How to use TEGs to create power with your coolant heat

[California98Civic]

Of course, put that many TEGs on the cooling system and you are turning so much coolant heat into electricity that the cooling effect on the engine could adversely effect fuel economy by keeping the engine quite a bit colder than desgined. You'd need to adapt the radiator size, too, I think. More cost. Better to stick to exhaust waste heat.

[oil pan 4]

To make 1kw you would need 3,412 BTUs if 100% efficient. So maybe 25% efficient so 13k BTUs.
If I remember correctly they aren't really efficient.
I think 100w is more realistic so you would only lose 1.3k BTUs. Which is a fraction of the heat you lose using the heater with the windows and the system on recirculation.

Plus if you build your teg unit up front and pipe the coolant to the unit you could control coolant flow with a valve and not open the valve till the engine warmed up.

[Daox]

Yeah, TEG efficiency is pretty horrific actually. Wikipedia says:

https://en.wikipedia.org/wiki/Thermo...tor#Efficiency

The typical efficiency of TEGs is around 5–8%.

[teoman]

But in combustion engines it is basically free energy

[teoman]

How durable are they ?

What would be roi? Or do they fail before roi?

[RedDevil]

FWIW, it's been done before, and researched.
https://link.springer.com/article/10...664-011-1580-6

We proposed and fabricated a thermoelectric generator (TEG) using the engine water coolant of passenger vehicles. The experimental results revealed that the maximum output power from the proposed thermoelectric generator was ~75 W, the calculated thermoelectric module efficiency of the TEG was ~2.1%, and the overall efficiency of electric power generation from the waste heat of the engine coolant was ~0.3% in the driving mode at 80 km/h. The conventional radiator can thus be replaced by the proposed TEG without additional devices or redesign of the engine water cooling system of the existing radiator.

I bet they meant 'alternator'. But 75 Watt ain't enough.

But one could simply buy a liquid to liquid type generator: https://thermonamic.en.alibaba.com/p...EG600_48V.html
600 Watt, that's more like it. 48 Volt, ah well that needs a buck converter.

Pity it weighs 75 kilograms. No free lunch :/

[ThermionicScott]

Originally Posted by oil pan 4

Use solar panel and teg to do an alt delete.
Use teg so the battery doesn't drain as fast while driving.
Then solar panels can replenish the battery during the day.
The teg would also continue to make some power after the car is turned off.

But if you have an electric vehicle you don't have to worry about any of that.

Put a switch on it, and you could have a control-alt-delete!

[IamIan]

If an ICE throws away around ~70% of fuel energy .. Just ~8% of that ~70% would be about ~5% of total original fuel energy .. such a ~35% ICE+TEG combination is a ~16% increase over such a ~30% ICE alone .. Such a ~16% increase to a ~50MPG driver would mean ~58MPG , same ~16% increase to a ~80MPG driver would mean ~92MPG, etc .. Although I myself suspect around ~10% increase over ICE alone is probably a more reasonable/realistic limit of DIY feasible for such waste heat recovery.

[oil pan 4]

Let's say this is for a liquid cooled stationary backup generator and size, weight aren't really a problem.

Also a MPPT charge controller might be a good idea, since the delta T power curve looks kind of like what you get out of solar panels at different light and weather conditions.

With an mppt controller you could get any where from 120% to 200% or more the power compared to just wiring them straight to a battery. Also you won't have to worry about over charging the batt.

Any idea how long thy last?

[teknomage2012]

Wow
I use TEG's similarly, but on my home furnace to get 50 free miles per day for milk and eggs runs!