The on-board tailpipe emissions measurement system (TOTEMS) : proof‐ of‐concept.

An on-board tailpipe emissions instrumentation system was designed, assembled and tested as proof-of-concept
for the University of Vermont’s Transportation Research Center (TRC) Signature Project #2 “real-world” vehicle
emissions data collection effort. This report summarizes the measurement system’s status as of June 2009 and
demonstrates that the study team can reliably collect on-board emissions/vehicle performance data. The purpose
of the new instrumentation package is to collect real-world exhaust emissions for regulated (CO, HC, NOx) and
unregulated (CO2, air toxics, particle number) pollutant species as well as vehicle operating parameters, all at 1Hz
temporal resolution, while a test vehicle is driven on the road network in Chittenden County, Vermont. Future
data collected using the on-board system will be used to model the modal emissions of alternative vehicles. This
report documents (i) the instrumentation system’s components and the research team’s proposed data collection
methodology; and (ii) presents initial data sets collected by quantifying real-world emissions from a 1999 Toyota
Sienna minivan that was used in previous studies conducted by the PI. Unlike previous studies conducted by the
PI (see Section 8 references for more detail), however, the new instrumentation package collects: (i) the full
number distributions of particle emissions using a particle spectrometer instrument that was not available
previously; and (ii) quantifies mobile source air toxic (MSAT) gaseous emissions in addition to criteria pollutant
(CO, NOx, HC) and greenhouse gas (CO2, N2O, CH4) using a high-speed FTIR instrument specifically designed
for on-board vehicle exhaust testing.
This report summarizes initial measurements made by the Signature Project #2 study team using The On-board
Tailpipe Emissions Measurement System (hereafter, “TOTEMS”) on-board the Toyota Sienna minivan as the
“proof-of-concept” vehicle prior to initiating testing of two Toyota Camry study vehicles: one hybrid and one
conventional. The Camry data will be used to build the first second-by-second, real-world emissions database for
hybrid and conventional light-duty vehicles under cold climate and hilly terrain conditions experienced in
Vermont.
As the data in this report document, TOTEMS is a fully functional set of instrumentation developed for
quantifying tailpipe gas and particle pollutant concentrations, exhaust flow rates, exhaust temperatures, sampling
temperatures, vehicle position, engine operating behavior, ambient conditions, and instrumentation condition. All
instrumentation is powered by an on-board battery power supply system to prevent artificial loads on the vehicle
engine.