Evaporative Cooling

[langwadt]

in principle evaporative cooling requires far less coolant (due to the large latent heat)
so would be relatively valuable with water coolant and unpressurised (as envisaged by RR pre WW2)
but then higher BP coolant and pressurisation allowed somewhat less coolant and smaller radiators anyway

current F1 limits cooling system pressure but not temperature as such ?
maybe these engines can stand a high coolant temperature

it's a lot simpler and more accurate to put a pressure relief valve on the cooling system than trying to limit temperature
and I'd assume they all use water so the pressure limit is also a temperature limit

I don't see how evaporative cooling could gain anything unless it was a total loss system, a closed loop system like in an refrigerator just moves heat from one place to another so you still need similar size radiators and use power to drive a compressor

[andylaurence]

If we want to make use of all that heat in the radiators, how about a Stirling Engine ERS?

[.poz]

I don't see how evaporative cooling could gain anything unless it was a total loss system, a closed loop system like in an refrigerator just moves heat from one place to another so you still need similar size radiators and use power to drive a compressor

Like the heat pipes used in electronic you can just put some liquid with an high vaporization latent heat in a pipe with low pressure to lower the boiling point

[langwadt]

I don't see how evaporative cooling could gain anything unless it was a total loss system, a closed loop system like in an refrigerator just moves heat from one place to another so you still need similar size radiators and use power to drive a compressor

Like the heat pipes used in electronic you can just put some liquid with an high vaporization latent heat in a pipe with low pressure to lower the boiling point

still it just moves heat from one place to another it doesn't magically make it disappear so you will still need the same
radiators, and you don't want lower boiling pressure the lower the temperature the bigger the radiators you need to get
rid of the heat and you get lower efficiency

[olefud]

in principle evaporative cooling requires far less coolant (due to the large latent heat)
so would be relatively valuable with water coolant and unpressurised (as envisaged by RR pre WW2)
but then higher BP coolant and pressurisation allowed somewhat less coolant and smaller radiators anyway

current F1 limits cooling system pressure but not temperature as such ?
maybe these engines can stand a high coolant temperature

it's a lot simpler and more accurate to put a pressure relief valve on the cooling system than trying to limit temperature
and I'd assume they all use water so the pressure limit is also a temperature limit

I don't see how evaporative cooling could gain anything unless it was a total loss system, a closed loop system like in an refrigerator just moves heat from one place to another so you still need similar size radiators and use power to drive a compressor

Evaporative cooling has the advantage of transferring heat with less coolant, i.e. less weight. A gram of steam will, upon condensing at the heat rejection means, transfer a much greater quantity of heat than a gram of liquid water cooled some ΔT at such means. Of course the greater ΔT for steam also helps.

[langwadt]

in principle evaporative cooling requires far less coolant (due to the large latent heat)
so would be relatively valuable with water coolant and unpressurised (as envisaged by RR pre WW2)
but then higher BP coolant and pressurisation allowed somewhat less coolant and smaller radiators anyway

current F1 limits cooling system pressure but not temperature as such ?
maybe these engines can stand a high coolant temperature

it's a lot simpler and more accurate to put a pressure relief valve on the cooling system than trying to limit temperature
and I'd assume they all use water so the pressure limit is also a temperature limit

I don't see how evaporative cooling could gain anything unless it was a total loss system, a closed loop system like in an refrigerator just moves heat from one place to another so you still need similar size radiators and use power to drive a compressor

Evaporative cooling has the advantage of transferring heat with less coolant, i.e. less weight. A gram of steam will, upon condensing at the heat rejection means, transfer a much greater quantity of heat than a gram of liquid water cooled some ΔT at such means. Of course the greater ΔT for steam also helps.

the old V8s had about 4 liters of coolant for the entire system, not a whole lot to gain
water increases about 1700 times in volume when it turns to steam so you will have to move a whole lot of volume

[Lycoming]

4L of water is 4 kg, I'd say that's significant.

