A Warning message in AFT Arrow

Full message is:

Maximum system pressure exceeded enthalpy table's maximum pressure of X. Enthalpy is extrapolated for pressures exceeding this value.

This warning indicates that the AFT Standard fluid library is being used with the Table Enthalpy model, and that the maximum pressure exceeded the maximum pressure for the enthalpy data. The Table enthalpy model uses interpolation based on the current pressure to calculate the enthalpy at a given temperature. If the pressure at a point in the model exceeds the maximum pressure data is available for in the AFT Standard fluid library, then the enthalpy must be extrapolated, leading to inaccuracy in the results. Extrapolation far above the maximum temperature will lead to increased inaccuracy, and may cause convergence issues. Consider using an alternate fluid library such as NIST Refprop or Chempak with a higher maximum pressure.