A cone clutch with cone angle 20° is to transmit 7.5 kW at 750 c. p.m. The normal intensity of pressure between the contact faces is not to exceed 0.12 N/mm2. The coefficient of friction is 0.2. If face width
is Yth of mean diameter, find : 1. the main dimensions of the clutch, and 2. axial force required
while running.
[Ans. R = 117 mm : b = 46.8 mm : r1 = 125 mm : r2 = 109 mm : 1395 N]​

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?