why does water/alky work ?

[vortecfiero]

Understanding that energy is neither created or destroyed.. just merely converted from one state to another...

How the heck does water/alky injection work ?
Where does the heat go ? In conventional intercooling A/A or A/W the heat is removed and released else where. With water/alky it is not removed.. perhaps it is converted to ??

or is it a matter of replacing oxygen density that has been removed by compressing the air ?

Inquiring minds need to know lol

 

[AlaskaTy]

Re: why does water/alky work ?

Understanding that energy is neither created or destroyed.. just merely converted from one state to another...

How the heck does water/alky injection work ?
Where does the heat go ? In conventional intercooling A/A or A/W the heat is removed and released else where. With water/alky it is not removed.. perhaps it is converted to ??

or is it a matter of replacing oxygen density that has been removed by compressing the air ?

Inquiring minds need to know lol

"we've known about magic for some time now..."

 

[Ian Turgeon]

Re: why does water/alky work ?

I believe its a result of the alcohol/water being converted into gas, it absorbs heat in the process. Kind of similar to how AC refrigerant works.

Of course theres also the effects of the alcohol as a fuel.

 

[dgoodhue]

Re: why does water/alky work ?

I believe its a result of the alcohol/water being converted into gas, it absorbs heat in the process. Kind of similar to how AC refrigerant works.

Not quite right with an AC analogy, because the condensor get quite hot.

Water has a high ability to absorb heat. When water is injected into the intake its usually cooler than the intakes air temperature already. Because of the high absorbtion properties of water, It also absorbs the heat with out reasing its own temperature as much.

It helps if you have an intercooler already, it would be much hard to get near ambient temperature without an intercooler.

Propane while coming out much much cooler than water, has little ability to absorb heat so it negliblity cools the intake charge.

 

[sytyguy]

Re: why does water/alky work ?

Entropy (from the 2nd Law of Thermodynamics) in that when a state change occurs, some energy is lost as heat. Water/alky/meth are all quite good at heat absorption, thus carrying the heat inward, away from the bulk of the air charge.

I am, by no means, a scientist, however.

Hood

 

[Ian Turgeon]

Re: why does water/alky work ?

Yea... its a little weak, but if you focus on only one side of the equation ( where the condensed freon expands and absorbs heat from the air) its quite similar.

But Im with Hood on this one, I'm gonna shut up before I have to shove my foot in my face.

Not quite right with an AC analogy, because the condensor get quite hot.

Water has a high ability to absorb heat. When water is injected into the intake its usually cooler than the intakes air temperature already. Because of the high absorbtion properties of water, It also absorbs the heat with out reasing its own temperature as much.

It helps if you have an intercooler already, it would be much hard to get near ambient temperature without an intercooler.

Propane while coming out much much cooler than water, has little ability to absorb heat so it negliblity cools the intake charge.

 

[Don W.]

Re: why does water/alky work ?

The condenser side of the AC is the "wrong" side of the equation here. It's the evaporator side that equates to this question. Just FYI, you can look at the heat in the condenser as the heat that -was- inside your cab.

Anyway, when water/meth turn from liquid to a vapor heat is required. The only place to get that heat is from the intake air charge so it is cooled.

 

[Teeleton]

Re: why does water/alky work ?

Well, you're almost right.

The air intake charge is somewhere in the 140*-180* degree range, and the water/alky that you're injecting is in the 60*-90* range depending on where you are, so the intake charge cools off, and the water/alky heats up and the net result is that the net temp of your intake charge (water included) is somewhere in the middle. Now, alky increases the octane of the intake charge, and water vapor raises the temperature at which fuel can flash over, so both inhibit knock in their own way.

There is no cooling by way of state change, because the water vapor is stable as a liquid at all temperatures involved. If you're getting above 212* where the water vapor turns to a gas, then you can talk state change.

Nitrous, however, is not stable at normal root temperature as a liquid, and converts immediately to gas when it's released from it's pressureized tank. The heat that is removed from this state change came from the force that the tank was exerting on the liquid to keep it in its liquid state.

Teeleton

 

[LandryPoole]

Re: why does water/alky work ?

One other thing to add, is that a given volume of gas at a certain temp puts off a given psi. When introduced to a cooling agent, that same air volume cools, and the pressure is reduced, therby allowing more volume of air to enter the same space at the same psi, back to the same temp. In other words, it isn't so much the temp drop, but that you can introduce more volume of air into the chambers because of the cooling affects of the meth/water inject. The last guy explained the high temp air compared to lower temp injection medium pretty well, so I'll leave it at that.

