Engineering task and calculation objective
The SPIE module generates tube sheet layouts for shell-and-tube heat exchangers – the complete population of the tubesheet with tubes, tie rods, dummy tubes and sealing strips. Anyone designing a tube bundle apparatus needs to calculate the tube sheet layout before thermal rating, tubesheet design and fabrication drawings can begin: tube count, tube pitch, pitch angle (30°, 45°, 60° or 90°), pass-partition lane widths for multi-pass designs and the baffle arrangement directly determine the heat transfer area and the shell-side flow pattern.
SPIE combines a graphical and a numerical part: the tube sheet layout can display up to 30,000 tubes, and every single tube can be edited, deleted or replaced by a tie rod or a dummy tube. From the layout, the program determines, among other results, the total heat transfer area, the final bundle length, the number and spacing of the baffles (including the distance between the tubesheet and the first baffle) and the baffle borehole diameters.
In practice, the module serves as the link between thermal design and mechanical engineering: segmental and disk-and-doughnut baffles, tube-side and shell-side passes, pairs of sealing strips against bypass flow and the number of tubes in the baffle window are captured consistently in one model and handed over to downstream calculations.
Calculation workflow
- Define the basic geometry: First, the shell diameter, tube outside diameter, tube pitch and pitch angle are defined. From these, the module generates an initial, fully populated tube sheet layout as the starting point.
- Define passes and lanes: The number of tube-side and shell-side passes is selected; the program places the corresponding pass-partition lanes (tube lanes) in the layout and removes the tube positions located there.
- Edit the tube sheet layout in detail: In the graphical editor, individual tubes are placed or deleted, tie rods and dummy tubes are positioned, and, where required, pairs of sealing strips are provided against the bypass flow between bundle and shell.
- Arrange the baffles: Type (segmental baffles or disk-and-doughnut), window height, central baffle spacing and the distance between the tubesheet and the first baffle are specified; from these follow the number of baffles per shell-side pass and the number of tubes in the window.
- Transfer the results: The module delivers tube count, total heat transfer area, final bundle length and the baffle borehole diameter. These data are handed over to the thermal rating and the mechanical design (e.g. the tubesheet calculation).
Input quantities
| Quantity | Symbol | Unit |
|---|---|---|
| Total area | Ages | m² |
| Shell inside diameter | Di | m |
| Diameter of helical baffle | DSpU | m |
| Bundle diameter at cross flow zone | DB | m |
| Height of baffle cut | H | m |
| Tube outside diameter | da | m |
| Tube inside diameter | di | m |
| Tube pitch (transverse) | s1 | m |
| Tube pitch (longitudinal) | s2 | m |
| Number of tube-side passes | rohrseitig | - |
| Number of tubes | n | - |
| Number of tubes, dummy tubes and tie rods in the upper and lower window | nF | - |
| Number of boundary tubes required/actual | RR / | - |
| Number of tube rows in a window | nR,F | - |
| Number of tube rows in the cross flow zone | nW | - |
| Number of tube rows in the end zone | nW,E | - |
| Durchgang | Durchgang | - |
| Durchgang | Durchgang | - |
| Durchgang | Durchgang | - |
| Durchgang | Durchgang | - |
| Durchgang | Durchgang | - |
| Durchgang | Durchgang | - |
| Durchgang | Durchgang | - |
| Durchgang | Durchgang | - |
Calculation options
Rating / Simulation or Design
Rating / Simulation · Design
->0
around central tube · staggered by 1/2 pitch
Adjust window height Yes = Y / No = N
Yes · No
No tubes in window?
No · Yes
Consider cams in tube sheet?
No · Yes
Frequently asked questions
What influence does the pitch angle have on the tube bundle design?
With 30° and 60° pitch (triangular layout), more tubes fit into the same shell diameter – more area in the same envelope. 45° and 90° pitch (square and rotated square) leave cleaning lanes between the tube rows and are preferable with fouling media on the shell side or where mechanical cleaning is required. The pitch angle also influences the shell-side pressure drop and heat transfer.
What are dummy tubes and sealing strips used for in the tube sheet layout?
Dummy tubes are tubes with no flow through them that fill gaps in the bundle – for example in the lanes of multi-pass units – and thereby reduce unwanted bypass flows on the shell side. Pairs of sealing strips close the annular gap between the outermost tube row and the shell; without them, a considerable share of the shell-side mass flow bypasses the bundle without effect, and the actual heat transfer falls short of the calculation.
Why is the distance between the tubesheet and the first baffle adjustable separately?
In the inlet and outlet regions, the nozzles including any impingement plates need space; the first and last baffle compartments are therefore usually longer than the central baffle spacing. For the thermal rating (e.g. by the cell method or Bell-Delaware), these end compartments must be captured correctly, because the cross-flow velocities there are lower and heat transfer is correspondingly poorer.
What role does the baffle borehole play?
The borehole diameter in the baffle is slightly larger than the tube outside diameter (typically per TEMA tolerances). The clearance determines the leakage flows through the baffle boreholes, which reduce shell-side heat transfer but also lower the pressure drop – and it influences the vibration support of the tubes.