Finding Quality Using Specific Volume?

[dillonmhudson]

Can you or can you not use specific volume to find quality? I know it can be found using mass but can you use specific volume?

 

[brewnog]

Quality of what?

 

[dillonmhudson]

Um THE quality:
http://www.engineersedge.com/thermodynamics/quality.htm

When given a mixture of water vapor and liquid water.

 

[dillonmhudson]

Vapor quality according to wiki:
http://en.wikipedia.org/wiki/Vapor_quality

 

[Q_Goest]

Can you or can you not use specific volume to find quality? I know it can be found using mass but can you use specific volume?

You could if you also know something else about the fluid. For example, pressure or temperature. You could also find it if you knew enthalpy, entropy, internal energy or some other https://www.physicsforums.com/showthread.php?t=54198", you need 2.

For example, let's say we have steam with a specific volume of 0.0435 ft³/lbm. If that steam is at atmospheric pressure (saturation temperature 212 F), the quality is roughly 0.1%. But if the pressure is 1000 psig (saturation temperature 547 F), the quality is roughly 44%. You need a second state variable to pin down the physical state of the fluid.

 

[NSSER]

You could if you also know something else about the fluid. For example, pressure or temperature. You could also find it if you knew enthalpy, entropy, internal energy or some other state variable. What you're trying to do is determine the state of the fluid, which you can't do with just one state variable, you need 2.

For example, let's say we have steam with a specific volume of 0.0435 ft³/lbm. If that steam is at atmospheric pressure (saturation temperature 212 F), the quality is roughly 0.1%. But if the pressure is 1000 psig (saturation temperature 547 F), the quality is roughly 44%. You need a second state variable to pin down the physical state of the fluid.

Q Goest, can you explain how you made these calculations? Are you references some table or using a formula?

Thanks.

 

[Q_Goest]

Q Goest, can you explain how you made these calculations? Are you references some table or using a formula?

I use a computerized database, basically steam tables on a computer.

 

[jehan60188]

v = x*vG + (1-x)vL

if you know pressure, or temperature, then you can look it up
i think you may need one more variable

check out steam tables, and start fiddling with the numbers (just start writing stuff down, make sure you do good book keeping, and something might pop out)

edit: ignore me, do what Q_goest says

edit again: if you know mass, then specific volume is a function of density. you'd need temperature, or pressure.
is there a specific problem you're trying to solve, or just curious?