are there any practical things we can do with hot radiator water ?

[Bicycle Bob]

Efficiency in heat engines is limited by the Carnot principle. (no pun intended) The greater the difference in temperature between the extremes in the system, the higher the percentage of the energy that can be extracted from the heat. So, even though most of the energy in gasoline winds up as waste heat, it is so degraded that further recovery is inefficient. A low-pressure steam engine, in turn, is bulky, and either quite intricate or high-maintenance. Steam-cleaned cylinders are hard to keep oiled and rust-free.

The best turbo-compound engine got up to 45% efficiency, trying to cool the exhaust but turbocharged ship diesels are getting over 50%, mostly by raising the peak temperature.

[modmonster]

the problems i forsee would be:

seals in the pump
general plumbing headaches
voltage/RPM matching in the generator
controlling it all
connection to the radiator


but i think its a lot less complicated than making an mpguino, which this forum has done already.

i could probably knock up a prototype in a weekend.

[modmonster]

i have no idea what you could get out of this type of mod but i think that 200w could be an achievable goal from waste heat that probably amounts to several killawatts. you would only need about 5% steam engine efficiency to replace the alternator. it might be really easy to do!

[Daox]

Well, go for it then! Any testing will give us a better idea of how we can capture more waste energy. Just be careful, we are still talking about a lot of power here.

[ConnClark]

I think an alternator puts out far more than 200W. 200W/12V = 16.6 Amps

[rmay635703]

Originally Posted by ConnClark

I think an alternator puts out far more than 200W. 200W/12V = 16.6 Amps

My subaru 360 has a 200watt motor generator.

I would guess most people could get buy daytime driving with 200watts on an older vehicle, if they ran non-modded lights, AC, heat or anything else they would probably have to charge the battery when they get home.

FYI Most alternators are around 60 amp

[ConnClark]

Its probably easier and cheaper to try and harvest energy from the shock absorbers like these MIT guys did.

Cars: MIT Shock Absorbers Harness Speed Bump Energy For Better Fuel Economy

[modmonster]

so the theoretical maximum carnot efficiency is = 1 - cold temperature/hot temperature
therefore if we assume hot coolant is at 90*C (363K) and cold radiator is at 40*C (313K).

= the max thermal efficiency is 14%.

[modmonster]

if my mod reduces cooling efficiency in the radiator or heat exchanger then this will have a negative effect on main engine efficiency. is this right? what is taken as the cold reservoir when doing the thermal efficiency calculation for the ICE?

[modmonster]

back to the thermos of hot coolant idea -does extra water in the system add to pumping losses? i remember it says somewhere on here to fill oil to minimum dipstick to reduce pumping losses.