Download Aptitude Crack
img not found img not found

Heat Transfer - Engineering

Q1:

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

ANS:B - 40.8

The inside heat transfer coefficient in a 1-2 shell and tube heat exchanger for turbulent flow of liquid in the tube side is proportional to the square root of the number of tube passes. Therefore, if the number of tube passes is increased from 2 to 8, the inside heat transfer coefficient will be increased by 8/2=4=28/2​=4​=2 times. Now, if the initial heat transfer coefficient is denoted by ℎ1h1​, the increased heat transfer coefficient after increasing the number of tube passes to 8 will be 2×ℎ1=2ℎ12×h1​=2h1​. However, the options provided seem to suggest a different factor of increase. Let's calculate:

  • Option 1: 20.8×ℎ120.8×h1​
  • Option 2: 40.8×ℎ140.8×h1​
  • Option 3: 40.4×ℎ140.4×h1​
  • Option 4: 20.4×ℎ120.4×h1​
Among these options, none directly corresponds to the correct factor of increase (which should be 2ℎ12h1​). It seems there might be an error in the provided options.