Re:Engineers boost output of solar desalination system by 50%
by Gibbon1 on Wednesday June 19, 2019 @07:47PM
(#20228477)
> why does distillation always seem to come in second best in terms of efficiency compared to the use of membranes?
Offhand I think two or three reasons.
1. You need a temperature differential to drive distillation. Multistage distillation helps somewhat. That temperature differential limits the ultimate efficiency you can achieve.
2. You need to create a phase change for all the water molecules. And then recover as much of the heat as possible. Vs membrane which operates directly on the sodium/chloride ions.
3. Distillation uses really low grade (low temperature) heat. Turning high grade energy sources to low grade heat tends to result in a dead loss. Vs membrane which uses pressure. Pressure is high grade energy.
Offhand I think two or three reasons.
1. You need a temperature differential to drive distillation. Multistage distillation helps somewhat. That temperature differential limits the ultimate efficiency you can achieve.
2. You need to create a phase change for all the water molecules. And then recover as much of the heat as possible. Vs membrane which operates directly on the sodium/chloride ions.
3. Distillation uses really low grade (low temperature) heat. Turning high grade energy sources to low grade heat tends to result in a dead loss. Vs membrane which uses pressure. Pressure is high grade energy.