Kevin T. Wyum

(Points at the post by Max) People dismiss intake temps far too easily thinking the IC is all that matters, keep in mind I have an interest in the intercoolers and I'm even supporting Max's point. Lower the intake temp and lower the overall system temp period. Think system wide.

ZeroBanger

I agree with your point kevin, but I also think the system would more effective after the intercooler. Wouldn't it be more effective after the ic, so the IC has already pre-cooled the air?

Maybe im just sleepy and missing something.

ZeroBanger

I agree with your point kevin, but I also think the system would more effective after the intercooler. Wouldn't it be more effective after the ic, so the IC has already pre-cooled the air?

Maybe im just sleepy and missing something.

Herblenny

iTrader: (13)

Mr Wyum,

So, do you think its more effective before the turbo than IC?? Hmm.. I'm trying to understand that concept, but having harder time. I guess in my opinion, air thats entering the turbo heats up, IC cools it, and if this contraption is after IC it will cool below ambion temp (maybe).. but also since its just cooling the tube, I'm not sure how effective it will be. I guess real world testing is in order.. to see if initial air entering the turbo have more effect or cooling the air after the IC or just before the IC.. My opinion, cooling the air after would be more productive.. but thats just my opinion.. I guess its the similar set up as water injection.. I know people shoot it somewhere after the turbo.. I haven't seen people shoot it pre-turbo.

SomeGuy_sg

Does anyone notice the casing of the DiiS ? all that frozen moisture on the casing .. what about in side the pipping ? Think of that inside the pipping , than you stop your car . That frozen moisture is gonna melt and collect at the lowest point, ie Intercooler...

Or am i wrong ?

Wargasm

While I think it's great that people are out there trying stuff out, I still don't think this will have any meaningful effect on intake temps. The only small effect you MIGHT see is that at VERY LOW airflow, like at idle, you might see a tiny drop... but even then I kinda doubt it. Of course if you mount your temp gauge on a piece of metal pipe connected to this box, you might "see" a drop, but only because the dry ice is cooling your metal pipes that your sensor is mounted in. I don't think that the actual air temp will change.

A MUCH better idea would be an ice water jacket on an IC. Plenty of drag racers do this already. The problem with it is that it's not useful for a street car since the ice water warms up and now you don't get any cooling.

Brian

Herblenny

iTrader: (13)

I want to say I don't think that would happen.. Dry Ice has temp of about -80 C (-112 F). Its cold but you have to also think about the surface area and air flow rate and how quickly it will cool that moving air. Outside of that box, air is more still.. And I'm sure that pic was taken about 5-10 minutes after just sitting out..

I completely agree with Wargasm. I think heat transfer and temp retained by the metal will lower the intake temp if the sensor is attatched near where this contraption is.... but I don't think it will be effective to acturally make the difference.. especially short distance of cooling.. Only way I could see this working would be to increase the area of cooling.. But than thats how IC works..

Kevin T. Wyum

My point was not where it would work better, I tend to agree with most others here that it would do very little no matter where it's placed for the already stated reasons of, small surface area and contact time.

On the cold intake issue and this belief that people seem to have that the turbos are just going to heat the air up anyway, a simple analogy:

Take a frozen can of soda and a slightly cold can of soda (Cold air intake, hot air intake) place these cans above a lit propane torch for 5 seconds (the turbo with an exagerated contact time) and then drink from the two cans. Hrmm oddly enough the frozen can is about the right temp to consume and the slightly cold can is hot as hell. Now lets put the cans back in the refrigerator (Intercooler) for 60 seconds and try again. They've both cooled down but the slightly cold can is still warmer than desirable.

A bit cheesy but it makes the point : ).

Kevin T. Wyum

Herblenny

iTrader: (13)

Mr. Wyum,

I understand the point you are making.. Sure, Cooler air going in will definitely have effect after the turbo (as analogy you used).. My concern was, if you had to pick one or the other.. Say cooling the initial air going into turbo or cooling the air coming out of the turbo.. which would be more affective? Like you have mentioned.. I also don't think this contraption will do any good.. due to surface area..

And since I'm not an expert and only going by small amount of knowledge in physics and chemistry.. I'm not sure what is acturally better.. Also, as I stated earlier, I've seen people put H2O sprayer after the turbo instead pre-turbo..

maxcooper

Someone needs to figure out how much heat energy a pile of dry ice can really absorb. If it lasts for hours, it seems unlikely that it is really removing a lot of heat from the intake charge, perhaps due to the small contact area and other physical limitations. However, if you improved the rate at which heat is removed from the intake charge, the dry ice might be gone in one pass down the drag strip.

This second question is the one I wonder most about -- can dry ice really help us much, assuming we could make some contraption to pump heat out of the intake charge efficiently? It seems to go from solid to gas, which is nice because you've got some phase changes, but it also doesn't seem to weigh that much and so might not have a lot of capacity.

I really don't know, I am just asking. Someone with the right background should be able to answer this pretty easily so we can all stop guessing.

-Max

Herblenny

iTrader: (13)

I have some idea about dry ice in that I recieve and ship stuff in them..

5lbs of dry ice in styroform insulated box, sealed will maintain around -50 to -80C for about 2 days..

Also, something to consider.. just FYI.. lot of overnight shippers have put limits to how much dry ice could be transported via airplane.. I've heard its due to some plane going down because CO poisoning.

If I could suggest.. I think dry ice would work great if you combine EtOH and Dry Ice based liquid intercooler.. One bad think will be that using EtOH, it has to be very well controlled..

Wargasm

I've worked in a few chem labs where I used dry ice all the time... A couple of interesting points....

