(1.School of Automotive and Transportation,Tianjin University of Technology and Education,Tianjin 300222,China;2.State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China;3.School of Automotive and Transportation Engineering,Hefei University of Technology,Hefei 230009,China)
By coupling the detailed chemical kinetic mechanism of methanol oxidation with onedimensional GTPower and threedimensional CFD simulation software, a onedimensional and threedimensional physical model of spark ignition methanol engine was established to study the unregulated emissions based on the parameters of a traditional diesel engine. The results show that the emissions of unburned methanol and formaldehyde reduce first and then increase with the increase of load. The emissions of unburned methanol and formaldehyde reduce more effectively by increasing spark advance angle under small loads. With the increase of engine speed, the emissions of unburned methanol increase, while the emissions of formaldehyde increase first and then reduce. The increase of EGR rate reduces the emissions of unburned methanol and formaldehyde significantly. When the compression ratio increases, the emissions also reduce. And when the compression ratio increases to 17.5, the emissions are almost close to 0. In addition, the emissions reduce effectively with the increase of equivalent ratio when the compression ratio is small. The unburned methanol and formaldehyde mainly distribute in the gap areas of cylinder wall, bottom surface of cylinder head and top surface of piston.