Ashort brass cylinder (ρ=8530 kg/m3, cp=0.389kj/kg°c, k=110w/m°c, and α=3.39x10-5m2/s) of diameter d=8cm and height h=15cm is initially at a uniform temperature of ti=150°c. the cylinder is now placed in atmospheric air at 20°c, where heat transfer takes place by convection with a heat transfer coefficient of h=40w/m2°c. calculate the center temperature of the cylinder 15 min after the start of the cooling.

The mass flow rate of the fluid remains constant in all steady flow process. a)- true b)- false

Afluid flows with a velocity field given by v=(x/t)i.. determine the local and convective accelerations when x=3 and t=1.

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.