Which of the following sets of terms indicates an ambiguous requirement? - efficient, meeting standards, and improved

- efficient, improved, and user-friendly

- user-friendly, efficient, and meeting standards

- meeting standards, improved, and user-friendly

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?

For a gate width of 2 m into the paper, determine the force required to hold the gate abc at its location.

Apressure vessel with an r/t 20 cannot be treated as thin walled vessel. a)-trune b)- false