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Flat Plate vs Parabolic Trough Efficiency

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Posted by Lee on April 15, 2007, 10:36 am
 
Hi,

See this table
http://www.contactshare.com/Renewables/EfficiencyTable/EfficiencyOfVariousSolarCollectors.JPG

It compares different types of collectors.    I was very interested
in
the figures especially Flat Plate (21%) vs Parabolic Trough (56%).

I'm not really sure I understand Carnot efficiency.  Let's say we
want
to heat water to 60 degrees C.   Is this table saying that a trough
would
be more than twice as efficient?

Regards,



Lee.


Posted by DJ on April 16, 2007, 1:03 am
 


tablehttp://www.contactshare.com/Renewables/EfficiencyTable/EfficiencyOfVa ...

Yes, pretty much. What it's NOT saying clearly (it does say it's a
single axis tracker), however, is that the trough needs to be
motorized and have a solar alignment tracking system so that it can
continuously follow the sun's path across the sky to achieve these
numbers, whereas a flat plate collector "just lays there".

This does add substantially to the cost of a trough collector.

DJ

DJ


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