{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "thermoacoustic-buffer-tube-liner",
 "name": "Thermoacoustic buffer-tube liner: 2 in, 0.5 wall, 180 and 140 mm",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Thermoacoustic & fluidyne",
 "year": null,
 "question": "What holds the hot exchanger in a thermoacoustic core, and what is the thermal buffer tube?",
 "tags": [
  "thermoacoustic",
  "thermal buffer tube",
  "liner",
  "tri-clamp",
  "long earth society"
 ],
 "aliases": [
  "thermal buffer tube liner",
  "thermoacoustic buffer tube 2 inch",
  "pulse tube liner tri clamp"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 2,
 "url": "https://xemstudio.com/objects/thermoacoustic-buffer-tube-liner/",
 "sheet_txt": "https://xemstudio.com/objects/thermoacoustic-buffer-tube-liner/sheet.txt",
 "sheet": {
  "basis": "Bore Ø47.5; lengths from the core layouts in tools/gen_ta_power.py",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "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."
  ],
  "table": {
   "columns": [
    "file",
    "outside_mm",
    "inside_mm",
    "length_mm"
   ],
   "rows": [
    [
     "tbt-liner-2in-140",
     47.5,
     46.5,
     140
    ],
    [
     "tbt-liner-2in-180",
     47.5,
     46.5,
     180
    ]
   ]
  }
 },
 "sheet_text": "Thermoacoustic buffer-tube liner: 2 in, 0.5 wall, 180 and 140 mm — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/thermoacoustic-buffer-tube-liner/  (CC BY 4.0)\nBasis: Bore Ø47.5; lengths from the core layouts in tools/gen_ta_power.py\nCatalog version: 2026-10-20\n\nSizes: see table below\n- 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.\n- 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).\n- 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.\n- Fit: outside slide in the bore; the ends bear on the exchanger inserts.\n\nfile  outside_mm  inside_mm  length_mm\ntbt-liner-2in-140  47.5  46.5  140.0\ntbt-liner-2in-180  47.5  46.5  180.0\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- 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 license at link] — https://doi.org/10.1121/1.429343\n- 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 license at link] — https://www.lanl.gov/org/ddste/aldps/materials-physics-applications/condensed-matter-magnet-science/thermoacoustics/\n- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 2 parts): https://xemstudio.com/files/hardware/thermoacoustic-buffer-tube-liner/index.json\nAPI: https://xemstudio.com/api/geometry?object=thermoacoustic-buffer-tube-liner\n",
 "sources": [
  {
   "publisher": "J. Acoust. Soc. Am. (S. Backhaus, G. W. Swift)",
   "title": "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",
   "url": "https://doi.org/10.1121/1.429343",
   "formats": [
    "web"
   ],
   "license": "journal article; cited",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "G. W. Swift (Acoustical Society of America / LANL)",
   "title": "Thermoacoustics: A Unifying Perspective for Some Engines and Refrigerators (Rott's equations, the energy equation, screen relations; the method behind DeltaEC)",
   "url": "https://www.lanl.gov/org/ddste/aldps/materials-physics-applications/condensed-matter-magnet-science/thermoacoustics/",
   "formats": [
    "web",
    "book"
   ],
   "license": "cited",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "thermoacoustic-bore-spacer",
  "thermoacoustic-slotted-exchanger-insert",
  "list-ta-ring-3x2in"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [
  {
   "feature": "outside",
   "exact": "Ø47.5",
   "mates": "2 in spool bore",
   "fit": "slide",
   "files": "all"
  },
  {
   "feature": "inside",
   "exact": "Ø46.5 (0.5 wall)",
   "mates": "gas passage (no contact)",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "end faces",
   "exact": "flat ring Ø46.5–Ø47.5",
   "mates": "hot and secondary exchanger inserts",
   "fit": "designed",
   "files": "all"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "Why so thin?",
   "a": "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."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "tbt-liner-2in-140",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/thermoacoustic-buffer-tube-liner/tbt-liner-2in-140.step",
   "stl": "https://xemstudio.com/files/hardware/thermoacoustic-buffer-tube-liner/tbt-liner-2in-140.stl",
   "note": "thermal buffer tube liner Ø47.5 / Ø46.5 × 140 (0.5 wall)"
  },
  {
   "file": "tbt-liner-2in-180",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/thermoacoustic-buffer-tube-liner/tbt-liner-2in-180.step",
   "stl": "https://xemstudio.com/files/hardware/thermoacoustic-buffer-tube-liner/tbt-liner-2in-180.stl",
   "note": "thermal buffer tube liner Ø47.5 / Ø46.5 × 180 (0.5 wall)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/thermoacoustic-buffer-tube-liner/index.md"
}