Enhancing the performance of syngas-diesel dual-fuel engines by optimizing injection regimes: From comparative analysis to control strategy proposal

This study introduced an innovative technology of syngas direct injection through the twinning injector system. This technology can simultaneously adjust the equivalence ratio and the mass of fresh gas, for a syngas-diesel dual-fuel engine converted from a conventional diesel engine. The current work was carried out in two stages, in which the evaluation of engine performance and mixture formation under two various syngas injection strategies such as the port-premixed mixture method and the direct injection method were examined in the first stage. In the second stage, the load control strategy of the syngas-diesel dual-fuel engine, which aims to attain low greenhouse gas emissions and maintain output power, was thoroughly presented. The results revealed that the syngas direct-injection strategy significantly influences the power derating of the dual-fuel engine at a fixed pilot diesel injection. Indeed, when the stop injection angle was held constant at 270°CA, the power derating of the dual-fuel engine increased from 3.78% to 22.74% as the start injection angle was increased from 60°CA to 100°CA, implying that this injection strategy could be suitable for dual-fuel engines with a minor variation in their loading regime. Nonetheless, when the start injection angle was fixed at 60°CA, the derating power of the dual-fuel engine increased from 7.41% to 27.84% as the stop injection angle was advanced from 280°CA to 220°CA, showing that this injection strategy was better suited for dual-fuel engines that experienced larger variations in their loading regime. Direct injection of syngas using the twinning injector system at an injection pressure of 6bar, in conjunction with a suitable start/stop injector strategy, constitutes an appropriate solution for maintaining power derating in syngas-diesel dual-fuel engines below an acceptable threshold of 10%.