HTFS accounting standard U-tube heat exchanger
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Recently, while using HTFS to perform calculations for U-tube heat exchangers, I encountered two problems: (1) The number of U-tubes entered was 114, for 2 passes； However, the heat exchanger report generated shows only 57 heat exchange tubes, and it’s unclear what’s going on ； (2) When performing the design calculations for the heat exchanger, the system indicates that an area of around 36 m2 is required. For a U-tube heat exchanger with 112 heat exchange tubes and 4 passes, the heat exchange area is 53.9 m2; the system shows a 55% margin in area ； When a U-tube heat exchanger is used, the number of heat exchange tubes is 114, with two passes; the heat exchange area is 54.9 m2, and the area margin displayed by the system is only 20% ； It’s confusing: with a larger heat exchange area, why does the remaining area shown by the system actually be smaller? ! For these two types of heat exchangers, why is the heat exchange area of the 4-pass type smaller than that of the 2-pass type? Since I am not familiar with the situation of the heat exchanger, I would like to ask everyone for advice. Thank you!
1. Inconsistencies may occur sometimes; the piping layout can be adjusted (changed to 30 degrees, 45 degrees, 60 degrees, 90 degrees) to match the piping diagram； 2, 4-pass, and 2-pass systems: if the shell diameter is the same and the geometric dimensions of the heat exchange tubes are identical, then the number of heat exchange tubes in a 4-pass system will be less than that in a 2-pass system. However, its efficiency should be higher than that of a 2-pass system; therefore, the percentage allowance for area needs to be larger, but the resistance in the tube side will increase. The area margin percentage is (Actual U-Required U)/Required U. Also, check your program again; there might be some issues as well. For reference only
(1) Two U-tubes are actually just one tube that has been bent. (2) Heat exchangers of roughly the same size have tube-side flow velocities that are about half those of those with four passes; as a result, the heat transfer coefficient also decreases. If the control thermal resistance is located on the tube side, the impact of this decrease in heat transfer coefficient will be significant
Thank you for your guidance; it was very informative:handshake:handshake:handshake