Fouling Heat Transfer

Reference data and engineering information about fouling heat transfer for heat transfer applications.

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Overview

Engineering reference data for Fouling Heat Transfer in heat transfer.

Key Formulas

Fourier's Law

$q = -k \nabla T$

Heat flux proportional to temperature gradient.

Convective Heat Transfer

$Q = hA(T_s - T_\infty)$

Heat transfer between surface and fluid.

Stefan-Boltzmann Law

$q = \varepsilon \sigma T^4$

Radiative heat flux from a surface.

Thermal Resistance

$R_{th} = \frac{L}{kA}$

Resistance to heat conduction.

Symbol	Description	Unit
$q$	Heat flux	W/m²
$k$	Thermal conductivity	W/(m·K)
$h$	Convection coefficient	W/(m²·K)
$T$	Temperature	K
$\varepsilon$	Emissivity	—
$\sigma$	Stefan-Boltzmann constant	5.67×10⁻⁸ W/(m²·K⁴)

Typical fouling factors (Rd) for various fluids in heat exchangers.
Material(-)	Fouling Factor (Rd)(m²K/W)
Alcohol vapors	0.00009
Boiler feed water, treated above 325 K	0.0002
Fuel oil	0.0009
Industrial air	0.0004
Quenching oil	0.0007
Refrigerating liquid	0.0002
Seawater below 325 K	0.00009
Seawater above 325 K	0.0002
Steam	0.00009

The fouling factor ( $R_d$ ) is used to adjust the clean heat transfer coefficient ( $U$ ) to account for the insulating effect of deposits. To determine the design heat transfer coefficient for a fouled exchanger ( $U_d$ ), use the rearranged formula:

$U_d = \frac{1}{R_d + \frac{1}{U}}$

This ensures the exchanger is sized to deliver the required heat duty even after fouling occurs. Selecting the appropriate $R_d$ from the table based on your fluid and conditions is a critical step in thermal design.

References

Original Source

Source: engineeringtoolbox.com