aonomus
Hazard to Self
Posts: 54
Registered: 18-10-2009
Location: Toronto, Canada
Member Is Offline
Mood: Refluxing
|
|
Homebuilt recirculating evaporative cooler
So I'm sure we all have the same problem, how to cool our condensers without wasting lots of water. I've seen alot of people that use buckets of water
with pumps in them to recirculate, and by sheer mass alone, the water doesn't increase in temperature much, however this wasn't good enough for me
So what I did was I built an evaporative water cooler based off of how power plant cooling towers work: shower of water downwards with airflow upwards
(forced or convection).
So water is pumped out of the sump at the bottom (bottom closed by pipe cap, unit is fully enclosed), to the condenser, and back to the top of the
unit, where it pumps into a regular shower head aimed downward. A fan pushes air in at the wye fitting, travelling upwards, cooling the water by
evaporation as it passes.
With water 10 degC above ambient, it reaches ambient in approximately 10 minutes. I want to do other tests with even warmer water, but I haven't had
time just yet. Because of the heat exchange, it gets more efficient as the temperature difference between water and air increases. The unit can keep
water at ambient, or just a hair below ambient temperature under sustained usage, I've distilled with water and methanol for 3-4 hours continuous with
no rise in temperature.
A safety feature is that because of the extremely low volume of water ever contained in the system at any one point in time (about 1.5-2L), you will
never really be able to flood your workspace should a hose fitting come loose. The bilge pump doesn't even reach down to the bottom, so the real
volume of water that could be pumped out is probably closer to 1L.
One downside is that you get a fine water spray out the top of the unit, which rains down on nearby objects. While this isn't a problem, it just means
you have to refill from time to time. The only other downside I can see to this is if you have a very low boiling solvent, or you are distilling a low
boiling solvent under vacuum. You cannot add ice to this unit (any water below ambient would just get warmed up anyway), so you are essentially
limited by air temperature.
An improvement I may make is to merge the top stack with a bucket so that ice can be added, and the fan/shower be enabled/disabled to give the best of
both worlds.
And just a nice looking picture of a distillation going (orange peels to see if I could get orange oil out of them, didn't work out well, but the
cooler did!)
|
|
|
bbartlog
Harmless
Posts: 38
Registered: 27-8-2009
Member Is Offline
|
|
That cooler is nice. Mind you, it's true that in every distillation I've done, it would have been easier to just start with somewhat more water than
to build a whole setup like this - but with this you could run something for 24 hours if you had to.
Are the orange peels in that boiling flask in big chunks (it looks like it)? I would recommend turning them into tiny bits in a food processor and/or
macerating them before doing distillation. Not that I had much better luck when I tried to get limonene from lemon peel, but my problems were later on
when I tried to isolate from the distillate -
|
|
|
aonomus
Hazard to Self
Posts: 54
Registered: 18-10-2009
Location: Toronto, Canada
Member Is Offline
Mood: Refluxing
|
|
Yes, with a setup like this I could run it happily unattended (if it wasn't for the heat/fire hazard), but other safety features would be necessary
(low water, low flow alarms, fire alarm, etc).
And the orange peels in that picture were larger chunks, but I did a second run with 500mL peels instead of 100mL approx, and with smaller sized (cut
up with scissors). I only got about 0.5mL...
But otherwise, the cooler works!
|
|
|
watson.fawkes
International Hazard
Posts: 665
Registered: 16-8-2008
Member Is Offline
|
|
Quote: Originally posted by aonomus  | | Yes, with a setup like this I could run it happily unattended (if it wasn't for the heat/fire hazard), but other safety features would be necessary
(low water, low flow alarms, fire alarm, etc). |
A float valve hooked up to a water supply would provide you
continuous water. Put the float in the sump at the bottom. You could likely use a float valve from a toilet tank, with a little plumbing effort.
For a foolproof system, you'd still want a low-water alarm. With a refilling device, though, it wouldn't go off in ordinary operation.
|
|
|
aonomus
Hazard to Self
Posts: 54
Registered: 18-10-2009
Location: Toronto, Canada
Member Is Offline
Mood: Refluxing
|
|
Unfortunately the sump is only 4" in diam, and even smaller after taking the pump into account. I most certainly will want to do a revisit to this
build when this one dies or becomes enough of a problem.
I would probably substitute the bottom cap fitting with a flange fitting, and bolt it to the lid of a sturdy bucket. This would allow for regular
fountain pumps to be used over a noisy bilge pump, give space for a float valve, and space to add ice in if you wanted cooling below ambient.
I could see this being quite handy for lengthy soxhlet extractions or refluxing reactions.
|
|
|
Sedit
International Hazard
Posts: 582
Registered: 23-11-2008
Member Is Offline
Mood: Metallic
|
|
I like it aonomus good thinking.
I was woundering what is inside of the cooling tower? Does the water just drop thru it or is there some sort of heat exchanger in there? Might I
suggest rolled up corregated cardboard inside of the tube to create a pretty efficient unit.
I may have to make something simular sometime just to play with thanks for sharing.
BTW as for the float valve there are sensors you can get for pans that go under airconditioners which are an electric version of a float valve and
they will send a signal down the line when the water is up. Something of this sort could be worked into the unit with ease.
A fire alarm would be as simple as placing a thin piece of wire above the most likely area of fire the distilling flask. If theres a fire it breaks
cutting current and triggering an alarm. These circuits are very basic and can be made with ease for about 5-10$ at the very most.
[Edited on 20-11-2009 by Sedit]
|
|
|
densest
Hazard to Self
Posts: 97
Registered: 1-10-2005
Location: in the lehr
Member Is Offline
Mood: recovering
|
|
| Quote: Originally posted by Sedit | I like it aonomus good thinking.
I was woundering what is inside of the cooling tower? Does the water just drop thru it or is there some sort of heat exchanger in there? Might I
suggest rolled up corregated cardboard inside of the tube to create a pretty efficient unit. |
I'd suggest glass wool to prevent mold & rot.
A loose glass wool plug at the top would catch a lot of the spray and return it to
the system.
| Quote: Originally posted by Sedit |
BTW as for the float valve there are sensors you can get for pans that go under airconditioners which are an electric version of a float valve and
they will send a signal down the line when the water is up. Something of this sort could be worked into the unit with ease.
A fire alarm would be as simple as placing a thin piece of wire above the most likely area of fire the distilling flask. If theres a fire it breaks
cutting current and triggering an alarm. These circuits are very basic and can be made with ease for about 5-10$ at the very most.
[Edited on 20-11-2009 by Sedit] |
Velleman &c. sell water sensor kits which can activate relays.
There are fusible links, low melting alloy chunks, sold to be put over house furnaces and oil storage tanks. They are normally used with steel braided
wires and a spring to forcibly shut off valves and switches in case of overheating. The spring is set to force the switch off. The wire and link hold
the switch open. If the link melts, the spring is free. The nice thing is that they last indefinitely (decades), are inexpensive, and operate at about
60-80C, well below temperatures which might start a fire.
|
|
|
mr.crow
Harmless
Posts: 41
Registered: 9-9-2009
Location: Canada
Member Is Online
Mood: 0xFF
|
|
Wow good work! Everyone needs a bong cooler 
What did you use for the water on top? Looks like a pipe with holes in it.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
