Flat Plate vs Parabolic Trough Efficiency

[Lee]

Hi,

See this table
Loading Image...

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.

[DJ]

See this tablehttp://www.contactshare.com/Renewables/EfficiencyTable/EfficiencyOfVa...
It compares different types of collectors. I was very interested
in
the figures especially Flat Plate (21%) vs Parabolic Trough (56%).
Is this table saying that a trough
would
be more than twice as efficient?

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