Dry / Dehydrate silica gel with a vacuum chamber and no heat

[@ShanesGettingHandy]

I scoured the internet for this video. All the general (mostly HVAC) information I was finding online seemed to claim this was not possible, but I refused to believe it to be true, as it did not make sense. Thank you for demonstrating it can be done with no heat, so long as you have time and patience.

[@emmettbrown9654]

Thank you sir. I had my reservations and seeing it was perfect

[@ivanbg5167]

Thank You Sir, I was wonder if I need to replace a perfectly good automotive condenser since the drier is none serviceable. But this shows that it can be dried if any moisture gets in during the compressor and expansion valve change out. I'm also planning on running a little nitrogen through the condenser during the 10 to 20 minutes the system is open to atmospheric pressure.

[@曾子建-f5e]

I think the key is the volumn of your chamber. Since 18 gram of water will turn into 22.4 liter of vapor! So the key might not be how long the vacuum pump operated, it's the volumn of vacuum chamber instead. If the chamber is not big enough, you might want to vacuum it a while and leave it sit there for a period of time. And repeat it a few times you can get the moisture out of the silica gel almost. By the way, did you ever try this method on molecular sieve?

[@supergiantbubbles]

It would have been helpful to weigh the packets before and after the vacuum drying to quantify the water loss. I'm sure they would have dried out much faster with some heat to drive the water out.

[@robertsalasidis7695]

The weight suggestion was a good one - should have thought about that. However, I was trying to see if no heat could be applied, and still achieve the desired results - albeit slower. The main reason to do this was to see if the silica gel desiccator inside an Air Conditioning unit could be dried by a prolonged vacuum application - this was an R410A AC unit with hydrophilic POE oil. I left the vacuum on for about 3 - 4 days steady, and then refilled, and has worked well since this video was made.

[@weaponizedautism6199]

Do you have anymore data from these experiments. How long were the samples under vacuum? How long running and not running but still under vacuum.

[@robertsalasidis7695]

No, I never repeated it, but it is not a fast process. It takes a few hours under vacuum - with the pump running. I did leave it overnight with the pump off as well, but most of the change happened while the pump was running. It would be much faster to dry them the traditional way - with heat. I did the experiment to see if an AC filter drier can be rejuvinated without replacement (you have to cut those out, buy new, reweld etc). Usually the driers get saturated if the POE compressor oil is exposed to air. I had drained the oil, and when hooking up the vacuum for about 1 day, I noticed a steady base vacuum level that I believe was humidity being extracted slowly - similar to what I saw in this experiment. I replaced the oil, refilled the refrigerant gas, and the AC unit has been working well for about 1.5 yrs.

[@weaponizedautism6199]

@@robertsalasidis7695 thank you so much for answering. I’m working on a desiccant water harvesting system that works with heat, I could easily add vacuum to the system if it would increase production. I really do appreciate your time.

[@robertsalasidis7695]

@@weaponizedautism6199 I think it would - it will increase the gradient to remove the water, by lower the boiling temperature of water www.engineeringtoolbox.com/water-evacuation-pressure-temperature-d_1686.html