Efficient range extender using E85 and thermochemical recuperation

University of Minnesota/Will Northrop

This research will enable efficient and environmentally sound utilization of ethanol blends in internal combustion engines. Future engines may play a supporting role in electrified vehicles by serving as battery charging range extender (REx) engine-generators. This project will use E85 and lower concentration ethanol/gasoline blends and a novel exhaust reforming strategy to increase the efficiency of REx engines. The proposed system utilizes the waste heat from an engine to reform a portion of the incoming fuel to a fuel mixture that has higher caloric value in a process known as thermochemical recuperation (TCR). E85 has advantages for TCR compared to pure gasoline or E10 due to its lower catalytic steam reforming temperature, enabling higher levels of reformed fuel, thus higher engine system efficiency. The PI and his team have developed a thermally integrated catalytic reactor that utilizes both the thermal energy contained in the engine exhaust and the chemical energy from oxidizing unburned fuel components from combustion to feed the reforming reaction.
The proposed work will allow development of key understanding regarding ethanol/gasoline blend steam reforming chemical kinetics. The fundamental understanding will then be applied by constructing a practical TCR reactor. The reactor will be constructed for application in a BMW i3 REx engine-generator already installed and operational at the UMN-MERL. The project will lead to demonstration that E85 can improve the efficiency of TCR-equipped REx engine-generators and provide a more renewable alternative to lower concentration blends, adding to the environmental benefits of electrification.