Multi-DS™
DOES2™
Concentrator
Emulsification
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The Technology
Large-Displacement Off- and Non- Road Diesel Engines
Portable Exhaust Emissions Field Sampling System
Large-displacement diesel engines for off- and non- road vehicle use can be tested for
exhaust emissions by testing the engine in two ways: in a test-facility setting using
an engine dynamometer; or by testing the vehicle itself under normal, in-use conditions.
The latter can be accomplished using ETC�s proprietary, portable exhaust emissions,
field sampling system, which can be installed on the vehicle for the sampling of the
engine�s exhaust stream while the vehicle is operating under normal-load conditions.
The US EPA has established a code of regulations for the measurement of criteria exhaust
emissions from locomotives under field conditions (CFR 40, Part 92).
A portable system that meets the criteria for in-use exhaust emissions, as established
by US EPA, has been developed by Environment Canada. The system consists of two partial
flow dilution tunnels, one for the sampling of gaseous emissions of total hydrocarbons,
carbon monoxide, oxides of nitrogen and carbon dioxide (plus other target compounds of
interest) and the second for particulate emissions. Each dilution tunnel is connected to
a separate sampling probe located in the engine�s exhaust pipe by a heated line. The
gaseous compound dilution tunnel has a controlled flow rate and is controlled by a mass
flow controller. Dilution air injected into the tunnel serves as the control for
establishing proportional samples.
Dilute exhaust samples are drawn from the tunnel through a filter to trap particulate
material, then into the sample media for the various types of compounds to be measured
(examples include semi volatiles, carbonyls, PAH/n-PAH, etc). The sample media are removed
from the system after the completion of the test and transferred to an analyzer bench for
analysis.
For continuous exhaust emissions analysis or modal analysis, an appropriate analyzer(s)
is connected to one of the tunnel probes instead of a specific sample media. The analyzer
output signal, which represents the sample analysis, is connected to the system computer
for data acquisition and processing.
In addition to the emissions sample collection, the system measures the exhaust temperature,
the engine RPM, vehicle speed and engine load.
The particulate mass is drawn from the exhaust pipe through a larger diameter probe, which
is connected to a heated line that is connected to the smaller diameter dilution tunnel,
which is fixed to exterior of the sampling system for the testing. Mass flow controllers
connected to the exit of the tunnel control the mass airflow rate of the compressor blower
that provides the airflow for the tunnel. As per the gaseous compound tunnel, dilution air
is injected into the particulate tunnel using a vacuum pump. A mass airflow controller based
on a signal received from the system computer controls the amount of air injected. This signal
is based on the same feed back signal used to determine the dilution airflow to the gaseous
compound tunnel. The ratio of dilution air to total tunnel air for the two tunnels is
identical for all of the testing.
The software for the portable sampling system has the following functions:
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records the output of the external devices(eg. thermocouples, mass flow controllers,
Hall Effect sensors, mass air flow meters, pressure transducers, etc)
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calculates the dilution flow rate on a per second basis and sends the signal to the
mass flow controller
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calculates humidity correction factor for determining oxides of nitrogen
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provides a spread sheet for entering data prior to the test that is used for
calculating mass emissions per unit fuel, per unit time and/or per engine load at
standard temperature and pressure
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provides for a simulated flow analysis to verify that all pumps, solenoids and mass
flow controllers are functioning prior to initiating a test procedure
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The same techniques and technology can be used in stationary or non-portable applications.
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