A steel tube (k = 50 W/m ∙ K) of inner and outer diameters D_i = 20 mm and D_o = 26 mm. respectively, is used to transfer heat from hot gases flowing over the tube (h_h = 200 W/m² ∙ K) to cold water flowing through the tube (h_c = 8000 W/m² ∙ K). What is the cold-side overall heat transfer coefficient U_c? To enhance heat transfer, 16 straight fins of rectangular profile are installed longitudinally along the outer surface of the tube. The fins are equally spaced around the circumference of the tube, each having a thickness of 2 mm and a length of 15 mm. What is the corresponding overall heat transfer coefficient U_c?