raw · notes · ingested 2026-07-02
DIY evaporator/condenser design & refrigerant choice for sorption cooling (research note)
confidence: high
Source: https://www.sciencedirect.com/science/article/abs/pii/S1359431116303441
Consolidates: SFU capillary/falling-film papers, Khattab valveless module, refrigerant decision matrix, ice-maker charge ratios. Credibility: High (peer-reviewed + authoritative).
Three evaporator archetypes
- Flooded — pool boiling; simplest; hydrostatic-limited (keep shallow).
- Falling-film — highest capacity, needs manifold + pump (parasitic).
- Capillary-assisted — fine fins wick from a shallow pool; near falling-film, no pump — best DIY. Fin pitch is critical: 0.635 mm (40 fpi) wicks; 1 mm/26 fpi does not.
Chilled-load coupling
- Pump chilled water through the tube bores, OR make the evaporator the ice tray (water around it freezes at night).
Condenser + receiver
- Air-cooled finned coil (natural convection ok small; water-cooled → lower Tcond, better COP) → receiver holds charge, feeds evaporator by gravity/capillary (valveless) or expansion valve.
- Lowest-parts-count (Khattab): one glass tube, bed at one end, combined evaporator+condenser at the other, no valves.
Refrigerant decides the vessel
Water/methanol → vacuum vessel; ammonia → pressure-rated tubing. Adsorbent:refrigerant mass ratio ≈ 4:1 (e.g. 42 kg carbon : 10 kg methanol).