[Terry Syd]

I've seen some discussion about using acetone in the water injection system as a surfactant for the water. In other words, it could be used to help decrease the surface tension to make the droplets smaller and help break them up. Has anybody any information on the use of a bit of acetone in a water/methanol blend?

I had thought that the alcohol itself would help break up the size of the droplets. However, there may be an additional effect i am not aware of. If so, then it might provide more surface area for cooling and less potential compressor wheel erosion in a pre-turbo application.

[dvldoc]

15% Methanol already does the same thing. Why run something that might ruin your pumps seals.

[Terry Syd]

OK, moving on from the idea of acetone, what about other surfactants such as washing machine rinse. Has any research been done to see if a couple of drops of such a surfactant would assist in breaking up a water/meth blend even further than it nomally would?

I've seen the chart on how methanol at different blend rates reduces the surface tension. Up to 10-15% methanol the change is fairly significant, however the effect begins to taper off fairly quick with higher blend rates. I'm wondering if the addition of a few drops of something like the washing machine rinse would reduce the surface tension even more, above and beyond what a 20% blend of methanol would do.

[dvldoc]

How many microns are you trying to get the water down to. If your already atomizing at 10 to 14 microns I don't think your going to see any real difference in performance but you can give it a try.

We really don't have the time to test it, Only our nozzle maker could really measure the difference in droplet size with their equipment but they for sure would not do it for free and probably not at all so the proof would be really up in the air.

Coming up with something accurate enough to prove the point would be hard to do. It's possible if you had a highly sensitive flow meter to measure the difference in flow or see what the pressure difference is on the same size nozzle on the same pump using the different mixes. but I'm just throwing things out there.

[Terry Syd]

It's an interesting concept, being able to add a few drops of an inexpensive off-the-shelf fluid that increases the atomisation of the water. It may not make a significant difference in my application with the M2 pre-turbo (and occasional additional M2 post-turbo), however someone running a higher rate of flow through larger nozzles might find a more significant benefit.

I'll have to try some testing, perhaps I might start with a litre of my 20% methanol blend and add some of the wetting agent and see how much it takes to make a visual change in the surface tension with the sides of a glass container. Then give it a go in the truck and see what effect it has, if any.

I'll get back with the results.

[Dust]

Devldoc, where are you getting the 10-14 microns from? Wouldn't decreased surface tension also marginally increase flow? I guess you could see if the surfactant increase the flow of water. May need dual m14 to get any real info.

[dvldoc]

Nozzle makers specs based on orifice size and psi you actually have to do a bit of math to get the numbers because they only give it in 100psi.

I think this might be some good reading for you




http://www.max-boost.co.uk/max-boost...acetension.pdf

They have been talking about this on one of the Diesel forums as well.

Just one members research.
Turbobuster

Justin,

You got me thinking (uh oh) so I went a researching. As it turns out, rinse aids are the wrong thing for this application (do the exact opposite.) They cause water to 'sheet out' by addition of copolymers, defoamers, and humectants. We don't want to promote sheeting. We want to promote fine atomization.

[Terry Syd]

Yes, I read that on the TDI forum. I wish people would give a link to their reference material when they start asserting something. I don't know whether the guy has his head screwed on tight or not.

I've looked at other research papers and there is a large body of evidence of surfactants reducing the droplet size. Further, the smaller the droplet, the more surface area for evaporation.

Perhaps he has found something in particular to these types of rinse agents, if so, I wish he would post it. Otherwise, he is stating something that is contrary to well established physics.

The surface tension acts like a balloon. A strong surface tension is like stronger rubber in a balloon. The stronger balloon rubber can hold more air inside the balloon, getting bigger and bigger until it finally bursts. Likewise, the stronger surface tension of the water droplet can hold more water inside that surface tension, thus creating a larger droplet.

If we decrease the surface tension, we will decrease the water droplet size. This phenomena is used is such things as pesticide sprays to get a finer droplet size.

Here's something else to consider, we notice from the chart above that as the methanol percentage decreases, the surface tension of the water molecule increases (and increases rapidly). Thus, as the methanol is boiled out of the droplets in the turbo and manifold, the water droplet surface tension increases. This would tend to slow down the evaporation of the water/meth. However, if there was a small amount of surfactant in the water, then the surface tension would not rise as quickly and perhaps allow a faster break-up and evaporation of the water/meth droplet.

Here is something I copied from another source:

"The thermal motion of a molecule of liquid must be sufficient to overcome the surface tension and evaporate, that is, its kinetic energy must exceed the work function of cohesion at the surface.

Evaporation therefore, proceeds more quickly at higher temperature, at higher flow rates between the gaseous and liquid phase and in liquids with lower surface tension."

[dvldoc]

Too much techno babble for me right now. Might research it further when I get some down time.

[Terry Syd]

Yeah, the theory is there, however it's just techno babble at this point. Maybe you can get one of the WI enthusiasts in the Phillipines to give it a try using the dyno. A back to back dyno run with the same juice, one without the rinse and one with, would quickly indicate if there was anything in the theory.

The higher humidity of the Phillipines would also provide a good testing environment as evaporation is more difficult with higher humidity. Those guys are keen on testing, I'm wondering when they will start rating the performance difference between Brandy and Vodka.

I might start using the rinse just for the color tint on the water/meth blend. I often have trouble seeing the level of fluid left in my reservoir. I could add it (or some other type of dye) to my methanol and then it would be easy to use when blending.