In a 2.5 cm inner diameter (id) tube, water enters at 90 ° c and 6 m / s. the tube is copper and it has a thickness of 0.8 mm and a length of 3m. in the normal direction outside the tube, ambient air circulates at 1 atm and 20 ° c, with h = 7 w /m^2 ° c. calculate the air temperature at tube outlet. what would be the effect of reducing the hot air stream in half ? . kcobre =378.7 w / (mk)

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk