1. Your choice of
using a standard Juice can is brilliant. I will go today to see if I
can buy juice in such a can (or "bum" from a restaurant) - and hope others
will report in on whether this can is locally available (or
a different preferred size and shape that may better fit their
stove).
Thanks. <blush> :-) Actually, it should be practical
and work quite well when the pot is in direct contact with the products of
combustion. However, it is perhaps not appropriate for use on a flat stove
top, as someone pointed out, because of the ridge on the
bottom..
(1+) I didn't explain
"brilliant" - and it hasn't quite been explicitly stated. We need a
"pot" that is identical and cheap and widely
available. I still don't know if your recommendation will work
everywhere, but I think it might and we haven't yet got another
recommendation that looks better. Yesterday, I bought my first such
1.36 liter can ($1.19 + tax) and have already enjoyed one glass of tomato
juice. There were 5 brand names with the same size (Campbell's, Del
Monte, V-8, Texsun, and Dole). I bought the local brand (part of the
Kroger chain) for price reasons. The other products available were
such as orange and pineapple juices - at prices up to $2.19 per can.
The key question is therefore not whether the units are aapt to be identical
nor if the cost is right, but rather if it is available around the
world. I hope researchers such as Rogerio, Elsen, Crispin,
etc. can report if these same large juice cans are available in their
countries. If not, we should drop this as an
option.
I also looked at larger
coffee cans and found a much wider range of sizes (such as 26, 33, 34.5, 36,
and 39 ounces (sorry for not having recorded these in metric units), which
are actually much wider and larger (because of differences in density)
than Kevin's 1.36 liter (46 ounce) juice can. For researchers
interested in a wider pot, and if we want something widely available across
the world, then we will need a recommendation on a specific size amongst all
those possible.
RWL 2+ and 3+
- No disagreement with Kevin's response on the issue of the cap.
To test the system, I "punched".(using two Phillips screwdrivers and a
hammer) two holes similar to Kevin's rules. After cleaning the can, I
then filled it with 1kg of water as closely as I could measure, (didn't
measure temperature and it was probably less than 10-15C) and set it on a
cold electric "burner" (the highest kW on my stove - probably at least 2.5
kW - it came to a dull red color) . I judged the penny moved
after just about 15 minutes. There was little doubt about the
timing. Kevin's rule will be easily to quantify - within a few more
seconds there was a vigorous ejection of steam. I don't think a
quarter rather than a penny would have made more than a few seconds
difference in timing. I turned off the burner within a few
seconds and measured the weight loss this AM and found a loss
of perhaps 10 gms (believed to be less than 1%) - which I am sure gives
an efficiency way less than that reported by Crispin (not worth my doing as
I need the electrical input kW to do anything meaningful). The
marginal cost of this test maybe around 2.5 kW*.25 hr* $.08/kWh = 5
cents. (Anyone got a dedicated kWh meter they can use for this
test?)
Kevin:
Bear in mind that this is intended to be a "fun thing",
rather than a test protocol for comparing "real world stove systems." The
hope would be that by focusing the creative efforts of Stovers on one of the
many facets of Stoves, significant advances to practical stoves could
follow.
Kindest regards,
Kevin Chisholm
(RWL-conclusion). True about being fun -
but your rules are probably not too far from what we eventually
need. I thank Crispin for having taken the game seriously and reported
his world-record times (and especially efficiencies). Apologies to
Dean for having extended the possibility of his being a bit more
"gobsmacked".
