An insulated steel pipe carries hot water at 80 ºC. The outer surface of the insulation...

An insulated steel pipe carries hot water at 80 ºC. The outer surface of the insulation loses heat to the environment by convection and radiation. For convection, assume hconv = 5.8 W/m2.ºC. The emissivity of the insulation is 0.88 and conductivity, k = 0.038 W/mK. The surroundings are at 30 ºC. Assume the inner surface of the insulation is at the water temperature. What is the surface temperature of the insulation?

Solutions

Expert Solution

Approach:

Use the thermal resistance analogy to find the unknown temperature.

Assumptions:

1. The thermal conductivity is constant.

2. Heat transfer is one-dimensional.

3. The heat transfer coefficient is uniform over the surface of the pipe and independent of temperature.

4. The insulation is gray and diffuse.

The total heat transfer coefficient is the sum of radiative and convective heat transfer coefficients, thus

samet mamat answered 1 year ago

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