Engine oil at 60°C flows at 0.5 kg/s in a duct with constant surface temperature of 20°C. Assume full developed flow. Find: (i) heat flux at entry, (ii) pressure drop per metre length for 3 cm...

Engine oil at 60°C flows at 0.5 kg/s in a duct with constant surface temperature of 20°C. Assume full developed flow. Find: (i) heat flux at entry, (ii) pressure drop per metre length for 3 cm diameter and for 3 x 1 rectangular duct of equal wall area. The properties of oil at 40°C are—