In a process industry, two pipes of an equal diameter of 0.025 m run parallel to each other. The two pipes are buried under the soil of thermal conductivity equal to 0.106 W/m^◦C. One of the pipes carries steam at 120^◦C while the other carries a cold organic fluid at −5^◦C. Determine the heat tran

Question

In a process industry, two pipes of an equal diameter of 0.025 m run parallel to each other. The two pipes are buried under the soil of thermal conductivity equal to 0.106 W/m°C. One of the pipes carries steam at 120 °C while the other carries a cold organic fluid at −5 °C. Determine the heat transfer from steam to organic fluid per meter length of pipes if the axes of the two pipes are 0.3 m apart.

Accepted Answer

We make use of the nomenclature in Fig. 5.31 and Eq. 5.136 for solving this problem.

Diameter of steam carrying pipe: [latex]D_{1} = 0.025 m[/latex]
Diameter of the organic fluid carrying pipe: [latex]D_{2} = 0.025 m[/latex]
Center to center distance between pipes: [latex]L = 0.3 m[/latex]
Steam temperature: [latex]T_{1}= 120°C[/latex]
Organic fluid temperature: [latex]T_{2} = −5 °C[/latex]
Soil thermal conductivity:[latex] k = 0.106 W/m°C[/latex]

The conduction shape factor is calculated using Eq. 5.136 as

[latex]S=\frac{2\pi }{\cos h^{-1}\left[\frac{4L^{2} -(D^{2}_{1}+D^{2}_{2} )}{2D_{1} D_{2} } ight] }[/latex] (5.136)

[latex]S=\frac{2\pi }{\cos h^{-1}\left[\frac{4 imes 0.3^{2} -(0.025^{2}+0.025^{2} )}{2 imes 0.025 imes 0.025 } ight] }=0.989[/latex]

Then the heat transfer from steam to organic fluid per meter length of the pipes is

[latex]q = 0.106 × 0.989 × (120 + 5) = 13.1 W/m[/latex]

Question 5.11: In a process industry, two pipes of an equal diameter of 0.0...

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