Smart crock pot -looking for fan cooled heat sink.

Where we discuss new analog design ideas for Pro Audio and modern spins on vintage ones.
User avatar
JR.
Posts: 3700
Joined: Sat May 24, 2008 7:21 pm
Contact:

Re: Smart crock pot -looking for fan cooled heat sink.

Post by JR. »

Well initial results are promising... With two P-devices in parallel It makes more than enough heat :D :D However in operation the cold side is still warm. The power supply is warm, not hot... So workable as is...

Now I will do an experiment with the two P-devices in series. This will dramatically drop my total power making capability but may shift more of the heating to P-action from IxE heat.

I am still learning...

More later...

JR
Cancel the "cancel culture", do not support mob hatred.
User avatar
mediatechnology
Posts: 5442
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: Smart crock pot -looking for fan cooled heat sink.

Post by mediatechnology »

You might consider a 12V version for the RV or boat.

Though most are going to have 120V power when parked or on shore power a 12V crock-pot would allow someone to cook the pot roast on LV power without having to run an inverter.
User avatar
JR.
Posts: 3700
Joined: Sat May 24, 2008 7:21 pm
Contact:

Re: Smart crock pot -looking for fan cooled heat sink.

Post by JR. »

Pelt1.JPG
Pelt1.JPG (57.49 KiB) Viewed 16799 times
Pelt2.JPG
Pelt2.JPG (56.84 KiB) Viewed 16799 times
I'm officially sticking a fork in this... I semi-seriously thought about hanging a third P-device on this but nooooo...

It would be cool if it was remotely cool, but in fact the bottom cold side sink was warm to the touch, not hot but far from cooling my kitchen which was the plan. In the lower photo you can see the gap between the hot side and the cold side, the P-devices side by side plus a 5/16" aluminum spacer so the cork insulation fit. The original plan worked like a charm and the cold side actually got cold when first turned on, but after a while with a pot full of food,,,and running at full tilt for hours (the top picture was this weekend's meal)...the cold side was not cold.

If I added a 3rd Peltier device, the 15A PS would just barely cover it when the P-devices are hot (roughly 4.8A each). So the 3x 15v x 4.8a would be close to 160W of joule heating, ignoring the 20-30w each of heat pumping...

As far as I can determine the joule heat shows up in both the cold and hot side, so more P-devices would be more heat to both the hot and cold side that is already not really cold.

At the end of the day I had to back up and review the design... The P-devices have another critical flaw, they are not recommended for working above 90' C so not even capable of boiling water, without potential deterioration/failure.

So to step back and review the last 9 months or so of using power resistors to cook the heat was adequate (192W max) in fact for much of the time the duty cycle only showed one or two LEDs of the 5 LED display on so 20-40% (<80W).

Resistance heat is adequate but looking at the wiring under the head spreader all the solder joints were dull and clearly over-heated... some of white wire insulation was turned brown, so not up to reliable high temperature robustness.

============

For less than I have invested in parts and metal, and power supplies, not to mention many hours of tweaking, I purchased a commercial counter top cooker that does what I want (ignoring the free cooling trick). Image

Programmable cook heat up to 400', 24hr slow cook time, 6qt removable aluminum pot, etc. ($160)... A premium version but it overcomes the classic limitations of cheap crock pots, and my expensive science fair projects,,, I know when I'm bested... I'll still make a thermal igloo for this new cooker so it will lose less heat into the room at least for summer-time cooking.

I still love my original concept but the science was just not up to the task...

JR

PS: there should be less chance of this commercial product catching fire and burning down my house... :lol:
Cancel the "cancel culture", do not support mob hatred.
User avatar
JR.
Posts: 3700
Joined: Sat May 24, 2008 7:21 pm
Contact:

Re: Smart crock pot -looking for fan cooled heat sink.

Post by JR. »

With several months of experience cooking with the smart crock pot, it is more clever by far than I need, but i think I'll keep it. :D
=======
I am bumping this thread with a Peltier related datum... I just ordered a Peltier de-humidifier... I don't know how effective this will be. Instead of listing how many pints a day it will pull from the air. it lists ounces per day. :oops:

Using a Peltier device instead of gas charged compressor to create the cold surface to precipitate out moisture, should be quiet enough to run in my bedroom at night (I hope).

I'll use my big dog (noisy) de-humdifier for the rest of the house.

JR
Cancel the "cancel culture", do not support mob hatred.
Post Reply