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$Reference

 

The $REFERENCE directive allows the default reference state for a specified fluid to be changed.  The format for this directive is

 

$REFERENCE Fluid ReferenceID

 

where 

 

Fluid is the name of the fluid, e.g., R134a.

 

ReferenceID is one of the following:

     

DFT -   the reference is reset to the default value.  See the fluid property information for the specified fluid to determine the default reference state

 

NBP -  the values of specific enthalpy and specific entropy are each set to 0 for saturated liquid at the normal boiling point.  Note that this option is not applicable to fluids for which the critical pressure is less than one atmosphere.  In this case, the reference will be reset to the default value.

 

ASH -   the values of specific enthalpy and specific entropy are each set to 0 for saturated liquid at -40C (-40F). This is the ASHRAE standard reference.   Note that this option is not applicable to fluids for which the critical temperature is less than -40C.  In this case, the reference will be reset to the default value. 

 

IIR -      the value of specific enthalpy is set to 200 kJ/kg and the value of specific entropy is set to 1.0 kJ/kg-K for saturated liquid at 0C (273.15 K). This is the standard reference state for the International Institute of Refrigeration.   Note that this option is not applicable to fluids for which the critical temperature is less than 0C.  In this case, the reference will be reset to the default value.   

 

The $Reference directive can not be placed in a Function, Procedure, Subprogram or Module.

 

 

See also: Property Plots, Directives