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Comment by mppm

Unless they have buried some really important caveat somewhere in the paper [1], it really looks like they are making claims that are incompatible with the second law of thermodynamics. They claim that water droplets are condensing on their nanomaterial at constant temperature and less than 100% relative humidity. This is absolutely forbidden by thermodynamics as we understand it. Under these conditions droplets can condense within pores (forming a concave surface), but they can never form a convex droplet on a flat surface.

Their mumbo-jumbo about water being "squeezed out" onto the surface by the hydrophobic component is totally bogus as well. The condensation will just stop earlier, without overflowing. Water condensing in concave pores and being squeezed into convex droplets requires hydrostatic pressure to be positive and negative at the same time.

The possibilities I see are: 1) contaminated surfaces 2) miscalibrated relative humidity or 3) they've neglected to mention a cooling plate that keeps the material below ambient.

1. https://www.science.org/doi/10.1126/sciadv.adu8349

parent mppm 1 year ago

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