Real Gas UDF
 

I am doing real gas analysis for that I used RK EOS-UDF (which is available in UDF manual).

I have doubt about the value need to give for H_REF and S_REF.
Please someone answer what is value needed to give at this H_REF and S_REF.

I have given H and S value corresponds to NIST data but RK EOS over estimates than H and S value.


Below is the part of the UDF.

/* REFERENCE STATE */

#define P_REF 101325
#define T_REF 288.15

/* OPTIONAL REFERENCE (OFFSET) VALUES FOR ENTHALPY AND ENTROPY */

#define H_REF 0.0
#define S_REF 0.0

Does the NIST data use the same reference points (T,P) and (H,S)?