A cubical piece of aluminium with the same properties, as given in P.3.1, is 10 mm on a side and is heated from 50°C to 300°C by a direct flame. How long should the aluminium remain in the flame if...

A cubical piece of aluminium with the same properties, as given in P.3.1, is 10 mm on a side and is heated from 50°C to 300°C by a direct flame. How long should the aluminium remain in the flame if the flame temperature is 800°C and the convective heat transfer coefficient between the flame and aluminium is 190 W/m²
K?

P.3.1

An aluminium plate (k = 160 W/m K,
 = 2790 kg/m³, c_p
= 0.88 kJ/kg K) of thickness 30 mm and at a uniform temperature of 225°C is suddenly immersed at time t = 0 in a well-stirred fluid at a constant temperature of 25°C. The heat transfer coefficient between the plate and the fluid is 320 W/m²
K. Determine the time required for the centre of the plate to reach 50°C.