等热值替代的天然气双燃料发动机的改装和控制策略

摘要

A direct injection, high-pressure common-rail diesel engine was converted into a diesel pilot-ignited dual fuel engine using a developed dual-fuel engine control unit (ECU) for better economy and lower emissions. A real-time diesel substitution rate control strategy for a dual fuel engine was proposed, and the control strategy was validated by experiments. The results show that the substitution rate error between the target and experiment was less than 5.2%, and the control strategy meets the demands of the dual fuel engine operation. For the engine performance curves and emissions, the curves of the dual fuel mode were consistent with those of the pure fuel mode. The maximum torque of the dual fuel mode increases 2.6% compared with that in diesel mode with CO2 and NOx emissions decreasing 40% and 33%, and with the total hydrocarbon and CO peak emissions increasing 20 and 6 times compared with those in the diesel mode. Therefore, the strategy is rational and feasible for controling natural gas dual-fuel engines.%为提高经济性和降低排放，开发了双燃料发动机电控单元（ECU）；对一高压共轨柴油发动机进行了双燃料改装，以实现柴油引燃天然气的燃烧模式。用实验方法，验证了基于柴油等热值替代的双燃料控制策略。结果表明：相比纯柴油模式原机，双燃料模式下给定替代率的实时控制的误差不超过5.2%；外特性曲线基本一致，最大扭矩增加了2.6%；CO2排放降低了40%，NOx排放降低了33%；但总碳氢化合物排放的最大值比原机高出20倍，CO排放的最大值高出6倍。这说明，本控制策略合理可行,适合天然气双燃料发动机。