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HYDROGEN IN CARS
| 题名： | HYDROGEN IN CARS |
| 正文语种： | eng |
| 摘要： | Hydrogen is in one way a practically perfect fuel for an internal combustion engine: just burn H_2 in oxygen and it produces useful heat and... water vapour. The reaction does not generate carbon dioxide (CO_2) or particulates because there is no carbon in the fuel. In practice a very small amount of CO_2 is produced, because some lubricating oil enters the combustion chamber via crankcase ventilation or past the piston rings. But this represents less than 1% of the carbon emissions of a conventionally fuelled engine. However, only around 21% of our atmosphere is oxygen - 78% of it is nitrogen, and at high combustion temperatures this reacts with oxygen to create polluting nitrogen oxides (NOx). So, much of the effort in designing hydrogen engines has been concentrated on reducing NOx emissions while maintaining power output and thermal efficiency. A conventional catalytic converter may not be necessary: EGR or water injection can be incorporated to reduce combustion temperatures, but the most significant way to eliminate NOx is to run the engine lean - at a λ value of 2 or more. Hydrogen can be burned over a very wide range of air/fuel ratios, and will work at much leaner mixtures than liquid fuels, at λ values of up to 4 or 5. As BorgWarner puts it: "In lean combustion mode, NOx emissions reduce to near-zero levels." |
| 出版年： | 2023 |
| 期刊名称： | Transport engineer |
| 期： | Dec. |
| 页码： | 20-21 |
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