Does pressure drop due to friction in a gas pipeline result in a Joule-Thompson temperature drop?

I believe it does, but my colleague disagrees.  I'm asking because he has a very accurate gas pipeline modelling spreadsheet and isn't sure if JT effect should be included in it or not.  Expert opinions to resolve the matter would be appreciated!

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Is your question as simple as it seems or do you have some kind of a problem?

My understanding is that there has to be throttling or an orifice for the J-T effect to occur.

More temperature will be lost due to the water temperature affecting the product on a sub-sea pipeline.

There are systems where leaks can be detected on gas pipelines using temperature sensors to identify cold spots due to the J-T effect at leak points. Again this uses the pressure through the orifice (leak site) principle.  

I've looked for J-T cooling effects due to the friction dP along pipelines and if it is there it is far too subtle for normal oil-field instruments.  In fact, the only times I've ever been able to measure J-T cooling was in choked flow (i.e., sonic flow through a nozzle, orifice, relief valve, or choke - where the upstream pressure was more than about twice downstream pressure).  Ditto for heating due to friction forces--maybe the two factors are so close that they cancel each other out?

Whether the flow is adiabatic or not is a whole other question.  I have checked temps on pipelines many times and always get an approach to soil temp after a reasonably short (meters, not kilometers) thermal entry length.  That heat transfer is far too rapid for an adiabatic assumption to be valid until you have passed the thermal entry length.  Normally when you are concerned about dT effects it is because of a big difference (e.g., 150F out of a compressor going into -10F ambient and then into 50F ground temp).  After a reasonably short distance underground (certainly less than a km) you'll reach an equilibribum where any temp change due to J-T cooling, heat of friction, or the body temperature of microbes will be lost to the heat sink that is the earth.

Heat transfer in pipelines can be very complicated due to the variance in the soil that occurs along the length of the pipeline. If you are trying to determine the distance between line heaters so that the temperature of the gas never falls below the hydrate temperature, then you have be be pessimistic in your estimation of soil type and pipeline depth. If the pipeline is long enough, the gas will eventually reach soil ambient temperature. As the pressure drop per unit length is small, the Joule-Thompson cooling will also be small and will usually be hidden by the heat loss to the soil. Since the difference between dry sandy soil and wet clay (for example) is so great, it is hard to find enough accurate soil information along the total length of the pipeline to accurately predict temperature change or its source.

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