 

[Don W.]

Re: why does water/alky work ?

I would agree, and stand semi-corrected. Would it be more correct to say that water tends to help more in the combustion chamber, changing state there, having arrived, mostly, as droplets? I would tend to disagree with "There is no cooling by way of state change" but that's starting to split hairs. Not sure of the vapor pressure of meth so can't swear as to how it arrives into the cyl but I suspect it is mostly vapor by then. Anyway I think we're all at least on the same page.

Just curious, did you agree with my AC comment?

 

[KETCH-UP]

Re: why does water/alky work ?

Good points! I always look at the air being more dense. At equal pressures, an engine will make more power with denser air. The alky also has a lower state change temperature than water. The water helps later in combustion cycle. Then change tranny!

 

[jordan0806]

Re: why does water/alky work ?

The one thing you have to remember about alky/meth injection is that the product ITSELF does not add HP. It does create lower intake temps and helps with oxygenization (sp?) in the cylinder.

By having this happen, a tuner can add more timing and less fuel ..essentially leaning it a little../.while still having a controlled temp in the cylinder. Of course we all know..more timing...less fuel....= more HP...

ALso, alky./meth is good for making up for shitty gas..like California 91 octane....if you have an agressive tune which might need a 91/100 octane mix....with meth injection, you can use 91 only and still have the same tune....now of course leaded gas provides a much more safer net for having higher boost temps and HP producing horsepower but with meth a solid tune is worth it sometimes...

where as paying $45 for a 5 gallon can of meth which will last about 3 to 4 weeks...as opposed to having a $60 tank of 100 which will last 3 - 4 days....

It's all in the tune...

 

[Teeleton]

Re: why does water/alky work ?

Just curious, did you agree with my AC comment?

Well, yeah. The condenser is where the heat is slowly dissapated to the atmosphere, but the cooling effect occurs in the evaporator, as evidenced by the condensation on the outside of it. That's where the freon goes from under pressure from the compressor, to lower pressure, and the temperature drops sharply because of it. It's the exact same effect as nitrous dropping temp because of the pressure release from the bottle.

Teeleton

 

[turbodig]

Re: why does water/alky work ?

Entropy (from the 2nd Law of Thermodynamics) in that when a state change occurs, some energy is lost as heat. Water/alky/meth are all quite good at heat absorption, thus carrying the heat inward, away from the bulk of the air charge.

I am, by no means, a scientist, however.

Hood

Maybe you mean Enthalpy....?

But generally, yeah. There are a lot of complexities in the combustion science of what
Water/Alcohol does in the chamber, but the temp drop occurs from the state change from
liquid to vapor. Both water and alcohol have a very high latent heat of vaporization, so they
"use" more heat in the state change.

Water has about double the LHoV of Methanol, but the bonus to methanol is that it's
actually flammable. Gasoline has a very poor LHoV, comparatively... this is why a richer
fuel mix will reduce knock, but it won't do it as well as Alky or Water.

Spray water or alcohol on your skin... you'll immediately notice the cooling effect. That's
the energy being used in the vaporization/evaporation.

Sir Harry Ricardo did much research on this in the 1920's... it's been around a long time.


later,

 

[Jer]

Re: why does water/alky work ?

I'm not a scientist but I know that it means I can run ~25psi on pump gas (91oct) instead of the 14-15psi I was able to run sans knock prior to methanol injection.

 

[sytyguy]

Re: why does water/alky work ?

Maybe you mean Enthalpy....?

http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookglossE.html#entropy

I always understood this to be the name for the process/function of what occurs. Enthalpy seems to fit the bill also, but I thought it was more the sum of the energy involved in the function, not the function itself.

Hood

 

[sytyguy]

Re: why does water/alky work ?

There is no cooling by way of state change, because the water vapor is stable as a liquid at all temperatures involved. If you're getting above 212* where the water vapor turns to a gas, then you can talk state change.

Don't forget that meth/alky boils at about 147 degF (@atm), so it wouldn't take long at all (once past the IAT sensor - which I assume is what your gauging IATs off of) for the mixture to begin to evaporate. I wasn't speaking of strictly a state change taking place pre-IAT sensor, as that's not what ultimately matters. Cooling the charge prior to combustion is where the full benefit of WI/AI/MI can be seen.

And while boiling points rise when it's contents are under pressure, there's no way it's not going to state change when exposed to cylinder temps (and to some degree, lower intake/cylinder head temps for that matter.)

Hood