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Old 03-01-2021, 11:03 AM   #11 (permalink)
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Quote:
Originally Posted by redpoint5 View Post
Don't have time to pay attention to the video at the moment (funny they dub male speakers with female voices).

This appears to be a series hybrid. I'm always confused if the first gen Volt was a series hybrid or not, but I know the BMW i3 with ICE was. Makes all kinds of sense to me, especially if they incorporate ~16 kWh battery that can be plugged in for an initial all electric range of 60 miles.

I'll really get excited when these technologies reach the vehicles most in need of them; larger trucks, SUVs, and vans.
The gen1 chevy volt was both, but was primarily a series hybrid. Only under very specific situations will the engine drive the wheels directly. Which is why it was only capable of mid to high 40's MPG on the highway whereas a toyota prius could easily do better.

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Old 03-01-2021, 11:54 AM   #12 (permalink)
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Quote:
Originally Posted by RustyLugNut View Post
. . . provided a white paper calculating that the application of the Atkinson Cycle to a diesel engine could yield a tad over 60% thermal efficiency. Use of various materials in construction could pull out a few more percentages. Your 70% efficiency target is not that far off for the intrepid.
There is a big difference between theoretical values, lab tests, and reality. A combined cycle gas plant is theoretically 95% efficient. The most efficient real combined cycle plant is the GE 7HA that is 63.8% efficient.

(I worked on the 7HA and 9HA programs at my first job out of university)
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Old 03-02-2021, 12:00 AM   #13 (permalink)
It's all about Diesel
 
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Originally Posted by rmay635703 View Post
A single speed atkinized Diesel could also get away with a much more simplistic emissions system
I won't really hold my breath for that. Just remember most of the emissions non-conformity observed on tests with Diesel vehicles in South Korea back in the Dieselgate days were related to harsh weather conditions (not the same as the deliberate fraud observed in Volkswagens and Audis).
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Old 03-11-2021, 04:04 PM   #14 (permalink)
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Well understood.

Quote:
Originally Posted by JSH View Post
There is a big difference between theoretical values, lab tests, and reality. A combined cycle gas plant is theoretically 95% efficient. The most efficient real combined cycle plant is the GE 7HA that is 63.8% efficient.

(I worked on the 7HA and 9HA programs at my first job out of university)
Peak thermal efficiencies for Class 8 diesel trucks are already at 48%. Large ocean going diesels are at 52%. A practical application of the Atkinson Cycle to the diesel cycle can push the 60% envelope. Use of ceramic coatings to reduce heat loss ( the main advantage of the large ocean engines due to cylinder size )
plus advanced injector technologies such as the defunct Transonic super critical fuel injection will nudge you within spitting range of 70% thermal efficiency. That's more than good enough to use as a constant load generator in a serial hybrid vehicle.
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Old 03-11-2021, 04:07 PM   #15 (permalink)
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This is where a single load point makes it much simpler.

Quote:
Originally Posted by cRiPpLe_rOoStEr View Post
I won't really hold my breath for that. Just remember most of the emissions non-conformity observed on tests with Diesel vehicles in South Korea back in the Dieselgate days were related to harsh weather conditions (not the same as the deliberate fraud observed in Volkswagens and Audis).
All engines coupled to drive a vehicle directly must provide variable power. They struggle to provide this variable power and thus fall into inefficient ranges both in thermal efficiencies as well as emissions. A single speed/load makes it so much easier.
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Old 03-12-2021, 12:48 AM   #16 (permalink)
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Originally Posted by RustyLugNut View Post
A single speed/load makes it so much easier.
As long as the emission controls keep their performance under all the different environmental and weather conditions it may be required to operate.
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Old 03-22-2021, 12:49 AM   #17 (permalink)
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Quote:
Originally Posted by ksa8907 View Post
The gen1 chevy volt was both, but was primarily a series hybrid. Only under very specific situations will the engine drive the wheels directly. Which is why it was only capable of mid to high 40's MPG on the highway whereas a toyota prius could easily do better.
I'd argue against this, simply by virtue of its transmission layout. It uses a very similar planetary gearset to a Prius. The electric motor is large enough and the gearing chosen such that the gas engine doesn't *need* to oppose the electric motor in order to operate at all normal road speeds, but ultimately it's still planetary gears. Torque into the system = torque out of the system.

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