Assume that a surface-grinding operation is being carried out under the following conditions: D = 250 mm D=250 mm, d = 0.4 mm d=0.4 mm, v = 0.5 m / s v=0.5 m/s, and V = 50 m / s V=50 m/s. These conditions are then changed to the following: D = 150 mm D=150 mm, d = 0.4 mm d=0.4 mm, v = 0.3 m / s v=0.3 m/s, and V = 25 m / s V=25 m/s. What is the difference in the temperature rise from the initial condition?

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?

The higher the astm grain size number, the finer the gran is. a)-true b)-false

Which one from below is not one of the reasons of planning failures? (clo3) a)-planner is careless. b-planner spend less time in the field but more time on the desk c)-planner is not qualified d)-planner does not have sufficient time to properly plan