ote
em ae ee ae ees te ae adel
ENVIRONMENT
ments, we now know what to
measure in the cloud of dispersing
natura!-gas vapors and how to
measure it. These tests have helped
us to design a sensor array and
data-acquisition system for 40-m3
spill experiments now in progress.
They have also permitted usto test
our ATMASdispersion code, to
verify the importance of the code’s
variable-wind-field capability, and
to pinpoint areas of needed im-
provement. These experiments
provided us with the first field
measurements of differential boiloff
of the various components of LNG
and also with preliminary estimates
of the horizontal and vertical diffusion coefficients. We have learned
that the lower flammability limit extends farther downwind than expected and that the vapor cloud is
warmer than predicted.
In our current 40-m° spill experiments we are attempting to
measure turbulent mixing in the
gas cloud and to obtain enough
gas-concentration data to generate
isopleth plots for comparison with
these generated by computer
models. We are also attempting to
measure heat transfer from various
sources into the cloud as it disperses downwind. Aerial infrared
imaging techniques permit us to
track the methane cloud through
the sensor array and beyond. All of
these tests will prepare us for the
larger-scale spill experiments
models and help DOE to understand LNG-handling accidents and
to set guidelines for minimizing adverse effects.
Key words: ATMAS; gas-concentration sensors: hydrocarbon fuels; infrared imaging:
liquefied natural gas; LNG: wind-field model.
Notes and references
1. A brief discussion of LNG hazards and our
plans to study them appeared in the Septem-
ber 1978 Energy and Technology Review
{UCRL-52000-78-9), p.ii.
2. Studies of the detonability of methane and
ethane mixtures were described in the May
1979 Energy and Technology Review
(UCRL-52000-79-5), pp. 18-23.
. G.E. Bingham, C. H. Gillespie, and J. H. McQuaid, Development of a Miniature, Rapid-
G2
sensors and measurement techniques. As @ result of these experi-
Response Carbon Dioxide Sensor, Lawrence
Livermore National Laboratory, UCRL-
52440 (1978).
4, D. L. Ermak, R.A. Nyholm, and R. Lange.
ATMAS: A Three-Dimensional Atmospheric
Transport Mode! to Treat Multiple Source
Areas, Lawrence Livermore National
Laboratory, UCRL-52603 (1978).
5. R. Lange, “ADPIC-A Three-Dimensional
Particle-in-Cell Model for the Dispersal of At- mospheric Pollutants and lts Comparison to
Regional Tracer Studies,” App. Meteor. 17,
320-329 (1978}.
6. The new w:nsor is described in the September 1980 Energy and Technology Review
(UCRL-52000-80-9), pp. 36-41.
{planned for 1982 and beyond),
which will verify our computer
37