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In methanol engines, mixedgas compression ignition can be achieved by increasing the compression ratio, using spark ignition, and adopting polyoxymethylene dimethyl ethers (PODE) as the active improved fuel. This approach overcomes the limitations imposed by flame propagation speed on thermal efficiency. Experiments were conducted to investigate and compare the combustion characteristics, thermal efficiency and emission properties of dualfuel sparkassisted compression ignition (SACI) mode and singlefuel methanol ignition at different loads and engine speeds. The main conclusions are as follows: the effect of dualfuel SACI on thermal efficiency varies with the load range. At a BMEP of 0.8 MPa, the thermal efficiency reaches 41.9%, an increase of 1.9% compared to methanol ignition. However, at BMEP levels below 0.4 MPa, the cyclic variability is higher and the thermal efficiency is lower than that of methanol ignition. Dualfuel SACI reduces NO, emissions, achieving a 79% reduction compared to methanol ignition at a BМЕР of 0.8 MPa. Increasing RPM accelerates PODE diffusion, aiding the formation of the initial combustible mixture, decreasing the proportion of compression ignition in combustion, and enhancing the proportion of flame propagation ignition. At low loads, HC emissions decrease with higher RPM. However, high RPM reduces the compression ignition ratio and increases NO, emissions. Low RPM and high load conditions are more favorable for efficiency and emissions. These findings provide valuable support for the application of methanol engines.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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