Thermodynamics question - which process is this?

In summary, the gas remaining in the cylinder expanded nearly adiabatically and reversibly when it pushed the gas out ahead of it. The gas that got pushed out through the valve experienced a flow process involving no enthalpy change (per unit mass), a so-called Joule-Thompson effect.
  • #1
GBA13
73
0

Homework Statement


Hello everyone!

I recently did an experiment, one of the parts was rapidly releasing some gas from a large vessel. We had previously increased the pressure, let it settle and then opened a value to let some out. I am wondering which thermodynamic process this approximates to.

Homework Equations


From the data collected the temperature definitely changed by a couple of degrees and of course the pressure changed as we let some air out!

The Attempt at a Solution


At the moment I am stuck between two answers, either isochoric or adiabatic. As far as I know the real difference between these two processes is Isochoric happens at a constant volume while adiabatic doesn't. This is what I am trying to figure out. If you think of the vessel as a control volume then the volume is constant but if you think of all the gas originally in the cylinder as the volume then it increases massively when some of it is left in the open.

Thanks for any help you guys can offer!
 
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  • #2
The gas that remained in the vessel expanded nearly adiabatically and reversibly when it pushed the gas out ahead of it. The gas that got pushed out through the valve experienced a flow process involving no enthalpy change (per unit mass), a so-called Joule-Thompson effect. So there were two basic things going on simultaneously.

Chet
 
  • #3
Chestermiller said:
The gas that remained in the vessel expanded nearly adiabatically and reversibly when it pushed the gas out ahead of it. The gas that got pushed out through the valve experienced a flow process involving no enthalpy change (per unit mass), a so-called Joule-Thompson effect. So there were two basic things going on simultaneously.

Chet

Ok thanks, Chet! That will mean that some work will be done BY the gas remaining the cylinder doesn't it?
 
  • #4
GBA13 said:
Ok thanks, Chet! That will mean that some work will be done BY the gas remaining the cylinder doesn't it?
Yes.
 
  • #5
Great, thanks very much!
 

Related to Thermodynamics question - which process is this?

1. What is thermodynamics?

Thermodynamics is the branch of science that deals with the study of heat and its relation to energy and work. It also encompasses the properties and behavior of matter at different temperatures and pressures.

2. What are the laws of thermodynamics?

The laws of thermodynamics are fundamental principles that govern the behavior of energy and matter in physical systems. They include the first law, which states that energy cannot be created or destroyed, only transferred or converted, and the second law, which states that the total entropy of a closed system always increases over time.

3. How is thermodynamics used in everyday life?

Thermodynamics has numerous practical applications in our daily lives, such as in the design of engines and refrigeration systems, cooking and food preservation, and even in the human body to regulate body temperature and metabolism.

4. What is an isothermal process?

An isothermal process is one in which the temperature of a system remains constant throughout the process. This can occur when heat is added or removed at the same rate as the system expands or contracts, resulting in no change in internal energy.

5. How is thermodynamics related to other fields of science?

Thermodynamics is a fundamental concept that is closely related to other fields of science, such as chemistry, physics, and engineering. It is essential for understanding the behavior of matter and energy in various physical and chemical processes, and is used in many other areas, including biology, geology, and meteorology.

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