Cold Flow Simulation of a Dual-Fuel Engine for Diesel-Natural Gas and Diesel-Methanol Fuelling Conditions

In this work, the possibility to perform a cold-flow simulation as a way to improve the accuracy of the starting conditions for a combustion simulation is examined. Specifically, a dual-fuel marine engine running on methanol/diesel and natural gas/diesel fueling conditions is investigated. Dual-fuel engines can provide a short-term solution to cope with the more stringent emission legislations in the maritime sector. Both natural gas and methanol appear to be interesting alternative fuels that can be used as main fuel in these dual-fuel engines. Nevertheless, it is observed that combustion problems occur at part load using these alternative fuels. Therefore, different methods to increase the combustion efficiency at part load are investigated. Numerical simulations prove to be very suitable hereto, as they are an efficient way to study the effect of different parameters on the combustion characteristics. These simulations often describe the engine with a limited engine geometry neglecting the inlet and exhaust duct. This gives rise to the need to assume certain starting conditions such as the turbulence coming from the intake valve and the homogeneity of the air/fuel mixture entering the combustion chamber. Hence this work presents the execution of a cold-flow simulation taking into account the whole engine geometry that can provide more realistic initialization values for combustion simulations.