What coolant/water ratio gives the best cooling?

[Jeremy]

An odd question to ask in the middle of winter, perhaps, but this isn't for an automotive application though it does have automotive applications.

A 50/50 antifreeze/coolant ratio is the standard, it gives a good compromise between reduced freezing point and cooling. The stuff is call "antifreeze" for a reason. The reduced freezing maxes out around 60/40 to 70/30 coolant/water and then rises from there. Pure glycol has a freezing point around -8 F, it's really only effective in solution with water. I can find references to this sort of thing.

What I can't find is what effect different coolant/water mixtures have on the coolant's ability to dissipate heat. This apparently diminishes as the ratio rises due to the fact that glycols have a lower specific heat than water. However, glycols also act as a surfactant which increases their heat transfer ability. Think of water wetter type products.

Reading some small airplane engine information, it seems people have realized some significant operating temperature reductions by changing their coolant mixture from 50/50 to 20/80 or 25/75. I've tried to find more information this, but have not been successful. If the goal is maximum heat dissipation while still retaining corrosion protection (ignoring freezing/boiling point concerns), what coolant ratio would be best?

Jeremy

[Scottinva]

The more water in the ratio, the better the cooling properties. Here in Virginia where I live the weather is warm enough you can run straight water. This is not suggested, obviously; However a ratio like 20/80 would have a better cooling ability than a 50/50. The best ratio would be just enough coolant to stop any corrosion, and the rest to be water. I'm not 100% on this, just my educated quess.

[bobaab]

I think it should depend on the liquid's specific heat. Water has a rather "high" specific heat, which means it takes more energy to change the temperature. Although this property can hold more heat, it doesn't gain nor lose heat as quickly as a liquid with a lower specific heat.

So my understanding with this is that a liquid of lower specific heat will be a better coolant. It can change temperatures quickly (ie, take heat/energy from engine block) and more quickly dissipate it through the radiator.

I forgot to add. The specific heat is also the capacity of the liquid to hold energy. From reading a little bit, antifreeze (some form of glycol) has a significantly less specific heat than water. This also means that you need to make a lot more of antifreeze to flow through the engine to get a similar cooling effect.

In your case, running water should be your best bet like said above!

[paul burke]

Water/soluble oil mix. Absolutely the best heat transferring non corrosive blend I have used. Mind you this blend will still freeze as plain water does but is an excellent summer alternative.

Paul

[redstu]

http://www.engineeringtoolbox.com/ethyl ... d_146.html


Eveverything you asked for and more!

[Coldswede]

I believe "Water Wetter" is a commercial form of what Paul is referring to ( I didn't read the link, I'n using the phone so...)

[Jeremy]

Water/soluble oil mix. Absolutely the best heat transferring non corrosive blend I have used. Mind you this blend will still freeze as plain water does but is an excellent summer alternative.

Paul

Paul, what exactly would this soluble oil mix be? Any specific products you like/prefer? This application will be indoors at all times, no worries about freezing. My primary concerns are heat transfer and anti-corrosive properties.

Jeremy

[redstu]

http://www.arrowheadradiator.com/14_rul ... obiles.htm

I found this as well, intersting.

[jmc1590]

We used to use water / soluble oil all the time when machining (end mill.) It does a great job at reducing the heat buildup on cutting tools.

[Brad D.]

Distilled water and Water Wetter (or equivalent) would provide the best cooling. The soluble oil helps reduce the surface tension of the water and reduces nucleate boiling pockets on the internal surfaces of the head.

[paul burke]

We used to use water / soluble oil all the time when machining (end mill.) It does a great job at reducing the heat buildup on cutting tools.

That's the stuff.

What Brad said also applies.

You can use Water Wetter. I believe Redline still makes It. I prefer to use real machinist water soluble oil, It has proven itself (to me anyway) to be more affective than the synthetic stuff. You can get it at machinery tool supply companies and NAPA stores still carry It. I usually mix it about one ounce per gallon.

It is dark brown in color, with the consistency of 40w motor oil.

Paul

[Jeremy]

Water Wetter also advertises that it provides corrosion protection, would soluble oil do the same? I can't find product information on it anywhere.

