Computer pictures

[gforce422]

Jason, when your computer is completely finished, you really should upload this to www.instructables.com. I'm sure there's a lot of people there who would totally love it.

[Segovia]

All of these comments are full of VICIOUSNESS and VENOM and is proof that DC has gone to hell.

You needed proof?

[Bocaj Claw]

As the proof is in the pudding, I shall bake a pudding with this thread as a principle ingredient. Also, it will be tapioca.

[Doc Sigma]

Tapioca pudding is pudding made with tapiocas, right? So, like, what are tapiocas? Are they the little balls in the pudding? What are tapiocas OUTSIDE OF THE SCOPE of tapioca pudding? Are they ever used for anything else?

[Bocaj Claw]

I actually watched a documentary on tapioca and those little things are leftovers bits from seaweed. Seaweed is used to make ice cream so tapioca was invented as a way to get rid of the bits they couldn't use, once mistaken as fish eggs, now acknowledged as just an outgrowth of the weed.

Its amazing how many beloved foods are just an attempt to get rid of scraps. Carrot cake for instance was invented to get rid of surplus freeze-dried carrot shavings after WWII.

[Tai]

Basically what we want is the force that's imparted on the air, to calculate how much force is compressing the air inside the case. Once we know how much more pressure is inside, we can calculate the thermal increase caused by the pressure and compare that to the formula for thermal conductance (since thermal conductance is based on temperature increase).

Ok so we have a net of 80 cubic feet per minute (160 in and 80 out) into the case.

Since SI is not feet that translates to 2.2653 cubic meters/min

Given that we know Jason lives 480 meters above sea level and generally keeps a house temperature of 23.5C (How personal this question gets!), and using local weather data to find out the dewpoint hovers around 5C and 30.07inHg (763.778mmHg), we can calculate Jason's air weighs about 1.19kg/m3. [fun fact there is technically no negative PSI! positive pressures are in PSI and negative vacuums are measured in Hg)

Calculating further with the fan (which we know is 120mm square, and extrapolating from my own 120mm has a fan depth of ~16mm) we can see that for 2.2653 cubic meters to pass though the fan per minute, the 2.2653 cubic meter cube would have to be 120mm square to fit though the fan.

The length (which turns out to be 157.3125 meters since a cube must be L*W*H, and the length/height are 120mm each) would effectively be the unit speed.
So, we get 157.3125 meters per minute, which becomes 2.621875 meters per second (~6MPH for the nonmetric WHICH I SUPPORT but at the same time abhor due to the complexities of calculating with it. If you ever wondered how fast 120mm fans usually push air, they push air about 6mph.)

ANYWAY

To find the acceleration, we need the mass of air moved, as well as the time taken to accelerate the air.

Since the fan blades are 16mm deep, we'll say that the base unit of air moved is 16x120x120mm. That much air is about .0002304m3 (I forgo engineering notation to show scale a bit more visually). .0002304m3 of air weighs about .000274176kg at Jacen's pressure. We'll ignore any vortex effects and assume that air is still right before the blade, and at peak speed after just leaving. In this way, the average airspeed is 1.3109 m/s (2.6218/2). Traveling across .016 meters at that speed would take .0122 seconds, leaving 2.62 to equal 0 + a*0.0122, setting acceleration to 214.754 meters per second per second.

Now, we have enough to finally find the force applied. Mass time acceleration yields .05888N. Going back to the area of the fan gives that force
over .0144 meters to yield 4.08N/m^2. That translates into .03068 additional mmHg applied into the case.

Ideal Gas Law gives about 1.4863 mol of ideal gas in Jacen's ideal computer. Changing the temperature, we get a temperature increase of .012C, bringing the temperature up to 23.512C.

And now the home stretch! The formula for air's thermal conductivity is valid from around 100K to ~1600K, and is as follows:

thermal conductivity = k = (.000000000015207 * TTT) - (.000000048574 * TT) + (.00010184E-4 * T) - (.00039333e-4)

where T = Kelvin

Thermal conductivity at 23.5C is .02672655191
thermal conductivity at 23.512C is .026727476334

THEREFORE

The conductivity gain is .026727476334/.02672655191

equaling a .000034588% increase in thermal conductivity, based on compressive power of the fans alone.


This assumes constant atmospheric temperature and pressure, that Jacen's computergas is ideal, fan acceleration is linear,
ignores the "give" of the case as extra pressure is exerted (as well as any holes in Jacen's case! Measuring Jacen's case for airtightness requires a
fairly specialized machine that he disappointingly does not own), fan speed is constant, the temperature shift given from the extra cooling/density,
air resistance, spin-up time for the fan, and a slew of other things

not the least of which is that I calculated correctly. Can someone check my work? Peer review is golden~




~~Errata aka where I screwed up~~




"The conductivity gain is .026727476334/.02672655191, equaling a .000034588% gain..."
.026727476334/.02672655191 = 1.000034588 which does NOT equal .000034588% gain. should read .0034588%.

"Changing the temperature, we get a temperature increase of .012C"
I actually change the pressure to the new pressure given by the force of the fan, whoops

[datherman]

Wut.

[Muninn]

not the least of which is that I calculated correctly. Can someone check my work? Peer review is golden~

I think you put the decimal point in the wrong place... somewhere.

[Doc Sigma]

Calculating further with the fan (which we know is 120mm square, and extrapolating from my own 120mm has a fan depth of ~16mm) we can see that for 2.2653 cubic meters to pass though the fan per minute, the 2.2653 cubic meter cube would have to be 120mm square to fit though the fan. If you ever wondered how fast 120mm fans usually push air, they push air about 6mph.) .0002304m3 of air weighs about .000274176kg at Jacen's pressure. Mass time acceleration yields .05888N.

[likeafox]

The increased temperature due to increased pressure boggles my mind. I didn't know that happened. Doesn't this mean that my case would actually be less efficient since the increased air temperature would vastly out-weigh any bonus conductivity?

[Bocaj Claw]

Your computer logic in this thread about tapioca is both confusing and lugubrious!