Slotted heater, regenerator and cooler liner for a 2 in hot spool (Ø48.00 / Ø40.00) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/stirling-slotted-regenerator-liner/  (CC BY 4.0)
Basis: Design values; slot heat transfer and friction from the laminar rectangular-duct values (Shah & London) and the cycle model on the engine pages
Catalog version: 2026-10-20

Sizes: see table below
- The displacer runs in the liner's Ø40.00 bore. The gas does not go round the displacer: it goes out through the liner, along 120 slots 0.5 wide and 3 deep cut in its outside under the flame (the heater), through the annular screen stack on its Ø42 neck (the regenerator), along the same slots under the water jacket (the cooler) and in through 16 ports at the cold end.
- The slots' fin tips are Ø48.00, a press fit in the finished bore, so the heat crosses from the spool wall into the fins. Heater 50 mm, regenerator 40 mm, cooler 45 mm.
- Slot gas volume: heater 9.0 mL, cooler 8.1 mL. Wetted area: about 42 cm² in each of heater and cooler, against about 75 cm² of plain bore.
- Fitting: the screen stack goes on the neck first, then the liner is pressed (or shrunk) into the hot spool until its feet touch the floor; the cold end then sits 1.95 mm inside the face, where the Type B gasket's lip holds it.

zone  z from the spool face  size
cold ring  1.95–5  Ø48.00 (slide)
plenum + ports  5–9  Ø44, 16 × Ø3 at z 7
cooler slots  9–54  120 × 0.5 × 3, tips Ø48.00
regenerator neck  54–94  Ø42.00
heater slots  94–144  120 × 0.5 × 3, tips Ø48.00
hot plenum  144–147.4  Ø44
feet  147.4–149.4  3 × 4 wide
bore    Ø40.00 (displacer land: run)

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Academic Press (R. K. Shah, A. L. London): Laminar Flow Forced Convection in Ducts (1978): fRe of rectangular ducts — book — book; correlation cited [verify license at link] — https://doi.org/10.1016/C2013-0-06152-X
- 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 — web — university course pages [verify license at link] — https://www.ohio.edu/mechanical/stirling/
- NASA (W. R. Martini): Stirling Engine Design Manual, 2nd edition, NASA CR-168088 (1983): decoupled second-order losses (shuttle, conduction, flow friction, regenerator) — PDF — US government report — https://ntrs.nasa.gov/citations/19830022057
- Cambridge University Press (J. R. Senft): Mechanical Efficiency of Heat Engines (2007): shaft work = E·W − (1/E − E)·W_forced — book — book; formula cited [verify license at link] — https://doi.org/10.1017/CBO9780511546105
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/stirling-slotted-regenerator-liner/index.json
API: https://xemstudio.com/api/geometry?object=stirling-slotted-regenerator-liner