3 ms·

I wonder what the power requirements are, The cooling system has to be cooling the air that passes through it down to the dew point, if the ambient temperature

I wonder what the power requirements are, The cooling system has to be cooling the air that passes through it down to the dew point, if the ambient temperature and the dew point are too far apart, it's going to consume too much power to be practical.

miahi 12y ago
It also looks solar powered-only, so its efficiency is not better when the dew point is closer (night/morning). Linking a small solar cell (I would say ~1W from the shown surface) to a Peltier element (known power hog, a really small one takes at least 4W) is not a solution for efficiency.
- NickNameNick 12y ago
  Wolfram alpha says it takes ~1.3kj to change the temperature of 1m^3 of air by 1 degree C. Obviously this will vary enormously with temperature and humidity, but it gives us a number to work with. Wikipedia, and a post by 'someone' tells us there is ~30cc of water per cubic meter of air at 100% humidity and 30c. (This could be a reasonable set of envoronmental conditions in Washington DC for example). The mass of water in 100% humidity air is 28c 27.22g http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubic+meter&f1=28+%C2%B0C&f=MoistAirMoistureContent.Tdb_28+%C2%B0C&f2=1+bar&f=MoistAirMoistureContent.P%5Cu005f1+bar&f3=100+%25&f=MoistAirMoistureContent.RH_100+%25 http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubi... 30c 30.34g http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubic+meter&f1=30+%C2%B0C&f=MoistAirMoistureContent.Tdb_30+%C2%B0C&f2=1+bar&f=MoistAirMoistureContent.P%5Cu005f1+bar&f3=100+%25&f=MoistAirMoistureContent.RH%5Cu005f100+%25 http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubi... So we can extract ~3g, or 3cc of water from saturated air, with the use of ~2.6kj (assuming 100% efficiency, which is unlikely) Some of the highest power density batteries I've handled are 5 cell, 5500mAh li-poly batteries for model aircraft use, with a total energy capacity of around 180kj, Or ~ 200g of water. I think I'd rather carry a water bottle.

miahi 12y ago

It also looks solar powered-only, so its efficiency is not better when the dew point is closer (night/morning). Linking a small solar cell (I would say ~1W from the shown surface) to a Peltier element (known power hog, a really small one takes at least 4W) is not a solution for efficiency.

NickNameNick 12y ago
Wolfram alpha says it takes ~1.3kj to change the temperature of 1m^3 of air by 1 degree C. Obviously this will vary enormously with temperature and humidity, but it gives us a number to work with. Wikipedia, and a post by 'someone' tells us there is ~30cc of water per cubic meter of air at 100% humidity and 30c. (This could be a reasonable set of envoronmental conditions in Washington DC for example). The mass of water in 100% humidity air is 28c 27.22g http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubic+meter&f1=28+%C2%B0C&f=MoistAirMoistureContent.Tdb_28+%C2%B0C&f2=1+bar&f=MoistAirMoistureContent.P%5Cu005f1+bar&f3=100+%25&f=MoistAirMoistureContent.RH_100+%25 http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubi... 30c 30.34g http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubic+meter&f1=30+%C2%B0C&f=MoistAirMoistureContent.Tdb_30+%C2%B0C&f2=1+bar&f=MoistAirMoistureContent.P%5Cu005f1+bar&f3=100+%25&f=MoistAirMoistureContent.RH%5Cu005f100+%25 http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubi... So we can extract ~3g, or 3cc of water from saturated air, with the use of ~2.6kj (assuming 100% efficiency, which is unlikely) Some of the highest power density batteries I've handled are 5 cell, 5500mAh li-poly batteries for model aircraft use, with a total energy capacity of around 180kj, Or ~ 200g of water. I think I'd rather carry a water bottle.