Integration of an ORC waste heat recovery with electrification and supercharging through use of a planetary gear system for a class 8 tractor application

Document Type

Technical Report

Publication Date



Department of Mechanical Engineering-Engineering Mechanics


A novel approach to the Integration of Turbocompounding/WHR, Electrification and Supercharging technologies (ITES) to reduce fuel consumption in a medium heavy-duty diesel engine was previously published by FEV. This paper describes a modified approach to ITES to reduce fuel consumption on a heavy-duty diesel engine applied in a Class 8 tractor. The original implementation of the ITES incorporated a turbocompound turbine as the means for waste heat recovery. In this new approach, the turbocompound unit connected to the sun gear of the planetary gear set has been replaced by an organic Rankine cycle (ORC) turbine expander. The secondary compressor and the electric motor-generator are connected to the ring gear and the carrier gear respectively. The ITES unit is equipped with dry clutch and band brake allowing flexibility in mechanical and electrical integration of the ORC expander, secondary compressor and electric motor-generator to the engine. This approach supports electrical integration of ORC expander when the turbine power output is low and mechanical/power-split integration when the turbine power output is high. At low engine speeds and high loads, the

secondary compressor can provide power from the ORC expander or from the electric motor. Furthermore, the electric motor-generator can be used for regenerative braking and providing torque assist to the engine when possible. Thus, the new configuration continues to provide a powersplit integra-tion of the applied technologies, helping to achieve optimal management of power flow. Previously, the ITES system functionality had been vali-dated through engine and vehicle drive cycle simulation utilizing the 48V motor generator unit for powersplit turbo-compounding, powersplit supercharging, start-stop, regenera-tive braking and engine torque assist functionality. The current study focuses on the simulation of the ORC expander equipped ITES system on an 11 liter six cylinder diesel engine that would replace a 15.0 liter six cylinder diesel engine applied in heavy-duty Class 8 tractor. The simulations reveal the ability of the power-dense 10.7 liter engine with ITES system to match the performance of the 15.0 liter six cylinder engine, thus demonstrating a reduction in both expense and space claim while improving the overall system efficiency in comparison to the independent implementation of individual technologies.

Publisher's Statement

© 2019 SAE International. All Rights Reserved. Publisher’s version of record: https://doi.org/10.4271/2019-01-0229

Publication Title

SAE International