- #1
PraAnan
- 77
- 1
Hey everyone,
So I came across a company which is working on desalinating water by freezing it and was wondering what everyone here thought about it:
http://cryodesalination.com/
A similar project was also being done by students of UC San Diego:
https://www.aicheprojects.org/uploads/9/8/6/9/9869628/cds_proposal__1_.pdf
There are also a number of research papers about this method when you search for it on google.
I noticed that they mention that cryodesalination could be more efficient than reverse osmosis. How much energy is required to turn 1 liter of water which is 20C into ice?
While doing some initial research reverse osmosis deslination seems to use about 4-6 watt hour to produce one liter of water while cryodesalination would use a minimum of 29 watt hour per liter.
First you need to cool down the water to zero. It takes about 4200 J per liter/degree. So to cool the water down you need to extract 4200 * 20 = 84 kJ. Then you need to turn the water into ice. It takes 333 kJ to solidify 1 l of water. So in total you need to extract 417 KJ of energy. You'll need to use some kind of a refrigerator to do it. The coefficient of performance of a good chiller could be about 4 which means you need 4 times less energy to transfer the amount of energy required.
So we get about 105KJ of energy spent (or 29Wh).
Am I missing something completely obvious / using wrong numbers or is cryo desalination way more energy intensive than reverse osmosis?
Thanks for reading.
So I came across a company which is working on desalinating water by freezing it and was wondering what everyone here thought about it:
http://cryodesalination.com/
A similar project was also being done by students of UC San Diego:
https://www.aicheprojects.org/uploads/9/8/6/9/9869628/cds_proposal__1_.pdf
There are also a number of research papers about this method when you search for it on google.
I noticed that they mention that cryodesalination could be more efficient than reverse osmosis. How much energy is required to turn 1 liter of water which is 20C into ice?
While doing some initial research reverse osmosis deslination seems to use about 4-6 watt hour to produce one liter of water while cryodesalination would use a minimum of 29 watt hour per liter.
First you need to cool down the water to zero. It takes about 4200 J per liter/degree. So to cool the water down you need to extract 4200 * 20 = 84 kJ. Then you need to turn the water into ice. It takes 333 kJ to solidify 1 l of water. So in total you need to extract 417 KJ of energy. You'll need to use some kind of a refrigerator to do it. The coefficient of performance of a good chiller could be about 4 which means you need 4 times less energy to transfer the amount of energy required.
So we get about 105KJ of energy spent (or 29Wh).
Am I missing something completely obvious / using wrong numbers or is cryo desalination way more energy intensive than reverse osmosis?
Thanks for reading.