection quantity and injection timing were fixed in order to minimize the influencing factors. Fuel injection pressures of 40 MPa and 120 MPa were used to verify the effect of the fuel injection pressure in both combustion regimes. The injection pressure significantly affected the combustion phase in the low temperature diesel combustion regime due to the longer premixing time relative to the conventional diesel combustion regime.
2013-03-25
Technical Paper
2013-01-0049
Kihyun Kim, Choongsik Bae
Combustion and emission characteristics were investigated in a compression ignition engine with dual-fuel strategy using dimethyl ether (DME) and gasoline. Experiments were performed at the low load condition corresponding to indicated mean effective pressure of 0.45 MPa. DME was directly injected into the cylinder and gasoline was injected into the intake manifold during the intake stroke. The proportion of DME in the total input energy was adjusted from 10% to 100%. DME DME injection timing was widely varied to investigate the effect of injection timing on the combustion phase. Injection pressure of DME was varied from 20 MPa to 60 MPa. Exhaust gas recirculation (EGR) was controlled from 0% to 60% to explore the effect of EGR on the combustion and emission characteristics. As DME proportion was decreased with the increased portion of gasoline, the combustion efficiency was decreased but thermal efficiency was increased.
2013-03-25
Technical Paper
2013-01-0010
Youngsoo Park, Choongsik Bae
In this study, single and double post injections were applied to diesel premixed charge compression ignition (PCCI) combustion to overcome the drawbacks those are high level of hydrocarbons (HC) and carbon monoxide (CO) emissions in a single-cylinder direct-injection diesel engine. The operating conditions including engine speed and total injection quantity were 1200 rpm and 12 mg/cycle, which are the representative of low engine speed and low load. The main injection timing of diesel PCCI combustion was set to 28 crank angle degree before top dead center (CAD BTDC). This main injection timing showed 32% lower level of nitric oxides (NOx) level and 8 CAD longer ignition delay than those of conventional diesel combustion. However, the levels of HC and CO were 2.7 and 3 times higher than those of conventional diesel combustion due to over-lean mixture and wall wetting of fuel.
2012-04-16
Technical Paper
2012-01-0424
Jaeheun Kim, Choongsik Bae, Gangchul Kim
A prototype of a small, spark-ignition free-piston engine combined with a linear alternator was designed to produce electric power for portable usage. It has a bore size of 25 mm and maximum stroke of 22 mm. The engine was fueled with liquefied petroleum gas consisting of 98% propane. The electric power generated by the linear alternator is a function of the piston dynamics and the electric conductance. Therefore, the purpose of current research is to investigate the effects of the basic engine controlling parameters such as the equivalence ratio of the mixture and the spark timing on the piston dynamics and study the relationship with the electric power generation performance. The equivalence ratio of the mixture was varied from 1.0 to 1.72, while the spark timing was varied at 3, 4, and 5 mm away from the maximum top dead center. Operating characteristics, namely, indicated mean effective pressure, electric power output, operating frequency and piston stroke were analyzed.
2006-04-03
Technical Paper
2006-01-1119
Jinwook Lee, Kyoungdoug Min, Kernyong Kang, Choongsik Bae
The More precise control of the multiple-injection is required in common-rail injection system of direct injection diesel engine to meet the low NOx emission and optimal PM filter system. The main parameter for obtaining the multiple-injections is the mechanism controlling the injector needle energizing and movement. In this study, a piezo-driven diesel injector, as a new method driven by piezoelectric energy, has been applied with a purpose to develop the analysis model of the piezo actuator to predict the dynamics characteristics of the hydraulic component (injector) by using the AMESim code and to evaluate the effect of this control capability on spray formation processes. Aimed at simulating the hydraulic behavior of the piezo-driven injector, the circuit model has been developed and verified by comparison with the experimental results.
