Simulation and performance comparison between diesel and natural gas engines for marine applications

The article shows the performance comparison between two marine engines, fuelled by diesel oil and natural gas respectively. Two different simulation codes, each for engine type, have been developed to extend the comparison to the whole working area of the examined engines. Although the maximum continuous power is very similar (about 2 MW at the same rotational speed), some differences exist in size, efficiency and pollutant emissions. The reasons are investigated through a specific thermodynamic analysis, by comparing the respective real cycles at several power and revolution values. In detail, the two combustion modes are analysed to explain the main differences that are found mostly in nitrogen oxides emissions