103
Ultrasonic
Detector for Carbon Dioxide--2B
Technologies, Inc.,
Dr.
John W. Birks, Principal Investigator, johnb@twobtech.com
Dr.
Mark J. Bollinger, Business Official,
DOE
Grant No. DE-FG02-03ER83823
Amount:
$750,000
The
quantification of sources and sinks of atmospheric carbon dioxide would be
greatly facilitated by the development of a new detector for this important
greenhouse gas. In particular a
lightweight CO2 sonde, similar to the widely used ozonesonde, could
be used to estimate landscape-scale (approximately 100 km2) fluxes of
CO2 from vertical profiles through the convective boundary layer.
This project will develop a new CO2 detector based on the
measurement of the speed of sound in air. The
ultrasonic detector will be highly selective for CO2 and have a
precision of one part in 3000 or better, corresponding to a detection limit of
0.1 ppmv. To
compliment the new CO2 detector, a small, lightweight calibration
system also will be developed. In
Phase I, an ultrasonic detector for gas chromatography was modified, using a
scrubber, to be selective for CO2. It
was determined that, over a wide operating range, the signal was independent of
pressure and flow rate. The best
precision was obtained at the lowest flow rate (5 cc/min) and highest pressure
(60 psig). Using measurements of
real air samples, the instrument was compared with a conventional CO2
analyzer and found to agree to within 0.3 ±0.3
ppmv. In Phase II, a new,
miniaturized, ultrasonic detector, specific for measurements of CO2 mixing
ratios, will be developed and tested. The
sample and reference cells will be in thermal contact to greatly reduce
temperature effects on precision and accuracy.
The new instrument will be compared with conventional instrumentation at
ground monitoring sites and aboard research aircraft.
Commercial Applications and Other
Benefits
as described by the awardee: The
ultrasonic detector should result in two commercial products:
(1) a new ultrasonic detector for atmospheric measurements with high
precision and accuracy, and (2) a portable calibration system, which does not
require compressed gas cylinders, for CO2 measurements.