2006-04-03
Technical Paper
2006-01-1546
Christos Chryssakis, Dennis N. Assanis, Choongsik Bae
Modern diesel engines operate under injection pressures varying from 30 to 200 MPa and employ combinations of very early and conventional injection timings to achieve partially homogeneous mixtures. The variety of injection and cylinder pressures results in droplet atomization under a wide range of Weber numbers. The high injection velocities lead to fast jet disintegration and secondary droplet atomization under shear and catastrophic breakup mechanisms. The primary atomization of the liquid jet is modeled considering the effects of both infinitesimal wave growth on the jet surface and jet turbulence. Modeling of the secondary atomization is based on a combination of a drop fragmentation analysis and a boundary layer stripping mechanism of the resulting fragments for high Weber numbers. The drop fragmentation process is predicted from instability considerations on the surface of the liquid drop.
2007-04-16
Technical Paper
2007-01-0218
Yongrae Kim, Kyoungdoug Min, Min Soo Kim, Suk Ho Chung, Choongsik Bae
A reduced chemical kinetic mechanism for a gasoline surrogate was developed and validated in this study for CAI (Controlled Auto Ignition) combustion. The gasoline surrogate was modeled as a blend of iso-octane, n-heptane, and toluene. This reduced mechanism consisted of 44 species and 59 reactions, including main reaction paths of iso-octane, n-heptane, and toluene. The ignition delay times calculated from this mechanism showed a good agreement with previous experimental data from shock tube measurement. A rapid compression machine (RCM) was developed and used to measure the ignition delay times of gasoline and surrogate fuels in the temperature range of 890K ∼ 1000K. The RCM experimental results were also compared with the RCM simulation using the reduced mechanism. It was found that the chemical reaction started before the end of the compression process in the RCM experiment. And the ignition delay time of the suggested gasoline surrogate was similar to that of gasoline.
2005-10-24
Technical Paper
2005-01-3837
Sanghoon Kook, Choongsik Bae, Paul C. Miles, Dae Choi, Lyle M. Pickett
The effects of charge dilution on low-temperature diesel combustion and emissions were investigated in a small-bore single-cylinder diesel engine over a wide range of injection timing. The fresh air was diluted with additional N2 and CO2, simulating 0 to 65% exhaust gas recirculation in an engine. Diluting the intake charge lowers the flame temperature T due to the reactant being replaced by inert gases with increased heat capacity. In addition, charge dilution is anticipated to influence the local charge equivalence ratio ϕ prior to ignition due to the lower O2 concentration and longer ignition delay periods. By influencing both ϕ and T, charge dilution impacts the path representing the progress of the combustion process in the ϕ-T plane, and offers the potential of avoiding both soot and NOx formation.
2004-03-08
Technical Paper
2004-01-0938
Sanghoon Kook, Choongsik Bae
A diesel-fueled premixed charged compression ignition (PCCI) combustion technique using a two-stage injection strategy has been investigated in a single cylinder optical engine equipped with a common-rail fuel system. Although PCCI combustion has the advantages of reducing NOx and PM emissions, difficulties in vaporization of a diesel fuel and control of the combustion phase hinder the development of the PCCI engine. A two-stage injection strategy was applied to relieve these problems. The first injection, named as main injection, was an early direct injection of diesel fuel into the cylinder to achieve premixing with air. The second injection was a diesel injection of a small quantity (1.5 mm3) as an ignition promoter and combustion phase controller near TDC. Effects of injection pressure, injected fuel quantity and compression ratio were studied with variation of an intake air temperature.
2004-10-25
Technical Paper
2004-01-2974
Jinyoung Jang, Kitae Yeom, Choongsik Bae
Combustion in engines can be controlled by the amount of residual gas, which has high temperature and heat capacity compared with fresh charge. Residual gas also acts like a dilution gas during combustion period. Accordingly, combustion duration increases, while the peak combustion temperature and nitrogen oxides (NOx) decreases. Amount of residual gas is affected by pressure difference between exhaust and intake, valve timing and engine speed. The main objective of this work is to identify the effects of exhaust throttle, valve timing and load conditions on residual gas fraction and engine performance. The intake valve open timing was varied freely under fixed exhaust valve close (EVC) timing. Additionally, exhaust throttle has been installed in the exhaust manifold to build up the exhaust back-pressure allowing extra amount of exhaust gases to be admitted into the cylinder during the valve overlap duration.
