Abstract

Addendum 4 analysed ALLFROMAIR® system performance under clear-sky conditions using passive radiative cooling. A critical operational extension is fog — a phenomenon occurring several hours per day across a wide range of climates, including coastal deserts. During fog periods, the wire-forest electrode structure already present in the system functions directly as a high-efficiency fog collector. The DEP field provides a modest additional steering correction for the larger droplets in the fog size distribution, and vibration-desorption ensures continuous drainage.

Calculations show that ALLFROMAIR® v2 achieves 0.26–0.97 L/m²/h during fog periods (Q = η × LWC_median × v × 3.6, η = 0.72), compared with 0.07–0.35 L/m²/h for conventional standard fog collectors (SFC). The combined daily yield (fog hours + pro-rated clear-hour radiative contribution, aligned with Addendum 4 v2 energy-budget-consistent values) reaches 3.8–11.3 L/m²/day for nine of ten climate classes. Tropical coastal climates (Lima/Atacama, 11.3 L/m²/day) and semi-arid coast (Agadir/Nairobi, 8.5 L/m²/day) remain the strongest performers. SEC is 34–53 kWh/m³ under active fan operation and falls to ~0.001–0.003 kWh/m³ under wind-driven passive operation — a regime that coincides naturally with fog occurrence in coastal climates.

Revision Note (v3)

  • DEP force claim tempered. v1 and v2 stated that the DEP field ‘actively directs droplets toward the electrode surface.’ Quantitative analysis (Section 2.3 below) shows that for typical fog droplet radii (5–25 µm), the DEP force is 0.7–18 % of the Stokes drag at 1 m/s airflow. DEP therefore constitutes a modest steering correction, not a dominant collection mechanism. The bulk of the collection-efficiency advantage over standard mesh collectors arises from wire-forest geometry (fine wire diameter, high solidity, multi-row depth).
  • Combined yields updated. Clear-hour radiative contributions are now computed from Addendum 4 v2 (energy-budget-consistent values). This lowers the combined-yield estimates for dry climates by 5–15 %.

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