**QUESTION**

Example 3-1(A): Water at an average temperature of 45°C flows through a 17.5 cm diameter cast iron pipe of internal surface roughness 0.00016 m. If the pipe is 100 m long and the flow rate is 48.9 kg/s., determine the pump hydraulic output required to maintain this flow rate. If the pump overall electrical to hydraulic efficiency is 78%, determine the required electrical input. If the pump is run continuously (ie 8760 hrs/yr) and the cost of electricity is £0.125/kWh, determine the annual running cost for the system.

Example 3-2(A): Engine oil at a temperature of 17°C (ρ = 890.0 kg/m3 , µ = 0.999 Ns/m2 [ cf water at this temp = 0.00108 Ns/m2 ]) flows with a velocity of 4.5 m/s through a 10 cm internal diameter steel pipe with internal surface roughness of 0.00006m. Determine the Reynolds number and relative roughness, and, hence, the friction factor for the pipe. If the pipe is 10 m long, determine the pump hydraulic output required to maintain the flow.