Direct Spray Liquid Cooling Systems in IC Engines

At first I was all for your concept.

Then I casually said to myself, "Self, where ya gonna get the water?" Assuming that it takes 5 gallons of water vaporization to remove the heat of 1 gallon of gas, we have a logistics problem.

A closed system puts us back to square one.

Other fluids are out of the question, I believe, due to environmental constraints.

Good luck.

"At first I was all for your concept..."

Thanks! Some ideas can seem good until some bright spark points out the blindingly obvious! For an amateur I'm always glad to know I'm not also naive!

Reading further down the thread the implication seems to be that fitting-in a large condenser could cause the most headaches.

Interesting idea. This chart looks about right, but the third item might be subdivided into fluid cooling without boiling (e.g., standard car radiator) versus with boiling (ebullient cooling, which is less familiar but is sometimes used.)

In either of these cases, the cooling water jacket surrounding the cylinder walls needs to be only a bit larger than the cylinder. On the other hand, a spray chamber would have to be fairly large in order to develop the spray pattern of whatever nozzles. Any clogged nozzles would result in localized hot spots in the cylinder wall.

The water evaporated could be condensed and recycled in a closed system.

Clogged nozzles are an issue, certainly! It would mean almost instantaneous shut-down of the engine with a single blockage. Using distilled water would be a necessity to avoid this and maintenance cycle would likely increase in frequency.

The size and weight of a phase change cooling system would be much less than the current systems. It would be similar to a freon refrigeration unit, except for the working fluid which could be water.

I wonder how glycol antifreeze would work with the higher temperature of the cooled surface.

There would be environmental advantages to having less coolant in the vehicle.

There could also be energy savings from the water pump moving smaller volumes.

I had considered the antifreeze issue.

I would suggest the system would benefit from an automated drain-drown procedure once the temperature dropped too low. This would also occur if the battery was low on charge as a precaution.

The external reservoir would be designed to withstand freezing pressures and as you remark the volume to be held would be considerably less.

Hi,

this system is intensively evaluated by some of the better car manufacturers and others.

The distance between spray-nozzles and outer wall need only be some few mm.

The pressure for an efficient spray has to be minimum 2 bar.

The freedom from rust and dirt will be a major issue.

Evaporating mixtures as water plus glycol for freezing protection is a problem as either a separation will occur or an azeotropic concentration will be needed: both evaporating at the same ratio. Or at the walls there will be more of one constituent than in the spray.

The condenser that is necessary for closed loop operation will need a lot of volume as it has to handle 60KW in a 90 KW motor.

So concluding: fascinating but not likely to come.

RHABE

http://en.wikipedia.org/wiki/Six-stroke_engine

"Suck, squeeze, bang, blow, squirt, chuff"?

Yes, I've been aware of Mr Crower's idea for sometime, but think it will always be hampered by water contamination issues.

In all the years of car development I would be surprised if not one single manufacturer had not looked at this (as you imply they have Rhabe). Before posting I did spend a short time searching online for examples or patents but turned up nought. I would be very interested if anyone can recommend where I might be able to get a more detailed picture of why this idea is not seen. I would have thought it might have been applied in lightweight marine applications.

I think it's a great idea. Why not consider extracting the latent heat of vaporization from the cooling fluid to do something useful, like driving a steam engine?

Oh the irony!

I just wrote the post below just before reading your's! Great minds, eh!

I suspect a brief study of thermodynamic principles will resolve this matter. Of course the idea will work, but it is doubtful that enough power can be extracted from it to make it worthwhile. The recovered heat would be a good source of heat for passenger comfort, but not much else.

That's true you could guarantee almost instantaneous cabin 'heat' no matter how cold the weather!

Here's a thought from left-field:

Would the vaporised water have anything like enough inertia to extract work (ie. in a tiny steam turbine, etc) ?

There would certainly be enough energy in the vapor to drive a turbine. The question would be whether it could do enough work to justify the cost of the extra mechanism. Rather than adding extra parts, I can see this eliminating parts. You probably wouldn't need a circulating pump. Propane powered refrigerators - an ammonia cycle - didn't use a pump. You would still need a pump to spray the cooling fluid. The newer vehicles are going to 42V flywheel alternator/starters. This higher voltage would allow the use of an inexpensive vaporizing pump.

This concept will also allow some flexibility in working fluid. Circulating something more benign than water will reduce the problem of contamination plugging the spray jets. Ammonia? Alcohol? Propane? The smaller volume makes this a possibility.