Fouling and Heat Transfer

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During operation with most liquids and some gases a dirt film gradually builds up on the heat-transfer surface. The deposit is referred to as fouling. 

The increased thermal resistance of the deposit can generally be obtained only from actual tests or experience. The fouling factor can be determined from the relation 

R_d = 1 / U_d - 1 / U   (1)

where 

R_d = fouling factor - or unit thermal resistance of the deposit (m²K/W)

U_d = thermal conductance of heat exchanger after fouling (W/m²K)

U = thermal conductance of clean heat exchanger (W/m²K)

Typical Fouling Factors

• Alcohol vapors : R_d = 0.00009 (m²K/W)
• Boiler feed water, treated above 325 K : R_d = 0.0002 (m²K/W)
• Fuel oil : R_d = 0.0009 (m²K/W)
• Industrial air : R_d = 0.0004 (m²K/W)
• Quenching oil : R_d = 0.0007 (m²K/W)
• Refrigerating liquid : R_d = 0.0002 (m²K/W)
• Seawater below 325 K : R_d = 0.00009 (m²K/W)
• Seawater above 325 K : R_d = 0.0002 (m²K/W)
• Steam : R_d = 0.00009 (m²K/W)

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Related Topics

• Thermodynamics - The effects of work, heat and energy on a system

Related Documents

• Conductive Heat Transfer - Heat transfer takes place as conduction if there is a temperature gradient in a solid or fluid
• Convective Heat Transfer - Heat transfer between a solid and a moving fluid is called convection. This is a short tutorial about convective heat transfer
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