5.18 Water flows through a straight length of pipe at the rate of o.5 kg/ s. The pressure drop from the inlet to the outlet of the pipe is 10

kPa. When a bend is introduced into the middle of the pipe the pressure drop increases to 20 kPa. Calculate the rate of entropy increase of the surrounding air at 20 °C for the pipe both with and without the bend. Assume that the temperature change of water is negligible and that its specific volume is o.001 m3 / kg.