Deriving Joule-Thomson Effect: CNGA Approximation

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In summary, the conversation is about someone looking for the derivation of the joule thompson effect, specifically the formula Uj = (nBTave^-n / Roh(ave) Cp) *Zave, which uses the CNGA approximation. They are looking for help and clarification on some variables, such as Pave and Z, and suggest using clearer terms in their question.
  • #1
codicil
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Hello ALL,

I am looking for the derivation of joule thompson effect to show that Uj = (nBTave^-n / Roh(ave) Cp) *Zave

where n = 3.825, B = 5287.Pave.10^1.785G
Pave in KPa(g) and Tave in K

using CNGA approximation.

Can anybody help me in this?

Thanks

Shabbir
 
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  • #2
maybe this will help
 
  • #3
Maybe this will help

I assume that CNGA means California Natural Gas Association.

Make sure that you are more clear when you state you question since not everybody is a expert necessarily in your field.

Pave is better as P(avg).

I assume Z is the compressibility and G is the gas Gravity based on (Air = 1.00)

Let me know if you need more
 

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1. What is the Joule-Thomson Effect?

The Joule-Thomson Effect is a thermodynamic phenomenon where the temperature of a gas changes when it undergoes a throttling process. This effect is observed when a gas experiences a pressure drop while passing through a valve or a porous plug.

2. How is the Joule-Thomson Effect derived?

The Joule-Thomson Effect is derived using the Clausius-Clapeyron equation, which relates the change in temperature and pressure of a gas during a throttling process. The derivation also takes into account the ideal gas law and the Maxwell relations.

3. What is the CNGA approximation in the derivation of the Joule-Thomson Effect?

The CNGA approximation, also known as the ideal gas approximation, is used in the derivation of the Joule-Thomson Effect to simplify the calculations. It assumes that the gas being studied behaves like an ideal gas, which means it follows the ideal gas law and has no intermolecular forces.

4. What are the limitations of the CNGA approximation?

The CNGA approximation is only valid for gases that behave like an ideal gas, which means they have low densities and high temperatures. It also does not take into account the effects of intermolecular forces, so it may not accurately predict the temperature change of gases with strong intermolecular forces.

5. How is the Joule-Thomson Effect used in real-world applications?

The Joule-Thomson Effect has many practical applications, such as in refrigeration and natural gas processing. It is also used in the production of liquefied natural gas (LNG) and in the design of gas pipelines to prevent freezing due to pressure drops. Additionally, the effect is used in various cooling systems, such as air conditioners and heat pumps.

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