Sapphonica

I've been reading about how hot the 8's exhaust is. 'Zactly how hot, I don't know (if anyone does, please let me know).

Wouldn't it be better if some of this thermal energy could do work instead?

One possibility I can see is an intercooler.

By using the exhaust as the heat source, with a condenser, heat sink, and perhaps LiOH as the fluid, it could be engineered to have natural circulation (no compressor to suck power out of the engine). The inlet charge could be supercooled at just about any point within the thermal stress limits of the components and physical constraints of routing the plumbing.

Getting 'air conditioning' without a compressor might sound like voodoo, but there are many industrial coolers with this setup, and some nuclear reactors also utilize natural circulation (no pumps) to a certain power level.

I don't have the equations to calculate what this would do to power, especially with the MAF & etc., but it would make the air coming into the combustion chamber cooler/denser by orders of magnitude. So, per unit time, more air+fuel could be processed. Probably make the cat last longer too & reduce thermal stress on the whole system.

SantozRx8

for some strange reason i totally believe that... wow, this gets into the twilight zone

MyRxBad

iTrader: (1)

I think this would weigh a lot more then a compressor to be effective enough. Then you are using more gas to get were you are going, etc...

Basically I don't think it would be worth it but a cool idea none the less.

rx8wannahave

One thing I would like to see is an electric AC compressor, no more using up some of our HP to power the AC...thus reducing fuel economy also. It's about time we remove the leaches off our engines and use the advancement of batteries & alternators to power more equipment like the AC, water pump, etc.

The only issue I can think of regarding what you are suggesting is added weight, complexity, and cost. Bad words in the automotive...heck, the whole engineer world.

therm8

In theory it could work, however to attain the thermal driving head necessary for natural circulation flow requires either a significant change in density or a significant change in height (accompanied by the change in density large enough to create flow). Height is constrained to the size of the vehicle, and is most likely not enough to achieve any sizable flow rate. Another problem I forsee, is losses due to small piping. Those nuclear reactors have huge pipes, with very few flow restrictions designed in. I don't know the properties of LiOH offhand, when does it go gaseous, density at the relevant temps?

Wurmfist

Some ideas are neat but alot of the technology in the every-day things we use today are used to be more cost effective. I'm sure if cost wasn't a factor we would have helicopter engines in our cars much like Jay Leno has in his bike. Then we would laugh at 9,000 rpms. There's alot of technology out there that we don't use just because it costs too much to produce.

Sapphonica

There are a lot of 'flow restrictions' for light water nuclear reactor coolant (I am a 'recovering' naval nuclear engineer), but a helluva lot of thermal energy to overcome them.

I forgot to mention that you'd need an evaporator, so the hot, compressed fluid is cooled then shot into the expansion volume, hence lowering its temperature much more as density decreases. The natural circulation LiOH coolers weren't part of the nuke plant, so I never learned that much about them.

Cost and weight wise, it wouldn't necessarily be that expensive. Given how much a turbo costs, it would be interesting to calculate the 'bang for the buck'.

Another possibility might be to use the waste heat to drive an air pump to push more air into the intake.

It wouldn't do much until the exhaust manifold heated up, but once it did, it would have an advantage over a turbo or super charger in that it wouldn't need to 'spool up' or be dependent on engine power/rpm to pump air.

What else could the waste heat be used for?

RX8-CARL

A Turbo would be the best thing for the exhaust gasses. :D