Wetwedding project 34
Sometimes (not infrequently, in DK's case), you get an idea that you just have to pursue. If this is enabled by useable parts lying about, more so.
Totoro sprang from DK's fascination with the usefulness of that fat lip, on the edge of the can. When she saw that lip, she filed it away to swim and bob about in the tossing waters of the squirrely brain, to ripen.
And then, by mistake, she ordered the wrong size tubing, for her plans.
She stared at the lovely peanut can, with that fat lip, and pondered her stupidity of wasting money on the wrong, non-returnable product, and fumed.
This was happening at the same time she was piecing together wetwedding plans, and pondering - obsessing, day-and-night - on how to optimize the system. Optimization for less maintenance time and cost, more fluid operation, and system longevity, which don't necessarily track together in the real world as parameters.
Reverse Osmosis membrane efficiency is a function of a few things. First, by quality of the membrane itself, so DK bought the gold standard, the Dow filmtec.
Second, by increasing the pressure differential across the membrane. You can do this by pushing harder on the front end, pulling harder on the back end, or both. DK has done both, using a pressure boosting pump on the front end and a permeate pump on the back end.
Sorta like our pictures last post, of raspberries in the jello, and the collander. If you want pure jello juice and want to ditch the raspberries, you push the jello mixture against the collander to squeeze out the jello and leave the raspberries in the waste stream. The harder you smash the jello into the collander, the faster you get jello juice and the more of it you get as the raspberry jello stream flows by.
But another way to increase efficiency is to increase the temperature of the feed water toward the ideal temperature for the membrane penetrance. Since DK's water is getting sucked out of the ground from a well deep down, it's pretty cool coming up into the sytem. Since DK's system is large capacity RO system, the water doesn't sit too long in the system before it's presented to the membrane, so it's not had time to warm up to room temperature.
Now, let's say we warm that raspberry jello up, to soupy. Imagine how much easier it is to squeeze the jello juice across that collander.
So, DK wanted to play around with warming the feed stream, to increase her reverse osmosis efficiency, and the peanut can and tubing were just the start.
What she made, Totoro, is a very crude heat exchanger, just to explore an idea. It's not by any means a very efficient one, due to the properties of pex tubing that conducts heat poorly. But it was enough to try an idea, get some data, see how it panned out.
And here, you see how she did it, with stuff from the barrels and bins. Down below, you can't see, but she made a clear Lexan plate to hold in the heat, but also allow out light to light her system during the run time, as a visual indicator it's running, and also to light her TDS monitor when needed.
She was able to change out the light bulb to different wattages, to see the effect, in fill time of the system. She originally wanted to track before and after exchanger heat using a temperature probe, but the ports for the probe wouldn't hold the system pressure without leaking, so she abandoned that method.
Without any bulb, system time to refill was 2 hours 36 minutes. An 18 watt spiral fluorescent bulb improved fill time by 4 minutes. She worked her way up to a 100 watt incandescent bulb, which took nearly half hour off her fill time! Crude, but she could definitely quantify the effects using fill times.
And, I think that's a-gonna be the end of Wetwedding posts.
Last edited by DKShrimporium; 03-12-2015 at 05:32 PM.