Apipe of outside diameter 200mm is lagged with an insulating material of thermal conductivity 0.06 w m-1k-1 and thicknes 75mm. the pipe carries a process fluid at a temperature of 300oc and above the average temperature of the outer surface of the lagging is 45c. (a) estimate the rate of heat loss per meter length of pipe. (b) explain why the thermal resistance of the pipe wall can be ignored.

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?

Aquick transition of the operating speed of a shaft from its critical speed will whirl amplitude. (a) increase (b) limit (c) not affect (d) zero

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