Numerical assessment of the performance and emissions of a compact Wankel rotary engine applied as a range extender on the BMW i3 model

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Amongst all the hybrid-vehicles technologies and layouts, range-extended electric vehicles are the ones with the real prospect to reduce the emissions produced by the thermal machine when in driving conditions, while assuring an adequate range for the common user. The BMW i3 represents one of the most successful series hybrid electric vehicles, having been on the market since 2013. Given the complexities of a hybrid layout employing both thermal and electrical machines, the range extender must have compactness and lightweight characteristics in addition to a suitable power output for the vehicle. Usually, standard 4- stroke small-displacement engines are employed for this application, with the BMW i3 employing a 2- cylinder range extender. More interestingly, a Wankel rotary engine can provide the same amount of mechanical power by reducing the weight and the volume of nearly a third to the equivalent 4-stroke engine. In this study a numerical assessment of the Advanced Innovative Engineering UK (AIE UK) 225CS Wankel rotary engine as a range extender for the BMW i3 was carried out. A full vehicle model of the BMW i3 was built in Siemens Simcenter Amesim 2021.2 to evaluate the behaviour of the aforementioned engine as a range extender. The engine sub-model used was a Mean Value Engine Model (MVEM) set up by implementing the experimental data collected during previous experimental campaign while the BMW i3 chassis sub-model was characterised by using the publicly available data from an Argonne National Laboratory benchmarking project (vehicle weight, front surface, drag coefficient, tires dimensions, etc.). Finally the model was tested over the standard Worldwide harmonized Light vehicles Test Procedure (WLTP) driving cycle in both Charge Depleting and Charge Sustaining modes.
Original languageEnglish (US)
Title of host publicationJSAE Powertrains, Energiy and Lubricants
StatePublished - Aug 22 2023

Bibliographical note

KAUST Repository Item: Exported on 2023-08-31
Acknowledgements: Thanks go to Innovate UK and the Advanced Propulsion Centre for funding this work. Thanks are also due to all of the ADAPT project partners: the University of Bath, Westfield Technology Group, Advanced Innovative Engineering UK Ltd, GEMS and Saietta. The authors express their deep gratitude to the team of researchers and technicians that worked on the ADAPT-IPT project for their valuable help in preparing the test cell and testing the engine. The authors express also their gratitude to Siemens and Penta3D for providing the software with academic licenses.


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