Pressure of Real Gas using Peng Robinson Equation Calculator

Peng-Robinson Equation:

\[ p = \frac{[R] \times T}{V_m - b_{PR}} - \frac{a_{PR} \times \alpha}{V_m^2 + 2 \times b_{PR} \times V_m - b_{PR}^2} \]

Temperature:

Molar Volume:

m³/mol

Peng-Robinson Parameter b:

Peng-Robinson Parameter a:

α-function:

Pressure (Pa):

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1. What is the Peng-Robinson Equation?

Definition: The Peng-Robinson equation is a thermodynamic equation of state used to describe the behavior of real gases.

Purpose: It provides more accurate pressure predictions than the ideal gas law, especially near the critical point.

2. How Does the Calculator Work?

The calculator uses the Peng-Robinson equation:

\[ p = \frac{[R] \times T}{V_m - b_{PR}} - \frac{a_{PR} \times \alpha}{V_m^2 + 2 \times b_{PR} \times V_m - b_{PR}^2} \]

Where:

\( p \) — Pressure (Pa)
\( [R] \) — Universal gas constant (8.314 J/mol·K)
\( T \) — Temperature (K)
\( V_m \) — Molar volume (m³/mol)
\( b_{PR} \) — Peng-Robinson parameter b
\( a_{PR} \) — Peng-Robinson parameter a
\( \alpha \) — α-function (temperature-dependent)

3. Importance of Peng-Robinson Equation

Details: This equation is widely used in chemical engineering and petroleum industries for modeling hydrocarbon systems and other non-ideal gases.

4. Using the Calculator

Tips: Enter all required parameters. Temperature and molar volume must be positive values. Parameters a, b, and α are typically determined from experimental data or correlations.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between ideal gas law and Peng-Robinson?
A: Peng-Robinson accounts for molecular size and intermolecular forces, making it more accurate for real gases.

Q2: How do I determine parameters a and b?
A: They are typically calculated from critical properties (Tc, Pc) and the acentric factor (ω) of the substance.

Q3: What is the α-function?
A: It's a temperature-dependent function that modifies the attractive term in the equation.

Q4: What units should I use?
A: Use Kelvin for temperature, m³/mol for molar volume, and consistent units for parameters a and b.

Q5: When is this equation most accurate?
A: It works well for non-polar and slightly polar compounds, especially hydrocarbons.