Low friction and on-demand thermal management for a high-efficiency internal combustion engine in a net zero CO ₂ hybrid powertrain

One key factor of a hybrid electric vehicle (HEV) is a maximized brake thermal efficiency (BTE) of the internal combustion engine (ICE). The new gasoline engine called NA16 is fully developed, tested and a high efficiency engine which is equipped with Phase Change Cooling (PCC) technology, low friction components (e.g. roller bearings), low pressure EGR and a high compression ratio combustion process. It operates with the optimal indicated specific fuel consumption (ISFC) in an engine power range from Peng =20-35 kW to show the overall potential of a bio- fuel (net zero CO2) compatible plug in hybrid electric powertrain. In addition, the goal was to reduce friction losses not only in the area of the ISFC best point but also in cold-start operation, which represents an additional challenge. The engine is also characterized by high EGR compatibility and/or lean combustion process, which is possible by the conversion to the PCC system. Characteristic is a homogeneous wall temperature that can be adjusted on-demand and with the new piston design a fast, stable and knock-free combustion is implemented at a high compression ratio. All engine components are very well suited for operation with bioethanol and therefore the developed powertrain combines a emission free short range mobility with CO2 neutral long range capabilities.