Heat transfer.

[fraggie]

Most people use water to transfer heat from an engine to a water storage tank. Would oil be better? if so what type ?

[Tony]

Unfortunately oil for the same volume carries a third of water's thermal capacity (not only is it less dense, but its specific heat capacity is less).

[dgs]

Thats hard to believe Tony, but I will take your word for it.

Any ideas on the thermal capacity of glycerol. I boiled some up the other day 290degs or so and it took ages to cool, kept throwing a little water into it and it kept frothing up. Did a good job of killing the grass around the vessel.

Just looked it up and surisingly glycerol is a lot less than water. The only liquid on the list that is considerably more than water is concentrated ammonia (880 ammonia)

[knighty]

yeah, water is about the best when it comes to liquids heat transfer


if you're going to use it for that, add some antifreeze to it (whatever type)it increases the boiling temperature so you can go a bit hotter, inhibits corrosion and decreases surface tension (so heat transfer to a solid surface is better)

[photoman290]

antifreeze, that's good to know. a bit more user friendly than ammonia,and cheaper. be useful for solar thermal as well.

[Julian]

Methanol used to be used as antifreeze until the health and safety police got involved.  I think it's still used in the US.

The way we buy it, it's way cheaper than commercial antifreeze, but won't have the corrosion inhibitors.

[1958steveflying]

This is far better.   

http://www.evanscoolants.co.uk/

[photoman290]

This is far better.   

http://www.evanscoolants.co.uk/

sounds very useful for those  engines prone to overheating and blown head gaskets. i used to
have a couple of rear engine skoda 136.s that would have m benefited.

[Tony]

Thats hard to believe Tony, but I will take your word for it.

It's actually closer to 2.5 in all fairness - there's a little calculator here:

http://www.biopowered.co.uk/forum/tools/heating.php

It's set up for rapeseed but if you put in the specific heat capacity of water (4.2 joules per gram per kelvin) and density of 1.0 you can see the energy cost difference.

I had a google for glycerol, the SHC seems to be ~2.43 but I'm not clear on the density (though I do know a 20l cubie of glyc is surprisingly heavy!)

[Keef]

This is far better.   

http://www.evanscoolants.co.uk/

Have you seen the price of that stuff?

I saw it used on a TV prog and it was nearly £100 to do a car!

[oakwoodtv]

This is far better.   

http://www.evanscoolants.co.uk/

Have you seen the price of that stuff?

I saw it used on a TV prog and it was nearly £100 to do a car!


It was on wheeler dealer the show that buys cars cheep and sells for a profit but ignores the cost of one hundred hours of labour.   

[Julian]

This is far better.   

http://www.evanscoolants.co.uk/

Have you seen the price of that stuff?

I saw it used on a TV prog and it was nearly £100 to do a car!

That's more than my car's worth!

[1958steveflying]

Yep not cheap, I used it in a Clio 172 that I used to use on track days and we use it in our 2 stroke race bikes, It is brilliant stuff.

[julesandtash]

That Wheeler Dealers episode was when they put it in a Daraq - an ancient car that they were taking on the London to Brighton Rally. Bearing in mind the car was probably worth more than my house, it was probably a wise investment
To replace water based coolant with waterless, you also first have to use a flushing liquid that absorbs the last traces of water, then drain that, then add the waterless so even more expense

[photoman290]

i think it depends on what can go wrong if your engine overheats. head skim and gasket set at the minimum.plus the time and tools to do it. 100 quid  seems cheap in comparison.but as  someone  pointed out people forget the cooling system till it goes wrong. even a  worn water pump could cause overheating. the lack of pressure seems the most useful thing. at least it means you could get home,or off the road at least and sort it without  risking a blown head gasket.