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This study investigated cold and hot start processes of diesel vehicles under different load conditions in summer using a heavy-duty chassis dynamometer, with a focus on analyzing NOx and NH3 emission characteristics and influencing factors. The results showed that during cold starts, the exhaust gas temperature and coolant temperature rose slowly, and the NOx sensor was delayed in activation, with over 82% of NOx emissions occurring before the sensor became operational. During hot starts, the SCR system and sensor entered operation rapidly due to higher system temperatures, leading to significantly lower NOx emissions. NH3 emissions were significantly affected by the start condition and simulated load. In the initial phase of cold starts, the NH3 emission factor was higher than average because of low SCR temperatures. During hot starts, rapid urea hydrolysis without sufficient reaction with NOx resulted in increased NH3 emissions. Micro-scale operational modal analysis revealed that the difference in NOx emissions was mainly determined by engine and SCR temperatures, whereas the difference in NH3 emissions was associated with SCR temperature and urea injection quantity. The study emphasizes the need to address pollutant emissions during summer cold-start processes and proposes synergistic optimization of temperature control and SCR urea injection strategies to reduce the environmental impact.
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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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