Liquid refrigerant pressure and temperature

AI Thread Summary
When a sealed can of refrigerant-134a is opened, the pressure and temperature inside drop rapidly due to the refrigerant boiling as pressure decreases. This boiling process causes the temperature to fall to -26°C at 1 atm, which is the saturation temperature for refrigerant-134a at that pressure. The cooling effect is primarily due to the conservation of energy, as the refrigerant absorbs heat during the phase change from liquid to gas. The discussion clarifies that while the Joule-Thompson effect relates to gas expansion, it does not apply here since the focus is on the boiling of the liquid refrigerant. Understanding these thermodynamic principles is essential for grasping the behavior of refrigerants under pressure changes.
Arvindaa
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Consider a sealed can of liquid refrigerant-134a in a room at 25 •C .Now if the lid is opened slowly and some refrigerant is allowed to escape, the pressure and temperature in the can start dropping rapidly.A thermometer inserted in the can will register -26°C when pressure drop to 1 atm. ,which is the saturation temperature of refrigerant-134a at that pressure.
Now my question is what causes to decrease the temp. of can .
 
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From thermodynamics book by cengel and boles
 
Acc. to above thread , can fluid gets cooled due to expansion but how it maintain its saturation temp. and pressure all the way.
 
Thanks for giving above link I found answer in that.
 
Mech_Engineer said:
The basic answer is conservation of energy, as a gas expands it cools.

See this thread from 2011 on the subject: https://www.physicsforums.com/threads/why-do-gases-cool-on-expansion.470311/
That's fine, but he's asking about the can of liquid, not the escaping air. The can of liquid cools because when the pressure inside the can drops, it starts to boil, nearly instantly dropping it to its boiling temperature at that pressure.

The Joule-Thompson effect is a bit confusing and tends to come up in places where it doesn't apply, such as this and air compressors. Joule-Thompson is about expansion of gas. This (and air conditioners) reduce pressure and boil liquids.
 
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