# Annular regenerator screen stack, Ø48 / Ø42 × 40 (50 mesh × 0.22 mm wire)

> How big should the regenerator screen stack be in a 2 in Stirling engine?

- Category: Hardware › Stirling & thermoacoustic
- Kind: Hardware
- Basis: Porosity of stacked square-weave screens 1 − π m d / 4; friction and heat transfer from the Urieli & Berchowitz screen correlations
- Page: https://xemstudio.com/objects/stirling-annular-screen-stack/ · JSON: https://xemstudio.com/api/geometry?object=stirling-annular-screen-stack · Plain text: https://xemstudio.com/objects/stirling-annular-screen-stack/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

- Annular screens punched Ø48.00 outside, Ø42.00 inside, stacked 40 mm deep on the liner's neck: about 91 screens of 50 mesh (per inch) × 0.22 mm wire, porosity 0.660, hydraulic diameter 0.43 mm.
- Gas volume in the stack 11.2 mL. In the cycle model its effectiveness is 0.966 on charged air at 600 rpm and 0.980 on helium at 1200 rpm.
- Finer screens raise the effectiveness and the pumping loss together; I swept 0.10 to 0.30 mm wire and 0.22 mm was the best shaft power on air and on helium.

## 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 | Ø48.00 | hot-spool finished bore | slide | all |
| inside | Ø42.00 | liner neck | slide | all |

## Sizes

| item | value |
|---|---|
| envelope | Ø48.00 / Ø42.00 × 40 |
| screen | 50 mesh × 0.22 wire |
| count | ≈ 91 |
| porosity | 0.66 |

## Where the files are

- Ohio University (I. Urieli): [Stirling cycle machine analysis (after Urieli & Berchowitz, Stirling Cycle Engine Analysis, 1984): Schmidt and simple analyses, wire-screen regenerator friction fr = 54 + 1.43 Re^0.78 and St = 0.46 Re^−0.4 / Pr](https://www.ohio.edu/mechanical/stirling/) — web — university course pages (verify at link)
- NASA (W. R. Martini): [Stirling Engine Design Manual, 2nd edition, NASA CR-168088 (1983): decoupled second-order losses (shuttle, conduction, flow friction, regenerator)](https://ntrs.nasa.gov/citations/19830022057) — PDF — US government report
- Cambridge University Press (J. R. Senft): [Mechanical Efficiency of Heat Engines (2007): shaft work = E·W − (1/E − E)·W_forced](https://doi.org/10.1017/CBO9780511546105) — book — book; formula cited (verify at link)
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/stirling-annular-screen-stack/index.json

- screen-stack-48x42x40-50mesh: [STEP](https://xemstudio.com/files/hardware/stirling-annular-screen-stack/screen-stack-48x42x40-50mesh.step) · [STL](https://xemstudio.com/files/hardware/stirling-annular-screen-stack/screen-stack-48x42x40-50mesh.stl) — regenerator screen stack envelope Ø48.00 / Ø42.00 × 40: about 91 annular screens, 50 mesh × 0.22 wire (porosity 0.66)

## Questions

**Can I use a different screen?**

Yes; keep the stack length and the porosity near 0.66 and re-run the numbers.

## Fits with

- [Slotted heater, regenerator and cooler liner for a 2 in hot spool (Ø48.00 / Ø40.00)](https://xemstudio.com/objects/stirling-slotted-regenerator-liner/)
- [Build list: Tri-clamp horizontal gamma generator, 2 in, chargeable](https://xemstudio.com/objects/list-tri-clamp-horizontal-gamma/)
- [Build list: Tri-clamp charged beta, 2 in](https://xemstudio.com/objects/list-tri-clamp-charged-beta/)