Length-diameter ratio of shell and tube heat exchangers
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What is the minimum length-to-diameter ratio for shell-and-tube heat exchangers? What is the smallest value you have ever used in your designs? Are there any below 2.5? This post was last edited by lucky1909 on 2009-4-3 08:09]
Tube sheet heat exchanger? Shell and tube?
Theoretically, for shell-and-tube heat exchangers, the larger the length-to-diameter ratio, the better the heat exchange efficiency; therefore, the heat exchanger configurations obtained using various heat exchanger calculation software are usually elongated in shape. However, it seems that those with a length-to-diameter ratio of less than 2.5 are relatively rare
For shell-and-tube heat exchangers, a length-to-diameter ratio of 4 to 6 is optimal.
I also saw in the information that the recommended value is 4–6, but GB151 does not specify any limits.
There are few standardized designs for heat exchangers; they are generally custom-made devices. Therefore, as long as the process requirements are met, there is no need to deliberately focus on the length-to-diameter ratio. As mentioned above, if this ratio is too low, the contact time between the hot and cold fluids is too short, which can result in low heat exchange efficiency. For small devices, and due to space constraints, the length-to-diameter ratio is small, but the tube side may consist of multiple passes (such as in steam heating).
For shell-and-tube heat exchangers, an aspect ratio of 4 to 6 is optimal. There is a slight difference between vertical and horizontal installation; in the case of vertical installation, the aspect ratio of shell-and-tube heat exchangers can be higher, with values of 10–12 having been observed.
A length-to-diameter ratio between 5 and 10 is quite common.
Regarding the length-to-diameter ratio of heat exchangers, a value of around 6 to 10 is commonly used. For specific details, you can refer to a question that was discussed earlier at http://bbs.hcbbs.com/viewthread.php?tid=421265&highlight=%B3%A4%BE%B6%B1%C8. The situation mentioned by the original poster, where the value is less than 2.5, does not seem advisable to me. For heat exchangers with an excessively small length-to-diameter ratio, the heat exchange tubes are relatively short and the number of tubes is relatively high, which results in a lower flow velocity per tube. When the flow rate is low enough, full pipe flow cannot even be ensured, which results in a significant amount of heat exchange area being wasted ； Furthermore, if the tube side temperature is high and the flow rate is very low, dirt is likely to accumulate, further reducing heat transfer efficiency.