The difference between smooth pipes and rough pipes
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When I was calculating the pressure drop in designs, I noticed that the friction factors for smooth pipes and rough pipes are different. What kind of tube is considered a smooth tube? Are the carbon steel, stainless steel, and copper tubes used in heat exchangers all classified as such tubes? Hope to get the answer, thank you
In general heat exchangers, most of the tubes used are plain tubes. Rough tubes refer to those designed to enhance heat transfer, such as threaded tubes or ribbed tubes. If there’s anything incorrect, please let me know
Smooth tubes result in a lower pressure drop, but their heat transfer efficiency is not ideal; many shell-and-tube exchangers in China use smooth tubes； To enhance heat transfer, methods such as threads, corrugated tubes, and tubes with external corrugations and internal threads can be used; this improves the heat transfer efficiency, but it also increases the pressure drop. Research generally focuses on high-efficiency heat transfer tubes with low energy consumption. :)
Thank you to the two people who replied above; I’ve been busy learning software these past few days and thus couldn’t respond. Here’s the details: when designing, I saw in the heat exchanger design manual that \"rough pipes\" refer to steel pipes or cast iron pipes. I’m not sure if there’s an error in the manual. Later, I checked fluid mechanics books and found the concepts of absolute roughness and relative roughness. I think the relative roughness should be used to determine whether a pipe is rough, but no clear threshold is specified there. I hope everyone can provide further explanations and discussions on this topic
Glass, brass, plastic, etc. are smooth pipes, while steel pipes, cast iron pipes, etc. are rough pipes. Of course, it also varies depending on the usage duration of the pipes, as well as the degree of corrosion and scaling ； There seems to be an explanation on the transformation origin.
So what coefficient is used to determine whether a tube is smooth or rough? What was said on the 3rd floor is also correct.
I just saw this part of Chemical Engineering Principles. I’m also very confused; please help
The difference between them lies in their relative roughness; the relative roughness coefficient is used to determine whether a pipe is rough or smooth.