The effects of methanol fuel on combustion in premixed dual fuel engine

Abstract

The environmental pollution and depleting fossil fuels have been considered as a critical issue all over the world. Many efforts have been devoted to investigating alternative fuels to tackle these problems. Alcohol fuels are potential candidates to alternative energy as it can mitigate pollutant emission. In addition, alcohol fuels can be applied to current diesel engines with technical modifications. This thesis mainly focuses on the effects of methanol fuel on in-cylinder process in premixed dual fuel engine. Different fuel ratios were tested to investigate the effects of methanol fuel. Existing diesel engine models, which have been developed by TU delft, were used to conduct computer simulations. To describe dual fuel combustion, separated vibe functions were adopted in the existing models. The simulation results indicated that the cooling effect caused by high heat of evaporation of methanol affected in-cylinder processes. With increase of methanol injection, start of ignition delayed due to the cooling effect. The longer ignition delay improved premixing of pilot fuel and it led to higher heat release rates. In case of maximum temperature, it was affected by both the cooling effects and diesel injection timing. With advanced diesel injection timing (-5.5 TDC), maximum temperature of dual fuel mode was higher than only diesel mode due to strong premixed combustion. Due to the lower LHV of methanol fuel, brake specific fuel consumption became higher with increase of methanol injection. Brake thermal efficiency decreased with increase of methanol injection due to lower combustion efficiency. The current models are not able to differentiate different combustion durations for diesel and methanol fuels. Further developments of the models are recommended to increase simulation accuracy. Furthermore, simulation on different diesel injection timing is recommended to better understand methanol combustion.Mechanical, Maritime and Materials EngineeringMarine and Transport TechnologyMechanical engineering / Sustainable Process and Energy Technolog