Car engine heat recovery

The Nipp

How much heat could one extract from an engine block after it stops running by continuing to pump coolant through it?

Since a lot of people have water based central heating around this part of the world and the heat is wanted when people get home from work would it be worth the trouble of connecting the central heating system to the car?

Mahatma coat

Interestin Concept.

Altho I dont think I'td be all that good for the engine to have it cool too rapidly too often, Maybe some of the smaller 1.0 - 2.0 engines could take it, but it'd have to be fair precise for something like the 4.2L I have in the Landcruiser, if you couldnt cool it evenly you run the risk of fatigue in the metal. and in fairness thats the Sort of engine y'd want to extract the heat from not some Hairdryer in a Micra.

Del2005

There's usually only a few litres of fluid in a cars cooling system and the engines mass can't hold much heat energy. The amount of heat you could get out wouldn't make that much difference to a domestic central heating system.

But what about doing it the other way? Use domestic heating water to pre-heat the car in the morning. That would raise the car's temp to ~20C and so reduce the need for people to sit in the car for several minutes to demist/defrost it. Would also get the cars oil/water closer to their optimal temp quicker using less fuel.

Capt'n Midnight

Heat capacity of metal is a lot lower than that of water, so you wouldn't heat a lot of water with it.

CJhaughey

Modern engines are so efficient that in some cases the cars own heating system is electrical rather than water based.
I don't think it would work well on modern vehicles.

Capt'n Midnight

Capt'n Midnight wrote: »

Heat capacity of metal is a lot lower than that of water, so you wouldn't heat a lot of water with it.

since water has the highest specific heat content it is perhaps the best way to store low grade heat, but you can imagine carrying all that extra water would not help fuel economy. I'm fairly sure that phase transfer doesn't retain as much heat energy, the main advantage of stuff like molten salt is that most of the heat energy is stored is released at a single temperature , the melting point.

Speaking of carrying water around a Harrier Jump Jets carries about 600Kg of water with them to cool the engines, it's only enough for 90 seconds if you are at max power. Sometimes crazy stuff works out.

Stuff that does work is putting turbines on the exhaust
You could have sterling engines running on the waste heat too

an alternative would be to insulate the engine bay and have clamshells - so you'd keep the heat in the engine - it does depend on climate and time of year.