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مهندسی ماشینهای کشاورزی
سایتی برای دانشجویان ماشین الات

بازدید : مرتبه
تاریخ : سه‌شنبه 25 اسفند‌ماه سال 1388

Abstract
Two Canadian federal government departments,
Agriculture and Agri-Food Canada (AAFC) and Environment
Canada, are collaborating in a pilot project aimed at
obtaining agricultural tractor exhaust gas emissions data
under actual field conditions. AAFC’s unique instrumented
research tractor will provide the platform for collecting these
data. This tractor was developed as a general purpose
research tool, and was fitted with a series of sensors and an
on-board data logger for measuring and recording tractor
operational parameters such as engine speed, drawbar load,
and fuel consumption as the tractor is doing normal field
work. An instrumented exhaust pipe is being developed to
measure exhaust gas temperature, flow, and NOx
concentration with provision for future sensors for CO, CO
and VOC. Signals from the exhaust pipe instrumentation will
be logged on the tractor data logger along with the other
tractor operational parameters. Field data can be used
directly, or to program a laboratory dynamometer to
reproduce the same engine load cycles for comparative
emissions measurements on other tractor makes and models.
The research will form a basis for development of emissions
factors for agricultural field operations


Introduction
Total emissions for agriculture have been estimated from
standard emissions factors and farm diesel fuel sales data.
Emissions factors, often derived from steady state laboratory
dynamometer tests do not account for the duty cycle of
agricultural tractors.
This research project is designed to measure tractor
exhaust gas emissions for typical agricultural field operations.
Emissions factors can be developed from these
measurements, and extrapolated to a regional or national
scale using data on cropping systems from agricultural
census, and soil types from national soil data bases.
Objective
1. To develop instrumentation for measurement of exhaust
gas emissions of agricultural tractors under actual field
conditions.
2. To document exhaust gas emissions for typical agricultural
field operations to provide a basis for development of
emissions factors for agriculture.
Description
The Agriculture and Agri-Food Canada instrumented research
tractor (McLaughlin et al. 1993) is being used as a platform for
exhaust gas emissions measurement for agricultural field
operations (Fig. 1). This unique tractor was fitted with a set of
instruments and an on-board data logger to measure and record
tractor operational parameters while the tractor is doing normal
field work (Fig. 2).
An instrumented exhaust pipe is under development (Fig. 3).
Emissions sensors include a Horiba Zirconia Oxide NOx sensor,
and a Horiba Mexa-700 excess oxygen sensor installed in the
exhaust pipe, with provision for future installation of CO, CO ,
and VOC sensors as the sensors and funds become available.
Exhaust gas flow will be measured directly with an Annubar
averaging Pitot tube installed in the exhaust pipe. Intake manifold
pressure and temperature measurements will provide base data
for determination of exhaust gas flow indirectly to provide a check
on the direct measurement.
The exhaust pipe will be installed on the tractor, and the
signals from the various emissions sensors logged on the tractor
data logger along with the other tractor operational parameters.
The combined data sets will allow development of emissions
factors for engine duty cycles typical of different agricultural field
operations.
2
Field Experiments
Engine power on the instrumented tractor is measured
indirectly by engine speed and axle torque. Field data show that
fuel consumption closely tracks engine power (Fig. 4). Using a
mathematical model of the engine map, engine power can be
estimated from fuel consumption and engine speed.
The tractor was fitted with a GPS (Global Position System) and
the fuel consumption and position data were logged for tillage
with a disc ripper in a 28 hectares (400 x 700 metres) field (Fig. 5).
The fuel consumption data were subsequently mapped (Fig. 6).
The map shows distinct patterns of varying fuel consumption, and
engine power, which were due to both field topography (i.e. slope
in direction of travel), and variability in the soil conditions.
Similar patterns of exhaust gas emissions are expected due to
the variability in engine power for tillage of the field. The exhaust
gas instrumentation system will allow us to quantify both the
average and the variability in emissions for typical field operations
for subsequent emissions factor development.
Secondary tillage in an east-west direction was done with a
field cultivator in the same field (Fig. 7). Fuel consumption was
subsequently mapped (Fig. 8). The north-east corner of the field
was sandy, and the higher fuel consumption (darker shading) was
noted. The cultivator wheels which control the operating depth,
sank deeper into the sand resulting in increased tillage depth and
higher fuel consumption. This is an example of an activity where
the operator could have reduced fuel consumption, and likely NOx
emissions, by raising the cultivator slightly while in the sandy soil.
Fig. 9 shows fuel consumption for a pass with the cultivator as
highlighted in Fig. 8. The pass started at point A on the east side
of the field, proceeded westbound to point B on the west side,
turned 180º, and returned east bound to point A on the east side.
The high fuel consumption for the sandy area in the north east
corner of the field is clearly evident at the beginning of the west
bound pass, and at the end of the east bound pass. Turning with
the implement in the soil at point B produced a very high peak in
fuel consumption. This could have been prevented by simply
raising the implement for turning.
Future Directions
Data from the instrumented research tractor can be
extrapolated to other makes and models of tractors via two
methods.
1. Engine load cycle for agricultural field operations can be
determined from field data collected with the
instrumented research tractor. These data can be used to
duplicate the engine load cycle with a programmable
tractor PTO (Power Take Off) dynamometer and emissions
measured for other tractors in a laboratory setting.
2. The instrumented exhaust pipe can be installed on other
tractors and emissions measured directly for field
operations.
Acknowledgements
References
Support of the Agriculture and Agri-Food Canada technical staff is
appreciated. Funding for the emissions instrumentation was provided
by Environment Canada's Criteria Air Contaminant Division.
McLaughlin, N.B., L.C. Heslop, D.J. Buckley, G.R. St.Amour, B.A.
Compton, A.M. Jones and P. Van Bodegom. 1993. A general purpose
tractor instrumentation and data logging system. Transactions of the
ASAE 36:(2) 265-273.
Fig. 10 Water brake PTO (Power Take Off) dynamometer connected to
tractor PTO. With a programmable dynamometer, field data collected
with the instrumented tractor can be used to duplicate engine load
cycles for laboratory emissions measurement with other tractors.
Fuel Consumption and Engine Power
40
50
60
70
80
0 50 100 150
Time (s)
Engine Power (kW)
15
20
25
Fuel Consumption (Litres/h)
Engine Power Fuel Consumption
Sample Pass Fuel Consumption
18
23
28
33
0 100 200 300
Time (s)
Fuel Rate (Litres/h)
Sand Sand
Turn
west bound east bound
Point A Point Point A
Fig. 1 Instrumented research tractor. The cab extension accommodates

