Alternative to ceramic coating ........ :P

[abently]

Remembered this the other day... but since I don't have time to design and run simulations, I thought I would let you guys know since I know what extreme's you guys will go to disprove this idea being replicated on Turbo exhaust manifolds as ludicrous.... lol

4.2. Retaining Heat of the Exhaust Gas
In order to retain heat of the exhaust gas from the
combustion chamber to the catalyst, two measures were
taken: The exhaust port has a stainless thin-walled
insert (made of heat resisting stainless alloy) and the
exhaust manifold has two layers of air layer for heat
insulation and small volume thin-wall inner tube. This
allows for the retention of exhaust gas heat from
combustion chamber to the catalyst. Because of the
heat retention, gas temperature at a catalyst upstream
could increase about 140 degree C in the USA LA-4
mode drive, improving catalyst’s conversion capability.
Fig. 24 shows structure of the exhaust port insert and
exhaust manifold.

Quote taken from the SAE paper on the RENESIS Rotary.

I don't believe they used this technique all the way from the Exhaust port to the catalyst but I can find out if need be.

[Hydra]

So it's really like putting a blanket on in bed - the 'trapped' air acts as an insulator.

Ceramic coating is cheaper and easier.

[oldcorollas]

Remembered this the other day... but since I don't have the knowledge to understandit, I thought I would let you guys know since I know what extreme's you guys will go to try and make me understand something basic.

what is the problem? it is a relatively common thing to do.

the problem: catalysts take time to heat up.
reason?: heat is removed from the exhaust gas by the COLD exhaust manifold, and COLD exhaust pipe, before the gas can heat up the COLD catalyst to abotu 300deg so it can work properly.
during this time, the engines emissions are not "corrected" and this is a major let down of any car trying to pass stringent emissions.

they use heat resisting (high nickel, high chrome) stainless in the port because it has slow thermal conduction. thin so it has small heat capacity.

exhaust manifold. thin inner layer to heat up faster, and then air layers to retain that heat..

all to make sure the catalyst warms up faster.


gee ab, with your knowledge, i thought you would have understood it without having to post on toymods to get an explanation, it is just very very simple heat conduction theory.....

[oldcorollas]

as for alternative to ceramic coating... how about i let you explain the pros and cons of each.... or don't you know?

[Gary]

[abently]

Air at 20C

Thermal conductivity: 0.0257
Density: 1.205

Air at 400C

Thermal conductivity: 0.0515
Density: 0.524

Air at 1000C

Thermal conductivity: 0.0810
Density: 0.2772

The EGT's from the RENESIS Rotary Engine aren't exactly below that of the 1000C safe limit for Turbine wheels (Reaches 900C in front of the Catalyst). So to say the results aren't reproducible to OEM quality standards isn't valid.

[oldcorollas]

they say the EGT's are above 1000C? i find that rather interesting... and a bold claim.

[abently]

they say the EGT's are above 1000C? i find that rather interesting... and a bold claim.

No they don't.... obviously the Air pump plays an interesting role also in raising EGT's but unfortunately someone with an RX8 will have to datalog it as its not documented publicly.

I believe the idea has merit given the right circumstances.

[oldcorollas]

i meant in regard to the turbines.