How to determine the number of tube passes and shell passes of a shell and tube heat exchanger? !
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Some books draw diagonal lines for the initial and final temperatures, and then draw horizontal lines to determine the shell number. I want to know what the basis for this is? Thanks. .
Some books draw diagonal lines for initial and final temperatures, and then draw horizontal lines.: Shell and tube heat exchangers generally use counterflow, with more than two tube passes. This ensures that the final heat exchange temperature of the cold stream of each shell is not higher than the final heat exchange temperature of the hot stream, that is, there should be no temperature crossover.
Two tubes? All I use are single-tube ones. There will be no temperature crossover on the single shell side. I think it has to do with economics. .
The flow rate of a single tube pass sometimes does not meet the requirements, the heat transfer coefficient is low, and the heat transfer area is larger, which is of course uneconomical. The method in the book is to avoid temperature crossover, upload the picture and let netizens help you analyze it.