Jeremy

[Coldswede]

Well, I do know the metal chips that fall into the water trough on a metal cutting bandsaw never rust in the oil/water solution.

[lawtemple]

The metal chips that fall into the water trough on a metal cutting bandsaw aren't exposed to 195 degree water, day after day, so those chips' experience may not tell the whole story. Hot water is, to quote Tom Clancy, murderously corrosive.

FWIW, I've run distilled water and Water Wetter in warm months here in the Midwest USA for three years. I take WW at its word as to anti-corrosion properties. This seems to provide the most effective cooling yet and I have no corrosion problems so far.

[bobaab]

Can anyone comment on part water, part coolant, part water wetter for an ultimate four-seasons coolant?

[Brad D.]

My thought is if you want year round service with freeze protection, add only enough antifreeze to achieve your desired freeze point by using a hydrometer. Any more than necessary and you are reducing the systems effectiveness. Adding any type of soluble oil (they all do the same thing by means of a reduction in surface tension) will help with or without antifreeze in the system.

[Coldswede]

As a small aside here. I wonder what the effect would be if you ran distilled water and a water soluble oil/water wetter on the galvanic effects between an Iron block and aluminum head? Would the oil prevent corrosion? would better grounds help? maybe some black magic?

Also, one of the main things radiator cleaners do is remove the black goop caused by various chemical reactions in the cooling system, which are largely caused by the anti-freeze solution reacting with combustion and oil by products (apparently head gaskets never quite seal 100% 99.99 maybe but not 100%.

Also there are water replacers for sale for like $2.00 a gallon I think the name is Freezone or something. any thoughts on this stuff?

[Mike W.]

Not a pure answer, but more comments. While not practical, water is best for heat transfer. I've tried Water Wetter and at least in the real world, couldn't tell the difference. Maybe in the lab, I don't know. The less anti freeze the better, cooling wise, and back in the 70's BMW used to spec either 1/3 or 30% antifreeze, I forget which, but they're about the same. And don't even think about the proplyene/glycol, low toxicity antifreeze, I've tried it, it seemed somewhat effective and one of the manufacturers confirmed the same to me when I inquired.

Water Wetter aside, there are corrosion resistant additives that can be added, in heavy trucks, often there are coolant filters which are changed rather than a system drain and flush, and tests run to monitor the inhibitor levels, to which some is added if it's too low.

[Bimmerguy2002]

I tried to get water wet once, it didnt turn out to well


I use 25% antifreeze

[tn535i]

Water Wetter aside, there are corrosion resistant additives that can be added, in heavy trucks, often there are coolant filters which are changed rather than a system drain and flush, and tests run to monitor the inhibitor levels, to which some is added if it's too low.

Pardon the company reference but this is who I work for and our website for these kinds of products for diesel.
http://www.cumminsfiltration.com/en/pro ... _sys.shtml

Well we make and market these but diesel trucks in heavy duty service have their own unique needs for protection from cavitation corrosion due to compression ignition and high combustion chamber pressures . It's an interesting topic and a friend of mine(at work) is one of the top authorities on the subject. We've talked many times on the subject.

In a nutshell I think he would say for your car...
The old inorganic systems protected better and were less sensitive to water quality but maybe did not last as long. Moot because we can hardly find them anymore.
The new OAT(Organic Acid) requires higher treat levels(chemical in the glycol) to get the corrosion protection and distilled water is highly recommended and why there is soo much pre-mix now. OAT is also more expensive and the high treat levels makes that even more true.
OK to lower the glycol concentration if the freeze protection is still OK but not below about 1/3.
The coolant is already formulated with defoamers and surfactants, you probably don't need anything added.

Please don't consider this a professional opinion although I'd guess it fundamentally agrees with everything the coolant makers say. It's what I do anyway.

[Jeremy]

OK to lower the glycol concentration if the freeze protection is still OK but not below about 1/3.

That's the kind of information I was looking for! I knew there had to be a happy medium between corrosion protection and heat transfer at some point on the curve. Would you mind confirming if this is the minimum he would recomend for all situations, or if that's specifically for diesel and/or gas motors? As I said earlier, my original reasons for asking this are non-automotive related.

Thanks

Jeremy