The hRefConst and eRefConst thermos that were local to
reacting*EulerFoam have been removed and the reference state that they
used has been incorporated into the standard hConst and eConst thermos.
The hConst thermo model now evaluates the enthalpy like so:
Ha = Hf + Hs
= Hf + Cp*(T - Tref) + Hsref (+ equation of state terms)
Where Ha is absolute enthalpy, Hs is sensible enthalpy, Cp is specific
heat at constant pressure, T is temperature, Tref is a reference
temperature and Hsref is a reference sensible enthalpy. Hf, Cp, Tref and
Hsref are user inputs. Of these, Tref and Hsref are new. An example
specification is as follows:
thermodynamics
{
Hf -1.34229e+07;
Cp 2078.4;
Tref 372.76;
Hsref 128652;
}
The ref quantities allows the user to specify a state around which to
linearise the relationship between temperature and enthalpy. This is
useful if the temperature range of the simulation is small enough to
consider the relationship linear, but linearity does not hold all the
way to standard conditions.
To maintain backwards compatibility, Tref defaults to standard
temperature, and Hsref defaults to zero, so a case using hConst thermo
requires no modification as a result of this change.
The only change to the default operation is that to calculate sensible
enthalpy Cp is multiplied by the difference between the current
temperature and the standard temperature, whether as previously Cp was
multiplied by the current temperature only. This means that at standard
conditions sensible enthalpy is now zero, and absolute enthalpy equals
the formation enthalpy. This is more consistent with the definitions of
the various enthalpies, and with other thermo models such as janaf. This
change should only affect reacting cases that use constant thermo
models.
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