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Anybody know what the equations in this image represents?

Anybody know what the equations in this image represents? - Physics Forum

Anybody know what the equations in this image represents? - Physics Forum. Discuss and ask physics questions, kinematics and other physics problems.


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  #1  
Old 08-04-2004, 05:37 PM
Steve Lee
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Default Anybody know what the equations in this image represents?



The image that contains the equations can be found over at
http://members.shaw.ca/ckcc/tmp/equations.gif.

It doesn't look like a pure physics equation, but I figured I might
have some luck in here. Thanks for your time and courtesy!
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  #2  
Old 08-04-2004, 10:02 PM
tadchem
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Default Anybody know what the equations in this image represents?


"Steve Lee" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ]...

You're right. It *doesn't* look like a pure physics equation, but it *does*
look like the kind of ad hoc expression that might be developed by an
engineer, especially the alternate expressions for k in (2) that depend on
the relative values of H/W and sqrt(3).

Also, the variables used are all consistent with variables used in fluid
flow: Q is often used for a flow rate, the Greek letter eta (the "n"-like
letter) for viscosity, T for temperature, v for velocity, the Greek letter
gamma (the "y"-like letter) for specific weight, H for hydrostatic head
(height), W for weight, T for temperature or kinetic energy or time or
torque, k for various constants, A for cross-sectional area, and d is a
symbol for a difference.

This collection of variables would seem to apply to flow of a viscous liquid
through a conduit. I can't help you much beyond that as I am a chemist, not
an engineer.

HTH


Tom Davidson
Richmond, VA


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  #3  
Old 08-05-2004, 02:45 AM
N:dlzc D:aol T:com \(dlzc\)
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Default Anybody know what the equations in this image represents?

Dear Steve Lee:

"Steve Lee" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ]...

tadchem has the right of it. Through sheer intuition and years of abuse at
the "hands" of engineers, he has correctly identified empirical relations
for heat transfer. The Q_dot is the giveaway, and it is "heat flow" (units
of watt or its ilk). I would guess some sort of convective heat transfer
from a surface "H" high, by "L" wide. Will it be necessary for me to dig
my Heat Transfer book out, and name the relation, or at least its
progenitor?

David A. Smith


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  #4  
Old 08-05-2004, 08:02 PM
tadchem
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Default Anybody know what the equations in this image represents?


"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:[Only registered users see links. ]> wrote in
message news:ebhQc.1624$xk.634@fed1read01...

<snip>


Thank you, David. I was stalled over why the 'dT' term would have been
there, but then I have never had to calculate characteristics of heat
exchangers before.


Tom Davidson
Richmond, VA


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  #5  
Old 08-06-2004, 12:56 AM
N:dlzc D:aol T:com \(dlzc\)
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Default Anybody know what the equations in this image represents?

Hi Tom,

"tadchem" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ]...
dig

It is poorly presented. This is usually "deltaT" or "/\T", representing
the difference between bulk fluid and.exchanger "root" temperature (if I
recall corrrectly). It should not have been presented in the "universally
recognized" differential form, even though no other "d_" term was present.

Leave it to an engineer...

David A. Smith


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  #6  
Old 08-06-2004, 04:38 AM
tadchem
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Default Anybody know what the equations in this image represents?


I understood that dT referred to w temperature *difference* rather than a
*differential.* I was just a bit slow in completing the relation:

[viscosity] + [temperature difference] => [convection]


Thanks again.

Tom Davidson
Richmond, VA


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  #7  
Old 08-06-2004, 01:49 PM
N:dlzc D:aol T:com \(dlzc\)
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Default Anybody know what the equations in this image represents?


"tadchem" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ]...

Understood. Welcome. And you are never "slow". ;>)

David A. Smith


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