Pre-Heating the cat?!

[NoD~]

I saw this article today...

https://arstechnica.com/cars/2018/05...id-sports-car/

And it says...

While I'm in awe of all of the teams' accomplishments, EcoCAR 3 is a competition, and that means there has to be a winner. As mentioned up top, yet again that was The Ohio State, which scored 895 points out of a maximum of 1,000. Among its achievements was a hybrid with 20-percent greater fuel efficiency than the rest, in part thanks to an electrically heated catalyst that dropped emissions upon startup by 85 percent.

Not sure what that would do for the rest of us who are looking at our bottom line MPG, but curious if anybody has looked into anything like this.

[RedDevil]

It isn't a new idea. In fact, it has been produced commercially more than 20 years ago:
Continental Emitec GmbH


Even so, there's a bunch of recent patents:
https://scholar.google.nl/scholar?q=...=1&oi=scholart

One relatively readable scientific publication:
https://pure.tue.nl/ws/files/3268429/Metis237278.pdf

Then there is...

Couldn't resist

[California98Civic]

Originally Posted by RedDevil

It isn't a new idea. In fact, it has been produced commercially more than 20 years ago ...

Totally agreed. I think BMW put electrically preheated CAT in a production vehicle 10 or 15 years ago. I did some light internet research on this about a year or two ago.

I don't see the major fuel economy gains, though, unless it is just by getting into closed loop sooner.

[California98Civic]

And this looks like a pretty cool set of developments (also a nice abstract of parts of the history):
http://www.emitec.com/fileadmin/user...d_catalyst.pdf

[Stubby79]

Just don't put it in the microwave, mmkay?

[twj347]

Originally Posted by California98Civic

I don't see the major fuel economy gains, though, unless it is just by getting into closed loop sooner.

It's not just about getting into closed loop faster. Modern cars are tuned to intentionally waste a bunch of extra fuel in order to heat the cat up faster.

Here are the things the stock tune on my Subaru does to (presumably) heat the cat faster:
- Idles in stratified fueling mode up to coolant temps of 60C (increasing fuel use by at least 50% at idle)
- Retards ignition timing for the first 3 minutes after engine start.
- Retards exhaust cam timing by 20 to 50 degrees until the coolant temperature is above 50C.
- 1800rpm idle speed up to coolant temps of 40C, and even for a while after hot starts.

I've pretty much tuned all these things out, with great benefits to short-trip fuel economy. They don't affect driveability. I can only assume the engine is tuned like this to heat up the cat quickly for regulatory reasons. I'd be surprised if overall NOx emissions were even reduced much.

[California98Civic]

Originally Posted by twj347

...Here are the things the stock tune on my Subaru does to (presumably) heat the cat faster: ... I've pretty much tuned all these things out ...

How did you find out the tune did all this and how did you adjust the tune? You have one of those software packages for monitoring and editing ECU parameters and such? Pretty cool.

[cRiPpLe_rOoStEr]

Presumably it's meant with emissions compliance as a higher priority than overall efficiency. But anyway, depending on what kind of heater core it may use, it would eventually be more efficient than other approaches to increase the EGT right after the engine start.

[teoman]

Would thermally insulating the exhaust manifold pipes and cat be at all beneficial?

[Natalya]

Originally Posted by teoman

Would thermally insulating the exhaust manifold pipes and cat be at all beneficial?

Yes, I think so. Usually cats have a heat shield on them. I lived in Canada for a few years and I got a car where the heat shield had rusted and fell off my catalytic converter. I fashioned a new one out of sheet aluminum to put back over it.