Advances in combustion control for natural gas-diesel dual fuel compression ignition engines in automotive applications: A review

Dual fuel engines that leverage gaseous fuels have existed for over a century, but advances in fuel injection technologies and electronic control have drastically changed the methods of combustion control used in automotive applications over this time. Early efforts to leverage natural gas on compression ignition engines utilized natural gas and diesel in a dual fuel arrangement but relied on map-based methods of dictating the quantities and timings of single injection events for each fuel. Multi-pulse injection and electronic fuel injection capabilities have enabled many new combustion strategies and necessitated the use of more complex control methods. Novel dual fuel combustion approaches like reactivity controlled compression ignition and the introduction of high pressure natural gas injection have provided cleaner, more efficient combustion processes for diesel-natural gas dual fuel engines but also introduced more complex combustion phenomenon. This paper examines the advances that have been made in combustion control on conventional and more advanced dual fuel engines that utilize natural gas along with diesel fuel and discusses the remaining challenges in this field.