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Since bigsleep's anno, below I have been pondering the
frictionless conversion of mechanical into heat energy.
In
lots of places, deforestation is driven by need for cooking
fuel. Cooking over wood or charcoal is smoky and slow.
If
there could be a pedal powered hot plate that would
never
wear out this would be a huge boon.
This would be a plate affixed to magnets that would spin
like a potters wheel. I suspect faster spinning would be
better and there would be a pedal or crank. The
simplest
version would be a stand over the spinning magnets
(maybe
enclosed in plastic to keep them clean) on which you
would
put your pan or wok. The pan would be heated via
induction and you would cook.
One level up of complexity involves an element designed
to
be heated well by induction. It seems like people use
aluminum. Wouldn't nichrome be better? It is an alloy
which heats up a lot with current. The pan would sit
atop
this.
Third level of complexity would be a heat reservoir. For
most cooking the wok or pan is itself the heat reservoir.
It cools off fast when you put the food in. This
reservoir heats up and then stays hot as you cook, so you
don not need to pedal the whole time. You could get
one
of the kids to spin it up to heat while you prepare
ingredients.
Bonus: no flames means no smoke and much less fire
risk.
Bonus 2: Moving parts could be bike parts: easy to fix
almost anywhere in the world. The magnets could be
speaker magnets: easy to replace if the field got weak
with age.
Problem: I do not have a good feel for the amount of
energy needed to heat a pan vs the amount easily
generated by a pedal. If you would need to pedal for
hours
to get the pan hot that would not be good.
//creating a large drag on the rotor and heating
the
plate//
A regenerative system could make a nice cup of
tea.
— bigsleep, May 31 2015
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A hot plate typically draws 1000 to 1400 watts. |
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A Tour de France cyclist typically generates 300 to 350
watts. Joe Average on a bicycle will go over 150 watts only
in short bursts. |
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(And remember: muscles generate heat, too - and they're
only 18-25% efficient. So the power peddler will be heating
up, but won't have the cyclist's breeze cooling their body
down... ) |
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[lurch], a typical hot plate is not an INDUCTION cooker. A
lot of those watts get wasted. However, even allowing for
greater heating efficiency, the numbers still probably don't
work out well enough. |
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What is needed to really do the math is cost: how
much a watt of human work is worth and how
much a watts-worth of cooking fuel is worth. Or:
how many watts of human work are expended
collecting cow chips or branches or other fuel that
can be had for free. |
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Lurch thank you for the math. It makes me thing
the heat reservoir type might be better as
cumulative work will be stored as heat. |
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Re peddler heating up: also a problem and it
makes me thing more efficient is better. Maybe a
full on bike connected as opposed to some puny
push pedal. |
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[Vernon] - //a typical hot plate is not an INDUCTION
cooker.// A typical house does not contain an induction
cooker; [bungston], in his last paragraph, admitted to not
being right on top of appliance power requirements, and
induction cookers are purchased primarily by people who
are very sensitive to such requirements. |
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An induction cooker will be usually rated at 1300 to 4000
watts; they will commonly operate at 400 to 700. The
higher rating is because they exhibit far lower impedence
when cold (less resistance to eddy currents), so you have
to run them at high power to get the ferropottery
warmed up to the efficient low-power temp. The
induction cooker requires AC current; it is optimized for
the frequency of the power supply on which it will be
used. |
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So, to explain the basic problem in relation to induction
cooking would be far more complicated and difficult than
using a simple resistive element of similar demands, with
no particular benefit. |
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//The induction cooker requires AC current;// and,
typically, between 120 and 240 V voltage. |
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