vena contracta static temperature drop

[MexTijuana]

Hello guys,

I try to calculate the temperature drop in the vena contracta of a pressure regulation valve to get an imagine, if propane condensate occurs.

The upstream pressure is app. 13 bar and the downstream pressure is 3 bar. It is a DN25 pipe and the mass flow is 200 g/s. The fluid is propane.

To my knowledge their should be a temperture drop due to Joule Thompson effect and a temperture due to the acceleration of the propane in the vena contracta. Drops the temperature below the dew point condensate occurs.

My Problem is that I do not know how to calculate the temperature drop.

Can you please help.

Thanks in advance!

 

[BigInch]

T2 = P2 * V2 * T1 / (P1 * V1)
For getting just an imagine, I don't think that your pressure and temperature is sufficiently high to worry about other effects.

Independent events are seldomly independent.

 

[MexTijuana]

I observed sereval times that the pipe downstream had ice on the outer surface. So propane condensate evaporateds and cools down the pipe. Therefore I think that the acceleration in the vena contracta leads to condensate formation.

 

[BigInch]

It is not acceleration. The ice is from the temperature drop from decompression. Joule-Thompson effect may contribute to that as well.

+Acceleration causes velocity increase. Velocity increase causes friction, which causes the product to heat up. In most gas cases the temperature increase from friction is less than the cooling effect of the pressure reduction and the pipeline will cool with length. Liquids can experience the opposite effect.

Independent events are seldomly independent.