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Q: Hirsch Tube, Hersh Tube ( Answered 5 out of 5 stars,   2 Comments )
Question  
Subject: Hirsch Tube, Hersh Tube
Category: Science > Physics
Asked by: kwd-ga
List Price: $5.00
Posted: 18 May 2005 19:46 PDT
Expires: 17 Jun 2005 19:46 PDT
Question ID: 523179
What is the name of the tube which is studied in High School Physics -
You force air in one end of the tube, and it splits air...into
warmer and cooler air....

Request for Question Clarification by justaskscott-ga on 18 May 2005 20:27 PDT
There is an apparatus called a Hirsch funnel.  Perhaps your physics
teacher used it as part of an experiment to split air into warmer and
cooler air.

I have not found such an experiment on the Web.  But if all you wished
to know is the name, I would be happy to post it as an answer.

Request for Question Clarification by pinkfreud-ga on 18 May 2005 20:33 PDT
Could you be thinking of a Hilsch Tube?

"A T-shaped device that admits air under pressure and outputs hot air
from side and cold from the other. The Hilsch Tube is a real device
that dates from 1928. A French physics student named George Ranque was
experimenting with a pipe that produced a vortex when he noticed warm
air coming from one end and cool air from the other. Pressurized air
blown into the single 'bottom' leg of the 'T' encounters a special
valve at the junction; if adjusted properly, hot air comes out of the
right side upper end at 100 degrees Fahrenheit and cold air comes out
the other end at -70 degrees Fahrenheit. Unfortunately, it was not
commercially viable at that time and was forgotten. It was picked up
again by a German physicist named Rudolph Hilsch, who published a
paper on the device."

http://technovelgy.com/ct/content.asp?Bnum=257

Clarification of Question by kwd-ga on 24 May 2005 03:16 PDT
This seems mighty weird to me, that there would
be a device known as a Hirsch Funnel and another [?]
device known as a Hilsch Tube.  It's even more curious
that they do the same thing, dealing with splitting air
into warm air / cool air.  I've found adequate stuff on
the Hilsch Tube [and ordered a book on the generic
Vortex device].  But is there also a Hirsch Funnel, and
what references to such a gizmo can you suggest?

Request for Question Clarification by justaskscott-ga on 24 May 2005 05:50 PDT
After reading about the Hilsch tube, I doubt that you are thinking of
the Hirsch funnel.  I believe that pinkfreud's proposed answer is
correct, and recommend that you authorize her to post an answer.

Clarification of Question by kwd-ga on 24 May 2005 07:18 PDT
Yes, I agree with justaskscott; pinkfreud's proposed answer 
suits me fine. How do I authorize her to post an answer?
I'd still like to get -- and I'd expect to pay for -- more
info on the Hirsch Funnel, tho!

Request for Question Clarification by justaskscott-ga on 24 May 2005 08:25 PDT
If you'd like, you can post a separate question on the Hirsch funnel. 
In the meantime, your most recent post will serve to notify pinkfreud
that you have authorized her to answer the current question.
Answer  
Subject: Re: Hirsch Tube, Hersh Tube
Answered By: pinkfreud-ga on 24 May 2005 10:46 PDT
Rated:5 out of 5 stars
 
Thanks for accepting my suggestion of "Hilsch Tube" as the official
answer to your question. I've gathered a bit of info about the Hilsch
Tube that I hope you'll find interesting.

"Compressed air at room temperature goes into a Hilsch tube and comes
out as a hot stream and a cold stream of air... Compressed air can be
split into its hot and cold components. The following explains how a
Hilsch tube accomplishes this. Compressed air shoots around a spiral
and forms a high-velocity vortex of air. Molecules of air at the
outside of the vortex are slowed by friction with the wall of the
spiral. Because these slow-moving molecules are subject to the rules
of centrifugal force, they tend to fall toward the center of the
vortex.  The net result of this process is the accumulation of
slow-moving, low-energy molecules in the center of the whirling mass,
and high-energy, fast-moving molecules around the outside.
'High-energy' and 'low-energy' mean high and low temperatures
respectively. The end result of this process: separation of a stream
of gas into hot and cold streams."

