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?

On a average work day more than work place firs are reorted

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.