Consider the transformer of Problem 8.103, whose lateral surface is being maintained at 47°C by a forced convection coolant line removing 1000 W. It is desired to explore cooling of the transformer by free convection and radiation, assuming the surface to have an emissivity of 0.80.
(a) Determine how much power could be removed by free convection and radiation from the lateral and the upper horizontal surfaces when the ambient temperature and the surroundings are at 27°C.
(b) Vertical fins, 5 mm thick, 75 mm wide, and 500 mm long, can easily be welded to the lateral surface. What is the heat removal rate by free convection if 30 such fins are attached?