Combustion control and operating range expansion in an homogeneous charge compression ignition engine with suppression of low-temperature oxidation by methanol: Influence of compression ratio and octane number of main fuel

2007 ◽  
Vol 8 (1) ◽  
pp. 139-145 ◽  
Author(s):  
H Ogawa ◽  
K Azuma ◽  
N Miyamoto
Keyword(s):  
Low Temperature ◽  
Compression Ratio ◽  
Range Expansion ◽  
Octane Number ◽  
Homogeneous Charge Compression Ignition ◽  
Compression Ignition ◽  
Low Temperature Oxidation ◽  
Compression Ignition Engine ◽  
Temperature Oxidation ◽  
Operating Range

Combustion control and operating range expansion in an homogeneous charge compression ignition engine with direct in-cylinder injection of reaction inhibitors

2005 ◽  
Vol 6 (4) ◽  
pp. 341-359 ◽  
Author(s):  
H Ogawa ◽  
N Miyamoto ◽  
N Kaneko ◽  
H Ando
Keyword(s):  
Low Temperature ◽  
Homogeneous Charge Compression Ignition ◽  
Water Injection ◽  
Combustion Efficiency ◽  
Compression Ignition ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Operating Range ◽  
Rapid Combustion ◽  
Charge Temperature

Light naphtha, which exhibits two-stage ignition, was induced from the intake manifold and water or a low-ignitability fuel, which does not exhibit low temperature oxidation, was directly injected early in the compression stroke for ignition suppression in an homogeneous charge compression ignition (HCCI) engine. Their quantitative balance was flexibly controlled to optimize ignition timing according to operating conditions. Ultra-low NOx and smokeless combustion without knocking or misfiring was realized over a wide operating range with water or alcohol injection. The water injection significantly reduced the low-temperature oxidation, which suppressed the increase in charge temperature and the rapid combustion caused by the high-temperature oxidation. Rapid combustion was suppressed by reductions in the maximum in-cylinder gas temperature due to water injection while the combustion efficiency suffered. Therefore, the maximum charge temperature needs to be controlled within an extremely limited range to maintain a satisfactory compromise between mild combustion and high combustion efficiency. Alcohols inhibit low-temperature oxidation more strongly than other oxygenated or unoxygenated hydrocarbons, water, and hydrogen. Chemical kinetic modelling with methanol showed a reduction of OH radical before the onset of low-temperature oxidation, and this may be the main mechanism by which alcohols inhibit low-temperature oxidation.

scholarly journals Influence of gas composition on the combustion and efficiency of a homogeneous charge compression ignition engine system fuelled with methanol reformed gases

2008 ◽  
Vol 9 (5) ◽  
pp. 399-408 ◽  
Author(s):  
T Shudo
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Waste Heat ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Temperature Oxidation ◽  
Hcci Engine ◽  
Recovery Capacity ◽  
Exhaust Heat ◽  
Engine System ◽  
Homogeneous Charge

A homogeneous charge compression ignition (HCCI) engine system fuelled with dimethyl ether (DME) and methanol-reformed gas (MRG), both produced from methanol by onboard reformers using exhaust heat, has been proposed in previous research. Adjusting the proportions of DME and MRG with different ignition properties effectively controlled the ignition timing and load in HCCI combustion. The use of the single liquid fuel, methanol, also eliminates the inconvenience of carrying two fuels while maintaining the effective ignition control effect. Because reactions producing DME and MRG from methanol are endothermic, a part of the exhaust gas heat energy can be recovered during the fuel reforming. Methanol can be reformed into various compositions of hydrogen, carbon monoxide, and carbon dioxide. The present paper aims to establish the optimum MRG composition for the system in terms of ignition control and overall efficiency. The results show that an increased hydrogen fraction in MRG retards the onset of high-temperature oxidation and permits operation with higher equivalence ratios. However, the MRG composition affects the engine efficiency only a little, and the MRG produced by the thermal decomposition having the best waste-heat recovery capacity brings the highest overall thermal efficiency in the HCCI engine system fuelled with DME and MRG.

Chemical and spectroscopic studies of blue flames in the auto-ignition of methane

1955 ◽  
Vol 230 (1180) ◽  
pp. 1-19 ◽  
Keyword(s):  
Spectroscopic Studies ◽  
Compression Ignition ◽  
Low Temperature Oxidation ◽  
Compression Ignition Engine ◽  
Temperature Oxidation ◽  
Carbon Particles ◽  
Cool Flames ◽  
Auto Ignition ◽  
Increasing Temperature ◽  
Normal Flame

A blue pre-ignition glow has been found with weak methane + air mixtures, using a motored compression-ignition engine with fixed compression ratio and speed; the temperature was controlled by preheating the inlet air. The limits of the glow and its transition to normal flame have been studied. Analyses of exhaust products and records of pressure and luminosity have been made. The spectrum of the glow shows formaldehyde bands, normally associated with cool flames. As the normal ignition limit is approached this spectrum changes smoothly, with increasing temperature or mixture strength, to a normal flame spectrum showing OH, CH and HCO bands. Using a stroboscope we have found slight indication that the CH 2 O bands precede the CH and OH. Less lean mixtures show yellow luminosity, associated with carbon particles. The possibilities that the CH 2 O emission results from polymerization of the methane, from partial oxidation to methyl alcohol, or directly from a cool-flame phenomenon in methane, are discussed in relation to conditions in the combustion chamber. The new observation of CH 2 O bands from methane may be interpreted in favour of its formation by reactions of methoxy radicals. Methane is known to knock in an engine at high compression ratios. Present results suggest that low-temperature oxidation processes may, as with other hydrocarbons, contribute to this knock.

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