A Si wafer of diameter D is placed at a height H above a small planar evaporation source. The evaporation flux is proportional to cos q where q is the angle the flux makes with the normal to the plane source. Derive an expression for the ratio of the deposited film thickness at the center of wafer to the deposited film thickness at the edge of the wafer in terms of D and H.

The mass flow rate of the fluid remains constant in all steady flow process. 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?

What is the main objective of using reheat rankine cycle?