A horizontal elevated pipeline in a chemical plant has an OD of 10 cm, an ID of 9.4 cm, and is covered with a layer of magnesia insulation that is 4-cm thick. A process liquid at 50◦C flows in the pipeline with a heat-transfer coefficient of 400W/m2 · K. The pipeline is exposed to the environment on a calm night when the air temperature is −5◦C. k magnesia = 0.067 w/m°C K pipe = 14.4 W/m°C (a) Make a reasonable guess for the temperature of the exterior surface of the insulation and use it to calculate the heat-transfer coefficient between the insulation and the ambient air. (b) Use the result of part (a) together with the other information given in the problem to calculate the rate of heat loss per meter of pipe length. (c) Use the result of part (b) to calculate the temperature of the exterior surface of the insulation and compare it with the value that you assumed in part (a)
A horizontal elevated pipeline in a chemical plant has an OD of 10 cm, an ID of 9.4 cm, and is covered with a layer of magnesia insulation that is 4-cm thick. A process liquid at 50◦C flows in the pipeline with a heat-transfer coefficient of 400W/m2 · K. The pipeline is exposed to the environment on a calm night when the air temperature is −5◦C.
k magnesia = 0.067 w/m°C
K pipe = 14.4 W/m°C
(a) Make a reasonable guess for the temperature of the exterior surface of the insulation and use it to calculate the heat-transfer coefficient between the insulation and the ambient air.
(b) Use the result of part (a) together with the other information given in the problem to calculate the rate of heat loss per meter of pipe length.
(c) Use the result of part (b) to calculate the temperature of the exterior surface of the insulation and compare it with the value that you assumed in part (a).
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