Thanks, you really know your stuff You work in the field, right?

Evaporation= going from a liquid state to a gaseous state

Sublimation= going from a solid straight to a gaseous state without becoming a liquid


Not bad for a liberal arts student 10 years out of college

yeah, i work for this company: Integrated Environmental Services

JJ

how many cans of beer can it hold?

I can't help but nit-pick and say it is not an exothermic reaction. Exothermic reactions get hot. endothermic reactions get cold. ie solvolysis of ammonium nitrate or ammonium persulfate in water. This is rather a physical process governed by the ideal gas law. pv=rt. r is the gas consant. if (v)olume is constant the (p)ressure decreases as you release the gas which inturn lowers (t)emperature.

sorry for bein a smart @$$...

i must also add that compressed gases are hotter than normal air especially in this case of forced induction. If this wasn't true the whole development of the diesel engine would not have occurred. Diesel effect is the idea that when air is compressed with diesel fuel the pressure increases the temperature of the air to the flash point of the fuel, which is the reason diesel engines don't use spark plugs. In your case of filling cylinders the compressed gas must cool, but that is because the energy you are adding to the system by increasing the pressure is let off as heat(back to first law of thermodynamics). it eventually cools to room temperature.

Wow!

ok, you got me on the first one, simple typo there.

your second post doesn't make too much sense. filling a cylinder or vessel will, of course, initially create the heat both you and i spoke of, but the vessel will eventually cool to ambient temperature, if no other input is allowed into the system

that's the point, too, of an intercooler. the compressed air is fed through the IC to draw heat off the intake charge.

JJ

I essentially said this, but I wasn't really trying to " get ya" just wanted to be clear.
D

Good question. Google some numbers to get the density of air, about 1.3 kg/m^3. Take some easy numbers like 6000 rpm and 200% volumetric efficiency (because of the turbo). That's 12,000 L/m --> 200 L/s --> 0.2 m^3/s, or about 0.26 kg/s. Not maxed-out by any means.

A quick sanity check, say a 13:1 afr (way too lean, I know) means 0.02 kg/s of fuel. At about 0.8 g/cc fuel density that's 25 cc/s --> 1500 cc/min or 375 cc/min per injector. The evo has 550 cc/min injectors but we assumed less than peak airflow and very lean, so we're on target.

Suppose we want to cool the intake by 20C, how much heat do we need to get rid of? The heat capacity of air (using Cv, which is significantly lower than Cp) is 720 Joules/kg/C. So we need to get rid of heat at a rate of about 3700 J/s (3700 Watts). The heat of sublimation of CO2 is 5800 J/g so we go through CO2 at about 0.65 g/s (not including the loss from all the other heat it's absorbing).

I'll leave it to an HVAC engineer to figure out how much surface area is needed to dump 3700 Watts with a temperature drop of about 85C (10C air to -75C CO2).

Dave

ok, some of u might understand what i'm talking about here
correct me if i say anything wrong, i'm still a student

ok, basicly.....heat transfer calculation be done with this equation

Q = mdot*CP*deltaT = U*A*deltaT

mdot is mass flow rate of air, cp is heat capacity
U is overall heat transfer coefficient, A is heat transfer area

U is determined from heat conductivity of the pipe, dry ice, and the air, and convection of air
since air is blowing by so fast, convection of air is big, so a correlation is needed
convection of air is derived from air's properties : pipe diameter, velocity, density, viscousity, and some dimensionless numbers such as reynolds, prandt, number and so.....
also heat conductivity of air and dry ice

for a given size of that dry ice box, temperature drop of air can be calculated with all above calculation. then will be able to know how much this dry ice idea can cool down the air and to see whether it's effective for the car or not