Flow Velocity Air Ducts

Overview

Engineering reference data for Flow Velocity Air Ducts in HVAC systems.

Key Formulas

Sensible Heat

$Q = \dot{m} c_p \Delta T$

Heat causing temperature change.

Latent Heat

$Q = \dot{m} h_{fg} \Delta\omega$

Heat causing moisture change.

COP (Cooling)

$COP = Q_c / W$

Coefficient of performance.

Variables

Symbol	Description	Unit
$Q$	Heat transfer	W
$\dot{m}$	Mass flow rate	kg/s
$c_p$	Specific heat of air	J/(kg·K)
$\Delta T$	Temperature difference	K

Recommended Air Velocity Guidelines

Air velocities in ducts and pipes should not exceed certain limits to avoid high pressure loss and unacceptable noise generation. The following table provides guidelines for some typical applications.

These velocity ranges are practical guidelines. Selecting a velocity within these limits helps balance energy efficiency, noise control, and system cost. High velocities increase pressure drop and fan energy consumption, while excessively low velocities may require oversized, costly ductwork.

References

• Original Source