With regard to the number of passes through the tubes of shell-and-tube heat exchangers, what statement is true?

Correct Answer: Option D — In two-pass and four-pass heat exchangers, the inlet and outlet tube-side fluid connections are at the same end.

In shell-and-tube heat exchangers, the number of passes is determined by the internal baffling of the heads. Multi-pass designs, such as two-pass or four-pass, force the tube-side fluid to reverse direction, resulting in both the inlet and outlet connections being located on the same end of the unit.