4 ms·

In F1 they now have waste heat recovery systems, as I understand it (please, F1 engineers, correct me if I'm wrong) in the form of mechanically decoupled turbin

In F1 they now have waste heat recovery systems, as I understand it (please, F1 engineers, correct me if I'm wrong) in the form of mechanically decoupled turbine and compressor wheels on the turbo. The (exhaust) turbine generates electricity which it can feed either to the battery or to the compressor wheel motor (acting like a regular turbo in the latter case). In this configuration, you can also electrically spool up the compressor wheel from the battery, giving exactly zero turbo lag, and they can also recover impressive amounts of energy that would otherwise be wasted - about 1 kWh in a 90 second lap. [For a longer while, we've had anti-lag systems on racecars that basically burn petrol in the manifold, always keeping the turbo spinning. These are horribly fuel-inefficient and destroy turbos etc. quickly.] I sincerely hope that electrically coupled turbo systems are adopted in road cars. The recent Audi/Bentley top-end (diesel!) SUVs with electric turbos are promising in this regard, but I don't think they do waste heat recovery per se.

davewritescode 9y ago
The coolest thing about current F1 engines is that they eliminate a major inefficiency of turbos. In a modern turbocharged, once the turbo hits maximum boost an electronically actuated wastegate opens to avoid over boosting the engine which wastes all the energy you worked to create. Coupling the turbine shaft to a generator allows you to recapture that energy normally lost to the wastegate.
Too 9y ago
Volvo has something similar in their latest engines, they call it power pulse. It's building up the turbo with an electric compressor and opposed to audi e-turbo the pressure is also stored in a pressure tank instead of constantly pumped by the compressor, which at least on paper sounds like it would reduce the lag even more. Anyone got more experience?
hvidgaard 9y ago
F1 nerd here. The turbo and compressor are still mechanically linked. Mercedes pioneered this eras engine with the exchaust side and intake side on opposite ends of the engine, and still managed to connect them with a shaft. If you know anything about turbos, think about this for a moment. They have mechanically connected two components with a shaft along the entirety of the engine block, rotating with 100.000 rpm. That is amazing. They have an electical motor on the same shaft that will either harvest or keep the turbo spinning. This beautiful arrangement means that they design the turbo to extract as much energy as posible, and control it with the motor, rather than rely exclusively on the wastegate. This as you state, means that they can recoupe quite a bit of extra energy. I would not be surprised if we see non turbo charged engines, with an exhaust energy recovery system for hybrid engines.

davewritescode 9y ago

The coolest thing about current F1 engines is that they eliminate a major inefficiency of turbos. In a modern turbocharged, once the turbo hits maximum boost an electronically actuated wastegate opens to avoid over boosting the engine which wastes all the energy you worked to create. Coupling the turbine shaft to a generator allows you to recapture that energy normally lost to the wastegate.

Too 9y ago

Volvo has something similar in their latest engines, they call it power pulse. It's building up the turbo with an electric compressor and opposed to audi e-turbo the pressure is also stored in a pressure tank instead of constantly pumped by the compressor, which at least on paper sounds like it would reduce the lag even more. Anyone got more experience?

hvidgaard 9y ago

F1 nerd here. The turbo and compressor are still mechanically linked. Mercedes pioneered this eras engine with the exchaust side and intake side on opposite ends of the engine, and still managed to connect them with a shaft. If you know anything about turbos, think about this for a moment. They have mechanically connected two components with a shaft along the entirety of the engine block, rotating with 100.000 rpm. That is amazing. They have an electical motor on the same shaft that will either harvest or keep the turbo spinning. This beautiful arrangement means that they design the turbo to extract as much energy as posible, and control it with the motor, rather than rely exclusively on the wastegate. This as you state, means that they can recoupe quite a bit of extra energy. I would not be surprised if we see non turbo charged engines, with an exhaust energy recovery system for hybrid engines.