Steam pipe - QuickField simulation example
Minimum insulation thickness for a steam pipe that limits heat loss to the specified allowable value under given steam and ambient temperatures.
How to calculate steam-pipe insulation thickness for allowable heat loss?
Answer Typical applications Geometry
R1 = 60 mm, R2 = 80 mm, R3 = ?
Given Task Solution Search of the optimal solution is automated via utility LabelMover, which creates and solves series of the problems with different values of R3, converging to the heat flux value of 2.1 kW.
Results
Reference
Engineering question
Use LabelMover to vary the insulation thickness until the calculated surface heat flux reaches the specified allowable limit.
steam pipelines, insulated steam pipes, process steam lines
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Simulation problem
Problem Type
Plane-parallel problem of heat transfer.
Thermal conductivity of steel λsteel = 42 W/(m·K);
Thermal conductivity of asbestos λasbestos = 0.8 W/(m·K);
Temperature of steam Tsteam = 150°C,
Temperature of air Tair = 20°C,
Convection coefficient on the steam side of the pipe αsteam = 100 W/K-m²,
Convection coefficient on the air side of the pipe αair = 30 W/K-m²,
Allowable power of heat losses f = 2.1 kW/m².
Determine the minimum thickness of the insulation (R3-R2) required for allowable heat losses.
Heat flux passing through any cross-section of the pipe is the same and could be measured at the pipe's surface. To solve the problem it is enough to take a piece of the pipe with arbitrary length, since the flux per meter of the length is the same. For convenience we choose such a length so that square of the steel surface equals to 1 m², i.e. Lz = 1/(2π·r2) = 2.122 m. In this case the heat flux density is numerically equal to the heat flux.
Temperature distribution in the pipe walls.
R3,mm
f, W/m²
QuickField
104.3
2102
Theory*
105
2100
Error
0.7%
0.1%
* Rajput R.K.(2010). Engineering Thermodynamics, Third Edition. Sudbury, MA:Jones and Bartlett Publishers, p. 813. Example 15.11.
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