In message <001401c351eb$9ab84d80$7bf1ee86@WONSILTP>, Mark Wonsil
<[log in to unmask]> writes
>Bruce asks:
>> In the article, while talking about inkjet printers and their 18
>> million droplets per second, she says, " Every one of those drops of
>> ink is heated to three times the temperature of the sun for two
>> milliseconds."
>>
>> I may be thicker than a whale omelette, but does this seem a bit
>> excessive to anybody else?
>
>Maybe she meant Sun Microsystems or Sun Valley, Idaho...
>
>For a technical answer, check out
>http://www.news.cornell.edu/releases/Oct96/bubble.jet.lb.html

The numbers just don't add up. With drops heated for 2 milliseconds
each, you'd get 2,000 through a nozzle every second. So to spray
18million drops/second, you'd need 9,000 nozzles.

But with the lowest heating rate in that 1996 article,100,000,000
degrees/second, you'd get up to 50,000 degrees in 2 milliseconds. Which
is certainly more than 3 times as hot as the surface of the sun.
However, I bet it's hotter in the middle, and perhaps that was where
Carly was talking about.

Of course, with the higher rate of 1 billion degrees/sec, you'd get
500,000 degrees. Way hot....

But let's try a couple of adjustments.

Firstly, let's assume Carly meant to say 2 microseconds (or actually
did, and was misquoted).

Then let's assume that what is three times hotter than the sun is not
the droplet, but the temperature the head would reach if you let it heat
for a second - that billion again.

2 microseconds gives you 9 heads needed - I imagine the printers have a
few more than this, but the order of magnitude comes out right.

And a droplet will reach 500 degrees - close on the 570 mentioned in
that article.

That article gives the heating time as 5 microseconds - 200,000 drops
per nozzle per second - so 2 microseconds per drop should be more than
feasible nowadays.

Though Carly says we've gone from 1 million drops to 18 million per
second, so perhaps we should be down to 0.3 microseconds. Or maybe we
have more nozzles now?

But if Carly actually said 'Every one of those drops of ink is heated at
a rate per second of three times the temperature of the sun, for two
microseconds' then I think we might be in the ballpark.

So - inadequately prepared History major, or inadequately transcribing
interviewer?

BTW: The Evil One???? What's that about? Carly may be qualified to write
history, but is she rewriting it here?
--
Roy Brown        'Have nothing in your houses that you do not know to be
Kelmscott Ltd     useful, or believe to be beautiful'  Wm Morris

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