Mixed Air Temperature
Calculate mixed air temperature from two gas streams using the weighted average formula. Free online thermodynamics calculator with charts for HVAC and physics.
About This Calculator
The Mixed Air Temperature Calculator computes the equilibrium temperature when two gas streams with different temperatures and concentrations are mixed together. This calculation is essential in thermodynamics, HVAC system design, ventilation engineering, and physics education.
The calculator uses the weighted average formula: T = (T₁ × P₁ + T₂ × P₂) / (P₁ + P₂), where T₁ and T₂ are the temperatures of the two gas streams, and P₁ and P₂ are their respective percentages. The result represents the final temperature after the gases reach thermal equilibrium.
This concept is fundamental to understanding the Zeroth Law of Thermodynamics and is widely applied in heating, ventilation, and air conditioning systems where outside air is mixed with return air to achieve desired supply air temperatures. The calculator also supports the HVAC mixed air temperature formula using flow rates for practical engineering applications.
How to Use
- Enter the temperature of Gas 1 in degrees Celsius
- Enter the percentage of Gas 1 in the mixture (0-100%)
- Enter the temperature of Gas 2 in degrees Celsius
- Enter the percentage of Gas 2 in the mixture (0-100%)
- Click Calculate to compute the mixed air temperature
Applications
Mixed air temperature calculations are used in HVAC system design for determining supply air temperatures, in thermodynamics for understanding gas mixtures and thermal equilibrium, in industrial processes where gas streams are combined, and in environmental engineering for air quality management.
Frequently Asked Questions
What is the mixed air temperature formula?
The mixed air temperature formula is T = (T1 × P1 + T2 × P2) / (P1 + P2), where T1 and T2 are the temperatures of two gas streams, and P1 and P2 are their respective percentages in the mixture. Since the percentages sum to 100%, this simplifies to the weighted average of the individual temperatures.
How do you calculate mixed air temperature in HVAC systems?
In HVAC systems, mixed air temperature (supply air temperature) is calculated using Ts = (cfm_oa × Toa + cfm_ra × Tra) / (cfm_oa + cfm_ra), where cfm_oa is the outside air flow rate, Toa is the outside air temperature, cfm_ra is the return air flow rate, and Tra is the return air temperature.
What is thermal equilibrium?
Thermal equilibrium is a state where two or more systems are at the same temperature and there is no net transfer of heat between them. This concept is based on the Zeroth Law of Thermodynamics and is fundamental to understanding mixed air temperature calculations.
How accurate is the mixed air temperature calculator?
The mixed air temperature calculator uses the standard weighted average formula and computes results to two decimal places for precision. The calculation is exact for ideal gas mixtures and provides accurate results for HVAC system design, thermodynamics problems, and physics experiments.
Can I share my mixed air temperature calculation results?
Yes, all input values are saved in the URL as query parameters. You can bookmark the URL or share it with others, and when they open it, the same inputs will be pre-filled and the calculation will run automatically.
What units are used for mixed air temperature?
The calculator uses degrees Celsius (°C) for temperature inputs and results. Percentages are used for the composition of each gas stream. The formula works with any temperature scale as long as all temperatures are in the same unit.
What happens if the percentages of the two gases do not sum to 100%?
If the percentages do not sum to 100%, the calculator still computes the correct weighted average using the actual total. The contribution of each gas is normalized so that the proportions are relative to the total mixture, giving the correct mixed temperature.
Is the mixed air temperature formula applicable to liquids?
Yes, the weighted average temperature formula applies to any substances at thermal equilibrium, including liquids and solids. However, it assumes no phase changes occur and that the specific heat capacities are similar. For precise calculations with different materials, calorimetry should be used.