In an electrochemical machining operation, the frontal working area of the electrode is 2.5 in2 . The applied current = 1500 amps, and the voltage = 12 volts. The material being cut is pure aluminum, whose specific removal rate C is 0.000126 in3 /A-min. (a) If the ECM process is 90 percent efficient, determine the rate of metal removal in in3 /hr. (b) If the resistivity of the

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?

Burgers vector is generally parallel to the dislocation line. a)-true b)-false

Heat transfer by is the fastest mode of heat transfer that requires no intervening medium. a)-conduction b)-convection c)-radiation d)-conduction and convection