Air side

AHU Airflow Sizing Calculator

Supply airflow, coil face area and equivalent duct diameter from a cooling load and supply-return ΔT. First-pass sizing to challenge over-specified plant.

Inputs

Cooling load (kW sensible)Supply-Return ΔT (°C)Coil face velocity (m/s)Duct velocity (m/s)

Result

Supply mass flow11.94 kg/s

Supply airflow9917 L/s

Supply airflow35702 m³/h

Coil face area3.97 m²

Main duct area1.65 m²

Equivalent round duct1451 mm Ø

How this works

Q = ṁ · cp · ΔT with cp,air = 1.005 kJ/kg·K and ρ = 1.204 kg/m³. Coil face velocity above ~2.8 m/s risks moisture carry-over on wet coils.

Main duct velocities of 5-7 m/s balance acoustics against space. Above 8 m/s consider acoustic attenuators and larger risers.

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