Consider atmospheric air at 25c and a velocity of 25 m/s flowing over both surfaces of a 1-m-long flat plate that is maintained at 125c. determine the rate of heat transfer per unit width from the plate for values of the critical reynolds number corresponding to 105 , 5 105 , and 106

The y form of iron is known as: a) ferrite b) cementite c) perlite d) austenite

Acompressor receives the shaft work to decrease the pressure of the fluid. a)- true b)- false

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?