Question 25 from the first morning session of the professional knowledge exam in 2014 – seeking expert help to solve it
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Steam is used to heat a certain solution inside the tank, with the inner diameter of the jacket being 2 m, a wall thickness of 8 mm, and the material being carbon steel; the heat transfer coefficient is w = 46.5 W/(m2·℃). If the heat transfer resistances on both sides of the wall are ignored, which of the following values is the total heat transfer coefficient? A 654 B 784 C 6024 D 5814. Calculating using K = q·t/b gives a value close to D, but the correct answer is A. Solve.
I also calculated it as D. With such a large diameter and such a thin wall thickness, it can be treated as a large flat wall; calculating it as a cylindrical wall doesn’t result in a value of A either – it’s even smaller than D
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Thank you for the answer! It turns out the question was incomplete.