Question

Steam flowing through a long, thin walled pipe maintains the pipe wall at a uniform temperature of 500 K. The pipe is covered with an insulation blanket comprised of two different materials, A and B. The interface between the two materials may be assumed to have an infinite contact resistance, and the entire outer surface is exposed to air for which T? = 300 K and h = 25 W/m2K. A. Sketch the thermal circuit of the system. Label all pertinent nodes and resistancesb. For the prescribed conditions, what is the total heat loss from the pipe? What are the outer surface temperatures Ts,2(A) and Ts,2(B)?

Answer 1

Answer: The heat loss from insulated pipes or tubes to surrounding air depends on several factors such as insulation thickness, ambient temperature, wind speed etc.

Step-by-step explanation: The heat loss can be calculated using the following formula: Q = 2 π L (ti - to) / [ (ln (ro / ri) / k) + (ln (rs / ro) / KS)] (2).

Where:

• Q = heat loss per unit length of pipe (W/m)

• L = length of pipe (m)

• ti = temperature inside pipe (K)

• to = temperature outside pipe (K)

• ro = outside radius of pipe (m)

• ri = inside radius of pipe (m)

• rs = outside radius of insulation (m)

• k = thermal conductivity of pipe material (W/mK or W/m oC, Btu/ (hr oF ft2/ft))

• ks = thermal conductivity of insulation material (W/mK or W/m oC, Btu/ (hr oF ft2/ft))

The total heat loss from the pipe can be calculated by multiplying Q with the length of the pipe. The outer surface temperatures Ts,2(A) and Ts,2(B) can be calculated using the following formula3:

Ts,2(A) = T? + Q/(hA) Ts,2(B) = T? + Q/(hB)

Where:

• T? = ambient temperature outside insulation blanket

• hA and hB are convective heat transfer coefficients for materials A and B respectively.

I'm sorry, but there really isn't enough information to solve the problem using what is given. However, I have provided you with a yellow brick road, so to speak, as how to solve the word problem. Hope this helps and have a great day!