4 ms·

We need a cooling technology that doesn’t emit hot air to the environment to prevent urban heat bubbles. https://nuscool.com/our-technologies/ https://nuscool.

We need a cooling technology that doesn’t emit hot air to the environment to prevent urban heat bubbles. https://nuscool.com/our-technologies/ https://nuscool.com/our-technologies/ presents an interesting candidate: Membrane-based water capture followed by evaporative cooling. No chemicals, lower energy requirements and no emission of hot air. Produces potable water in the process.

Karrot_Kream 5y ago
Interesting, this is similar (and much more thoroughly researched lol) to an idea I've had myself. It runs a dessicant dehumidification process along with an evaporative cooler. I wanted to try a more DIY version of this by using a dehumidifier to pump water into an evaporative cooler. I live in a dry area though so I'm never in need of dehumidifcation myself shrug.
- CorrectHorseBat 5y ago
  Doesn't work, all the evaporative cooler does is absorb the energy back that was released during dehumidification.
  - Karrot_Kream 5y ago
    You would have to drain some of the water out. It's not as simple as directly pumping it. Ice might help as well.
    - CorrectHorseBat 5y ago
      Why the evaporative cooler if you want to drain water? Letting water condense and then evaporate is a zero sum operation. Using ice is just moving your heat pump to another location. Maybe interesting if you can't install airco for some reason, but you're not improving the efficiency.
  - crishoj 5y ago
    Correct me if I’m wrong, but membrane based air dehumidification seems to require a lot less energy than other approaches. https://www.researchgate.net/publication/270721905_A_review_of_membrane-based_air_dehumidification https://www.researchgate.net/publication/270721905_A_review_...
    - CorrectHorseBat 5y ago
      I guess one might be able to make something that works somewhat better than a compressor, those don't use ideal Carnot cycles. Better than a Carnot machine isn't possible, you will always release heat when turning water vapor into liquid, so doing the evaporation afterwards and ending up with a cooler room is completely bollocks. You can't cool a room without discharging heat to the environment, the heat has to go somewhere.
agilob 5y ago
My parents and grandparents have something ecological, made probably in 1950 or 1960 and in late 1990s https://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger https://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger It doesn't need plastic or electricity to work
- TeMPOraL 5y ago
  > It doesn't need plastic or electricity to work Not even fans to move the air around? That's neat, fully passive systems are awesome - though not always easy or possible. In context of not blowing hot air out, the useful nugget here is heat exchange with the ground - which can also be used with a heat pump. Plenty of homes are built with such systems. But it's tricky to do in a multi-floor apartment complex, I haven't heard of any using ground-coupled heat exchangers. Perhaps some new constructions? Of course, while the ground has amazing thermal capacity, it has rather poor thermal conductivity - for larger loads, your exchanger will need to be large and buried deep. This might be another factor limiting application in cities.
  - agilob 5y ago
    >Not even fans to move the air around? Only in the hottest days when all room were occupied, as I no longer live there with my siblings, they no longer have fans there. There was one bath-vent-like-fan before. >fully passive systems are awesome - though not always easy or possible. I wouldn't install this in the UK as gardens are tiny, full of concrete and air humidity is high. Works well in central Poland. >or larger loads, your exchanger will need to be large and buried deep. This might be another factor limiting application in cities. yes, you need trees around, and grass not concrete or bricks.
CorrectHorseBat 5y ago
Too bad the laws of thermodynamics forbid this kind of systems. Absorbing water from air and then evaporating it will result in nothing changed. Either you make a dehumidifier or you make a swamp cooler, combining them is pointless.
- crishoj 5y ago
  The idea is to remove moisture from the air using a membrane, not by way of condensation.
  - CorrectHorseBat 5y ago
    Doesn't matter, laws of thermodynamics still apply.

Karrot_Kream 5y ago

Interesting, this is similar (and much more thoroughly researched lol) to an idea I've had myself. It runs a dessicant dehumidification process along with an evaporative cooler. I wanted to try a more DIY version of this by using a dehumidifier to pump water into an evaporative cooler. I live in a dry area though so I'm never in need of dehumidifcation myself shrug.

CorrectHorseBat 5y ago
Doesn't work, all the evaporative cooler does is absorb the energy back that was released during dehumidification.
- Karrot_Kream 5y ago
  You would have to drain some of the water out. It's not as simple as directly pumping it. Ice might help as well.
  - CorrectHorseBat 5y ago
    Why the evaporative cooler if you want to drain water? Letting water condense and then evaporate is a zero sum operation. Using ice is just moving your heat pump to another location. Maybe interesting if you can't install airco for some reason, but you're not improving the efficiency.
- crishoj 5y ago
  Correct me if I’m wrong, but membrane based air dehumidification seems to require a lot less energy than other approaches. https://www.researchgate.net/publication/270721905_A_review_of_membrane-based_air_dehumidification https://www.researchgate.net/publication/270721905_A_review_...
  - CorrectHorseBat 5y ago
    I guess one might be able to make something that works somewhat better than a compressor, those don't use ideal Carnot cycles. Better than a Carnot machine isn't possible, you will always release heat when turning water vapor into liquid, so doing the evaporation afterwards and ending up with a cooler room is completely bollocks. You can't cool a room without discharging heat to the environment, the heat has to go somewhere.

agilob 5y ago

My parents and grandparents have something ecological, made probably in 1950 or 1960 and in late 1990s https://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger https://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger It doesn't need plastic or electricity to work

TeMPOraL 5y ago
> It doesn't need plastic or electricity to work Not even fans to move the air around? That's neat, fully passive systems are awesome - though not always easy or possible. In context of not blowing hot air out, the useful nugget here is heat exchange with the ground - which can also be used with a heat pump. Plenty of homes are built with such systems. But it's tricky to do in a multi-floor apartment complex, I haven't heard of any using ground-coupled heat exchangers. Perhaps some new constructions? Of course, while the ground has amazing thermal capacity, it has rather poor thermal conductivity - for larger loads, your exchanger will need to be large and buried deep. This might be another factor limiting application in cities.
- agilob 5y ago
  >Not even fans to move the air around? Only in the hottest days when all room were occupied, as I no longer live there with my siblings, they no longer have fans there. There was one bath-vent-like-fan before. >fully passive systems are awesome - though not always easy or possible. I wouldn't install this in the UK as gardens are tiny, full of concrete and air humidity is high. Works well in central Poland. >or larger loads, your exchanger will need to be large and buried deep. This might be another factor limiting application in cities. yes, you need trees around, and grass not concrete or bricks.

CorrectHorseBat 5y ago

Too bad the laws of thermodynamics forbid this kind of systems. Absorbing water from air and then evaporating it will result in nothing changed. Either you make a dehumidifier or you make a swamp cooler, combining them is pointless.

crishoj 5y ago
The idea is to remove moisture from the air using a membrane, not by way of condensation.
- CorrectHorseBat 5y ago
  Doesn't matter, laws of thermodynamics still apply.