Green hydrogen has become more attractive as a fuel for engines to reduce greenhouse gas emissions. By mixing it with natural gas (NG), the modification work on the engine can be minimized but the carbon dioxide emissions from combustion can still be decreased. In this paper, an experimental study was accomplished to investigate the performance of a spark-ignition engine fueled with hydrogen-natural gas blends by either keeping a constant ignition timing or changing it. Up to 25 mol-% hydrogen was mixed into natural gases with different compositions and the methane number and Wobbe index were calculated and compared to the requirements set by Euromot. The results show that up to 15 mol-% hydrogen can be blended into NG to meet the limits of Euromot. However, when 25 mol-% hydrogen was mixed into NG the methane number varied between 56 and 64 depending on the gas composition. This would most likely cause knock for a mixture consisting of higher hydrocarbons but during the executed tests knock was never a problem. Furthermore, it was detected that the methane number alone cannot tell the knock tendency of a gas in a certain engine and an additional condition is needed such as the hydrogen level. An adjusted ignition timing was also preferable compared to a constant one to keep the engine component temperature at a moderate level.

中文翻译：

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氢-天然气混合气体SI发动机性能实验研究

绿色氢作为减少温室气体排放的发动机燃料变得更具吸引力。通过将其与天然气（NG）混合，可以最大限度地减少发动机的改造工作，但仍然可以减少燃烧产生的二氧化碳排放量。在本文中，通过保持恒定点火正时或改变点火正时，完成了一项实验研究，以研究以氢-天然气混合物为燃料的火花点火发动机的性能。将高达 25 mol-% 的氢气混合到不同成分的天然气中，计算甲烷值和沃泊指数，并与 Euromot 设定的要求进行比较。结果表明，最多可将 15 mol% 的氢气混合到 NG 中，以满足 Euromot 的限制。然而，当 25 mol-% 氢气混合到 NG 中时，甲烷值根据气体成分在 56 到 64 之间变化。这很可能会导致由高级碳氢化合物组成的混合物发生爆震，但在执行的测试中，爆震从来都不是问题。此外，还发现仅靠甲烷值无法判断某种发动机中气体的爆震倾向，还需要附加条件，例如氢气水平。与恒定点火正时相比，调整点火正时也更可将发动机部件温度保持在适中水平。