09-03-17 Topic — Issues regarding single-arch baffle plates (prize for participation)
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Let’s discuss the impact of piping and non-piping in the window area of a single-arch baffle on thermal parameters such as the shell-side pressure drop, shell-side heat transfer coefficient, overall heat transfer coefficient, and heat transfer area. Additionally, we will examine whether, taking all these effects into account, the efficiency and overall economic viability of the shell-and-tube heat exchanger increase or decrease Note: This topic was provided by member jy03018705. Please keep an eye on it; a summary or the correct answer should be provided within 24 hours. If you have any good topics, feel free to share them with us. You can find the dedicated thread for submitting daily and monthly topics in the pinned post at the top of the forum: http://bbs.hcbbs.com/thread-335484-1-1.html. There are prizes for participation, and you can also enter the end-of-month competition with generous rewards – act now!
Heat transfer and flow resistance tests were conducted on single-arch baffle plates with expanded and unexpanded tube holes. The results show that appropriately enlarging the tube holes at suitable positions on the baffle can improve the heat transfer efficiency of the heat exchanger and reduce the pressure drop in the shell side, thereby achieving good energy-saving and consumption-reduction effects. With the optimized hole-expansion scheme, the Nusselt number in the shell side can be increased by 1.7% to 8.3%, the resistance coefficient can be reduced by 9.8% to 13.0%, the comprehensive performance index of Nuo/ξo^0.29 can be improved by 5.9% to 11.6%, the logarithmic mean temperature difference of the heat exchanger can increase by 1.3% to 3.6%, and the heat flux density can be increased by 4.6% to 5.6%.
Heat transfer and flow resistance tests were conducted on single-arch baffle plates with expanded and unexpanded orifices. The results show that appropriately enlarging the tube holes at suitable positions on the baffle can improve the heat transfer efficiency of the heat exchanger and reduce the pressure drop in the shell side, thereby achieving good energy-saving and consumption-reduction effects. With the optimized hole-expansion scheme, the Nusselt number in the shell side can be increased by 1.7% to 8.3%, the resistance coefficient can be reduced by 9.8% to 13.0%, the comprehensive performance index of Nuo/ξo^0.29 can be improved by 5.9% to 11.6%, the logarithmic mean temperature difference of the heat exchanger can increase by 1.3% to 3.6%, and the heat flux density can be increased by 4.6% to 5.6%.
How could two people just copy the abstract of Professor Yu Jiuyang’s paper? There’s absolutely no sincerity in such an approach; it has nothing to do with the actual issue at hand. Is it all for the sake of getting good grades? ?
I don’t know much about heat exchangers, but I’d like to participate and learn a bit, to liven up the atmosphere, haha. I want to learn more knowledge from all of you, experienced folks:victory:
There are no specific figures available, but the heat exchange area for piping with an arc-shaped notch should be determined based on the percentage of the notch, the diameter of the heat exchanger, and the specifications of the heat exchange tubes. Using grooved piping reduces the flow velocity of the fluid on the shell side, which is effective in reducing vibrations; however, this design actually increases vibrations as well. The actual effects depend on computational analysis. Furthermore, if no tubes are placed at the gaps, it will reduce the heat exchange area significantly; the greater the diameter of the heat exchanger, the more significant this reduction is, which results in poor economic efficiency. Generally, other methods can be used to reduce vibration
The influence of the arc-shaped baffle on heat exchange performance is mainly reflected in the size of the openings in the baffle and the distance between the baffles. . . Generally, the smaller the board spacing, the smaller the openings and the better the heat exchange effect, but practical considerations must be taken into account. . Consider the flow velocity of the fluid within the pipe, the pressure drop, the vibrations caused by the flow, as well as factors such as the ease of cleaning and maintenance. In my opinion, piping in the window area reduces pressure drop, lowers the heat transfer coefficient in the shell side, reduces the overall heat transfer coefficient, and increases the heat transfer area. .
LS’s answer seems to have some issues; piping in the window area would result in a higher pressure drop. The advantages of not using piping are as follows: 1. The pressure drop is only 1/3 that of piping. 2. The flow on the shell side is uniform, similar to ideal flow, resulting in a high heat transfer coefficient and reduced tendency to form scale. 3. The pressure drop in the window area is very small; accordingly, the bypass flow and leakage flow are also low
For the heat exchange area of a tubular arrangement with an arc-shaped notch, it should be determined based on the percentage of the notch, the diameter of the heat exchanger, and the specifications of the heat exchange tubes.
The HTRI user manual mentions Segmental/NTIW: No-tubes-in-window (NTIW), which means that no tubes are placed in the arc-shaped area; thus, all tubes are supported by all the baffle plates. This approach is generally used when it is necessary to take into account the risk of tube damage due to vibration. It has the following characteristics: a The pressure drop is only about 1/3 that of a single arc-shaped baffle; b The flow in the shell side is uniform, similar to that in an ideal tube bundle, resulting in a high heat transfer coefficient and reduced tendency to scale; c The pressure drop in the window area is very small, with low bypass and discharge flows; d Approximately 15%~25% of the tubes do not pass through the arc-shaped notch area, and it is possible to use smaller arc-shaped notches, increase the flow velocity in the shell side, or appropriately increase the shell diameter to maintain the same number of tubes.