How to Determine Superheated Ammonia Vapor Density?

[MAPower]

How do you determine the vapor density of superheated ammonia vapor at the following conditions:

- pressure = 15 psig
- temperature ~ 130 deg F

 

[25362]

The value is 0.081121 lb[sub]m[/sub]/ft[sup]3[/sup] taken from

http://webbook.nist.gov/cgi/cbook.cgi?Name=ammonia&Units=SI

press on fluid properties.

 

[mbeychok]

MAPower:

You could also use the ideal gas law to calculate the density:

lb/ft[sup]3[/sup] = (MW/10.73)(P/T)

where:
MW = molecular weight = 17.03 for ammonia
P = absolute pressure in psia = 15 + 14.696 = 29.696 psia
T = Temperature in deg Rankine = 130 + 460 = 590 deg R

lb/ft[sup]3[/sup] = (17.03/10.73)(29.696/590) = 0.0799

which is within 1.5% of the NIST value of 0.081121 given you by user 25362.

You might find it useful to read:

http://www.air-dispersion.com/formulas.html

Milton Beychok
(Visit me at www.air-dispersion.com)
.