Page 177 - Fundamentals of Enhanced Oil and Gas Recovery

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Thermal Recovery Processes

Figure 5.8 Heat transfer through insulation.

To calculate the heat loss through steam line some assumptions are considered:
• Negligible heat loss from tube and scale.
• Temperature of distribution line is equal to steam temperature
There are three mechanisms for heat transfer from insulation:
• Convection
• Radiation
• Natural convection

5.2.9.1 Heat Transfer Through Insulation/L
The conduction heat transfer in insulation is represented in Fig. 5.8.
i
2πK ðT 1 2 T 2 Þ
_
Q i 5 (5.92)
lnðr 2 =r 1 Þ
i
where Q i is the heat transfer through insulation (heat loss) and k is the thermal con-
ductivity of insulation.

5.2.9.2 Rate of Heat Loss 2 Distribution Lines
Heat transfer from insulation to the surroundings by a combination of radiation and
convection mechanisms is represented as follows:

Q i 5 Q lr 1 Q lc (5.93)
The heat is lost by convection or radiation to environment: Q lr is the heat loss
through radiation and Q lc is the heat loss through convection.
For high velocities of wind, the dominated heat transfer mechanism would be
forced convection.