Energy conservation and application uniformity for irrigation systems
Date
2002
Authors
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ORCID
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Degree Level
Masters
Abstract
The need for high energy input is one of the primary limitations to the
sustainability of centre pivot irrigation. The purpose of this project was to evaluate a
relatively new technology known as Low Elevation Spray Application (LESA) irrigation
to obtain Saskatchewan specific performance data for this technology.
Preliminary studies were conducted on small, research scale, linear and centre
pivot systems. Afterwards, a two tower centre pivot irrigation system equipped with
standard impact nozzles was modified by the addition of LESA equipment: drop tubes and
low pressure nozzles with static spray pads. This system was capable of operating either
standard above lateral mounted impact sprinklers or LESA technology on the same piece
of land. Later, seven field scale systems with various makes of nozzles and spray pads
were added to the study to ensure that the data collected from the research systems was
applicable to field conditions.
For all of the systems tested the, coefficient of uniformity, application efficiency
and specific energy consumption were determined and compared for a variety of wind
speeds.
Results showed that for the two tower research centre pivot the coefficient of
uniformity was similar for impact and LESA technology with static spray pads. The
application efficiency for the impact nozzles and low pressure nozzles showed that, while
they both had a trend in decreasing efficiency with increasing wind speeds, the low
pressure nozzles had a better efficiency at all wind speeds. The trends showed that the application efficiency for the impact nozzles ranged from approximately 69% to 86% and
the low pressure nozzles ranged from approximately 74% to 98% indicating an average
efficiency gain of approximately 8% greater for the LESA technology.
The energy consumed by both the impact and LESA systems indicated that both
systems had an increasing energy consumption with increasing wind speed. However, the
low pressure system showed a trend of using on average, one half of the energy required
by the medium pressure system (0.107 kWh/m3 as compared to 0.057 kWh/m3)to deliver the same amount of water.
Field comparisons indicated that the system equipped with the same LESA
technology as the research system (drop nozzles and static spray pads) had similar results
for coefficient of uniformity, application efficiency and specific energy consumption. Field
systems equipped with spinner or rotator spray pads showed an increase in all factors
measured.
Results indicate that LESA technology offers promise for increasing the efficiency
of centre pivot irrigation systems in Saskatchewan.
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Citation
Degree
Master of Science (M.Sc.)
Department
Environmental Engineering
Program
Environmental Engineering