Help with determination of water flashing volume.

[JEarlB]

I am trying to determine the volume of gas (water vapor)from 1 lb. of water that is generated (flashed) within a vacuum chamber with the following conditions.

Chamber Pressure: minus 27.96 In. Hg.
Liquid Inlet Flow Temp.: 140 degrees F

The vacuum pressure within the chamber will remain constant at 27.96 In. Hg. with the use of a vacuum pump.

Is the answer to this question found on a Steam Saturation Table? Is the answer, the Specific Volume Steam cu. ft./lb: 333.0?

Thanks in advance.

JEarlB

 

[zekeman]

h(incoming liquid)=h(sattemp liquid @ 27.96 in Hg vac) + x*hfg
x is the quality or fraction of water that is vaporized.
So, find the specific volume of the vapor and multiply by x to get the flash volume for each pound of water.
where
h(sat temp @27.96 in Hg vac)= enthalpy of flashed water
h1 = enthalpy of incoming 140 deg water
hfg= heat of vaporization