Related Questions

If the cross-sectional area of the channel in n-channel JEFT increases, the drain current ___________
A is increased
B is decreased
C remains the same
D none of the above
When the emitter terminal of a UJT is open, the resistance between the base terminal is generally ___________.
A High
B Low
C Extremely low
D None of the above
When a UJT is turned ON, the resistance between emitter terminal and lower base terminal ___________
A Remains the same
B Is decreased
C Is increased
D None of the above
In most of the shell and tube heat exchangers, the tube pitch is generally __________ the tube diameter.
A Less than
B 1.25-1.50 times
C 2.5 times
D One-fourth of
For the same diameter and thickness of tube, a water tube boiler has ________ heating surface as compared to fire tube boiler.
A More
B Less
C Equal
D None of these
Minimum tube pitch recommended for shell and tube heat exchangers is about __________ times the outside diameter of the tube.
A 1.25
B 1.75
C 2.5
D 3.5
For the same diameter and thickness of tube, a water tube boiler compared to a fire tube boiler has
A More heating surface
B Less heating surface
C Equal heating surface
D Heating surface depends on other parameters
In a shell and tube heat exchanger, the tube side heat transfer co-efficient just at the entrance of the tube is
A Infinity
B Zero
C Same as average heat transfer co-efficient for tube side
D None of these
For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it
A Decreases the pressure drop
B Decreases the outlet temperature of cooling medium
C Increases the overall heat transfer coefficient
D None of these
Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
A Finned tube heat exchanger with air inside and steam outside
B Finned tube heat exchanger with air outside and steam inside
C Shell and tube heat exchanger with air inside tubes and steam on shell side
D Shell and tube heat exchanger with air on shell side and steam inside tubes

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