Consider a low-speed open-circuit wind tunnel operating at sea level with a nozzle contraction ratio of 12. when the tunnel is turned on, the pressure difference betweenthe inlet (the settling chamber) and the test section is read as a height difference of 10 cm on au-tube mercury manometer. (the density of liquid mercury is 1.36 x 104 kg/m3). calculate the velocity of the air in the test section.

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?

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false

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