Effective Thermophysical Constants of Thousands of Fluids. I: Critical Temperature, Critical Pressure, Critical Density, and Acentric Factor

Thermophysical constants of pure fluids, including critical temperature, Tc, critical pressure, pc, critical density, ρc, and acentric factor,
ω, are fundamental for calculating thermophysical properties
over wide pressure and temperature ranges. However, complete sets
of (Tc, pc, ρc, and ω) values, along with traceable
determination methods and careful evaluations, are available only
for a limited number of fluids in commonly used databases. To address
this gap, we compiled, examined, and fitted complete (Tc, pc, ρc, ω) values of 1422 pure fluids, mainly from three sources:
NIST’s REFPROP 10.0 database, NIST’s ThermoData Engine
10 and Dortmund Data Bank 2023. The fitting was carried out using
the experimental temperature, pressure, and density (T, p, ρ) data and saturated temperature and
pressure (Tsat, psat) data, primarily with the Yang-Frotscher-Richter EoS. The
results should be considered optimized values that best match experimental
data, rather than absolute physical constants. The reliability of
each value was assessed to guide future experimental research. This
study is the first in a series aimed at determining effective thermophysical
constants of thousands of fluids for the accurate calculation of all
important thermophysical properties. The results will be implemented
in the software OilMixProp and Ebsilon for practical applications.