University of Colorado: Hilsch Tube
http://www.colorado.edu/che/CLASSES/3320f/pages/hilsch.html

"The origin of the device is obscure. The principle is said to have
been discovered by a Frenchman who left some early experimental models
in the path of the German Army when France was occupied. These were
turned over to a German physicist named Rudolf Hilsch, who was working
on low temperature refrigerating devices for the German war effort.
Hilsch made some improvements on the Frenchman's design, but found
that it was no more efficient than conventional methods of
refrigeration in achieving fairly low temperatures. Subsequently the
device became known as the Hilsch tube."

Society for Amateur Scientists: About a Remarkably Simple Device to
Attain Low Temperature
http://www.sas.org/E-Bulletin/2003-07-25/labNotesAS/body.html

SX List: The "Hilsch" Vortex Tube
http://www.sxlist.com/images/com/visi/www/http/~darus/hilsch/hilsch.html

"The Ranque-Hilsch vortex tube confines two vortices formed from
compressed air within a tube. Through an unknown phenomenon two
streams of air are produced, one hot, the other cold... While the
vortex tube has found a respectable niche of spot cooling in
manufacturing, the tube has never gained widespread use for many
reasons. Perhaps most important is the lack of understanding the
mechanism by which the two streams of air are produced. Currently no
one can definitively explain why the vortex tube operates as it does.
The process itself is straightforward. Compressed air is inserted into
a tube from one or two tangentially arranged input valves. The air
begins to spin around the wall of the tube at high speeds creating a
vortex. The air begins to move to the far end of the tube, known as
the hot end. At the hot end, a conical valve allows only air spinning
closely against the tube wall to escape. The rest of the air is forced
back through the low-pressure center of the first vortex, creating a
second, inner vortex, which moves towards the opposite end of the
tube, known as the cold side. At the cold side only air from the very
center of the tube is allowed to escape, the rest is pulled back into
the first vortex and repeats the process."

University of California, Berkeley: Ranque-Hilsch Vortex tube
http://www.ocf.berkeley.edu/~dlk/tangents/vortex/vortex_public.php

More information than you're likely to need is available in this FAQ
from EXAIR, a company that manufactures vortex tubes:

EXAIR: Vortex Tube FAQ
http://www.exair.com/faq/faq_vortex_tubes.htm

My Google search strategy was greatly simplified by the fact that I
was aware of the Hilsch Tube, having been a Science Fair Geek in the
1960s. Vortex tubes were much discussed in Science Fair Geek circles
in the sixties. ;-)

Google Web Search: hilsch tube
://www.google.com/search?hl=en&q=hilsch+tube

Since my colleague juskaskscott has piqued your interest in the Hirsch
Funnel, I suggest that you post a new question on that subject. If you
place a phrase such as "For justaskscott-ga" in the subject title,
this will ensure that he will be the one to post your answer.

I hope this is helpful! If anything is unclear or incomplete, please
request clarification; I'll be glad to offer further assistance before
you rate my answer.

Very best regards,
pinkfreud
kwd-ga rated this answer:5 out of 5 stars
Thank you for your answer.  Accurate, complete and suited my needs!

Comments  
Subject: Re: Hirsch Tube, Hersh Tube
From: jadbal-ga on 19 May 2005 11:35 PDT
 
easy to find these on the web by searching "vortex tube."  they fit on
the nozzle of an air compressor and split the air.

http://www.exair.com/vortextube/vt_frmain.htm
Subject: Re: Hirsch Tube, Hersh Tube
From: mikewa-ga on 24 May 2005 11:31 PDT
 
What sort of scale is practical here? It sounds as if you could use
this as a heat pump for heating and cooling the house without needing
refrigerant, but if it were that simple I am sure it would already be
in use

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