# Thermoacoustic hot-cavity liners: Ø47.5 / Ø44 tubes that set a 40 mm hot exchanger flush with a closed hot end's face

> How do I hold a hot heat exchanger at the top of a closed tri-clamp hot end?

- Category: Stirling engines › Thermoacoustic & fluidyne
- Kind: Hardware
- Basis: Design values: lengths = the hot section's inside depth (length − 3 mm closed end) − four 10 mm hot exchanger discs
- Page: https://xemstudio.com/objects/thermoacoustic-hot-cavity-liner/ · JSON: https://xemstudio.com/api/geometry?object=thermoacoustic-hot-cavity-liner · Plain text: https://xemstudio.com/objects/thermoacoustic-hot-cavity-liner/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**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.

## Notes

- A plain tube that stands on the inside of a closed 2 in hot end and holds the hot heat exchanger at its top, so the exchanger's top face is flush with the hot end's clamp face. The stack in the next section then stands on the exchanger, across the hot joint.
- Bore Ø44: the gas inside the liner is the engine's hot cavity, the gas spring at the hot end that sets how much the gas moves through the stack. Outside Ø47.5: the spool bore, a slide fit.
- It runs at the hot end's temperature: it has to take that temperature. The file is the geometry; what it is made of is the builder's choice.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| outside | Ø47.5 | closed hot cup / closed-end spool bore Ø47.5 | slide | all |
| inside | Ø44 | hot cavity gas (no contact) | designed | all |
| lower end | flat ring Ø44–Ø47.5 | the cup's closed end (inside floor) | designed | all |
| upper end | flat ring Ø44–Ø47.5 | the lowest hot exchanger disc's outer ring | designed | all |
| length | 17 / 47 / 77 / 109.4 | sets the top hot disc flush with the hot section face | designed | all |

## Sizes

| part | hot section | section length_mm | inside depth_mm | liner_mm | hot exchanger above_mm |
|---|---|---|---|---|---|
| ta-hot-liner-2in-17 | cup-2in-60 | 60.0 | 57.0 | 17.0 | 40.0 |
| ta-hot-liner-2in-47 | cup-2in-90 | 90.0 | 87.0 | 47.0 | 40.0 |
| ta-hot-liner-2in-77 | cup-2in-120 | 120.0 | 117.0 | 77.0 | 40.0 |
| ta-hot-liner-2in-109.4 | closed-spool-2in-152.4 | 152.4 | 149.4 | 109.4 | 40.0 |

## Where the files are

- Xem Studio: [tools/gen_ta_modular.py: the section geometry, the network model and every number on these pages](https://xemstudio.com/) — code — CC BY 4.0
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (4 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/thermoacoustic-hot-cavity-liner/index.json

- ta-hot-liner-2in-17: [STEP](https://xemstudio.com/files/hardware/thermoacoustic-hot-cavity-liner/ta-hot-liner-2in-17.step) · [STL](https://xemstudio.com/files/hardware/thermoacoustic-hot-cavity-liner/ta-hot-liner-2in-17.stl) — hot-cavity liner Ø47.5 / Ø44 × 17: stands on the closed end of cup-2in-60 and carries the four hot exchanger discs, whose top is then flush with the face
- ta-hot-liner-2in-47: [STEP](https://xemstudio.com/files/hardware/thermoacoustic-hot-cavity-liner/ta-hot-liner-2in-47.step) · [STL](https://xemstudio.com/files/hardware/thermoacoustic-hot-cavity-liner/ta-hot-liner-2in-47.stl) — hot-cavity liner Ø47.5 / Ø44 × 47: stands on the closed end of cup-2in-90 and carries the four hot exchanger discs, whose top is then flush with the face
- ta-hot-liner-2in-77: [STEP](https://xemstudio.com/files/hardware/thermoacoustic-hot-cavity-liner/ta-hot-liner-2in-77.step) · [STL](https://xemstudio.com/files/hardware/thermoacoustic-hot-cavity-liner/ta-hot-liner-2in-77.stl) — hot-cavity liner Ø47.5 / Ø44 × 77: stands on the closed end of cup-2in-120 and carries the four hot exchanger discs, whose top is then flush with the face
- ta-hot-liner-2in-109.4: [STEP](https://xemstudio.com/files/hardware/thermoacoustic-hot-cavity-liner/ta-hot-liner-2in-109.4.step) · [STL](https://xemstudio.com/files/hardware/thermoacoustic-hot-cavity-liner/ta-hot-liner-2in-109.4.stl) — hot-cavity liner Ø47.5 / Ø44 × 109.4: stands on the closed end of closed-spool-2in-152.4 and carries the four hot exchanger discs, whose top is then flush with the face

## Questions

**Why a liner and not a ledge?**

A closed-end spool is plain tube inside; a liner standing on the closed end puts the exchanger exactly at the top without any welding or machining of the spool.

**Which liner for which hot section?**

Match the hot section: the table lists the liner for each closed hot end that takes the modular engine's column.

## Fits with

- [Build list: Modular free-piston thermoacoustic engine, 2 in tri-clamp (stack sections and a clamp-in linear alternator)](https://xemstudio.com/objects/list-ta-modular-free-piston-2in/)
- [Tri-clamp closed-end spool: 2 in × 152.4 mm (6 in) with a welded closed end](https://xemstudio.com/objects/tri-clamp-closed-end-spool/)
- [Tri-clamp cups: closed-end spools (ferrule on a capped tube), 1.5, 2 and 3 in](https://xemstudio.com/objects/tri-clamp-cups/)
- [Thermoacoustic heat exchangers, hot and cold, parallel plate, for 1.5, 2 and 3 in tri-clamp spools](https://xemstudio.com/objects/thermoacoustic-heat-exchanger/)
- [Thermoacoustic bore spacers and liners for 2 in tri-clamp spools: 9.8, 60 and 61.7 mm](https://xemstudio.com/objects/thermoacoustic-bore-spacer/)