re: solar collector air flow
31 dec 2001
>...good airflow instrumentation is beyond almost everyone's budget...
from a recent paper, "smart controls for whole house fans" by pablo
la roche and murray milne of ucla, at the 10/4-7/01 arizona state u
cooling frontiers symposium:
air velocity is measured with a kestrel-2000 thermo-anemometer,
which has a small electronic rotating vane anemometer and
a lightweight impeller. it has a speed range of 0.3 m/s to 40 m/s
and an on-axis accuracy of the greater of +/- 3% of the reading
or 0.1 m/s. the exhaust snout [of their test cell] has been
designed to match snugly with the diameter of the anemometer
and is always perpendicular to the wind.
they measured fan-forced airflow with a restriction (the snout :-) just
for measurement purposes, but it seemed to be accurate. pablo la roche
said the cost of this non-logging anemometer was about $200.
they also used a $400 tattletale tfx-11 data logger-controller from onset
computer corp (makers of fine $85 hobos), which contained 68hc11 and pic
16lc62a processors with 8 analog channels, a tfbasic programming language,
128k of ram, a hardware real time clock, and a 472k flash eeprom. this
talked to a pc via a serial port. onset thermistor temp sensor accuracy
was +/-0.9 f at 70 f, with a range of -40 to 212 f, over 50' wires.