Question 39 QMED02 - Electrician-Refrigerating Engineer

The Correct Answer is A ### 2. Explanation for Option A (Correct) Option A ("The number of fluid passes cannot be determined.") is correct because the arrangement of the inlet and outlet connections on the shell-and-tube heat exchanger only dictates the number of passes for the **shell-side fluid** or potentially indicates an odd number of passes (like 1, 3, 5, etc.) for the **tube-side fluid** if both connections were on the same side. However, the question specifies that the inlet and outlet connections for the sea water (the tube-side fluid, as is typical in a seawater-cooled oil cooler) are on **opposite end waterboxes**. * If the inlet is on the left and the outlet is on the right, the sea water must travel through the tubes at least once (single-pass). * Crucially, the number of passes is determined by the configuration of the **pass partitions** (or baffles) inside the waterboxes, which direct the fluid flow back and forth through different sets of tubes. * A tube-side fluid with inlets and outlets on opposite ends can be 1-pass, 2-pass, 3-pass, or any number of passes, depending on how the tubes are grouped and sealed by these pass partitions. The physical location of the nozzle connections merely defines the overall flow path direction, not the internal complexity. Therefore, without information about the internal pass partitioning, the number of tube-side passes cannot be determined. ### 3. Explanation for Other Options (Incorrect) **B) The tube-side fluid flow pattern is single-pass.** A single-pass design requires the inlet and outlet to be on opposite ends, but the opposite-end connection configuration *allows* for single-pass; it does not *guarantee* it. Single-pass designs are less common for high heat transfer requirements where fluid velocity and turbulence enhancement (achieved via multiple passes) are needed. **C) The tube-side fluid flow pattern is four-pass.** Four-pass designs require the inlet and outlet to be on opposite ends (unless they were a specialized, common-side, U-tube configuration, which is not typical here). While possible, there is no physical information provided in the question (like the presence of three internal partitions) to confirm that the design is four-pass. **D) The tube-side fluid flow pattern is two-pass.** A two-pass design is very common for oil coolers and requires the inlet and outlet to be on opposite ends. However, just like options B and C, the external nozzle location only makes a two-pass configuration *possible*, not mandatory. The internal dividing partition must be present in the waterboxes for it to be two-pass. Without confirming the internal partitioning, this statement cannot be confirmed as true.