The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid_________________?

Related Mcqs:

1. 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

2. In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is_________________?

   A. ∞
   B. 0
   C. Equal to the difference between hot and cold fluids inlet temperature
   D. Equal to the difference between hot fluid inlet temperature and cold fluid outlet temperature

3. 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

4. In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is _____________ the outlet temperature of the cold fluid?

   A. Equal to
   B. More than
   C. Less than
   D. Either more or less than (depending upon the fluid)

5. In a parallel flow heat exchanger, if the outlet temperature of hot and cold fluids are the same, then the log mean temperature difference (LMTD) is_________________?

   A. Minimum
   B. Maximum
   C. Zero
   D. Infinity

6. In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass _____________ through the heat exchanger ?

   A. Once
   B. Twice
   C. Thrice
   D. Four times

7. 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

8. If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is_________________?

   A. 1
   B. 2
   C. 1/2
   D. 4

9. LMTD correction factor which is to be applied for a cross-flow heat exchanger increases with increase in the number of shell passes. Its value for a single pass cross flow heat exchanger is __________________?

   A. 0
   B. 1
   C. > 1
   D. < 1

10. 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