3 ms·

That seems like exactly the unit. Just like when measuring rainfall, the amount collected scales with the area of the equipment. What would you prefer, mm/(mm)^

That seems like exactly the unit. Just like when measuring rainfall, the amount collected scales with the area of the equipment. What would you prefer, mm/(mm)^2? I would assume time is on the scale of per day; that seems, at least to me, the only time unit they wouldn't have specified here. Of course, in an article this bloggy it's not a given that the reasonable interpretation of such vague units is the interpretation intended--but I think that there is a reasonable interpretation.

delecti 9y ago
Volume per unit of collection area per unit time at a given absolute humidity. It might be a bit too technical, but anything less really can't give you a sense of scale.
- swsieber 9y ago
  I'd assume that since the thing depends on the day/night cycle, it'd be millimeters / day.
- nkurz 9y ago
  The actual paper (https://www.nature.com/articles/s41467-018-03162-7 https://www.nature.com/articles/s41467-018-03162-7) actually gives something very close to numbers you want, although they express it as liters/day/kilogram @ humidity. Here's the abstract: Water scarcity is a particularly severe challenge in arid and desert climates. While a substantial amount of water is present in the form of vapour in the atmosphere, harvesting this water by state-of-the-art dewing technology can be extremely energy intensive and impractical, particularly when the relative humidity (RH) is low (i.e., below ~40% RH). In contrast, atmospheric water generators that utilise sorbents enable capture of vapour at low RH conditions and can be driven by the abundant source of solar-thermal energy with higher efficiency. Here, we demonstrate an air-cooled sorbent-based atmospheric water harvesting device using the metal−organic framework (MOF)-801 [Zr6O4(OH)4(fumarate)6] operating in an exceptionally arid climate (10–40% RH) and sub-zero dew points (Tempe, Arizona, USA) with a thermal efficiency (solar input to water conversion) of ~14%. We predict that this device delivered over 0.25 L of water per kg of MOF for a single daily cycle. https://www.nature.com/articles/s41467-018-03162-7 https://www.nature.com/articles/s41467-018-03162-7
CamperBob2 9y ago
That seems like exactly the unit. Just like when measuring rainfall, the amount collected scales with the area of the equipment. If you live in a desert, you're not trying to measure the water. You're trying to drink it.

delecti 9y ago

Volume per unit of collection area per unit time at a given absolute humidity. It might be a bit too technical, but anything less really can't give you a sense of scale.

swsieber 9y ago
I'd assume that since the thing depends on the day/night cycle, it'd be millimeters / day.
nkurz 9y ago
The actual paper (https://www.nature.com/articles/s41467-018-03162-7 https://www.nature.com/articles/s41467-018-03162-7) actually gives something very close to numbers you want, although they express it as liters/day/kilogram @ humidity. Here's the abstract: Water scarcity is a particularly severe challenge in arid and desert climates. While a substantial amount of water is present in the form of vapour in the atmosphere, harvesting this water by state-of-the-art dewing technology can be extremely energy intensive and impractical, particularly when the relative humidity (RH) is low (i.e., below ~40% RH). In contrast, atmospheric water generators that utilise sorbents enable capture of vapour at low RH conditions and can be driven by the abundant source of solar-thermal energy with higher efficiency. Here, we demonstrate an air-cooled sorbent-based atmospheric water harvesting device using the metal−organic framework (MOF)-801 [Zr6O4(OH)4(fumarate)6] operating in an exceptionally arid climate (10–40% RH) and sub-zero dew points (Tempe, Arizona, USA) with a thermal efficiency (solar input to water conversion) of ~14%. We predict that this device delivered over 0.25 L of water per kg of MOF for a single daily cycle. https://www.nature.com/articles/s41467-018-03162-7 https://www.nature.com/articles/s41467-018-03162-7

CamperBob2 9y ago

That seems like exactly the unit. Just like when measuring rainfall, the amount collected scales with the area of the equipment. If you live in a desert, you're not trying to measure the water. You're trying to drink it.