The cooling coil of an air - conditioning system is a heat exchanger in which air passes over tubes through which refrigerant 22 flows. air enters with a volumetric flow rate of 40 m3/min at 27degreec, 1.1 bar. and exits at 15degreec. 1 bar. refrigerant enters the tubes at 7 bar with a quality of 16% and exits at 7 bar, 15degreec. ignoring heat transfer from the outside of the heat exchanger and neglecting kinetic and potential energy effects, determine at steady state the mass flow rate of refrigerant, in kg/min. the rate of energy transfer, in kj/min. from the air to the refrigerant.

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?

The thermal expansion or contraction of a given metal is a function of the f a)-density b)-initial temperature c)- temperature difference d)- linear coefficient of thermal expansion e)- final temperature f)- original length

Water at the rate of 1 kg/s is forced through a tube with a 2.5 cm inner diameter. the inlet water temperature is 15°c, and the outlet water temperature is 50°c. the tube wall temperature is 14°c higher than the local water temperature all along the length of the tube. what is the length of the tube?