Methanol cold start for a serial hybrid powertrain

Green methanol is a renewable fuel with many advantages when used in a spark ignition combustion process. Methanol has a comparatively high enthalpy of vaporization, leading to lower combustion temperatures (com-pared to gasoline combustion) and, hence, lower wall heat losses as well as a reduced tendency to pre-ignition. Therefore, a brake efficiency of more than 40 % and furthermore minimal emissions are possible. The serial combination with an electric powertrain provides a disconnection of the load demand of the powertrain and the operating point of the combustion engine. In this case, a high volumetric and gravimetric power density, easy energy storage, and proven infrastructure of fuel distribution is combined with electric driving, high efficiencies, minimal emissions and a closed carbon cycle for the energy provision. Nevertheless, the high flash point of methanol at 11°C indicates a challenging cold start. The described procedure enables the cold start of pure methanol down to 20°C without additional engine components (e.g. heated injectors, grid heaters, etc.), when using a serial hybrid propulsion system. Besides a serial hybrid powertrain offers the possibility of preheating the exhaust aftertreatment in addition to a reliable methanol cold start during the vehicle is running.