This information is part of the Modelica Standard Library maintained by the Modelica Association.

This function calculates the density and temperature of R134a from absolute pressure and specific entropy in one-phase region. The function calls the fundamental helmholtz equation of Tillner-Roth (1994) which is requiring density and temperature for input. Thus, a newton iteration is performed to determine density and temperature. The newton iteration stops if the inputs for pressure difference delp and specific entropy difference dels are larger than the actual differences derived from the newton iteration.

Restrictions

The function shall only be used for one-phase inputs since the fundamental equation is not valid for two-phase states. The iteration could fail for liquid states with high pressures.

(d, T, error) = dtofpsOnePhase(p, s, delp, dels)

p	Type: AbsolutePressure (Pa) Description: Pressure
s	Type: SpecificEntropy (J/(kg·K)) Description: Specific entropy
delp	Type: AbsolutePressure (Pa) Description: Absolute iteration accuracy
dels	Type: SpecificEntropy (J/(kg·K)) Description: Absolute iteration accuracy

d	Type: Density (kg/m³) Description: Density
T	Type: Temperature (K) Description: Temperature
error	Type: Integer Description: Error flag: trouble if different from 0