Steam Energy Flow

[rob_mather]

Hi,
I need to calculate the energy flow down a steam line. I have the mass flow, gauge pressure and temperature of the steam and would like an equation/formula to put into the SCADA/DCS to work out the Energy flow in the line. There is a variable amount of superheat in the steam so I need to compensate with the temperature. Has anyone got a simple formula to calculate it dynamically?
The gauge pressure ranges from between 3 and 5 barg and the temperature between 180 and 220°C, normal operation conditions 3.5 barg and 205°C.
Thanks in advance

[Hudson]

Find something called a Mollier chart for steam.

[rob_mather]

Thanks Hudson. Unfortunately I haven't got the facility to look up a value in a table or chart. I was after the equation that would produce the curve on the chart to enter in the scada for the calculation. I thought there might be a rough mathematical relationship between the variables to enable a viable energy figure to be worked out, especially since I'm only looking at a narrow operation band, but it is looking like it is too complex to work out

[Cake of Doom]

The "simple" equation is h=u+Pv.

h=Enthalpy (kJ/kg)

u=internal energy

P=pressure

v= Volume

You'll be screaming out for chart or a big old MathCAD lesson after you're done trying to have fun with this.

PS

I hated Thermodynamics. Still do, to a degree.