2004-03-08
Technical Paper
2004-01-0127
Cheolwoong Park, Sanghoon Kook, Choongsik Bae
Diesel fuel injection system is the most important part of the direct-injection diesel engine and, in recent years, it has become one of the critical technologies for emission control with the help of electronically controlled fuel injection. Common rail injection system has great flexibility in injection timing, pressure and multi-injections. Many studies and applications have reported the advantages of using common rail system to meet the strict emission regulation and to improve engine performance for diesel engines. The main objective of this study is to investigate the effect of pilot-, post- and multiple-fuel injection strategies on engine performance and emissions. The study was carried out on a single cylinder optical direct injection diesel engine equipped with a high pressure common rail fuel injection system. Spray and combustion evolutions were visualized through a high speed charge-coupled device (CCD) camera.
2004-03-08
Technical Paper
2004-01-0982
Youngmin Woo, Kitae Yeom, Choongsik Bae, Seungmook Oh, Kernyong Kang
Exhaust gas recirculation (EGR) and lean burn utilize the diluents into the engine cylinder to control combustion leading to enhanced fuel economy and reduced emissions. However, the occurrence of excessive cyclic variation with high diluent rates, brings about an undesirable combustion instability within the engine cylinder resulting in the deterioration of both engine performance and emissions. Proper stratification of mixture and diluents could improve the combustion stability under high diluent environment. EGR stratification within the cylinder was made by adopting a fast-response solenoid valve in the midst of EGR line and controlling its timing and duty. With EGR in both homogeneous mode and stratified mode, in-cylinder pressure and emissions were measured. The thermodynamic heat release analysis showed that the burning duration was decreased in case of stratified EGR. It was found that the stratification of EGR hardly affected the emissions.
2003-10-27
Technical Paper
2003-01-3076
Seokhwan Lee, Choongsik Bae, Jongik Jeon, Taesik Han
This paper describes the results of a DOE (design of experiment) applied to an exhaust heat exchanger to lower the exhaust gas temperature mainly under high load conditions. The heat exchanger was installed between the exhaust manifold and the inlet of the close-coupled catalytic converter (CCC) to avoid thermal aging. The DOE evaluates the influence of the selected eight design parameters of the heat exchanger geometry on the performance of the exhaust gas cooling system, and the interaction between these parameters. To maximize the heat transfer between exhaust gas and coolant, fins were implemented at the inner surface of the heat exchanger. The design parameters consist of the fin geometry (length, thickness, arrangement, number of fin), coolant direction, exchanger wall thickness, and the length of the heat exchanger. The acceptable range of each design parameter is discussed by analyzing the DOE results.
2008-06-23
Journal Article
2008-01-1659
Jinyoung Jang, Kiseon Yang, Kitae Yeom, Choongsik Bae, Seungmook Oh, Kernyong Kang
The combustion and exhaust emission characteristics of a DME fueled HCCI engine were investigated. Different fuel injection strategies were tested under various injection quantities and timings with exhaust gas recirculation (EGR). The combustion phase in HCCI was changed by an in-cylinder direct injection and EGR, due to changes in the in-cylinder temperature and mixture homogeneity. The gross indicated mean effective pressure (IMEPgross) increased and the hydrocarbon (HC) and carbon monoxide (CO) emissions decreased as the equivalence ratio was augmented. The IMEPgross with direct injection was greater than with the port injection due to retarded ignition timing resulting from latent heat of direct injected DME fuel. It was because that most of burn duration was completed before top dead center owing to higher ignitability for DME with high cetane number. However, HC and CO emissions were similar for both injection locations.
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