Freeze-drying Jello gelatin with an improved cold trap

[TerraGamerX]

I see "Jell-O", I hear crunching. I feel weird.

[embraceyourinnerdino]

Yum.

[XC2long4u]

Use a window ac evaporator for the condenser.

[bkraz333]

@XC2long4u A single-stage refrigeration loop is probably not cold enough to solidify water vapor at those pressures.

[XC2long4u]

@bkraz333 It most certainly is. I didn't say you wouldn't have to modify it. You would need to increase the captube length. Then with the charge you would pull a vacuum and bring back up to 0psi with R744 which is CO2. Then you would charge with either R22, R410, or R290. The suction side should be below -20°C. You wrap the captube around the suction line before it goes into the evaporator. That will be cold enough to condense the R744 into liquid. That will yield a few degrees cooler

[XC2long4u]

@XC2long4u You have to be careful with the CO2 because it is a fine line between a liquid and a solid at those temps and pressures. You don't want it to solidify in the captube but it should be alright.

[XC2long4u]

@bkraz333 It would be cold enough with some modification. You can make a pseudo cascade or an auto cascade with a single stage system. I can get a window unit down to -40°C with no modification.

[toubasbu]

It seems like there are a lot of issues and cost with the cold trap. Is the cold trap necessary for the process? Do vacuum pumps exist that could pull the water out and just release it to the air or a drip pan and bypass the trap?

[robot797]

how can i make a coldtrap when i have no acces to dryice or licuid nitrogen?

[bkraz333]

@robot797 The cold trap must be colder than the material being freeze dried so that it will solidify the water being sublimated from the material. If the ice cream is at -30*C, the cold trap should be below eg -60*C. Commercial freeze driers probably use cascaded refrigeration loops to create -60*C (or colder temperatures). Buying dry ice is the easiest and least expensive way to get cryogenic temperatures.

[mzietek]

Incredibile, wonderful videos! Fruits may be interesting things to put into cold trap. Which ones do you think off? banana, orange, kiwi - tomato maybe? What about an egg? what would happen after "cold trap adventure"?

[commodore256]

You should Dehydrate a Pizza Hut Pizza and Re-Hydrate to level four, please.

[mikelboi87]

Love your videos.

[rovku]

Already having experimented with coffee beans, I'm surprised you haven't freeze-dried your own coffee yet?

[clodester]

You could approach the plugging cold traps in two ways. 1) like you suggest; you could physically change the way the cooling water is collected, so that it pools and freezes away from the inlet.

But another thing you should consider, is to pipe the water inlet through an "ice trap"....basically through a pool of high conc deicing solution. The bowl, looks big enough to allow for water run off and deicing solution, even accounting for reduction of conc

[wowcolors]

Don't you need to cool the outside of the cold trap? If there is basically no air in the cold trap under vacuum how does the cold center stainless bowl cool the outside of the trap? What am I missing here?

[bkraz333]

@wowcolors The purpose of the cold trap is to solidify water molecules as they flow through the device and "trap" them before they can leave. We can do this by directing the molecules at a very cold surface where they solidify and stick. The whole trap doesn't need to be cold, just the trapping surface. It's more efficient to only have the trapping surface cold, not the outer surface since it would be trying to cool down the whole room. With insulation, only the needed part is cold.

[wowcolors]

@bkraz333 Thanks for the response! To clear up my remaining confusion... Since almost all of the air is gone, what draws the remaining moisture in the material you are freeze drying migrate to the cold trap? Is this just due to convection? Also why does the remaining moisture need to be trapped is it that even after all the air is evacuated there is still moisture in the material you are freeze drying?

[bkraz333]

@wowcolors It is not convection, it is the natural random movement of molecules. The water is in vapor form, and the vapor diffuses through the hose toward the cold trap. The same phenomenon allows you to smell food being cooked in the kitchen when you are sitting a few rooms away and there are no fans or air currents involved. Even after removing *most* of the air from the system, there is still a lot of water in the food which takes time to sublimate.

[ocamsrazor]

Commercial freeze dryers usually just use a drum with an inlet pipe that sticks out from the wall a few centimetres.You might not need the surface area (and clogging risk) of a bowl within a bowl.

[klj2503]

Hi Ben !

How about heating the inlet of the cooling chamber so to prevent the moisture from freezing right at the inlet but to keep it as a gas untill it have entered the cooling chamber compleatly - Maybe you could use the stripheater you used in the supercritical carbon dioxide video, I only think you have to raise the temperature a little for it to work so maybe you have to restrict the stripheater.

Last I just want to mention I enjoy your videos a lot - Keep up the good work. Thanks

[Morkvonork]

Very nice. Does this work with a container with very hygroscopic material instead of a cold trap too? Maybe zeolith or sulphuric acid?

[smitty3919]

This is why I use to watch Mythbusters.....but then, they stopped showing the whole build of their projects. only the end result...

I think you do a great job! keep up the good work!!

[abigblackdick]

it's aerojello!

[frac]

If you made the outlet a separate fitting, then held it in place with a similar gasket arrangement, could you warm it slightly (a few watts) to discourage icing/clogging without warming the cold trap significantly?

[menushadesanayaka255]

put many pipes to the inlet so even when one gets blocked the will be redundancy!!!

[aqcd]

What kind of vacuum are you pulling on this setup?

[bkraz333]

@aqcd When the temperature of the food is at -30*C, the vacuum pump will readily pull the system down to 400 mtorr. The pressure rises when I apply heat via the incandescent lamp (or just by removing the foam insulation), and I keep the pressure below 650 mtorr by adjusting the amount of heat input. Water can exist as a liquid above 950 mtorr, so that is the upper limit for freeze-drying.

[jdflyback]

man i wish i but this much effort into the things i do, how much isopropanal have you used because in the ice cream video you where just pouring a lot into the water cooler.

[xXdenhartXx]

Oh but awesome video and thumbs up as always ;)

[xXdenhartXx]

Aw i'll keep saying "Freeze dry coffee!" until you respond :P

[Fast2405]

Another excellent video! How about freeze drying cheese? Or a yogurt?

[CheeseBon]

@Fast2405 toooo much fat

[Fast2405]

@CheeseBon Hmmm, I'm sure i've seen freeze dried cheese and yogurt advertised somewhere (i'll try and find the source), I'm guessing it wouldn't be impossible? Maybe just a lot more difficult?

[CheeseBon]

@Fast2405 yeah nothing is impossible i guess.

[Fast2405]

@CheeseBon This is just one US example w w w [dot]healthyharvest[dot]com/fr­eezedriedgratedcheddarcheese[d­ot]aspx and a UK company also w w w[dot]kanegrade[dot]com/produc­ts/freeze-dried-cheese/ I guess you can pretty much freeze dry anything if you try hard enough.

[onefivefour]

Please freeze dry beer and report back...

[revolutiongames2004]

You should make a liquid fluoride thorium reactor :)

[TimeShin]

Dude you're awesome. Think you can do something with an emp device? There's directions on amazing1.com

[89rafa]

you're so mean, eating all those goodies... Can you send us some?

Love your videos. Keep them coming.

[yellowmetalcyborg]

first

[hitachi088]

@yellowmetalcyborg omg, your so original.

[yellowmetalcyborg]

@hitachi088 I'm sorry, it doesn't happen very often, and I seized the opportunity.