7 replies to this topic

[kangas]

Hello, 

 

which law of thermodynamics is associated with the temperature change of a liquid after pressure drop.

For instance, I have a liquid at 50bar and I want to reduce the pressure at 1bar. How I will determine the temperature change?

 

Thanks

[breizh]

Hi,

Consider this resource to support your work 

Properties with Variant Fina Pressure – Quest Consultants

 

Simulators will do the job .

 

Good luck

Breizh 

[kangas]

Hi,

Consider this resource to support your work 

Properties with Variant Fina Pressure – Quest Consultants

 

Simulators will do the job .

 

Good luck

Breizh 

Thanks nice tool.

 

I would like to better understand the thermodynamics though. I can understand that if you pump something, heat is input. If you expand something energy is released. Does this mean that for every liquid temperature will decrease or are there cases where temperature will increase.

[MrShorty]

Are you thinking of something like a Joule-Thompson type experiment/process? I know that the temperature of most liquids will increase when the pressure is dropped along an isenthalp (as in a JT type process).

 

Thermodynamics is often about processes, which means you may need to know more than just the initial and final states. It may be necessary to explain the process you are using to go from the initial state to the final state.

[latexman]

From a practical standpoint, for this range of pressure drop the answer is ~ 0 when there is no flashing of vapor at the lower pressure, right?  You could probably debate whether your real world process (CV?)  approaches isenthalpic or adiabatic, but in my experience it is usually closest to isothermal.  Maybe, the temperature goes up 1^oC or there abouts, but in my little world that is negligible.  How is this small of a change important to you and your process?

[horatorres]

This topic is a thermodynamics one...  Here after link to deep it

 

https://ntrs.nasa.go...19720020315.pdf

 

for natural gas calculations, there are  extensive papers

 

horacio

[breizh]

Hi,

To answer to your question consider this paper from 1999 published in Chemical engineering magazine :working with fluid that warm upon expansion .

Good luck

Breizh 

[kangas]

Thanks all for your great help!