Cooling capacity of a Co2 cartridge/powerlet

Good to know

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@LAndras - I can leave it at the space possibly Tuesday evening but certainly after my class next Saturday. Are you familiar with using Arduino. This needs a Wemos driver added and uses the Serial Monitor. On the other hand, I could add a small LCD display since it seems you only need a few readings and it would only require power. I have a wall wart.

@TBJK - This does not use the Arduino ADC. It is generally packaged in a TO-92 with three leads like so many transistors but uses a 9-12 bit ADC depending how fast vs accurate you require. Mine have the waterproof packaging and look like a thermocouple.

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supercritical CO2 has amazing properties and is a very hot topic in thermodynamics these days.

I’m headed out of town this week/end so if you wanted to meet on tuesday and show me how to run it, we could do that. Otherwise next week/beyond would work best for when I run the experiment.
I’ve done some stuff with arduino but not enough to really know my way around the ecosystem or what I’m doing with one.

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I’m always glad to meet people and talk Arduino! I’ve changed my direction some to better implement the KISS principle. Since you only need a very few readings and its not time critical, I’ll just put a Nano and an LCD display on a breadboard with the temperature probe connections. Plug it in and the temperature will update every 15 seconds. No need to connect to a PC. I’ll put it in my storage box and let you know but I’ll still be glad to meet.

Congrats!!! You stimulated a lot of interest from several aspects here.

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Its ready. I’ll let you know when I get it to the space. In case wires come loose, the connections are described in the program.
image
http://pamplin.com/dms/co2_temperature.txt

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Very nice. Thank you so much for your assistance. :smiley:

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I’m currently planning to run the test on friday (7/19), around 7pm near/in science.
I doublechecked my regulator and it looks like it maxes out at 30psi so it might take a bit longer to vent than anticipated.

@bpamplin @TBJK @HoarseHorace @michaelb @Josh_Melnick @artg_dms @Russell_Crow @mjasso @ioport51

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This is an interesting question, to me, as I’ve recently seen online discussions of using CO2 in place of freon for refrigeration systems. Of course, the plus side is that it won’t have any effect on ozone depletion and negligible effect on global warming. I think the negative is that the systems will be operating at between 1000 to 1100 psi.

Yep which means it’s not as efficient. There is documentation that shows CO2 as having higher GWP due to energy consumption than the current R-410a

I’m guessing a CO2 cartridge has about 462 Joules of cooling capacity. Is this calculation way off?

So, in a container with 1000 g of water (1 liter), the temp should drop 0.462’ C

You’re going to need a very accurate thermometer.

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The DS18B20 temperature probe referenced above is not great on accuracy without calibration but the resolution is set to 12 bits in the program. Resolution is the important feature here.

Yes.

I wrote “accurate”, should have been “precision” for that very reason.

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Partial success!
Initial results show a 1° drop in temp over 1L of H20. This gives about 4.2kJ.
@michaelb 's math checks out.

There was some water loss due to… Energetic bubbling. I also did not have a mechanism to keep the reg/cartridge below water while opening the valve. So some losses of water and CO2 occurred.

I will be retesting on Monday if my new parts order arrives in time (7/22, 8pm). I have 3 cartridges left.

Improvements for next time:
I will build a simple 3d printed scaffold to keep the regulator in place, with a cover to prevent water getting blown out of the vessel. I will also have a valve on the regulator output connected to a long, slender rod, so that I can vent the gas while the system is under water and the vessel is covered.
I will let the system sit in the water for an hour to allow more time for it to equalize with the room. I may build a hose diffuser for equal gas venting.

Thoughts: the CO2 rapidly escapes the water, leading to little heat transfer. A diffuser made of coiled tubing with many micro holes may allow for greater heat transfer to the water and less spillover from the Co2 rapidly rising/expanding. This should also allow for the whole system to be consistenly mixed via the venting of gas throughout the whole container.

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You might look at the air stones used in aquariums for aerating the water. Like this -

Russell Ward

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Thanks! I may pick one up… I just hope it can handle higher pressures without exploding all over. Guess we’ll find out.

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Late update from Monday night, I ran three more tests and all were just about 1 degree change in 1L of water. Best result vented in just under 2 minutes, temperature stabilized by 4min mark.
Huge thank you to @bpamplin for taking the time to put together the temperature logger for me.

If anybody needs some gently used aquarium air stones or a CO2 reg, lmk… I have no further need for either.

Say $5?

And $20 for the reg? There still might be a bit of water in the reg, it’s proved hard to evacuate all of it.

I also have a 1/4" npt ball valve, 1/4" hose barb, and a 1/8" to 1/4" npt coupler.

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“Initial results show a 1° drop in temp over 1L of H20. This gives about 4.2kJ.”

1 J = 1’C change in 1 gram of H20. Shouldn’t 4200 Joules in 1000 grams of H20 cause a 4.2’C change?

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Specific heat of water is 1 calorie/gram °C, =4.186 joules/gram °C.

I’ve seen it stated as 1cal=4.186J and also =4.184J so somewhere in that ballpark for standard conditions.

The metal of the cartridge should also have dropped temperature by the same amount. That’ll be a (minor) contribution to the total energy.