Length Belt Fans Motors

Overview

Engineering reference data for Length Belt Fans Motors 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

Belt Types and Applications

Belt-driven fans are common in heating, ventilation, air-conditioning and cooling (HVAC) systems. The belts (or chains) transfer power and convert torque through rotational motion between shafts. There are two primary types:

• Friction belts: Transfer power through friction between the pulley and the belt.
• Synchronous belts: Transfer power through a mechanical linkage between the teeth in the belt and the grooves in the pulley.

Belt Length Calculation Details

The formula for calculating the belt length (l_b) assumes a specific geometry between two pulleys (sheaves) of different diameters. The derivation accounts for the arcs of contact on each pulley and the straight sections of the belt between them.

$l_b = \frac{\pi d_m}{2} + \frac{\pi d_f}{2} + 2 l_{fm} + \frac{(d_f - d_m)^2}{4 l_{fm}}$

Where:

• d_m is the motor pulley diameter
• d_f is the fan pulley diameter
• l_{fm} is the center-to-center distance between the motor and fan pulleys
• The term (d_f - d_m)^2 / (4 l_{fm}) is a correction factor for the difference in pulley sizes.

Belt Speed Reference Table

The following table provides belt velocity (ft/min) for common pulley pitch diameters (inches) at various motor speeds (rpm).

Interactive Charts

References

• Original Source