{
 "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-hot-shroud",
 "name": "Thermoacoustic hot-head shroud: flame shroud and flue for a vertical 2 in tri-clamp core",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Thermoacoustic & fluidyne",
 "year": null,
 "question": "How do I heat the hot exchanger of a vertical thermoacoustic core with a propane torch?",
 "tags": [
  "thermoacoustic",
  "shroud",
  "flame",
  "torch",
  "burner",
  "flue",
  "tri-clamp",
  "long earth society"
 ],
 "aliases": [
  "thermoacoustic heat shroud",
  "torch shroud tri clamp",
  "propane heated thermoacoustic engine",
  "flame shroud hot heat exchanger"
 ],
 "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-hot-shroud/",
 "sheet_txt": "https://xemstudio.com/objects/thermoacoustic-hot-shroud/sheet.txt",
 "sheet": {
  "basis": "Bore = ASME BPE 2 in tube OD Ø50.8; positions from the loop layout in tools/gen_ta_family.py; ISO 273 medium clearance for M4",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "The loop's core stands vertical with its hot exchanger above the thermal buffer tube, hot end up, so the buffer tube does not convect (Backhaus & Swift ran theirs the same way). A torch cannot fire straight up at the middle of a vertical tube, so the shroud does it: a closed band round the tube at the hot exchanger, with a flue that comes down beside the loop to a torch standing on the bench.",
   "Flame and hot gas go up the Ø35 flue (132.6 mm), into the chamber, round the tube over a 40 mm band (the top 20 mm of the buffer tube, the hot exchanger, the first 10 mm of the regenerator) and out of the vents in the top. No clamp, gasket or jacket is inside the band.",
   "Two halves split across the tube: the front half carries the flue; one M4 × 25 and nut each side close them on the tube. The end walls are bored at the tube OD.",
   "What it is made of is the builder's choice; the file is the geometry. It runs at flame temperature."
  ],
  "table": {
   "columns": [
    "feature",
    "value"
   ],
   "rows": [
    [
     "band",
     "40 tall, Ø80 round the tube"
    ],
    [
     "flue",
     "Ø40 / Ø35 × 132.6, 100 in front of the tube axis"
    ],
    [
     "walls",
     "2.5"
    ],
    [
     "vents",
     "8 × Ø6 on r 31.5, 3 × Ø8 over the lobe"
    ],
    [
     "bolts",
     "M4 × 25 + nut, one each side"
    ]
   ]
  }
 },
 "sheet_text": "Thermoacoustic hot-head shroud: flame shroud and flue for a vertical 2 in tri-clamp core — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/thermoacoustic-hot-shroud/  (CC BY 4.0)\nBasis: Bore = ASME BPE 2 in tube OD Ø50.8; positions from the loop layout in tools/gen_ta_family.py; ISO 273 medium clearance for M4\nCatalog version: 2026-10-20\n\nSizes: see table below\n- The loop's core stands vertical with its hot exchanger above the thermal buffer tube, hot end up, so the buffer tube does not convect (Backhaus & Swift ran theirs the same way). A torch cannot fire straight up at the middle of a vertical tube, so the shroud does it: a closed band round the tube at the hot exchanger, with a flue that comes down beside the loop to a torch standing on the bench.\n- Flame and hot gas go up the Ø35 flue (132.6 mm), into the chamber, round the tube over a 40 mm band (the top 20 mm of the buffer tube, the hot exchanger, the first 10 mm of the regenerator) and out of the vents in the top. No clamp, gasket or jacket is inside the band.\n- Two halves split across the tube: the front half carries the flue; one M4 × 25 and nut each side close them on the tube. The end walls are bored at the tube OD.\n- What it is made of is the builder's choice; the file is the geometry. It runs at flame temperature.\n\nfeature  value\nband  40 tall, Ø80 round the tube\nflue  Ø40 / Ø35 × 132.6, 100 in front of the tube axis\nwalls  2.5\nvents  8 × Ø6 on r 31.5, 3 × Ø8 over the lobe\nbolts  M4 × 25 + nut, one each side\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): regenerator |Z| 15–30 ρc/A with p and U nearly in phase, thermal buffer tube, inertance and compliance, jet pump against Gedeon streaming — PDF — journal article; numbers cited [verify license at link] — https://sites.science.oregonstate.edu/~hetheriw/energy/topics/doc/thermo/heat_eng/Stirling_engine/thermoacoustic-Stirling.heat.engine.detailed.study.j.acous.soc.2000.pdf\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-hot-shroud/index.json\nAPI: https://xemstudio.com/api/geometry?object=thermoacoustic-hot-shroud\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): regenerator |Z| 15–30 ρc/A with p and U nearly in phase, thermal buffer tube, inertance and compliance, jet pump against Gedeon streaming",
   "url": "https://sites.science.oregonstate.edu/~hetheriw/energy/topics/doc/thermo/heat_eng/Stirling_engine/thermoacoustic-Stirling.heat.engine.detailed.study.j.acous.soc.2000.pdf",
   "formats": [
    "PDF"
   ],
   "license": "journal article; numbers 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": [
  "tri-clamp-torch-stand",
  "thermoacoustic-heat-exchanger",
  "thermoacoustic-water-jacket",
  "list-ta-loop-2in"
 ],
 "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": "end-wall bores",
   "exact": "Ø50.8",
   "mates": "2 in tube OD",
   "fit": "slide",
   "files": "all"
  },
  {
   "feature": "split",
   "exact": "1.0 total (0.5 per half)",
   "mates": "the other half",
   "fit": "clamp",
   "files": "all"
  },
  {
   "feature": "ear holes",
   "exact": "Ø4.5",
   "mates": "M4 clearance (ISO 273 medium)",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "flue",
   "exact": "Ø40 / Ø35",
   "mates": "torch flame from the torch stand below (no contact)",
   "fit": "designed",
   "files": "ta-shroud-2in-front"
  },
  {
   "feature": "vents",
   "exact": "8 × Ø6, 3 × Ø8",
   "mates": "exhaust (no contact)",
   "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 not heat it from below?",
   "a": "The hot exchanger is half way up a vertical core, above the buffer tube; a flame from below would heat the lower clamp, jacket and buffer tube first."
  },
  {
   "q": "Where does the torch go?",
   "a": "On the bench under the flue, its head in the torch stand's ring with the ring top 25 mm below the flue."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "ta-shroud-2in-front",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/thermoacoustic-hot-shroud/ta-shroud-2in-front.step",
   "stl": "https://xemstudio.com/files/hardware/thermoacoustic-hot-shroud/ta-shroud-2in-front.stl",
   "note": "front half (y ≥ 0.5): 40 tall band round the Ø50.8 tube, Ø80 chamber joined to a Ø40 lobe at y 100, 2.5 walls; Ø40 / Ø35 flue 132.6 long down from the chamber; vents in the top; ears with Ø4.5"
  },
  {
   "file": "ta-shroud-2in-back",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/thermoacoustic-hot-shroud/ta-shroud-2in-back.step",
   "stl": "https://xemstudio.com/files/hardware/thermoacoustic-hot-shroud/ta-shroud-2in-back.stl",
   "note": "back half (y ≤ −0.5) of the same band: Ø80 chamber, vents, ears with Ø4.5"
  }
 ],
 "markdown": "https://xemstudio.com/objects/thermoacoustic-hot-shroud/index.md"
}