A. Remove dirt
B. Increase heat transfer rate
C. Reduce vibrations
D. Reduce heat transfer rate
Submitted by: Faheem Zaman Dhaunroo
Related Mcqs:
- Baffles are provided in heat exchangers to increase the________________?
A. Fouling factor
B. Heat transfer area
C. Heat transfer co-efficient
D. Heat transfer rate - Indirect contact heat exchangers are preferred over direct contact heat exchangers, because_________________?
A. Heat transfer co-efficient are high
B. There is no risk of contamination
C. There is no mist formation
D. Cost of equipment is lower - 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 - The main function of baffles provided in a shell and tube heat exchanger is to______________?
A. Facilitate the cleaning of outer tube surface
B. Enhance turbulence
C. Hold the tubes in position
D. All A , B & C - A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be__________________?
A. Greater than that for un-insulated steam pipe
B. Less than that of the un-insulated steam pipe
C. Equal to that of the un-insulated steam pipe
D. Less than the steam pipe with 5 cms insulation - Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the________________?
A. Surrounding temperature
B. Average temperature of the fin
C. Temperature of the fin end
D. Constant temperature equal to that of the base - Use of transverse baffles in a shell and tube heat exchanger is done to increase the___________________?
A. Rate of heat transfer
B. Flow velocity
C. Turbulence of shell side fluid
D. All A., B. and C. - In a shell and tube heat exchanger, the height of 25 percent cut baffles is equal to (where, D = inside diameter of shell) ?
A. 0.25 D
B. 0.50 D
C. 0.75 D
D. None of these - Baffles in the shell side of a shell and tube heat exchanger ?
A. Increase the cross-section of the shell side liquid
B. Force the liquid to flow parallel to the bank
C. Increase the shell side heat transfer co-efficient
D. Decrease the shell side heat transfer co-efficient - Heat exchangers operating, when the asymptotic range is reached, ?
A. Provide very large heat transfer co-efficient
B. Results in making part of the heating surface inactive
C. Results in abruptly increased velocity
D. None of these
