Chapter 8, Problem 8.103P

An electrical power transformer of diameter $\text{23}0\text{mm}$ and height $\text{5}00\text{ mm}$ dissipates $\text{1}000\text{ W}$ . It is desired to maintain its surface temperature at $\text{47}°\text{C}$ by supplying ethylene glycol at $\text{24}°\text{C}$ through thin-walled tubing of $\text{2}0-\text{mm}$ diameter welded to the lateral surface of the transformer. All the heat dissipated by the transformer is assumed to be transferred to the ethylene glycol.

Assuming the maximum allowable temperature rise of the coolant to be $\text{6}°\text{C}$ , determine the required coolant flow rate, the total length of tubing, and the coil pitch S between turns of the tubing.