raw · papers · ingested 2026-07-19
US Patent 4,293,030A — Method of and means for passively cooling a shelter containing a heat source
Source: https://patents.google.com/patent/US4293030A/en
Filed: December 13, 1978. Granted: October 6, 1981. Inventor: Claude Rambach. Assignee: Ormat Turbines Ltd.
The design
A small telecom equipment shelter, approximately 1m × 1m × 2m (≈2 m³ / ~80 ft³), cooled by a pure passive (no pump) dual thermosiphon loop, with a 300-liter accumulator tank. Pipe diameter ~25mm, loop conduits inclined 2°–5°, flow velocity ~0.1 m/s. Circulation initiates with a temperature differential as small as 2–3°C.
Why it matters for this archive
The closest documented real precedent for “small-building-scale passive thermosiphon” found in this research round — and it is still roughly 30x larger by volume than a 2.5 ft³ target, needed 25mm tubing, and required a meter-plus of vertical rise to sustain flow on a thin (2–3°C) driving margin. Directly informs Miniature thermosiphon scaling limits: shrinking a thermosiphon loop below this scale runs out of driving head before it runs out of physics.