A. Give larger area per tube
B. Use metal fins of low thermal conductivity
C. Facilitate very large temperature drop through tube wall
D. Are used for smaller heat load
Related Mcqs:
- 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 - Which of the following parameters is increased by use of finned tube in a multipass shell and tube heat exchanger ?
A. Tube side pressure drop and the heat transfer rate
B. Convective heat transfer co-efficient
C. Effective tube surface area for convective heat transfer
D. All A. B. and C. - 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 - The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by ______________ times, when the number of tube passes is increased to 8?
A. 20.8
B. 40.8
C. 40.4
D. 20.4 - 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 - Steam is to be condensed in a shell and tube heat exchanger, 5 m long with a shell diameter of 1 m. Cooling water is to be used for removing the heat. Heat transfer co-efficient for the cooling water, whether on shell side or tube side is the same. The best arrangement is_____________?
A. Vertical heat exchanger with steam on tube side
B. Vertical heat exchanger with steam on shell side
C. Horizontal heat exchanger with steam on tube side
D. Horizontal heat exchanger with steam on shell side - The advantage of using a 1 – 2 shell and tube heat exchanger over a 1 – 1 shell and tube heat exchanger is_________________?
A. Lower tube side pressure drop
B. Lower shell side pressure drop
C. Higher tube side heat transfer co-efficient
D. Higher shell side heat transfer co-efficient - Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately ?
A. 32
B. 37
C. 45
D. 50 - For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus- Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of________________?
A. 1
B. 1.74
C. 6.1
D. 37 - A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter ‘d’. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to_____________________?
A. d0.8
B. d-0.2
C. d-1
D. d-1.8
