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Quotes - Engineering - SalesU-Tube Bundle Design
A U-tube bundle is a set of compromises resolved together rather than in sequence. A tighter bend radius packs more surface into the shell but thins the tube wall. Closer baffle spacing raises the coefficient but costs pressure drop and shortens the unsupported span. More passes raise velocity and multiply pressure drop. The rating software resolves the thermal side; the mechanical checks decide whether the answer survives.
Process Requirements
Thermal Solutions
As a working rule the centerline radius should be at least twice the tube outside diameter. Bending tighter thins the wall on the outside of the bend, so the tube gauge often has to increase to compensate. Some alloys, particularly duplex and high-strength grades, need a larger minimum than others.
Because the innermost tubes cannot be bent to zero radius. The minimum bend radius leaves an untubed lane running down the centre of the bundle, so for a given shell diameter there is slightly less surface than in a straight-tube bundle.
By balancing heat transfer against pressure drop, bounded by the maximum unsupported tube span that avoids vibration. Closer spacing raises velocity and coefficient and costs pressure drop; wider spacing does the reverse and risks vibration.
Yes. The bend region is where tubes are longest and least restrained, and it is where vibration damage most often starts. Proper bundle design includes support for the bends rather than treating the final baffle as sufficient.
