U-tube heat exchange area
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This post was last edited by huawei on 2011-10-13 19:10. The heat exchange area of U-tube heat exchangers – GB151 3.7.1: The heat exchange area of U-tubes does not include the bent sections； However, this requirement is not specified in the TEMA standard ； 5 O* K w! F( e. c' J I’m not sure whether the heat exchange area listed on the data sheet for the external U-tube heat exchanger includes the bend sections or not 0 e3 s, |, d. Y: u- Is there a clear specification in the P( x2 B9 _ TEMA standards? Looking forward to answers from experts
For the heat exchange area of U-tube heat exchangers, generally only the area of the straight tube section outside the tube sheet is taken into account, and this is also the standard requirement； Whether the area of the bent pipe section is included or not depends on the location of the shell connections at that bend: 1. If the shell connections are located near the tangent line of the bent pipe, then only the area of the straight pipe section outside the tube sheet is calculated ； 2. If the connection point of the casing is located behind the tangent line of the elbow, and the fluid flows completely through the elbow section, then the area of that elbow section can be included ； However, typical heat exchangers usually include a certain margin of safety; using the area of the elbow section as a safety reserve would be a good approach, wouldn’t it?
Reply to 1# Diyu: Do you have any drawings of foreign-made U-tube heat exchangers? If there are any, you can calculate it by yourself to find out. If you don’t know how to do it, you can post the relevant parameters of the U-tube bundle here, and others can help you with the calculation. In this way, won’t everyone understand the design concept behind the foreign party’s drawings?
Actually, you can just ask your process designers to see if the bend sections have been taken into account in the heat calculation. It seems that both 151 and tema are insignificant.
The calculation of the heat exchange area should be the responsibility of the process engineering team; therefore, there should be no requirements in TEMA regarding this aspect.
The second floor is the correct answer. As a supplementary point, for the first scenario, the standards specify that the heat exchange area should be calculated based on the outer diameter of the heat exchange tubes； For the second case, the area is calculated based on the average diameter of the heat exchange tubes.