New thermoelectric generator converts vehicle exhaust heat into electricity, boosting fuel efficiency
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Your explanation about where the energy comes from with turbochargers sounds wrong to me.
When exhaust gas passes through a turbocharger,
You're skipping a crucial step here. The exhaust gases get pushed through input of the exhaust gas impeller on the turbocharger by the movement of a piston in the engine during the exhaust cycle. This "work" isn't free. Its energy that comes from the other pistons on their combustion cycle. If there is more resistance on the exhaust coming out of the engine (which there is to drive the turbocharger impeller), that energy must be added (robbed) by the energy at the crankshaft that ultimately powers the wheels.
The extra boost of power we experience in an engine from using a turbocharger is that the turbocharger allows more oxygen to be put into the combustion chambers (and the engine puts more fuel in at the same time). The extra energy is from burning - - more fuel in the same period of time than without turbocharging. The fuel is the source of the energy, the turbocharger isn't recovering any energy.
The article is covering technology is actually recovering energy turning heat (thermal energy) back into electricity (electrical energy).
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Molecules interact with each other. Energy is transferred as they bump around. If you were to follow a single molecule it would move around randomly. What we can measure is usually the average of many molecules.
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Show this to any automotive engineer and count how many seconds before they start laughing
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So it’s less of vibrating and more about smashing around into things?
This is easier to envision with a gas: like a chamber of balks all ricocheting like mad. It’s harder to envision for a solid. But I guess a molecule will be up smack against its neighbors, getting repelled, not so much bounding freely?
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Fools logic was meaning this type of technology doesn't have a purpose when it definitely does and that is how your post came off lack of context I guess, it is the internet.
While it won't power the locomotion of the car it will help to power accessories even on a 40w basis even more so over trips and somewhat lengthy drives.
Your post lacked any of your clarifications so it comes off as you simply think this is an ignorant waste of time concept as a whole. Energy recovery is a useful premise.
But making micro machines to do it, or retrofitting old cars with this wouldnt help much but manufacturing newer more effecient vehicles isn't a viable strategy like the guy explains above you. There's other uses besides moving a vehicle. There's other fields and applications this could be used for having nothing to do with configuration. All I was saying was that this tech has viability.
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Even solids are mostly nothing. This is why neutron stars are so dense - there is a lot less nothing between the neutrons, largely due to gravity.
Here's another way to think about it. A gas is like a bunch of balls bouncing around a room, hitting the walls and occasionally each other. A solid is like a ball pit, but the balls are vibrating. There is still a lot of bouncing, but most of themstay together.
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The article opens with saying only 25% of the fuel's energy gets used by the motor, 75% is in the heat of the exhaust. I'll take that as a given. Let's assume a small motor (in this inventions favour) with a nominal power of only 60 kW, running only at half tilt, 30 kW.
That gives us 90 kW in the exhaust heat by the numbers of the article. So the 56 W it captured in the simulation would be 0.046% of the total 120 kW power being converted by burning the fuel, raising the efficiency from 25% to 25.046%.
The headline is so massively overstated it's basically just a lie. If the device was built, not just simulated, and you'd manage to substitute part of the alternator's ouptut with the thermoelectic generator's output, the effect on fuel economy would be below the measurable level.
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Yeah, I do apologize - I'm somewhat simplifying my explanation because when you start going into the full detail, it just brings up more questions.
So yes, like the other comment says, the particles are constantly bouncing into other things.
- If they're bounded in by something - walls of a container, or even just more gas surrounding the specific sample you're looking at - they'll bump into that, and transfer some of their energy to that.
- If they don't have something to bump off of and the particles are free-floating, they'll take off in any given direction. If they only have something to bump off of in a limited number of directions, they'll take off in the other direction. (For instance, in a rocket engine, we make a lot of molecules really, really hot and then surround them with barriers in every direction except the one we want them to zoom out in.)
- In some cases, the molecules have electromagnetic bonds with each other, which take more energy to break than the energy contained in their "bouncing around". So they'll stay stuck, just bouncing off each other, even in a vacuum, (Or at least, until they radiate away their heat via electromagnetic energy... another whole story.)
