Thermal Insulation Handbook for the Oil, Gas, and Petrochemical Industries

1.5. Heat Transfer Through Insulation

In this section the heat transfer equations that relate the heat flow through the insulation to the insulation thickness and to the thermal conductivity of insulation materials for flat and cylindrical insulation are presented. The symbols and units are as follows:

Q = heat flow in W/m

T₁ = temperature of hot surface in °C

T₂ = temperature of cold surface in °C

L = thickness of insulation in meter

λ = conductivity in W/mK

• Equation for heat transfer for one thickness of flat insulation:

Q=T1−T2L/λ

(1.2)

Figure 1.4

shows a diagram of heat transfer through a single flat material.

Example 1.1

If the temperature of insulation ...