Pressurized Gas Canister Release Question

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Homework Help Overview

The discussion revolves around two pressurized gas canisters, both with a capacity of 60 liters, filled with 120 liters of ideal gas. Canister A is heated to 100 degrees Celsius, while Canister B is heated to 2000 degrees Celsius. Participants are exploring which canister will empty first when both valves are opened, considering factors such as pressure and gas expansion.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the implications of pressure differences between the canisters after heating and question the assumptions about the expansion of both the gas and the canisters themselves. There are varying interpretations of what "empty" means in this context, whether it refers to pressure or mass of gas.

Discussion Status

The discussion is ongoing, with participants providing different perspectives on the factors influencing the rate at which each canister empties. Some suggest that Canister B will empty first due to higher pressure, while others raise questions about the effects of pressure differentials and the physical expansion of the canisters.

Contextual Notes

There is some ambiguity regarding the initial conditions of the canisters and the assumptions made about their physical properties during the heating process. Participants are also considering the effects of gas dynamics and pressure differentials in their reasoning.

s.p.q.r
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Hi,

I have 2 pressurized canisters, both are 60 litres in size. Both are filled with 120 litres of ideal gas. Canister A is heated to 100 degrees celsius (373 kelvin) and Canister B is heated to 2000 degrees celsius (2273 Kelvin).
Canister B will obviously expand more than Canister A.
But, I have a few questions.
If both canister valves are opened to release the gas, which canister will empty first? Canister A that has lower volume of gas and lower pressure or Canister B that has larger volume and higher pressure?

Cheers
 
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Assuming the canisters don't expand much (so their volume difference is isn't much and the pressure is high), canister B will be at much higher pressure and will therefore expel it's gas faster on a per mass basis.
 
initial pressure and volume in both canisters are same(not different as you say).
after the heating, pressure of can B will be obviously more. therefore canister B will empty first.
 
ank_gl said:
initial pressure and volume in both canisters are same(not different as you say).
after the heating, pressure of can B will be obviously more. therefore canister B will empty first.
How can two identical containers, with the same amount of gas in them, at two different temperatures have the same pressure?

Are we discussing reality, because, if we are, the flows will be choked coming out of the canisters...
 
Last edited:
i was talking about the state of the containers before heating.
OP says "I have 2 pressurized canisters, both are 60 litres in size. Both are filled with 120 litres of ideal gas. "
then the process of heating starts.
and sorry i didnt understand this line, the first time "Canister B will obviously expand more than Canister A. " i thought that he meant the expansion of gas in higher temp container would be more.
and i don't think that canister expansion ll have much effect.
for example, if aluminium canister is used, thermal CoE for which is
0.000023 per K, volume change for 2000K is 0.138cubic units
 
ank_gl said:
i was talking about the state of the containers before heating.
OP says "I have 2 pressurized canisters, both are 60 litres in size. Both are filled with 120 litres of ideal gas. "
then the process of heating starts.
and sorry i didnt understand this line, the first time "Canister B will obviously expand more than Canister A. " i thought that he meant the expansion of gas in higher temp container would be more.
and i don't think that canister expansion ll have much effect.
for example, if aluminium canister is used, thermal CoE for which is
0.000023 per K, volume change for 2000K is 0.138cubic units
Ahhhh...I see what you mean.

I don't think that the OP meant to consider physical expansion of the canisters but we don't know that right now. The question isn't very specific. I am assuming the only expansion involved is what the gas is trying to do due to the temperature.
 
Ahh, sorry guys, i was not specific enough. In the OP i did not mean that we should consider the expansion of the actual containers, but the expansion of the gas. The first response by Russ was the most accurate and what I was looking for. I will have another question regarding expanding gases soon, so look out for this post. Thanks for all the replies.
Cheers.
 
spkr:
which canister will empty first?

What does empty mean ?

It means whith less pressure ( 1 ) or whith less mass of gas ( 2 ) ?

In case 1, note that for the canister whith high pressure it will take a time to reach the conditions of the canister whith less pressure and then they will be at same pressure. So canister A ( 100 ºC ) will empty first.
 
well i didnt get which condition are you referring to alvaros. gas ll be pushed outward because of the pressure differential. canister B has a higher pressure differential.
apply bernoulli, velocity of rushing gas is directly proportional to pressure differential. both cans have same amount of gas so B ll empty first
 
  • #10
ank_gl said:
well i didnt get which condition are you referring to alvaros. gas ll be pushed outward because of the pressure differential. canister B has a higher pressure differential.
apply bernoulli, velocity of rushing gas is directly proportional to pressure differential. both cans have same amount of gas so B ll empty first

The condition is pressure.

Suppose canister A is at 2Kg/cm2 and B at 10 Kg/cm2.
Yoou open the valves and, after a while, canister B will have 2 Kg/cm2, but then canister A will have less than 2 Gg/cm2, canister A will always be ahead.
 

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