Enhancements were made to the (VB). For developers, the FORTRAN code was reorganized to be threadsafe, enabling the use of multi-core processing. Furthermore, NIST introduced a 64-bit version of the Dynamic Link Library (DLL) for seamless integration with 64-bit versions of Excel and MATLAB. This update made high-performance property calculations more accessible and scalable than ever before.
For mixtures not explicitly calibrated (e.g., a proprietary blend), REFPROP 9 uses a mixing rule for viscosity. Always validate against a single experimental data point if possible, or simply note the increased uncertainty in your reports.
Supercritical carbon dioxide (scCO2) is used for decaffeination, dry cleaning, and particle formation. REFPROP 9 accurately predicts the dramatic changes in density and solubility near the critical point (Tc=304K, Pc=73.8 bar), which is impossible with cubic equations of state.
To calculate mixture properties, REFPROP 9 employs a Helmholtz energy mixture model (often implementing Kunz and Wagner's GERG models for natural gas components). This model applies advanced mixing rules to the pure-fluid equations, using interaction parameters derived from experimental binary mixture data to account for how different molecules interact with one another. Software Integration and Interfaces nist refprop 9
Even today, REFPROP 9.1 represents a stable, mature, and historically vital snapshot of the state of the art in its time. It serves as a crucial reference for understanding the evolution of fluid property models and remains a functional tool for maintaining legacy systems. For anyone in the field of thermodynamics, understanding the features and impact of REFPROP 9 provides invaluable context for the ongoing development of this ever-evolving standard.
Released as a stable, mature version, REFPROP 9 represents the culmination of years of experimental data correlation. It supports over 147 pure fluids (depending on the specific sub-version) and allows users to calculate properties for mixtures containing up to 20 components.
The reliability of REFPROP 9 stems from its implementation of highly accurate mathematical models. Enhancements were made to the (VB)
Near the critical point, REFPROP 9 may struggle with iteration. If you receive an "iteration limit exceeded" error, switch the input to temperature-density (T,ρ) instead of temperature-pressure (T,p). Density remains single-valued in the two-phase region, even when pressure does not.
Version 9.0 introduced updated equations of state for fluids like cyclopentane, R-1234yf, and R-1234ze(E), and expanded the number of binary mixtures with interaction parameters from 303 to 639. Technical Architecture
REFPROP 9 supports a vast library of pure fluids and allows users to create custom mixtures of up to 20 components. Pure Fluids REFPROP uses highly complex
Engineers designing compressors, expansion valves, and heat exchangers use REFPROP 9 to model the exact refrigerant behavior. For example, calculating the isentropic efficiency of a compressor requires precise entropy values at the inlet and outlet. Using REFPROP 9 reduces design margin risks from 10% (using ideal gas tables) to under 1%.
NIST REFPROP 9 is a computer program designed to calculate the thermodynamic and transport properties of industrially important fluids and their mixtures. Rather than relying on simple ideal gas laws or coarse generalized correlations, REFPROP uses highly complex, empirical equations of state that have been fitted to high-precision experimental data.
Used for transport properties like viscosity and thermal conductivity when experimental data is sparse.
Users can access the program through a Graphical User Interface (GUI) .