Multidimensional Numerical Simulation on Dimethyl Ether/Methanol Dual-Fuel Homogeneous Charge Compression Ignition (HCCI) Engine Combustion and Emission Processes

2007 ◽  
Vol 21 (2) ◽  
pp. 812-821 ◽  
Author(s):  
Mingfa Yao ◽  
Chen Huang ◽  
Zhaolei Zheng
Keyword(s):  
Numerical Simulation ◽  
Dimethyl Ether ◽  
Homogeneous Charge Compression Ignition ◽  
Dual Fuel ◽  
Compression Ignition ◽  
Hcci Engine ◽  
Engine Combustion ◽  
Homogeneous Charge

Numerical study of the combustion mechanism of a homogeneous charge compression ignition engine fuelled with dimethyl ether and methane, with a detailed kinetics model. Part 2: the reaction kinetics of dimethyl ether and methane dual-fuel

2005 ◽  
Vol 219 (10) ◽  
pp. 1225-1236 ◽  
Author(s):  
M Yao ◽  
J Qin ◽  
Z Zheng
Keyword(s):  
Heat Release ◽  
Methane Oxidation ◽  
Dimethyl Ether ◽  
Homogeneous Charge Compression Ignition ◽  
Numerical Study ◽  
Kinetics Model ◽  
Dual Fuel ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Homogeneous Charge

A numerical study was carried out using a zero-dimensional detailed chemical kinetics model to investigate the chemical reaction phenomena encountered in the homogeneous charge compression ignition process of a dimethyl ether (DME) and methane dual-fuel mixture. The results show that the heat release of DME/methane dual-fuel combustion is a typical two-stage process: the first stage is mainly associated with DME oxidation, and the second is mainly the result of methane oxidation. The low-temperature reaction (LTR) of DME is inhibited, the second molecular oxygen addition of DME is restrained, and β-scission plays a dominant role in DME oxidation. Therefore, methane changes the paths of the LTR of DME. Most of the formaldehyde (CH2O) is produced from H abstraction of methoxy (CH3O) rather than from the LTR of the DME. The heat release by DME oxidation and the existence of H2O2 generated by DME oxidation make methane oxidation occur at a low initial temperature. However, methane oxidation also promotes hot flame reactions of DME. During the second stage of heat release, OH is produced in many different ways rather than only by way of H2O2 decomposing in neat DME oxidation; this results in higher OH mole fraction when dual fuel is used compared with DME alone. Finally, the major paths of the DME/methane HCCI reactions occurring in the engine cylinder are clarified.

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.

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