Learning Forum

[cwl6750084]

I am wondering if anyone knows how does Fluent compute the enthalpy values given in Surface Integral > Temperature > Enthalpy. The values that I got from fluent for a flow through CD nozzle are in the range of -50000 to 40000 J/kg. These are way off than the values given in any steam table. Why are there negative values as well? I could not figure out what is the reference value (the thermal condition that give zero enthalpy) in Fluent to try to shift the results.nnAny helps appreciate.n

[Rob]

Have a look in the material properties, there's a reference value there. The usual mistake (without phase change) is not correctly accounting for a variable cp in the hand calculation. n

[cwl6750084]

Thanks for your suggestion. If I add the enthalpy given by surface integral and the value in the materials properties, that number should match the one given in steam table? For example, the enthalpy of the following would be 29515140/18 + 53606 = 1693336 J/kg if I look it up in a steam table? nnn

[cwl6750084]

I tried adding the values together, however, they are still way off from the tabulated values in the steam table. Even the enthalpy for pure water at the inlet are way off.n