Question 59 QMED04 - Boiler Technician-Watertender

The Correct Answer is C **Explanation for Option C (Correct):** Option C states, "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 tube passes ($N_{tp}$) determines the arrangement of the tubes and the location of the tube-side connections. * **Even Number of Passes (e.g., 2, 4, 6):** When the fluid must pass through the tubes an even number of times, a dividing baffle (partition) is required in the front-end head (channel head). This baffle directs the fluid into half of the tubes for the first pass and then back into the other half of the tubes for the second pass, and so on. To facilitate this internal redirection, both the tube-side inlet and the tube-side outlet connections (nozzles) must be located on the same fixed tubesheet (the front-end head). This is true for all standard heat exchangers with an even number of passes, such as two-pass (2-4 type) and four-pass (4-8 type) configurations. **Explanation of Incorrect Options:** * **A) In single-pass and two-pass heat exchangers, the inlet and outlet tube-side fluid connections are at the same end.** * This is incorrect because a single-pass heat exchanger requires the fluid to enter at one end and exit at the opposite end (opposite ends). It is only true for the two-pass configuration. * **B) In two-pass and four-pass heat exchangers, the inlet and outlet tube-side fluid connections are at opposite ends.** * This is incorrect. As explained for option C, two-pass and four-pass heat exchangers have an even number of passes, necessitating a partition plate in the channel head, which requires both connections to be located at the same end. * **D) In single-pass and two-pass heat exchangers, the inlet and outlet tube-side fluid connections are at opposite ends.** * This is incorrect. While it is true for single-pass heat exchangers (1-1 type), it is false for two-pass heat exchangers, which must have their connections at the same end.