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.
synapse1278@lemmy.world 1 week ago
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Basically, slap Peltier modules on the exhaust pipe. This ain’t gonna do much. We can invent a thousand applications for Peltier modules, until there is a massive technology breakthrough in terms of semi-condutor materials, it’s kinda pointless.
Reusing heat energy from exhaust is what turbos are doing for 120 years now.
Telorand@reddthat.com 1 week ago
I thought turbos converted air (exhaust) kinetic energy into mechanical energy, not the heat itself. If exhaust was cold, the turbo would still work, no?
Not saying that these Peltier devices are going to be game changers, but it sounds like they do something different from turbos in that they are capturing additional wasted energy.
Zonetrooper@lemmy.world 1 week ago
Yes, and no. Heat and kinetic energy are fundamentally all just energy. What we call heat is, technically, the kinetic energy of molecules vibrating around.
When exhaust gas passes through a turbocharger, it is both slowed and reduced in pressure, resulting in it being slightly cooler than when it entered. This device is using a different method of getting energy out of the exhaust gas, but it’s fundamentally still the kinetic energy of those very energetic exhaust gas molecules bouncing against one side of the thermoelectric generator and giving up their energy into it. I would still expect the exhaust gas to come out of it slightly cooler and slower.
herrvogel@lemmy.world 6 days ago
This concept isn’t new either. Factories have been using very similar methods to use the heat of the exhaust gasses to power the sensors and whatnot on top of their smoke stacks for some time now, for example.