Related Questions

A semicircular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi circular disc and horizontal surface is µ. This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will
A Remain horizontal
B Slant up towards direction of pull
C Slant down towards direction of pull
D None of the above
If air (a non-condensing gas) is present in a condensing vapor stream, it will __________ the condensation rate of vapor.
A Increase
B Decrease
C Not affect
D Increase the condensing film co-efficient as well as
The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases,
A Will be higher
B Will be lower
C Will remain unaffected
D May be higher or lower depending upon the nature of non-condensable gases
Presence of a non-condensing gas in a condensing vapour
A Increases the rate of condensation
B Decreases thermal resistance
C Is desirable to increase the film co-efficient
D None of these
Vertical condenser is advantageous to the horizontal condenser from operation point of view, when
A Hydrostatic head is required for refluxing the condensate
B Only the function of condensation is to be carried out
C Sub cooling of condensate is desired
D Both the functions of condensation & sub cooling are carried out in a single unit
Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is
A Same
B Less
C About 3 times
D About 0.33 times
The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is
A More
B Less
C Some
D Either more or less ; depends on the nature of vapor
In case of non-condensing steam engines, the pressure of steam in the cylinder during exhaust stroke is _________ the condenser pressure.
A Equal to
B Lower than
C Higher than
D None of these
The film co-efficient between condensing vapour and metal wall increases with
A Increasing temperature of the vapour
B Decreasing temperature of the vapour
C Increasing viscosity of the film of condensate
D Increasing temperature drop
The film thickness for laminar film condensation on vertical surface __________ from top to bottom.
A Cummulatively increases
B Cummulatively decreases
C Remains constant
D And the surface conductance increase

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