The marine large 2-stroke dual fuel engine with lean burn pre-mixed combustion technology was awarded the Marine Engineering of the Year (DOKOU’s memorial award) 2017. This technology that many engineers had considered to be technically difficult to develop was invented by IHI, DU, and WinGD. When this new engine runs in gas mode, it emits little SOx and less GHG. Moreover, due to its higher NOx reduction capability, this has become the first 2-stroke engine that can comply with the IMO NOx Tier3 regulations without any exhaust gas after-treatment system. In addition, against all expectations, the authors successfully developed the world’s first large-size Dual-Fuel engine (X72DF) using this technology. Since several ships equipped with this engine have been launched into service, the Dual-Fuel engine has a significant impact on marine engineering. This paper describes the development history of and key points about this technology.
The effect of fuel property on nanostructure of soot particles from small DI diesel engine was investigated experimentally. By using fuel oil A and light oil as test fuels, the soot nanostructure was examined by laser Raman spectroscopy and transmission electron microscopy (TEM). The analysis of Raman spectra of soot showed that graphitic crystallites in soot particles from fuel oil A were smaller than those in particles from light oil. This finding was substantiated by the results of observation using TEM images. We assumed that the difference in the size of graphitic crystallites was attributed to a gap in sulfur contents in the two fuels.
Transient and quasi-steady state heat transfers were measured in vertical small tube with exponentially increasing heat inputs．The flow velocities，the inlet liquid temperatures and the inlet pressure were ranging from 1.0 to 7.5 m/s，295 to 355 K and 645 to 858 kPa．The forced convection water flow test loop made of stainless steel consists of a multistage canned-type circulation pump with high pump head，a heater，a cooler，a flow meter，a pressurizer，an expansion tank，an ion exchanger and a test tube．The heat generation rate was raised through an exponential function，Qoexp(t /τ)，where Qo is an initial heat generation rate, t represents time and τ is e-folding time．It was obtained that the heat transfer coefficient increased with the decreasing of inner diameter of test tube．The heat transfer coefficient also increased with decreasing of the e-folding time of the heat generation rate at a flow velocity．In spite of the e-folding time，the heat transfer coefficient increased with an increase in flow velocity．Moreover, the Nusselt number under the transient condition was affected by the Fourier number and the Reynolds number．