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71.

The distribution of shear stress in a steeam of fluid in a circular tube is

A.	linear with radius for laminar flow only	B.	linear with radius for turbulent flow only
C.	linear with radius for both laminar and turbulent flow	D.	parabolic with radius for both limiar and turbulent flow

72.

The Colburn analogy applies over a range of Prandtl numbers from

A.	0.6 to 120	B.	0.46 to 590
C.	0.006 to 0.06	D.	120 to 590

73.

In the absence of adequate data the Parndtl number for most of the dry gases can be assumed as

A.	0.1	B.	120
C.	10	D.	0.72

74.

For laminar film condensation what is the ration of heat transfer to a horizontal tube of large diameter to that to a vertical tube of the same size for the same temperature difference ?

A.	0.64 (L/D)1/2	B.	0.64 (L/D)1/3
C.	0.64 (L/D)1/4	D.	0.64 (L/D)1/5

75.

What L/D ratio will produce the same laminar film condensation controlled heat transfer rate to a tube in both the vertical and with the condensate thickness.

A.	5.89	B.	0.64
C.	0.023	D.	1.13

76.

Film wise condensation

A.	is characterized by a thin liquid film forming over the entire surface	B.	is less common than dropwise condensation
C.	occurs on nonwettable surfaces	D.	is characterized by high heat transfer coefficients than that for dropwise condensation.

77.

For laminar film condensation on vertical surface the local surface conductance.

A.	is directly proportional to the film thickness	B.	changes inversely with the film thickness
C.	is independent of the firm thickness	D.	varies as the square root of the film thickness

78.

For laminar film condensation on vertical surface the film thickness

A.	remains constant from top to bottom	B.	cumulatively decreases from top to bottom
C.	cumulatively increases from top to bottom	D.	the surface conductance increase from top to bottom

79.

The presence of small amounts of non-condensing gas in a condensing vapor

A.	greatly increases the rate of condensation	B.	seriously reduces the rate of condensation
C.	does not affect the rate of condensation	D.	increases the condensing film coefficient

80.

For laminar film condensation on vertical surface the average heat transfer coefficient is inversely proportional to. where ?T = temperature drop across condensate film.

A.	(?T)1/4	B.	(?T)4
C.	(?T)5/4	D.	(?T)4/5