Firefighters have been called to the scene of a warehouse fire. The battalion chief informs the crew that the warehouse is used to store cleaning fluids, which are highly flammable. What should the firefighters use to extinguish the fires with these types of fuels? A.) Class A foams

B.) Class B foams

C.) water

D.) oxygen

ANSWER: B

The mass flow rate of the fluid remains constant in all steady flow process. a)- true b)- false

The temperature of air decreases as it is compressed by an adiabatic compressor. 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?