Help with Heat Transfer Problem - Homework Statement

[hsnbrg7]

Homework Statement

Hey guys. I've been cracking whole day over this question to no avail. I mean I have no idea if it's correct or wrong. And I desperately have to get it done by tomorrow and it's already midnight here so would really appreciate any sort of help I can get. Here are the doubts that I'd like to clear.

1. Should it be counter flow or parallel flow? (I chose counter flow and I can't justify why)
2. Should the water fluids flowing from the inner or outer and why? (I chose inner and I can't justify why as well)
3. Is the term for inner tube called annulus?
3. Is the final answer obtained 6 sections?

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[Valkarie]

The attached image contains the problem along with the diagram. Homework Equations N/AThe Attempt at a Solution 1. The flow between the inner and outer tubes should be counterflow. This is because when hot water flows through the inner tube, heat will be transferred from it to the surrounding environment. If the flow is in parallel, heat from the inner tube will be transferred to the outer tube instead of the environment. 2. The water should flow from the inner tube. This is because the purpose of the counterflow heat exchanger is to transfer heat from the inner tube to the environment. If the water were to flow in the opposite direction, heat would not be able to be transferred properly. 3. Yes, the term for the inner tube is called an annulus. 4. Yes, the final answer should be obtained in 6 sections.