[langwadt]

4L of water is 4 kg, I'd say that's significant.

if you could remove 4kg yes, but you can't, you still need some coolant and you need much bigger pipes to move it around
as steam

what I've seen on the old V8s were; 4 liter coolant, ~125'C in ~135'C out, 270l/min

it takes ~55 time more energy to make water to steam than to heat it 10'C but the volume increases 600 times (at 3bar)
so you have 600/55 = ~11 times the volume, so 270*11 = 2945 l/min coming out of the engine

[olefud]

I didn’t mean to say evaporative cooling was the hot setup, but it can transfer a good bit of heat energy. Where it fails is the air to water vapor heat transfer that requires way to much radiator –that’s why it was tried with large surface cooling in aircraft. Mostly during the thirties the aircraft people did a lot of work in this area. Straight ethylene glycol was tried since it had a high boiling point. But it was rather oleophilic and, at high engine temperatures, tended to leak. RR went to a pressurized water system with enough ethylene glycol to prevent freezing about the time the Spitfire was coming together and that’s still what we use with lubricants rather than ethylene glycol when freezing isn’t a problem.
But just in terms of a heat transfer medium water to steam to water will move a lot of energy,

[Dragonfly]

I think that we are missing a very significant point - what is being cooled. In an ICE if the evaporative heat transfer flow stalls for whatever reason just a fraction of a second, especially in the combustion chamber zone, you have the engine cooked. And with the complex geometry of the surfaces to be cooled I think it will be a very difficult task. Evaporative cooling is based on the principle that the evaporated fluid/agent is immediately replaced by returning liquified amount. And they usually work at pressure lower than atmospheric. I don't say it is impossible but it will require additional means for circulating the vapor to the exchangers and pumping back the liquified agent to the various zones of the engine, possibly adding weight and nullifying the overall gain.
A liquid in a well organized flow, while not transferring heat as fast as the evaporative method, will prevent a momentary critical rise of temperature in the hottest zones. A kind of thermal buffer IMO.

[autogyro]

Heat is wasted energy in this context.
Such a pity the regulations do not allow an evaporative cooling system that drives a generator.

[Tommy Cookers]

maybe this is covered within a suite of patents, eg BMW not unrelated to the Turbosteamer ?
so Mercedes didn't fancy it

though non-evaporative cooling might be viable for Rankine or Stirling etc compounding with relatively high coolant temperatures
these compounding cycles would surely make integrated use of coolant heat and exhaust heat
compounding the compounding

[trinidefender]

But when you turn water to steam, you're not "using up" the energy because it still remains in the system. When you condense the steam back to water as you will inevitably need to do for a closed cycle system, all that heat you "used up" comes back into play. So I don't get how you can use smaller heat exchangers, because the power you need to dissipate doesn't change and as far as I can tell, the efficiency of dissipation into the free stream has in no way improved.

Yes a condenser is needed however due to design the condenser can be much smaller than today's radiators and requiring less airflow therefore allowing for smaller entrance and exit cooling ducts.

For whoever down voted this take a look at olefud's post.

[CBeck113]

Here's some Information from Sapphire Technology, a graphic card maker and afaik the first to implement vapor cooling:

http://www.sapphiretech.com/VaporX/VaporX_paper.html

The major issue, as as always with cooling solutions, is the heat and the necessaary surface area - a graphic card has a typical surface area on the chip of ~400mm^2 and thermal Dissipation of ~230W, and need a cooler with 84 fins (surface area of each fin is about 2,000mm^2) making 168,000mm^2 necessary for 230W. Scaling that up to an F1 engine would mean ~700,000W * 60% heat loss (40% Efficiency, THIS IS AN ESTIMATE, NO DISCUSSIONS ABOUT "MERCEDES HAS MORE" WILL BE ACCEPTED!!!) makes 420000W, and therefore 306,800,000mm^2 would be necessary. That sounds high, so let's say our radiator fins are 500mm x 200mm (200,000mm^2 of surface area), 1534 fins would be necessary, and each would need a gap to insure air flow...maybe if the entire floor is used, and the air could be drawn from the ground (fan cars anyone?), it could possibly work .
I'm sure that the technology could be modified for vast improvements (increased pressure, other fluids & materials, etc.) but many avenues are restricted , so this could end up a dead end...sadly.
The greatest advantage of this system is that it requires no help to work, it starts and runs on thermodynamics =D>. Forced air flow is necessary, however, so it isn't completely free.

[olefud]

Somewhat regarding evaporative cooling, many years ago I had a discussion with Cray computer people about the problems they were having with the heat from emitter coupled logic. More or less factiously I suggested immersing the whole thing in a vapor degreaser that at that time used trichlor solvent. I can’t say that this led to their use of Freon to immerse the whole computer, but I’ve wondered a bit.