Compressed water properties
Compressed water properties
(OP)
Hello-
I was wondering if anyone had info on compressible water. I have a water system that is operating between 3000-4000psi. I'm using Pipe-Flo software to do my preliminary design and it is telling me that the fluid is changing state. The steam tables show a critical pressure of 3208psi @ 750deg. My fluid will be at most 80 deg.
I was wondering if anyone had info on compressible water. I have a water system that is operating between 3000-4000psi. I'm using Pipe-Flo software to do my preliminary design and it is telling me that the fluid is changing state. The steam tables show a critical pressure of 3208psi @ 750deg. My fluid will be at most 80 deg.





RE: Compressed water properties
http://www.nist.gov/data/nist23.htm
I did a quick check and it looks like about 1% increase in density for water between atmospheric pressure and critical pressure at about 80F.
Above critical pressure, the fluid isn't really "liquid" any more since it can't boil, but below critical temperature it is also hard to call it a "gas." It is now a "supercritical fluid." So it could be that the software you are using is having a hard time classifying it, I don't know. Or maybe it is just an informational message and your run isn't stopping. But if the software lets you, you can still get away with calling it "incompressible liquid" as long as you don't go too much higher in pressure or temperature.
RE: Compressed water properties
RE: Compressed water properties
When you heat water/steam above a temperature of 705 F you can no longer liquify it by compressing it. The vapor pressure of water at 705 F is 3200 psi and these are called the critical properties. But water at this pressure and 80 F is still just water. This is the pressure you would find about 1.75 miles down in the sea. It would probably be a bit colder than 80 F, but it's still just water.
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