Series and parallel connection issues of heat exchangers
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This post was last edited by a847431589 on 2016-10-12 at 10:59. Currently, a hot fluid (gas) and a cold fluid (gas) exchange heat in counterflow within a shell-and-tube heat exchanger. To minimize the outlet temperature of the hot fluid, the original heat exchange method has been improved; one approach is to use two heat exchangers in parallel, with the flow rate of the hot fluid in each exchanger being half of the original value. One approach is to use two heat exchangers in series, with the flow rate of the hot fluid remaining constant. Whether in series or in parallel, the cold fluid in each heat exchanger is independent; in other words, in series, the hot fluid flows continuously through two identical heat exchangers. Which method is more effective? Ignore the thermal resistance of the pipe walls and fouling as well as heat losses.
I don’t know; the first one is equivalent to increasing the heat transfer area. The second one has a higher velocity than one, which increases the heat transfer coefficient, but it also increases the flow resistance. It seems that an analysis of (exergy) loss is necessary; my humble opinion might be incorrect, so please forgive me
This post was last edited by youngestman on 2016-11-9 at 12:20. The heat exchanger is already in pure counterflow mode; why change it?
The last edit to this post was made by wanlirn on 2016-11-12 at 12:37. Parallel connection is equivalent to increasing the shell diameter; the length of the heat exchange tubes remains unchanged, while the number of heat exchange tubes increases； In series connection, it is equivalent to keeping the shell diameter unchanged while increasing the length of the heat exchange tubes; a comprehensive consideration is required. . . Without doing too many comparisons, I choose parallel connection, with the two devices serving as backups for each other and acting as bypasses for one another ；