h a l f b a k e r yAsk your doctor if the Halfbakery is right for you.
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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.
[link]
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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. |
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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. |
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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. |
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// and that the cigarette lighter output is limited to a
couple hundred watts// |
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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. |
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//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. |
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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. |
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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. |
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