Question

Floating head heat exchangers are used for the

• A. Heat transfer between corrosive fluids
• B. Cases where temperature difference between the shell and the tubes is more (>50°C)
• C. Co-current heat transfer systems
• D. Counter-current heat transfer systems

Hint:

Floating head heat exchangers accommodate thermal expansion due to large temperature differences (\(>\)50°C) between shell and tubes, preventing stress and damage.

Answer 1

The Correct Option is B

Step 1: Understand floating head heat exchangers.
A floating head heat exchanger is a type of shell-and-tube heat exchanger where one tube sheet is fixed, and the other is allowed to “float” (move freely). This design accommodates thermal expansion and contraction of the tubes due to temperature differences between the shell-side and tube-side fluids, reducing thermal stress. 

Step 2: Analyze the purpose of floating head design. 
Thermal expansion: When the temperature difference between the shell-side fluid and the tube-side fluid is significant (e.g., >50°C), the tubes expand or contract more than the shell due to differences in material or temperature. A floating head allows the tubes to move, preventing damage from thermal stress.
Corrosive fluids: While floating head heat exchangers can handle corrosive fluids (with appropriate materials), this is not their primary purpose; corrosion resistance depends on material selection, not the floating head design.
Flow arrangement: Floating head heat exchangers can be used in both co-current and counter-current configurations, but the design is not specific to either flow type; it addresses thermal expansion, not flow direction. 

Step 3: Evaluate the options. 
(1) Heat transfer between corrosive fluids: Incorrect, as the floating head design is not specifically for corrosive fluids; it’s about thermal expansion. Incorrect.
(2) Cases where temperature difference between the shell and the tubes is more (>50°C): Correct, as the floating head design is used to accommodate large temperature differences that cause significant thermal expansion, preventing stress and damage. Correct.
(3) Co-current heat transfer systems: Incorrect, as the floating head is not specific to co-current flow; it can be used in any flow arrangement. Incorrect.
(4) Counter-current heat transfer systems: Incorrect, as the floating head is not specific to counter-current flow; it addresses thermal expansion, not flow direction. Incorrect. 

Step 4: Select the correct answer. 
Floating head heat exchangers are used for cases where the temperature difference between the shell and the tubes is more (\(>\)50°C), matching option (2).