1 - Dry ice sublimes from solid to vapor. What this means is that unless it is always pressed against the pipes, the cooling is mostly going to be done by the vapor phase which we know isn't a good (rapid) conductor of heat. If the dry ice is kept pushed up against the pipes, this problem would go away....

2 - You could try to solve problem 1 by making a dry ice/water bath. The idea being that you would cool the water with the dry ice and then since the water is a liquid, it touches all around the pipe and carries away heat. I think the problem you'd face here is that a large volume of water "melts" dry ice fairly quickly because it is a liquid and surrounds the dry ice. Compared to dry ice, room temperature water is pretty hot and it disappears pretty quickly. If you use less water, it just ends up freezing on the surface of the dry ice... Basically I'm saying I don't think that would work that well.

3 - the best thing to do with dry ice is throw hunks in a toilet and then listen to the sounds of fear when your friends go in to use it... it makes it look like a bubbling cauldron... another fun thing to do is to take a small piece and hold it down against a smooth, flat surface. This "melts" the face of it flat.. and then you can slide it on the flat surface and it really GOES... since there is a small amount of solid-> vapor phase change going on on the bottom surface it has a hovercraft effect and slides like a puck on an air hockey table.

If you really want to know what to look up... you can figure out the heat of sublimation for carbon dioxide (dry ice) and you can look up the heat of fusion (if you want to know solid->liquid) or heat of vaporization (liquid->vapor) for water...

Of course... all these calculations are great and everything, but by far the most difficult thing to figure out is how much heat will transfer from the intake air to the cooling vessel given the surface area and the time allowed.

If you ask me, "how much heat does it take to sublimate 10 grams of dry ice?" ... that's EASY to figure out... if you ask me, "if I have 10 grams of dry ice in this contraption, how much is my 100 degree intake air temp going to drop assuming I'm going at 7000 rpm, my turbo efficiency is 73%?"... that's HARD.

Wargasm

god damn double post

Wargasm

DOUBLE POSTS FROM HELL!

Wargasm

I'd be hesitant to use a flammable fluid that gives off flammable vapors (ethyl alcohol) in my engine bay... I mean if I was going to do that, I'd use liquid oxygen

I think a better solution would be a dry ice/ethylene glycol bath.

B

ZeroBanger

Im taking Kevin's advice and putting ICE in my water injection system when i'm at the drag strip. I created a second tank that has a very large opening, it will have 1.25 gallons of ice water, the other tank will contain methanol. The system will drink equal from both tanks.

as far as this intake chiller idea in this thread goes, I would still like to see the results after its been tested and try to keep an open mind.

maxcooper

So lets start here. How much energy does it take to vaporize 5 lbs of dry ice?

-Max

Wargasm

Well the heat of sublimation for dry ice is about 25,000 Joules/mol.

5 pounds is 2268 grams

The number of moles = (grams substance) / (molar weight)

moles = 2268 / 44 = 51.5 moles of CO2

51.5 moles * 25000 J/mol = 1,288,636 Joules of energy

Wargasm

Well the heat of sublimation for dry ice is about 25,000 Joules/mol.

5 pounds is 2268 grams

The number of moles = (grams substance) / (molar weight)

moles = 2268 / 44 = 51.5 moles of CO2

51.5 moles * 25000 J/mol = 1,288,636 Joules of energy

Wargasm

Assuming that a 10 degree C drop is "significant", how much air could 1.3 million Joules of energy cool by 10 degrees?

1.3 million Joules is about 310,707 calories.

Heat = (mass of air) * (temp change in C) * (specific heat capacity of air)

So, rearranging... mass = (heat)/((temp change) * (spec heat))

310707 / (10 * 0.25 cal/gC) = 124,283 grams of air

Ah but now we've gone and opened up a can of worms... in order to figure out how much volume of air that 124,283 grams is, we need to know the temperature, the pressure, and the amount of moisture in the air... getting harder now...

I don't feel like trying to figure it out now (it's late), but I'd have to guess that at normal summer day intake air temps, the density of that air at 15 PSI after the turbo and intercooler is... maybe 2 kg/cubic meter.

So our 124 kg of air works out to 62 cubic meters which works out to around 47,000 engine revolutions (assuming good filling of the chambers)...

So you'd be able to theoretically cool the air by 10 C for about 6 minutes of full throttle running.

However, I think we all intuitively know that if you throw 5 pounds of ice in this contraption, and go drive the hell out of your car for 6 minutes, probably 95% of that ice will still be there... meaning it didn't do its job....

Plus, I'm really tired and I could easily have messed up a calculation anyhow... so don't put me in charge of the next Hubble....

In the end, I predict this will not be effective, but I totally would love to try it out to prove whether or not it will work.

Herblenny

iTrader: (13)

Only reason I suggested using EtOH is because when I quick freeze cells, I use Methanol and Dry Ice. Otherwise, dry ice will freeze water and most liquids. so, maybe just ice water would be good..

b005td7

hey it's not good for your engine to breath in CO2, you are having a box of dryice in your engine bay the engine is going to breath in more or less unless you seal the intake real good

Herblenny

iTrader: (13)

I don't think CO2 level is that high to really affect the car.. Its as or less than if you were to tail gate someone.. I dont know.. just kidding about the tail gating thing.. but over all what you are talking about shouldn't be that much of an issue.

Kevin T. Wyum

That nifty aluminum (read high thermal conductivity) box sitting in the 100 degree C ambient engine bay with a larger surface area than the tube inside would likely consume the bulk of energy absorption of the dry ice. Since the person went to the trouble of making it though they should probably put it in a car and get some real data points, as someone else mentioned, make sure the temp probes are well away from the box.

Wargasm

I agree with Kevin, sometimes it's easier to just make something and try it out rather than attempt to calculate the hell out of it.