What are throttling process and Joule Thomson effect?

[ahmad.hasan]

dear all

What is the throttling Process?
what is Joule homson Effect?

 

[FredGarvin]

Google is your friend.

http://en.wikipedia.org/wiki/Joule-Thomson_effect
http://www.answers.com/topic/joule-thomson-effect
http://www.chm.wright.edu/grossie/chm457/3_2_06.pdf
http://www.madsci.org/posts/archives/apr99/924233920.Eg.r.html
http://www.mmr.com/jt.htm

 

[Cyrus]

A throttling process is a process that is isenthalpic. Thus, $$h_1 = h_2$$. This means that the following is also true, $$u_1 + P_1 v_1 = u_2 + P_2 v_2$$. So if you drop pressure in a throttling value, you increase the internal energy, and vise versa.

The Joule -thomson- effect deals with the fact that as you expand a gas it looses temperature. Note that for hydrogen; however, it gains temperaturee as it expands. This makes hyrdogen particularly dagnerous.

 

[ahmad.hasan]

Pressure drops in CNG kit Pressure regulator from 300 bar to 4 bar in 1st chamber due to expansion is it throttling process? temperature also drops in it.

 

[Cyrus]

Yes, that is exactly what it is.

Edit: wait, what do you mean by expansion? Is it going through a nozzle?

 

[ahmad.hasan]

no it is going throug valve (sloninoid valve) from storage cylinder through high pressure pipe into solinoid valve and then in the 1st stage chamber of pressure regulator.

 

[Cyrus]

Yes, it is a throttling valve.

 

[ahmad.hasan]

what is the value of joule-thomson coefficient for methane