Pump Development for an Exhaust Heat Recovery Box on Heavy Duty Trucks

orc2019 Tracking Number 56

Nearly 30 percent of the fuel energy in an internal combustion engine is lost as waste heat in the form of hot exhaust gases. Nowadays it seems clear that the heavy duty manufacturers will implement bottoming Rankine cycles to recover the exhaust heat on their long haul trucks in the 2020s as an answer to future stringent regulations and the still increasing customer pressure for reductions in operating costs. The Exoès company developed several components for an organic Rankine system packaged in a box and installed in a truck tractor close to the exhaust pipe. This paper is focusing on the pump development results. We developed a pump prototype and a dedicated test rig in order to assess its performance and to perform endurance tests. The key challenges for such a product development are to keep a good volumetric efficiency with high pressure difference between outlet and inlet around 30bars and with corrosive and low viscosity fluids such as ethanol, pumped in saturated liquid state at quite low flows. Leakage path are then critical to the pump efficiency as well as the electric actuator design to match the pump torque and speed requirements with high efficiency. Another challenge is to maintain this leakage rate under control in time despite wear. The choices made for the pump architecture and materials will be presented as well as test results. The road map for the necessary technical improvements will displayed.