h a l f b a k e r yNaturally, seismology provides the answer.
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Ever found yourself miles from anywhere, with no source of
electricity, no possibility of making a fire, no means of rapid
transport, and very much in need of a small, weapons-grade
espresso? Well, no, probably not. But if you did...
MaxCo. is whelmingly proud to present its Machine for Coffee.
Unlike
other so-called "coffee machines" - which involve
electricity, fire, or pre-boiled water - the MaxCo. Machine for
Coffee requires none of these things.
In its closed-and-holstered configuration, the Machine for
Coffee vaguely resembles a pair of bolt-cutters, with a pair of
long heavily-chromed handles lying side-by-side, attached to
what can only be called the business-end of the machine.
The business end contains a water reservoir, a perforated
metal container for ground coffee, and some other clever
bits.
To operate, simply open out the two handles to their widest
angle (about 60 degrees). You will notice considerable
resistance, because the handles are cunningly geared to two
sets of intermeshing closely-spaced discs in the water
reservoir. Now close the handles again, as forcefully as
possible. Open, close, open, close...constantly spinning the
discs to and fro.
Where is all that effort going? Well, obviously it is going into
the water which, degree by degree, gets heated up to and
beyond 100°C.
Eventually, the small red button on the side of the head will
pop up. This is the pressure indicator, telling you that the
water has reached the perfect point of superheatedness. At
this point, it is quite important that you stop pumping.
Now turn the heavy Bakelite knob on the other side of the
head, releasing the superheated water into the coffee holder,
whilst holding the nozzle over your cup. Gadulka! A
perfectly perfect cup of espresso.
Tangentially related link
https://what-if.xkcd.com/71/
Can you boil a cup of tea by stirring it? [hippo, Feb 05 2015]
Could it make.... calorie-neutral coffee??
Calorie-neutral_20Confection
Also relevant: Joule's kettle [mitxela, Feb 05 2015]
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Annotation:
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I particularly like the bit that says://Eventually, the small
red button on the side of your head will pop up.// I have
often wondered why I have that small red button on the
side of my head and what makes it operate. Most
enlightening. |
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An alternative design of coffee machine to this, also designed around the notion of converting kinetic energy to heat energy, could be imagined for those who prefer their coffee shaken, not stirred. |
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33,500 J to get 100ml of water from 20-100C, say you want
to do it in 2 mins, with about 20% losses. 335 Watts. Now,
humans can do that. Not with your arms though. So you'd
need an exercise bike type set up. |
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There's a wonderful line in Red Dwarf: "it's just not possible
to fry an egg using a bicycle powered hairdryer". Sort of
prior art... |
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In you plan ahead and spend 2 hours doing it, you only need 6 Watts (neglecting losses*). |
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* 2 days if you want to account for losses |
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[-] for lack of ill-considered and highly inadvisable use of pyrotechnics and/or exothermic chemical reactions. i.e far too safe and therefore boring. |
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One wonders if the Borg ever get tired of exploding memes. Or even exploding mimes. Or memes about mimes on mines... |
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//say you want to do it in 2 mins, with about 20%
losses. 335 Watts. Now, humans
can do that. Not with your arms though.// |
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(a) 100ml of weapons-grade espresso is probably
more than you'd want to
handle, at least without training. We used to brew
coffee in the lab, and the
apparatus only made enough for about 30ml each.
We made it strong enough to
be dangerous in those quantities. With some clever
fluidics, I think we can get
the dead volume down to 10ml, meaning 40ml in
total. |
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(b) My domestic espresso maker takes about 8
minutes to make a cup (although
she is getting older and slower). I could compromise
and go for 5min. |
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So, 40% of the volume in 2.5x the time, meaning that
you only need a power
output of 54 Watts. |
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Now, can we manage this, arm-wise? Well, let's
assume
that the travel of the arms
(of the machine) is 60cm (ie, each arm moves back
and forth by 30cm), and that
each push and each pull takes 1 second (ie, total
travel 0.6m/s). Energy=force x
distance, and hence power = force x speed. Hence
force = power/speed =
54/0.6 = 90N. Thencefore, you'll be pushing and
pulling against a resistance of
about 9kg, or 20lb if you live in the US. I think I
could manage that. |
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//pyrotechnics// Perhaps we could interest the Borg
in our MarkII machine? It is identical to the MarkI,
but the delivery man pops a grenade through your
letterbox when he delivers it. |
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