On 3/21/2021 10:00 PM, Mike Duffy wrote:
> On Sun, 21 Mar 2021 18:40:29 -0400, Dave Smith wrote:
>
> Maybe he was speaking about 'engineering'. My hazy memory says that a
> normally aspirated 4-stroke has a theoretical maximum efficiency around
> 25% at standard temp & pressure. (0 C & 1 atm).
>
> However, supercharged 2-stroke diesel train locomotive engines are in
> service which achieve around 67% with a 'boost' of 20 or so.
>
> Engineer - trains, get it?
>
> Seriously, what I do not understand is why they don't use mechanical
> oxygen concentrators to bring it up a few notches. If you get rid of the
> 80% inert nitrogen and pipe a turbocharger into the supercharger, just
> imagine what could happen.
>
> Yeah, I know. Hot metal and pure oxygen is a recipe for disaster. We just
> need to figure out how to make ceramic pistons, etc.
>

The concentrator would be huge. Gas to oxygen is about 1:14.

How big is the engine?
A 4-stroke engine with one litre
displacement operating for 60 minutes at 2500 rpm is
estimated to consume 1 L x 2500/2 rpm x 60 minutes/hour =
75,000 litres of air.