138
New thermoelectric generator converts vehicle exhaust heat into electricity, boosting fuel efficiency
(www.inceptivemind.com)
this post was submitted on 14 Feb 2025
138 points (85.2% liked)
Technology
63001 readers
4235 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related content.
- Be excellent to each other!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, to ask if your bot can be added please contact us.
- Check for duplicates before posting, duplicates may be removed
- Accounts 7 days and younger will have their posts automatically removed.
Approved Bots
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
I'll admit I'm at the edge of my knowledge here, but are you saying that if we were increasing the pressure in the cylinder from, say pure nitrogen (or another inert), instead of atmosphere (which contains oxygen), and we kept the same amount of fuel from natural aspiration, we're still get the majority of the benefit of turbocharging even overcoming the parasitic portion of extra energy needed during the compression cycle and the exhaust cycle against the turbocharger impeller?
Let's assume the contrary. Let's assume it can't. Let's assume the turbocharger is a net drag on the engine, and any gains are only from enabling the engine to burn more fuel. If this is all true, then the turbocharger should not be able to function without the reciprocating engine. Without the "push" from the pistons during the exhaust stroke, the turbo shouldn't be able to turn.
If we can show that the turbo can not only spin without the piston engine, but that additional energy can be harvested, we will have disproven this assumption.
So, let's get rid of the pistons. Plumb the intake manifold directly to the exhaust manifold. We have one combined intake/exhaust manifold. We stick a couple spark plugs into that manifold and turn it into a combustion chamber.
Now we have air passing through a compressor turbine, into a combustion chamber and then through an exhaust turbine. Sound familiar?
Engineers discovered that some turbos were capable of producing more power than the engines they were attached to. They discovered that the reciprocating engine was a drag on the turbo. The only reason to keep the reciprocating engine was because material science hadn't caught up. We didn't have turbos capable of directly handling the heat of combustion.
That discovery gave us the jet engine.
No. The heat of combustion increases the gas temperature. But this temperature increase is relative to the mass of the gas. The heat is relative to fuel/oxygen mass combusted. (Combustion energy + Ideal gas law)
Add mass without adding combustion, you get lower pressure and temperature out. So you get less boost from the turbo and make more work for the compression cycle.
The major point of the turbo is to use wasted heat to add more oxygen by packing more air in. So it's a bit of an odd question to answer. The point is there's a lot of energy wasted in a naturally aspirated engine's exhaust. Turbos mostly use that wasted energy, and not power from the crank.
Oh yeah, the turbo is going to have an efficiency ratio for converting exhaust pressure into boost. So that added backpressure on the exhaust is going to be offset in the intake stroke by that ratio. Not important to the point, hat a tidbit. These things are so complicated lol.