Attention Engineers... Help please!

[JusFlyinBy]

Alright, so I have a thermodynamics problem here for you smart peoples... :D Im here at work and im having a serious brain fart and would rather not bug the boss...

Check it out. Im using a bottle of mixed gas at 1200 PSI in a bottle with a volume of 142 SCF. I will be using that gas at a flow of 0.28 SLM. So the question is, how long will it take for that bottle to deplete at that flow rate?

Im thinking... PV = nRT, but then, where do I go from there? Well, just a shot in the dark to ask this on an Fbody forum, but hey, maybe someone can help, thanks!

[camaronat]

First off..what are SCF and SLM?

[JusFlyinBy]

Standard Cubic Feet... Ft^3

Standard Liters per Minute... L/min

P.S. The bottle is outside around 70°F, so 22°C, 295.15 K.

[TealV6]

Originally posted by JusFlyinBy:
Standard Cubic Feet... Ft^3

Standard Liters per Minute... L/min

P.S. The bottle is outside around 70°F, so 22°C, 295.15 K.

huh

Man... that's just way too much to think abotu before noon!! [img]graemlins/rant.gif[/img]

[lastbird]

1. I am not sure How long it will take but it will last for a good amount of time.
2. that i one heavy gas you are useing. what is it.
3. what are you useing as a flow controller

[sac2165]

that does'nt sound too bad, too bad I have'nt had a thermo class in a couple of years. :(

[camaronat]

I am having trouble coming up with anything cuz I don't have my books here at work. I do know that you can't use the ideal gas law cuz you don't have a time variable in it.

I will keep looking though.

[camaronat]

I am thinking it is something that I haven't covered yet in class because it is not a constant system.

The only thing that is really constant is your volume.
Pressure will go down, temp will go down, and volumetric flow rate will go down over time.

[JusFlyinBy]

Originally posted by lastbird:
1. I am not sure How long it will take but it will last for a good amount of time.
2. that i one heavy gas you are useing. what is it.
3. what are you useing as a flow controller

1. I wish it were that easy though, but my entire test plan revolves around how much I can get out of this bottle, so I need a pretty accurate answer.

2. Its a blend of gasses, if I told ya, Id hafta kill ya.

3. Its an electronic flow controller... is that what you are asking?

[camaronat]

If it helps any...your stuff converted into the same units is:

P=8273.708 kN/m^2
V=4020.99 L
Q=.00466667 L/s

[JusFlyinBy]

Originally posted by camaronat:
I am thinking it is something that I haven't covered yet in class because it is not a constant system.

The only thing that is really constant is your volume.
Pressure will go down, temp will go down, and volumetric flow rate will go down over time.

I think itd be safe to assume temperature remains constant. Why would my volumetric flow rate go down over time?

[JusFlyinBy]

Whoa whoa whoa, Why did I not catch this earlier??? There is no way in hell that bottle is 143 ft^3. Id be lucky if it was 10! Told you I was having a serious brain fart this morning. Either way, just pretend it is 143, youd solve this the same way either way... [img]tongue.gif[/img]

As you can tell, I have not put forth any effort into this problem yet... lol.

[camaronat]

Because the pressure decreases. There won't be as much force on the gas, so it will come out slower.

(If I am not mistaken)

[camaronat]

I can't come up with anything without my books. I didn't pay that much attention in thermo.

[JusFlyinBy]

Nah, because I am controlling it at .28 SLM, you wont have to worry about the flow rate dropping below that until the bottle is practically empty.