Re: Dry Ice payload testing

Dennis Klipa - N8ERF

As a research chemist, I used dry ice a lot to cool reactions to low temperatures,  -78°C.

I would suggest you set your payload in your cooler and then pour dry ice powder over it.

Dry ice comes in a block a couple inches or so thick as you know.  I would use a rubber mallet/hammer to break the block into a few large chunks and put the dry ice chunks into a heavy denim bag.  Gather the top of the bag and beat the dry ice chunks with the mallet.  The chunks will break up into a course powder resembling sleet that you can easily pour from the bag to surround and cover your your payload giving good contact with your payload  This should give you good heat transfer and a good test of your heater.  I am not sure 8 lbs will be enough, depending on the size of your payload and cooler.

Best Regards,
Dennis, N8ERF

On Mon, May 3, 2021, 1:35 AM Hank Riley via <> wrote:
How big is that payload box if it's a snug fit inside the large cooler?   How was the CO2 distributed?  All just at the bottom of the cooler (not too good), or some against all four vertical surfaces of the payload and maybe over the top as well (best)?

Offhand it seems that just a hour might not be nearly enough to realize a decent low temp. of the sort desired.

Just to be concrete, I'd suggest trying something more like 4 to 8 hours.

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