Critical Pressure of Real Gas using Reduced Wohl Equation given Actual and Critical Parameters Calculator

Critical Pressure Formula:

\[ P_c = \frac{P}{\left(\frac{15T_r}{4(V_r - \frac{1}{4})}\right) - \left(\frac{6}{T_r V_r (V_r - \frac{1}{4})}\right) + \left(\frac{4}{T_r^2 V_r^3}\right)} \]

Pressure of Gas (P):

Temperature of Real Gas (T):

Critical Temperature (T_c):

Molar Volume (V_m):

m³

Critical Molar Volume (V_c):

m³/mol

Critical Pressure (P_c):

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1. What is Critical Pressure of Real Gas using Reduced Wohl Equation?

Definition: This calculator determines the critical pressure of a real gas using the reduced Wohl equation, which relates actual gas parameters to their critical values.

Purpose: It helps in thermodynamic analysis and prediction of gas behavior near critical conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ P_c = \frac{P}{\left(\frac{15T_r}{4(V_r - \frac{1}{4})}\right) - \left(\frac{6}{T_r V_r (V_r - \frac{1}{4})}\right) + \left(\frac{4}{T_r^2 V_r^3}\right)} \]

Where:

\( P_c \) — Critical Pressure (Pa)
\( P \) — Pressure of gas (Pa)
\( T_r \) — Reduced temperature (\( T/T_c \))
\( V_r \) — Reduced volume (\( V_m/V_c \))
\( T \) — Temperature of real gas (K)
\( T_c \) — Critical temperature (K)
\( V_m \) — Molar volume (m³)
\( V_c \) — Critical molar volume (m³/mol)

Explanation: The formula accounts for deviations from ideal gas behavior using reduced parameters.

3. Importance of Critical Pressure Calculation

Details: Critical pressure is essential for understanding phase behavior, designing industrial processes, and predicting thermodynamic properties of real gases.

4. Using the Calculator

Tips: Enter the gas pressure, temperature, critical temperature, molar volume, and critical molar volume. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is reduced temperature and volume?
A: Reduced parameters are ratios of actual values to critical values (T/Tc and V/Vc).

Q2: Why use the Wohl equation?
A: The Wohl equation provides a simple yet accurate way to model real gas behavior.

Q3: What are typical critical pressure values?
A: Critical pressures vary widely (e.g., 3.39 MPa for water, 7.38 MPa for CO₂).

Q4: How accurate is this calculation?
A: Accuracy depends on how well the Wohl equation fits your specific gas.

Q5: What if I get negative results?
A: Check your input values - all must be positive and physically meaningful.