Water at 20 °C flows at 3 m/s in a tube with a diameter of 50 mm. a) What is the pressure drop over 30 meters if the walls of the tube are smooth? Water at 20 °C flow at 3 m/s in the annulus of a concentric tube heat exchanger. The inner wall of the annulus has a diameter of 25 mm and the outer wall a diameter of 50 mm. What is the pressure drop over 30 meters if: b) The walls are taken as smooth? c) The walls are made of commercial steel?

Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 mpa and -10°c at a rate of 0.05 ka/s and leaves at 0.8 mpa and 50°c. the refrigerant is cooied in the condenser to 0.72 mpa and 26'c. it is then throttled to 0.15 mpa. sketch the t-s diagram for the system and evaluate: 6) the rate of heat removai from the refrigerated space (kw), it) the power input to the compressor (kw), ii) the isentropic efficiency of the compressor (%), and iv) the cop of the refrigerator.