Regarding the issue of the center distance between heat exchange tubes
Thread Content
Dear seniors, can the center distance between heat exchange tubes not follow the requirements specified in GB/T151? For example, can it be increased? Urgent! Thank you all
GB/T151 — “The center distance should not be less than 1.25 times the outer diameter of the heat exchange tube””； The standard specifies the “usual center distance between heat exchange tubes”. Personally, I think it’s okay not to follow the standard when selecting the center distance: lol
Of course, it’s possible to increase the scale, but the heat exchange efficiency will be lower, and the pressure drop on the shell side will also be smaller
You need to have the process calculated using htri
Of course, it is possible to avoid using the standard recommended center distance, but the spacing between pipes affects the heat transfer efficiency, which is also a factor that must be taken into account. A safer approach is to increase the spacing first and then conduct heat transfer calculations
The values given in GB151 are recommended values; for example, the minimum ratio is 1.25 times the outer diameter of the tube. If this ratio is lower, it becomes difficult to weld the tubes to the tube sheet for standard tube sizes. For ratios greater than 1.5 times the outer diameter, the utilization rate of the tube sheet is too low, and the heat exchange efficiency also decreases. Therefore, a more economical range is 1.25 to 1.5 times. The TEMA standards adopted in HTRI dictate that, in principle, deviations in calculations increase when going outside this range
The spacing between the heat exchange tubes can be increased. However, when the spacing is increased, disturbances and the flow direction of the heat exchange medium must be taken into account; otherwise, the dead zones for circulation increase, reducing the effective heat exchange area
When scaling up, the utilization rate of the tube sheet and the size of the equipment are the main factors to consider; other process-related influences depend on specific circumstances. Increasing the tube spacing in refrigeration vessels has no negative effect on heat transfer: hug:
It can be enlarged for special reasons, but it is rather wasteful; meanwhile, the impact on the manufacturing process must also be taken into account.