CN2091433U — Solar adsorption ice-maker with V-groove + selective absorber (patent)

Source: Google Patents CN2091433U (utility model, ~1991). Credibility: High for prior-art purposes (granted utility model). Confidence: medium (patent, not peer-reviewed performance).

Key points

• Direct intermittent activated-carbon/methanol ice-maker; the box is the collector/adsorber.
• Sun-facing face carries a solar-spectral-selective absorbing coating AND a V-groove structure under a transparent glass cover (cuts convective loss, maximizes absorption).
• Positioned as avoiding expensive black-chrome coatings.
• 0.94 m² collector, ~4 kg ice/day, COP 0.10-0.12 at 16,000-19,000 kJ/m².

Relevance

This is the closest prior art to the geometric-blackness-solar-adsorption-bed-face experiment: it already combined a V-groove geometry with a selective coating on a direct adsorption bed face. Note it pairs geometry WITH a selective coating — consistent with the finding that geometry alone is the weaker optical lever.