Half a croissant, on a plate, with a sign in front of it saying '50c'
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Replace "light" with "sausages" and this may work...

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Peltier Crock Pot

More Efficient, With Cooling
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The Crock Pot, or slow cooker for some of the rest of us, is a simple device. Take an earthenware pot, a lid, put a medium power (150-300W) resistive heating element in the base, add a switch and you're done. Every now and then, paint it blue, cow print, or whatever. Some gimmick to remind people they still exist and maintain them in the popular imagination. Anyway, they're dull. Here's the re-boot.

Start off with a nice chunky piece of aluminium. With fins, a heatsink, flat side up. On top, a nice big thermoelectric element, a Peltier device*. On top of that, a bit more shaped aluminum then your earthenware pot, with lid. Maybe add a little more insulation so as not to be quite so shamelessly inefficient. Now instead of simply taking electricity and piling it into a bit of resistive wire, we're being a little more elegant and pumping heat from the environment, and adding some from our inefficiencies. If it happens to be summer, you're onto a winner. In winter it will at worst perform the same as a regular crock pot, or at best will steal a little excess heat from somewhere**.

The real benefit is in the microcontroller model. This model will carefully control the heat, then, after a predetermined time, may reverse the effect and cool your food down to a safe 4C storage temperature. It will all be entirely programmable, very popular with the sous vide crowd I'd imagine. Everyone will be very impressed with the miraculous technology***

Add WiFi and a phone app for "have it warm when I get home-ability."

It will run on 12V, so will need a power brick, hidden advantage: it will work in the car. Super hidden advantage: labs will use the higher power and mass produced costing to do PCR on the cheap****

How to beat Crock Pot, don't, sidestep them. Call it Croc- Pot and have a charming Crocodile logo, maybe paint it green, possibly play on the cold-blooded thing, I dunno, I'm not interested in marketing.

*TEC devices exist going up to 200C.

**You may have gas heat, or you could place the device on a cat.

*** That we lifted wholesale from a laboratory thermal cycler.

****possibly while driving.

bs0u0155, Nov 06 2014

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       How much power does a peltier crockpot take to run? Alternators are not infinite power sources, and there needs to be something left to keep the car running.
RayfordSteele, Nov 07 2014
  

       A couple of hundred Watts. For scale, it wouldn't be unusual for a car to have a couple of hundred thousand Watts. It'd be up there with the entertainment system.
bs0u0155, Nov 11 2014
  

       Charge margins (as well as inverter package space) are precisely the reason most cars don't come with 120V power outlets, and that the cigarette lighter output is limited to a couple hundred watts.
RayfordSteele, Nov 11 2014
  

       // and that the cigarette lighter output is limited to a couple hundred watts//   

       That is an issue. Maybe I could release a special smaller car model just in time for thanksgiving? Maybe the regular one could come with two plugs? Or, a clamp-on 300W wind turbine! I think driving at a steady 60 mph would make getting 300W from a turbine relatively easy... and so much more efficient than stealing all that power from the alternator.
bs0u0155, Jan 26 2016
  

       //A couple of hundred Watts// You might want more than that, for cooling. Peltiers generate heat even as they pump it away, so the effective cooling power of a 200W Peltier will be much less than 200W.
MaxwellBuchanan, Jan 26 2016
  

       I borrowed a 12V Peltier-powered car fridge thing called a Koolatron over the summer, that worked very nicely. A quick google of the mains to 12V power supply suggests that it's a 12V 5 Amp output. So that's working on only 60W. I'm actually more worried about the heating. Admittedly, the inefficiencies are working in your favor with heating, but if you want 100C, you might need to maintain a 80C gradient, that's a lot harder than the 15-25C gradient you need for cooling.
bs0u0155, Jan 26 2016
  

       Fair enough.   

       As for heating, your PCR machine has no problem hitting 100°C, and as far as I know that comes entirely from the Peltiers, if it's less than 20 years old.   

       So, you're good to go.
MaxwellBuchanan, Jan 26 2016
  
      
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