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Annular regenerator screen ring: 100 mesh, Ø47.5 / Ø41.5, for a 2 in tri-clamp Stirling
How do I make an annular regenerator for a 2 in tri-clamp free-piston Stirling? · Hardware · basis: Urieli & Berchowitz screen relations: porosity 1 − π m d / 4, hydraulic diameter d·β/(1 − β); heat transfer and friction from Gedeon & Wood (1996)
Long Earth Society build part. The regenerator of my free-piston generator. The engines
Exact dimensions. Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part. Mating features
- sizes
- 5 in table
Notes
- 389 rings of 100 mesh, 0.1 mm wire screen stacked 77.8 mm high in the annulus between the liner (Ø41.5) and the hot spool's bore (Ø47.5), on the liner's spokes and under its rim.
- Porosity 0.691, hydraulic diameter 0.223 mm, frontal area 419 mm². At the design point the regenerator's NTU is 165 (effectiveness 0.9940), its enthalpy loss 5.4 W.
- Stack the rings with the weave of each layer turned a little against the last; fill the annulus exactly, so the rim holds the stack.
Sizes
| feature | value |
|---|---|
| ring | Ø47.5 / Ø41.5 × 0.2 |
| count | 389 |
| screen | 100 mesh, 0.1 mm wire |
| porosity | 0.691 |
| hydraulic Ø mm | 0.223 |
Mating features
Drawn at the exact size. Open press, slide, run and socket features by your process's clearance; leave designed gaps and clamp fits as drawn.
| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| OD | Ø47.5 | hot spool bore | slide | all |
| ID | Ø41.5 | liner tube OD | slide | all |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Ohio University (Urieli) | Stirling cycle machine analysis: ideal adiabatic and simple analysis (after Urieli & Berchowitz, Stirling Cycle Engine Analysis, 1984) | web | author's site |
| NASA (NTRS, public domain) | Gedeon & Wood (1996), Oscillating-flow regenerator test rig: correlations for screens and felts, NASA CR-198442 (f = 129/Re + 2.91 Re^-0.103; Nu = (1 + 0.99 Pe^0.66) β^1.79) | US Government work, public domain | |
| Long Earth Society | Engine builds | web, video | LES site |
Free files
★ Free files 1 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| regen-ring-41.5x47.5x0.2 | regenerator ring: one layer of 100 mesh woven screen (0.1 mm wire) cut to Ø47.5 / Ø41.5, drawn 0.2 thick (two wire diameters) | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=fpse-regenerator-screen-ring
How it fits
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Questions
Why 100 mesh?
At 40–50 Hz in helium the gas needs a fine matrix to give up and take back its heat each stroke; 100 mesh keeps the effectiveness above 0.99 while the friction stays a fraction of the cycle's work.