Mixed Air Calculator

Your details

Barometric pressure at the mixing location. Sea level = 101.325 kPa. Adjust for high-altitude sites.
kPa
Volumetric flow rate of the fresh outside air stream.
m3/min
Dry-bulb (standard thermometer) temperature of the outside air.
C
Relative humidity of the outside air stream (0-100%).
%
Volumetric flow rate of the conditioned return air stream from the building.
m3/min
Dry-bulb temperature of the conditioned return air from the space.
C
Relative humidity of the return air stream (0-100%).
%
Mixed air dry-bulb temperature
26.14

Resultant dry-bulb temperature of the combined air stream

Mixed air relative humidity54.8%
Mixed air humidity ratio11.615
Mixed air dew point16.33
Mixed air enthalpy55.9
Mixed air specific volume0.8636
Mixed air flow rate100
Outside air fraction0.2%
Outside air enthalpy90.15
Return air enthalpy47.79
Outside air enthalpy90.15
Return air enthalpy47.79
Mixed air enthalpy55.9
54.8 % RH
Dry<30Comfortable30-60Humid60-80Very humid80+

Mixed air temperature is 26.1 C at 54.8% RH and 55.9 kJ/kg enthalpy.

  • The outside air carries more total heat by 42.4 kJ/kg. Mixing will increase the enthalpy load on the coil.
  • Outside air fraction is 19.1%, a typical commercial HVAC blending ratio for occupied spaces.
  • Mixed air humidity ratio is 11.61 g/kg, corresponding to 54.8% RH - within the comfortable 30-60% range.
  • Dew point is 16.3 C. Cooling the mixed air below this temperature will cause condensation on the coil, which removes latent heat and dehumidifies the supply.

Next stepUse the mixed air conditions as the entering condition for your cooling or heating coil sizing. Compare enthalpy to the desired supply air condition to find total coil load.

 = Powered by OnlyCalculators