Xem Studiomeasured geometryLibrary › Stirling engines › Thermoacoustic & fluidyne ·
Thermoacoustic buffer-tube liner: 2 in, 0.5 wall, 180 and 140 mm
What holds the hot exchanger in a thermoacoustic core, and what is the thermal buffer tube? · Hardware · basis: Bore Ø47.5; lengths from the core layouts in tools/gen_ta_power.py
Long Earth Society build part. The buffer-tube liners in my generator cores. 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
- 2 in table
Notes
- The thermal buffer tube is the open length between the hot exchanger and the secondary ambient exchanger: the gas oscillates in it without touching anything, so the heat stays at the hot end. It runs hot end up (hot gas over cold), so it does not convect.
- The liner is what the hot exchanger stands on: a thin tube at the bore, 0.5 wall, so it conducts as little heat as it can (the model counts its conduction with the tube wall's).
- 180 mm in the ring engine's cores, 140 mm in the twin engine's: in the model the ring's gas moves about ±9 mm at the liner's ends, well inside its length.
- Fit: outside slide in the bore; the ends bear on the exchanger inserts.
Sizes
| file | outside_mm | inside_mm | length_mm |
|---|---|---|---|
| tbt-liner-2in-140 | 47.5 | 46.5 | 140.0 |
| tbt-liner-2in-180 | 47.5 | 46.5 | 180.0 |
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 |
|---|---|---|---|---|
| outside | Ø47.5 | 2 in spool bore | slide | all |
| inside | Ø46.5 (0.5 wall) | gas passage (no contact) | designed | all |
| end faces | flat ring Ø46.5–Ø47.5 | hot and secondary exchanger inserts | designed | all |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| J. Acoust. Soc. Am. (S. Backhaus, G. W. Swift) | A thermoacoustic-Stirling heat engine: detailed study, JASA 107(6), 3148 (2000): torus with inertance and compliance, thermal buffer tube, jet pump against Gedeon streaming | web | journal article; cited verify |
| G. W. Swift (Acoustical Society of America / LANL) | Thermoacoustics: A Unifying Perspective for Some Engines and Refrigerators (Rott's equations, the energy equation, screen relations; the method behind DeltaEC) | web, book | cited verify |
| Long Earth Society | Engine builds | web, video | LES site |
Free files
★ Free files 2 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| tbt-liner-2in-140 | thermal buffer tube liner Ø47.5 / Ø46.5 × 140 (0.5 wall) | STEP · STL |
| tbt-liner-2in-180 | thermal buffer tube liner Ø47.5 / Ø46.5 × 180 (0.5 wall) | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=thermoacoustic-buffer-tube-liner
How it fits
In these build lists
Thermoacoustic-Stirling ring generator, three 2…A double-acting thermoacoustic-Stirling generator in 2 in tri-clamp: three cores…Thermoacoustic-Stirling engine with twin…Backhaus & Swift's thermoacoustic-Stirling torus in 2 in tri-clamp with two oppo…You might also need
Questions
Why so thin?
Every square millimetre of wall carries heat from the hot end to the cold end by conduction; the liner only has to locate the exchangers.