Interesting story behind these - I was fascinated when I first learned of
it. They are the cooling fins of a system to protect the permafrost, like
those shown at shown at:
<http://www.faculty.virginia.edu/ribando/modules/ExtendedSurface/pipeline4.g
if>
and described at
<http://www.faculty.virginia.edu/ribando/modules/ExtendedSurface/>:
The Trans-Alaska Pipeline Passive Cooling System
Extended surface heat transfer devices (cooling fins) are very prominent at
the condenser end of the heat pipes that are part of the vertical support
members along the Trans-Alaska Pipeline. Some 380 miles of pipeline in the
north are insulated and buried, a few miles with active refrigeration, most
without. Further south, where the heat generated overcoming fluid friction
in the pipeline could cause thawing of the permafrost and possible
structural damage to the pipeline, the pipeline is elevated on vertical
support members. There are two heat pipes for each vertical support member.
The heat pipes (actually they are Perkins tubes, a type of thermosyphon,
because they use gravity rather than capillary action in a wick for the
return flow of the condensate to the evaporator end) are designed so that
during the winter they remove as much heat as possible from the area around
the base of the VSM¹s. During the summer, the working fluid (anhydrous
ammonia) sits idle at the bottom of the tube. Essentially the heat pipe
acts as a thermal ³diode² actively promoting heat transfer upward in the
winter and inhibiting downward heat transfer in the summer. The idea is to
chill the permafrost so thoroughly during the winter that it will remain
solid through the following summer. The winter and summer operation of the
heat pipes is shown here in schematic form. More technical details about
the TAP may be found at the Alyeska website and more about heat pipes may be
found in An Introduction to Heat Pipes: Modeling, Testing and Applications,
by G.P. Peterson, Wiley (1994).
Michael
On 2/19/09 5:29 PM, Sue Pearce wrote:
> They look like heat exchangers of some sort, but note in number 8, they are
> connected to the structural supports, not the pipeline. Don't know why.
>
> Bill Pearce
> ----- Original Message -----
> From: "Johan Malmström" <jmalmstrom@xxxxxxx>
> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
> Sent: Thursday, February 19, 2009 4:10 PM
> Subject: Re: [OM] Delta Junction 2008
>
>> 19 feb 2009 kl. 17.53 skrev siddiq@xxxxxxx:
>>
>>> http://privat.johanmalmstrom.se/Delta2008/large-1.html is my fav. In
>>> the photos of the pipeline (?) what are the brown vertical things with
>>> two look like heatsinks? (not heatsinks, but like finned pipes often
>>> used to slowly bring up liquidised gasses gaseous temperature--so
>>> heatsink in reverse).
>>
>>
>> There is something about old car behinds. I found this car quite far
>> from the road in between trees.
>>
>> I think the pipes is to minimies vapour around the pipeline. It's the
>> Trans Alaska Pipeline.
>>
>> Thanks for !
>> /jOhan
--
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