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Mazda’s rotary engine in the age of the electric car

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Re: Mazda’s rotary engine in the age of the electric car

#91

Post by alexose »

coryrc wrote: post #28
sethhochberg wrote: post #16

Earlier quoted context omitted.

They have a pretty narrow power band (produce efficient max power at a small range of RPMs) which always somewhat limited their use for normal ICE cars, but is a pretty workable constraint for an electrical generator. So you have compact size, good power to weight ratio, and power limitations that don't really matter for range extender purposes. Lots of potential. I can't find the article right now, but I'd swear I r…

Then you may as well use a gas turbine, which is pretty much better in every way that matters for generating purposes.

Cosworth appears to have developed a microturbine for this purpose. And it (maybe?) has found a home in Ariel's latest insane car: https://www.carscoops.com/2022/09/ariel-hipercar-is-an-1180-...

Re: Mazda’s rotary engine in the age of the electric car

#92

Post by elevatedastalt »

philwelch wrote: post #86
coryrc wrote: post #56

Earlier quoted context omitted.

You're probably being silly, but for anyone else, gas turbines as used for generators don't have jet exhausts on them, i.e. https://www.youtube.com/watch?v=yR5oVn-Fvvg

So what do they do with the exhaust?

The reason jet engines have that sort of exhaust is because the primary purpose of the gas turbine there is to dump all the excess energy into the exhaust to make it go fast (so that the plane can be pushed ahead by the reaction force). They produce very little power, just enough to power the Auxiliary Power Unit (that manages the plane electronics, air-conditioning etc.).

If you want to use a gas turbine for producing power, you will set it up such that most of the energy goes into the work generated, rather than the exhaust, so it would be a cooler, slower exhaust, similar to an IC-engine.

Re: Mazda’s rotary engine in the age of the electric car

#93

Post by 01HNNWZ0MV43FF »

elevatedastalt wrote: post #92
philwelch wrote: post #86

Earlier quoted context omitted.

So what do they do with the exhaust?

The reason jet engines have that sort of exhaust is because the primary purpose of the gas turbine there is to dump all the excess energy into the exhaust to make it go fast (so that the plane can be pushed ahead by the reaction force). They produce very little power, just enough to power the Auxiliary Power Unit (that manages the plane electronics, air-conditioning etc.). If you want to use a gas turbine for produci…

Depending on the plane and engine. Big jetliners have high-bypass turbines where they do intentionally produce a lot of torque, to spin a large compressor fan, but most of the fan air does not go through the combustion step, it's just used to react off of.

Re: Mazda’s rotary engine in the age of the electric car

#94

Post by [deleted] »

coryrc wrote: post #56
WalterBright wrote: post #38

Earlier quoted context omitted.

Gas turbine cars have been built, but they tend to set anyone on fire if they walk behind the car. https://bandimere.com/previewing-the-brakes-plus-jet-car-nat...

You're probably being silly, but for anyone else, gas turbines as used for generators don't have jet exhausts on them, i.e. https://www.youtube.com/watch?v=yR5oVn-Fvvg

[deleted]

Re: Mazda’s rotary engine in the age of the electric car

#95

Post by brucethemoose2 »

486sx33 wrote: post #2

Does it produce more low end torque verses a traditional gasoline combustion engine? If not then why is it better suited for electrical generation? Is it more efficient with less load? The article mostly makes it sound like Mazda just loves the wankle and wants to find any possibly way to bring it back - even though it has “high” emissions… so coupling it with a hybrid electric motor makes it happen.. That can’t be t…

Power/Weight is extremely high. A tiny wankel will do the job, and weight is everything on cars.

It does prefer a narrow RPM band, which is fine.

Reliability is the biggest concern TBH, but maybe that's not a huge bummer if its more of a backup/assistant engine.

Re: Mazda’s rotary engine in the age of the electric car

#97

Post by 01HNNWZ0MV43FF »

kyleee wrote: post #70
userbinator wrote: post #62

Earlier quoted context omitted.

Actually far simpler than a piston engine; the fuel consumption and high production cost was what made them become extinct. https://en.wikipedia.org/wiki/Chrysler_Turbine_Car

Of course Jay Leno has one; not sure if he’s featured it on his youtube channel (I don’t recall seeing it). Awesome

Yep I've seen it on his YouTube. The "EcoJet" https://www.youtube.com/watch?v=10q9_pB6unU

He said that they had to put really big brakes on it. I guess for some reason you can't just have a clutch. Personally if I was going for eco I'd want something more clever than "bigger brakes" but maybe building something like a Hybrid Synergy Drive is harder than building a turbine.

Re: Mazda’s rotary engine in the age of the electric car

#98

Post by suprjami »

brucethemoose2 wrote: post #95
486sx33 wrote: post #2

Does it produce more low end torque verses a traditional gasoline combustion engine? If not then why is it better suited for electrical generation? Is it more efficient with less load? The article mostly makes it sound like Mazda just loves the wankle and wants to find any possibly way to bring it back - even though it has “high” emissions… so coupling it with a hybrid electric motor makes it happen.. That can’t be t…

Power/Weight is extremely high. A tiny wankel will do the job, and weight is everything on cars. It does prefer a narrow RPM band, which is fine. Reliability is the biggest concern TBH, but maybe that's not a huge bummer if its more of a backup/assistant engine.

Reliability for rotaries hasn't been a concern for a long time. Modern apex seals work well and last a reasonably long time. There is a need to stop parroting facts from the 1980s.

Re: Mazda’s rotary engine in the age of the electric car

#99

Post by cjbgkagh »

coryrc wrote: post #28
sethhochberg wrote: post #16

Earlier quoted context omitted.

They have a pretty narrow power band (produce efficient max power at a small range of RPMs) which always somewhat limited their use for normal ICE cars, but is a pretty workable constraint for an electrical generator. So you have compact size, good power to weight ratio, and power limitations that don't really matter for range extender purposes. Lots of potential. I can't find the article right now, but I'd swear I r…

Then you may as well use a gas turbine, which is pretty much better in every way that matters for generating purposes.

AFAIK I think there is some difficulty in getting turbines to scale down efficiently with a need of a recouperator to maintain a higher core temperature for better efficiency. The recouperator is additionally expensive on top of the already expensive turbine cost.

Having a rotary with a turbo should be able to work better at a lower scale for a pretty cheap production cost.

Re: Mazda’s rotary engine in the age of the electric car

#100

Post by avalys »

bob1029 wrote: post #83
user_7832 wrote: post #73

Earlier quoted context omitted.

Apparently they really don't scale well. I found this reddit post explaining it better: > Gas turbines scale extremely poorly. They rely on small clearance between the rotating blades and the housings for efficiency. The smaller the turbine, the greater the relative clearance and the more energy is lost. Gas turbines, at least with established technology, make very little sense below 300ish HP. As a real life compari…

300 HP = ~220 kW I believe a Tesla can charge its battery pack at approximately this rate.

What's your point?

There's no reason to have a generator that charges the pack in a hurry. It really only needs to cover the maximum sustained average draw - driving up an extended grade at high speed. That's a lot less than 300 hp - it's probably not more than 80 hp or so at most.

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