**Hao Guo, Song Zhou \*, Majed Shreka and Yongming Feng**

College of Energy and Power Engineering, Harbin Engineering University, Harbin 150001, China; guohao618@hrbeu.edu.cn (H.G.); majed.shreka@outlook.com (M.S.); fengyongming@hrbeu.edu.cn (Y.F.) **\*** Correspondence: songzhou@hrbeu.edu.cn; Tel.: +86-138-4506-3167

Received: 4 November 2019; Accepted: 17 November 2019; Published: 21 November 2019 -

**Abstract:** In recent years and with the increasing rigor of the International Maritime Organization (IMO) emission regulations, the shipping industry has focused more on environment-friendly and efficient power. Low-pressure dual-fuel (LP-DF) engine technology with high efficiency and good emissions has become a promising solution in the development of marine engines. This engine often uses pre-combustion chamber (PCC) to ignite natural gas due to its higher ignition energy. In this paper, a parametric study of the LP-DF engine was proceeded to investigate the design scheme of the PCC. The effect of PCC parameters on engine performance and emissions were studied from two aspects: PCC nozzle diameter and PCC nozzle angle. The results showed that the PCC nozzle diameter affected the propagation of the flame in the combustion chamber. Moreover, suitable PCC nozzle diameters helped to improve flame propagation stability and engine performance and reduce emissions. Furthermore, the angle of the PCC nozzle had a great influence on flame propagation direction, which affected the flame propagation speed and thus the occurrence of knocking. Finally, optimizing the angle of the PCC nozzle was beneficial to the organization of the in-cylinder combustion.

**Keywords:** Computational Fluid Dynamics; two-stroke; dual-fuel engine; simulation; pre-combustion chamber
