How this calculator works
An adiabatic mixing balance with equal specific heats makes temperature a mass-flow-weighted average. The fraction mode therefore uses stream 1 mass fraction. The volume-flow approximation is valid only for equal densities or flow rates converted to one common reference state. If inlet densities or humidity differ materially, use the full mixed-air tool, which balances dry-air mass, water vapour and enthalpy.
Formula
Tmix = f T1 + (1 - f)T2; f = m1/(m1 + m2). At a common reference density, f = Vdot1/(Vdot1 + Vdot2).
Worked example
Mixing one part of 280 K air with three parts of 300 K air gives 295 K. Equal mass flows at 290 K and 310 K give 300 K.
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Frequently asked questions
Does the fraction have to total 100%?
Only stream 1 is entered; stream 2 automatically makes up the remainder.
Can the result be outside both inlet temperatures?
Not for passive adiabatic mixing under these assumptions.
Should I use actual inlet volume flows at different temperatures?
For better accuracy, use the full mixed-air calculator to account for different inlet densities and moisture.