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This is just as exciting as when it came up in 2020. One of the nice features of this system is that, overnight, the wick self-cleans, diffusing accumulated sa
by ncmncm 4y ago
This is just as exciting as when it came up in 2020.
One of the nice features of this system is that, overnight, the wick self-cleans, diffusing accumulated salt back to the sea water.
Another way to recycle the heat of condensation, in a bigger system not relying on capillary action, would be to circulate incoming brine in the condenser on its way to the evaporator, pre-warming it while cooling the vapor; and run outgoing brine through a heat exchanger to further warm incoming brine.
A key observation in design of low-cost desalination is that there is no need to minimize the amount of brine circulating in the system. So long as heat collected in the brine is not wasted, you are better off circulating more brine. The less you concentrate the brine, the easier it is to get water out.
- bertil 4y ago> diffusing accumulated salt back to the sea water. A big issue of desalinisation is the increase in salt in water: brine streams coming out of osmosis plants are dead zones in the sea. I'm not sure this is a good idea for the shore.
- ncmncm 4y agoAs I noted, there is no need to concentrate the brine to such a degree that discharging it could be a problem. But even if you did, discharging the brine through a long, leaky pipe or hose would avoid creating any dead zones.
- cma 4y agoHow do you create a long leaky pipe without bio-fouling clogging it up? I guess the high salinity itself could prevent fouling.
- ncmncm 4y agoWith positive pressure and small holes, it would be hard for bio to get in and foul it. Generally you are more worried about biofouling on water intakes, with good reason.
- labrador 4y agoIt's only seems like a big issue to people who don't know a lot about the ocean. I grew up surfing in a town at "sewer peak". The effluent from a sewage treatment plant was nearby. It was too close to shore, so they moved the discharge further out into deeper water. Discharging water with a higher salt content than the ocean wouldn't cause any harm at the discharge point, so this concern always seemed like a canard or unfounded theory to me. Some people don't want desal plants near them, so they throw this out there for NIMBY reasons.
- ncmncm 4y agoI gather San Diego discharged sewage into the sea forever. When they finally got to cleaning it up, maybe to appease surfers, they were forbidden because an ecosystem had grown up dependent on it the way it was.
- labrador 4y agoSanta Cruz didn't clean it up because of surfers, who didn't care because it wasn't very noticeable, although you knew you were taking a chance of getting mildly sick. It's really difficult to resist going out when the waves are good. It was because the fecal bacteria count was over the new environmental standards that came to be in the last two decades of the 1900's. Many people don't realize there's an acceptable amount of mouse dung and insect carcasses in the food they buy, so it may sound gross to surf in gray water, but it really wasn't. It may be a bigger problem in San Diego because the water is much warmer than the cold currents the come down the coast from Alaska to Santa Cruz (along with some good waves)
- hamlsandwich 4y ago> Discharging water with a higher salt content than the ocean wouldn't cause any harm at the discharge point Sewage and hot, concentrated brine are not the same. Plenty of studies show that there is harm to ecosystems, that's often not properly addressed. - https://www.ccc.tas.gov.au/wp-content/uploads/2018/11/Apx-22-Desalination-Plants-Uni-Sydney-Brine-Discharge-Marine-Env-Impact.pdf https://www.ccc.tas.gov.au/wp-content/uploads/2018/11/Apx-22... - https://phys.org/news/2019-01-brine-discharge-desalination-good-news.html https://phys.org/news/2019-01-brine-discharge-desalination-g...