CFD Online Logo CFD Online URL
Home > Forums > CFX

Static enthalpy in CFX with IAPWS

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   January 18, 2017, 08:35
Default Static enthalpy in CFX with IAPWS
New Member
Join Date: Apr 2012
Posts: 27
Rep Power: 7
Delcraft is on a distinguished road
Sponsored Links
Hello all,

I have the following problem: I calculate steam turbine in ANSYS CFX and when performing the post-processing I encountered large discrepancies between correlating variables.
Suppose I want to derive static enthalpy at my inlet boundary using the static entropy, temperature, pressure and density with the following formula (all parameters are massflow-averaged except pressure which is surface-averaged):

H_{in} = T_{in} \cdot S_{in} + \frac{p_{in}}{\rho_{in}}

but when I calculate the static enthalpy using the formula massFlowAve(Static Enthalpy)@INLET, I get the value which is two times lower than that of the expression above.

One of my ideas was that I didn't take into account the reference entropy and temperature to subtract it from the expression, but in CFX Theory Guide it is written that reference enthalpy and entropy for IAPWS library are set to 0 [J/kg]:

The reference state for the IAPWS library is the triple point of water. Internal energy, entropy and enthalpy are all set to zero at this point.
But I found from IAPWS database that the reference conditions for steam are Sref = 9.155 [kJ/kg/K] and Tref = 273.16 [K]. However, even when I substracted these values (Sref*Tref) from the first expression I didn't get the same numbers.

Maybe someone encountered such problem and can help me with that.

Thanks in advance,

Delcraft is offline   Reply With Quote
Sponsored Links


enthalpy equation, iapws, reference values

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Differences between CFX and OpenFOAM regarding convergence and robustness! magjohan OpenFOAM Running, Solving & CFD 4 February 26, 2015 11:26
fprint problem MASOUD Fluent UDF and Scheme Programming 5 October 30, 2011 17:08
ATTENTION! Reliability problems in CFX 5.7 Joseph CFX 14 April 20, 2010 15:45
static enthalpy computation in cfx Ben Akih CFX 2 May 10, 2006 05:31
potential energy& static enthalpy in buoyant flow Atit CFX 0 May 3, 2006 10:05

Sponsored Links

All times are GMT -4. The time now is 11:55.