纯氢和天然气掺氢燃料发动机的试验研究

在某点燃式发动机上，试验研究了纯氢和不同比例天然气掺氢的燃烧与排放特性。结果表明：纯氢燃料燃烧快，燃烧持续期短，缸压和放热率升高率大且峰值较高，λ=1．1时，峰值压力为3．9MPa，燃烧持续期为12℃A。氢燃料的稀燃界限宽，过量空气系数λ=3时，峰值压力降低到1．7MPa，NOx排放趋于零。天然气掺氢可以改善天然气燃烧特性，拓展天然气的稀燃极限。在相同工况下，掺氢30％的混合气燃烧持续期比天然气缩短20℃A，但缸压峰值和NOx排放增加，这可以通过稀燃和优化点火提前角来降低峰值压力和NOx排放。掺氢30％的混合气可以在λ=1．857时稳定的工作，此时峰值压力降低到1．57MPa，NOx的排放小于50×10^-6。

Experimental Investigation Involving Pure Hydrogen and Addition of Hydrogen to Natural Gas on a SI Engine

Engine performance and emissions characteristics were investigated on a SI engine fueled with pure hydrogen and hydrogen/natural gas mixture.Results show that combustion duration of hydrogen is short due to high flame propagation velocity.Pressure and heat release rate increase fast and peak values are high.At λ=1.1,peak pressure is 3.9 MPa,and combustion duration is 12 ℃A.Hydrogen engine has wide lean burn limit.At λ=3,peak pressure is reduced to 1.7 MPa and NOx concentration is approximately zero.Addition of hydrogen to natural gas is an effective way to enhance combustion performance of natural gas,and widen lean burn limit.At the same condition,combustion duration of natural gas blended with 30%vol hydrogen is 20 ℃A less than that of natural gas.Cylinder peak pressure and NOx emissions increase as addition of hydrogen to natural gas,but it can be reduced by lean burn and optimizing ignition timing.Natural gas blended with 30%vol hydrogen can work stably at λ=1.857.Peak pressure is reduced to 1.57 MPa and NOx concentration is less than 50 ppm.