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You are confusing me with other person. Read the names.
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Nothing to apologize for - thank you for elaborating.
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Oh damn
my bad. -
So in a solid, you can imagine each atom connected to each other by springs (bonds). They can vibrate on these springs. If they vibrate too much (by heating) then they can break the bonds and escape as a gas. Gasses basically have too much energy to bond again.
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The exhaust gases are at a high pressure after combustion due to combustion heat. The turbo does indeed increase exhaust pressure, and therefore extracts some work from the crank but it's extracting significantly more from the high pressure of the expanded hot gas. It's not "free" because it's energy that is usually just wasted in a naturally aspirated engine. There are many examples of engine configurations where a turbo is used to boost efficiency by reducing displacement.
There were systems on old aircraft engines which used exhaust power recovery turbines geared directly to the crank. Those wouldn't physically function under your concept.
The increase in manifold pressure doesn't just increase oxygen in the cylinder. It also increases the manifold pressure, or the total mass of gases. The increase of oxygen does allow for more fuel and total energy in the ignition event but the extra inert gas also expands when heated. So both play a factor in increasing mean effective pressure, and therefore energy output per cycle (power).
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If they only have something to bump off of in a limited number of directions, they’ll take off in the other direction. (For instance, in a rocket engine, we make a lot of molecules really, really hot and then surround them with barriers in every direction except the one we want them to zoom out in.)
I'm sorry, but this is also wrong too when related to your description of the heat requirement part.
We don't make a rocket engine hot to make it work. It becomes hot as a byproduct of what we really want which is liquid/solid fuel and oxygen in liquid/solid form, which take up very little space. We make them take up a LOT of space and by becoming high speed expanding gases. We aim these gases which take up a lot more space (and are moving very fast) out the back of the rocket in a desired redirection to take advantage of Newton's Third Law of Motion. The "hot" happens because its the fastest/easiest way to change the liquids/solids into a gas is by ignition/fire.
There's examples of engines/thrusters that are room temperature or even crazy cold that produce thrust to move a vehicle. There are toy rockets that work on pressurized room temperature water, 3rd law physics still applies here. There's also nitrogen thrusters which operate at -50°C. There are even ion thrusters that get as cold as -100°C.
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It's pretty much like billiards. They just bounce. Different chemicals (types of molecule) are different phases at different temperatures e.g. nitrogen is a gas at room temp, water is liquid. Stuff that's a gas at room temp just has less bonding forces (and often mass) than liquids or solids. So they don't take as much heat to go fast. There's a lot of heat even at room temp, and even at -40deg. The temperature for nitrogen to sit in one place is -210C or -346F.
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The turbo does indeed increase exhaust pressure, and therefore extracts some work from the crank but it’s extracting significantly more from the high pressure of the expanded hot gas.
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?
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OMG they’ve actually introduced the 2025 Turboencapulator.
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The exhaust gases get pushed
The "pushing" (exhaust stroke) isn't particularly relevant.
When the valves close at the beginning of the compression stroke, the pressure in the cylinder is atmospheric: zero psig. The valves don't open until the piston has risen (compression) and fallen (power) again. Without combustion, the pressure at the time the exhaust valves open is again at atmospheric. The gasses were compressed, and re-expanded.
With combustion, the pressure at the bottom of the stroke is substantially higher than atmospheric: the combustion event has radically increased the pressure of those gasses. At the end of the power stroke, just before the exhaust valves open, the pressure inside the cylinder is still extremely high.
It is the expansion of those gasses - not the "pushing" of those gasses - that drives the turbo.
I think it might be beneficial to think about the next evolution in aircraft propulsion. The turbocharger operates by expanding gasses through a power turbine, and using that energy to drive a compressor turbine. Remove the cylinders and pistons from the path, carefully tune those turbines, and you have a turbojet.
If the pistons are "pushing" the turbocharger, the turbojet would be impossible. It is the expansion of the gasses, not the displacement of the pistons, that drives the turbocharger.
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It being a diesel, it didn't need to fire sparks though.
That's cheating
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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.