the data logger operator, data logger and signal conditioning





Field Experiments
Engine power on the instrumented tractor is measured
indirectly by engine speed and axle torque. Field data show that
fuel consumption closely tracks engine power (Fig. 4). Using a
mathematical model of the engine map, engine power can be
estimated from fuel consumption and engine speed.
The tractor was fitted with a GPS (Global Position System) and
the fuel consumption and position data were logged for tillage
with a disc ripper in a 28 hectares (400 x 700 metres) field (Fig. 5).
The fuel consumption data were subsequently mapped (Fig. 6).
The map shows distinct patterns of varying fuel consumption, and
engine power, which were due to both field topography (i.e. slope
in direction of travel), and variability in the soil conditions.
Similar patterns of exhaust gas emissions are expected due to
the variability in engine power for tillage of the field. The exhaust
gas instrumentation system will allow us to quantify both the
average and the variability in emissions for typical field operations
for subsequent emissions factor development.
Secondary tillage in an east-west direction was done with a
field cultivator in the same field (Fig. 7). Fuel consumption was
subsequently mapped (Fig. 8). The north-east corner of the field
was sandy, and the higher fuel consumption (darker shading) was
noted. The cultivator wheels which control the operating depth,
sank deeper into the sand resulting in increased tillage depth and
higher fuel consumption. This is an example of an activity where
the operator could have reduced fuel consumption, and likely NOx
emissions, by raising the cultivator slightly while in the sandy soil.
Fig. 9 shows fuel consumption for a pass with the cultivator as
highlighted in Fig. 8. The pass started at point A on the east side
of the field, proceeded westbound to point B on the west side,
turned 180º, and returned east bound to point A on the east side.
The high fuel consumption for the sandy area in the north east
corner of the field is clearly evident at the beginning of the west
bound pass, and at the end of the east bound pass. Turning with
the implement in the soil at point B produced a very high peak in

fuel consumption. This could have been prevented by simply







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