__________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side.

ANS:B - U-tube

The most suitable heat exchanger configuration when the temperature of the shell side fluid is much higher than that of the tube side is the U-tube heat exchanger. Explanation:

1. U-Tube Heat Exchanger: In a U-tube heat exchanger, the tube bundle is bent into a U-shaped configuration. One fluid flows through the tubes, while the other fluid flows through the shell surrounding the tubes. The fluids enter and exit the heat exchanger from opposite ends.
2. Advantages for Temperature Difference: The U-tube heat exchanger configuration is particularly well-suited for handling large temperature differences between the shell side and tube side fluids. This is because the U-shaped design allows for a more efficient and balanced heat transfer process, even when one fluid has a significantly higher temperature than the other.
3. Minimizing Thermal Stress: In cases where the shell side fluid is much hotter than the tube side fluid, using a U-tube heat exchanger helps minimize thermal stress on the tubes. The U-shaped configuration allows for thermal expansion and contraction of the tubes without causing damage or deformation.
4. Flexibility in Design: U-tube heat exchangers offer flexibility in design and can accommodate various temperature differentials and flow rates. They are commonly used in applications where thermal efficiency and reliability are important considerations.

In summary, when the temperature of the shell side fluid is much higher than that of the tube side, the U-tube heat exchanger configuration is preferred due to its ability to handle large temperature differentials effectively while minimizing thermal stress on the heat exchanger components.