Flexible Reduced Order Modelling Applied to the Performance Optimization of a Catalytic Range Extender for Electric Vehicles
2022-01-0718
03/29/2022
- Event
- Content
- A major inhibitor to large scale adoption of battery electric transportation systems is their single-charge range. For passenger vehicles, limited charging infrastructure gives rise to range anxiety, whereas for commercial fleets, the higher cost of such vehicles still outweighs the gains from better overall efficiency and tax concessions. One way to mitigate such barriers is through the inclusion of a range extender in the drive train. These devices take on different forms, but generally offer improvements in the critical customer requirements of power-to-weight ratio and overall running cost. Delta-Cosworth have developed a catalytic range extender based on a recuperated Brayton cycle. This system comprises a rotating shaft on which are mounted a centrifugal compressor (φ 89.5 mm), a radial turbine (φ 106 mm), and an electric machine with an inverter to capture the net shaft power. Between the compressor and turbine, a heat exchanger raises the air temperature to 650°C followed by a fuel-agnostic catalyst which further increases the gas temperature to the cycle maximum of 1050°C. The target output power of this machine is 35 kW at a design air flow rate of 240 g/s and a pressure ratio of 4.3:1. The real thermal efficiency of the machine is contingent on an array of aerodynamic, mechanical, and thermal losses. Therefore, the final optimisation demands understanding of its sensitivity to small modifications to each of its sub-stages. To this end, a suite of quasi-1D simulation tools were developed to simulate the entire machine; these were then validated against machine test data. The tools were deployed to estimate the return on investment of several changes, namely (a) optimisation of the compressor stage intake flow path; (b) fine tuning of the turbine volute A/r; (c) flow conditioning devices within the heat exchanger; and (d) compressor diffuser vane count and scroll design. This paper details the gains forecasted from each of the modifications.
- Citation
- Mason, A., "Flexible Reduced Order Modelling Applied to the Performance Optimization of a Catalytic Range Extender for Electric Vehicles," SAE Technical Paper 2022-01-0718, 2022, .