Thermodynamic analysis of improving fuel consumption of natural gas engine by combining Miller cycle with high geometric compression ratio
Thermodynamic analysis of improving fuel consumption of natural gas engine by combining Miller cycle with high geometric compression ratio
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DOI：
10.1016/j.enconman.2022.115219
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发表时间：
2022-02
影响因子：
10.4
通讯作者：
Kong Xing;Haozhong Huang;Xiaoyu Guo;Yi Wang;Zhanfei Tu;Jialong Li
中科院分区：
文献类型：
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作者：
Kong Xing;Haozhong Huang;Xiaoyu Guo;Yi Wang;Zhanfei Tu;Jialong Li
这项工作的目标是通过将米勒循环与高几何压缩比（GCR）相结合来解决化学计量天然气发动机热效率低的问题。建立了带涡轮增压器的化学计量天然气发动机的一维热力学模型，并通过实验数据验证了其有效性。在此基础上，详细研究了高GCR结合进气门提前关闭（EIVC）或进气门延迟关闭（LIVC）实现的米勒循环对燃油消耗的影响。结果表明，GCR与进气门升程廓线的合理匹配有利于改善燃油消耗。油耗改善的上限由涡轮增压器的性能决定。 EIVC50 + GCR14和LIVC75 + GCR13.5解决方案不仅可以确保负载和爆震水平与基准发动机（IVC558 + GCR11.5）一致，而且可以获得最佳的燃油经济性。热力学分析进一步揭示了节油机理。油耗可提高4.1%，这主要得益于理论效率和燃烧损失之间的良好平衡。此外，气体交换损失的减少进一步改善了燃油消耗。不幸的是，传热损失和摩擦损失的增加限制了燃料消耗的进一步改善。
The goal of this work is to solve the problem of low thermal efficiency of stoichiometric natural gas engines by combining the Miller cycle with a high geometric compression ratio (GCR). A one-dimensional thermodynamic model of a stoichiometric natural gas engine with turbocharger is established, and its effectiveness is verified by experimental data. On this basis, the influence of the high GCR combined with the Miller cycle achieved by early intake valve closing (EIVC) or late intake valve closing (LIVC) on the fuel consumption is studied in detail. The results show that the reasonable matching of the GCR and intake valve lift profile is beneficial to improve fuel consumption. The upper limit of fuel consumption improvement is determined by the performance of the turbocharger. The EIVC50 + GCR14 and LIVC75 + GCR13.5 solutions can not only ensure that the load and knock level are consistent with the baseline engine (IVC558 + GCR11.5), but also obtain the optimal fuel economy. Thermodynamic analysis further reveals the fuel-saving mechanism. The fuel consumption can be improved by 4.1%, mainly thanks to a good balance between theoretical efficiency and combustion loss. In addition, the reduction in gas exchange loss further improves fuel consumption. Unfortunately, the increase in heat transfer loss and friction loss limits the further improvement in fuel consumption.