We’re excited to announce a major expansion in CHEMCAD simulation accuracy: the integration of REFPROP into the CHEMCAD user interface.
With the newest release of CHEMCAD NXT (version 1.2.0), REFPROP is available as a built-in thermophysical property calculator, allowing users to seamlessly switch between CHEMCAD’s default models and REFPROP’s high-fidelity calculations for pure fluids and mixtures. This integration brings new levels of precision to simulations involving refrigerants, natural gas blends, and supercritical fluids without requiring separate installation or licensing.
What is REFPROP and Why Does It Matter?
REFPROP is an advanced database and calculation tool developed by the National Institute of Standards and Technology (NIST) for the accurate prediction of thermophysical properties. Despite often being referred to as a “database,” REFPROP is technically a calculation engine that uses highly detailed equations to calculate thermodynamic and transport properties. These detailed equations are considered to be the most accurate available worldwide, trusted in both industry and academia.
With the integration of REFPROP, CHEMCAD offers expanded capabilities for cases where REFPROP provides higher accuracy prediction for thermophysical properties. This flexibility allows users to select the best tool for the job, whether optimizing refrigeration cycles, evaluating low-GWP refrigerants, or designing supercritical CO₂ systems.
Key Considerations
Integrating REFPROP into CHEMCAD brings powerful advantages for engineers modeling complex fluids and mixtures. While unmatched in its precision for fluid property calculations, REFPROP is not universally applicable. As with any model, its effectiveness depends on the context and process requirements.
Here's what to expect when using REFPROP within CHEMCAD:
- Access to the most accurate thermophysical property models available for pure fluids and well-known mixtures
- Component selection exclusively from the REFPROP chemical database (maximum of 20 components per simulation)
- Improved simulation fidelity for specialty gases, refrigerants, hydrocarbons, alcohols, glycols, and natural gas blends
- Reliable performance under extreme conditions such as high pressure, low temperature, and near-critical or supercritical states
- Enhanced design accuracy for heat pumps, refrigeration cycles, and energy systems, reducing overdesign and energy waste
- Easier evaluation of low-GWP refrigerants to support sustainability and regulatory compliance
- Safeguards to prevent users from attempting to model processes that are outside the scope of REFPROP’s design, including three-phase distillation and solids handling
Understanding REFPROP’s strengths and limitations helps engineers choose the right property model for their simulation goals, balancing accuracy with performance and feature availability.
Example: Supercritical CO2
Supercritical CO₂ systems are a prime example of where REFPROP adds significant value to CHEMCAD simulations. Supercritical CO2 is important in power generation, carbon capture, refrigeration, and chemical extraction, where accurate property prediction is essential for performance and safety.
Traditional models often struggle at extreme process conditions, leading to errors in density, phase behavior, and equipment sizing. REFPROP provides significantly better alignment with experimental data, especially at low temperatures and high pressures.
Engineers can use CHEMCAD to run sensitivity analyses, compare results to equation-of-state models, and optimize designs with greater confidence. This level of accuracy is especially valuable for:
- Closed-loop Brayton cycles for high-efficiency power generation
- CO₂ pipeline transport and sequestration in carbon capture projects
- Heat pumps and refrigeration systems
- Supercritical extraction processes in chemical and food industries
By using REFPROP in CHEMCAD, engineers can reduce uncertainty, improve reliability, and make better-informed design decisions for systems operating near or above the critical point.
How Can I Get Started Using REFPROP in CHEMCAD?
To access REFPROP, users must upgrade to CHEMCAD version 1.2.0 or later, where the integration is available directly within the CHEMCAD interface. Once installed, navigate to the Thermophysical tab in the command ribbon, where you’ll find a new section labeled Library. This is where you can switch between CHEMCAD’s traditional property library and the REFPROP calculation engine.
Before switching, make sure your flowsheet meets the minimum criteria. The Component Selection dialog after switching looks familiar, but only displays REFPROP’s pure components and does not allow user-defined chemicals, solids, electrolytes, or petroleum assays.
To learn more about REFPROP’s capabilities and limitations, click the Help button within the CHEMCAD interface or reach out to the CHEMCAD support team for guidance. Whether you rely on traditional models or switch to the REFPROP engine, you can rely on CHEMCAD’s simulation capabilities built for accuracy, flexibility, and performance.