Mixed Air Calculator

Gas 1 Temperature (\( T_1 \)):

Gas 1 Composition (\( P_1 \)): %

Gas 2 Temperature (\( T_2 \)):

1. What is Mixed Air Calculator?

Definition: This calculator computes the composition percentage of Gas 2 (\( P_2 \)) and the resulting mixed air temperature (\( T \)) when combining two air streams with known temperatures and the composition percentage of Gas 1.

Purpose: It is used in HVAC systems and environmental engineering to determine the mixed air temperature and composition for air conditioning and comfort.

2. How Does the Calculator Work?

The calculator uses the mixed air temperature formula:

\( T = T_1 \times P_1 + T_2 \times P_2 \)
\( P_2 = 100 - P_1 \)

Where:

\( T \): Mixed air temperature;
\( T_1 \): Temperature of Gas 1;
\( P_1 \): Composition percentage of Gas 1 in the reservoir (%);
\( T_2 \): Temperature of Gas 2;
\( P_2 \): Composition percentage of Gas 2 in the reservoir (%).

Steps:

Enter the temperature of Gas 1 (\( T_1 \)) and its unit (°C, K, or °F).
Enter the composition percentage of Gas 1 (\( P_1 \)) in the reservoir (0 to 100%).
Enter the temperature of Gas 2 (\( T_2 \)) and its unit.
Convert all temperatures to Celsius for calculation.
Calculate \( P_2 \) as \( 100 - P_1 \).
Compute the mixed air temperature \( T \) using the formula.
Convert the mixed air temperature to the selected output unit.
Display the results, formatted in scientific notation if the absolute value is less than 0.001, otherwise with 4 decimal places.

3. Importance of Mixed Air Calculation

Calculating the mixed air temperature and composition is crucial for:

HVAC Systems: Determining the temperature of air after mixing return and outdoor air to maintain desired indoor conditions.
Energy Efficiency: Optimizing the performance of heating and cooling systems by predicting mixed air properties.
Environmental Engineering: Ensuring proper air mixing in industrial processes and environmental control systems.

4. Using the Calculator

Example 1 (Mixing Two Air Streams): Calculate the mixed air properties:

Gas 1 Temperature: \( T_1 = 20 \, \text{°C} \);
Gas 1 Composition: \( P_1 = 60\% \);
Gas 2 Temperature: \( T_2 = 30 \, \text{°C} \);
Gas 2 Composition: \( P_2 = 100 - 60 = 40\% \);
Mixed Temperature: \( T = 20 \times 0.6 + 30 \times 0.4 = 24 \, \text{°C} \);
Result: \( P_2 = 40.0000\% \), \( T = 24.0000 \, \text{°C} \).

Example 2 (Different Units): Calculate the mixed air properties with different units:

Gas 1 Temperature: \( T_1 = 68 \, \text{°F} \);
Gas 1 Composition: \( P_1 = 70\% \);
Gas 2 Temperature: \( T_2 = 303.15 \, \text{K} \);
Convert units: \( T_1 = (68 - 32) \times 5/9 = 20 \, \text{°C} \), \( T_2 = 303.15 - 273.15 = 30 \, \text{°C} \);
Gas 2 Composition: \( P_2 = 100 - 70 = 30\% \);
Mixed Temperature: \( T = 20 \times 0.7 + 30 \times 0.3 = 23 \, \text{°C} \);
Result in °F: \( T = 23 \times 9/5 + 32 = 73.4000 \, \text{°F} \), \( P_2 = 30.0000\% \).

5. Frequently Asked Questions (FAQ)

Q: What does the mixed air temperature represent?
A: The mixed air temperature is the resulting temperature after combining two air streams, weighted by their composition percentages.

Q: Why must \( P_1 \) and \( P_2 \) add up to 100%?
A: Since the two gases are the only components in the mixture, their composition percentages must sum to 100% to represent the total composition.

Q: Can this calculator handle more than two air streams?
A: This calculator is designed for two air streams. For more streams, you would need to extend the formula to include additional terms for each stream.