Virtual design of an opposed piston Range Extender engine
2022-01-0516
03/29/2022
- Event
- Content
- In the last decade, the 2-stroke opposed piston CI engines have demonstrated their potential as clean and efficient power-plants. However, most of the recent prototypes are relatively big, not suitable for a typical automobile range-extender, rated at 25-30 kW. The purpose of the paper is the virtual development an OP engine for this particular application. Generally speaking, an auxiliary power unit for an electric vehicle must be very compact, clean and efficient. Moreover, its operations should be as quiet as possible, with low vibrations A single cylinder, OP CI engine, coupled to two small electric motors (one for each crankshaft) can be a perfect candidate. First, the two-stroke cycle permits a reduction of load for the target power rate, enabling the implementation of a low temperature combustion mode (PCCI), that can provide ultra-low pollutant emissions and high thermal efficiencies. Second, the absence of poppet valves and camshafts is a fundamental advantage for reducing friction losses and weight and manufacturing cost. Third, the level of turbulence within the cylinder, along with the dilution of the charge, can be easily controlled by means of the design of the scavenge and exhaust ports, and the management of an electric supercharger. Fourth, the synchronization of the two crankshafts permits a perfect balance of the inertia forces, while the rotors of the electric motors make not necessary the presence of flywheels. One of the main challenges of the project is the development of a scavenging and a combustion system, tailored for the specific range extender application. The guidelines for this task were provided by a patent, that also permits to use a single injector and a flat piston crown The study of the scavenging and combustion process at the condition of maximum power (30 kW at 3000 rpm) was carried out by using a CFD-3D code, for about 10 consecutive cycles. Brake performances are predicted by CFD-1D engine simulation (by GT-Power)
- Citation
- Mattarelli, E., and Rinaldini, C., "Virtual design of an opposed piston Range Extender engine," SAE Technical Paper 2022-01-0516, 2022, .