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My interests are
broadly in energy and environmental systems, including: modeling and evaluation of advanced
energy conversion (e.g.,combustion, gasification) and environmental control
systems; measurement and modeling of real-world fuel use and emissions of
onroad and nonroad vehicles; development and application of methods for
quantification of variability and uncertainty and for sensitivity analysis
in systems models; and exposure and risk analysis. Air pollutant emissions of interest include
criteria pollutants, hazardous air pollutants (“air toxics”), particulate
matter, and greenhouse gases. More
details on my teaching, current and past research activities, publications,
professional advisory
activities, research group, and computer laboratory are available in the links above.
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Latest News:
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Dr. Frey’s group has just published two new papers in Environmental Science and Technology. One paper, by postdoctoral research
associate Dr. Hyung-Wook Choi and Dr. Frey, is regarding a method for
quantifying the real-world energy use and emissions of a plug-in hybrid electric school bus. The other, by Dr. Frey, Dr. Kaishan Zhang
(now with the California Air Resources Board, and Dr. Rouphail (director of
the Institute for Transportation Research and Education located at NCSU) is
regarding a method for modeling the
emissions of individual vehicles based on second-by-second data obtained
from Portable Emissions Measurement
Systems.
   
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Dr. Frey and colleagues have recently published in Transportation Research Record a
methodology for inventorying construction fleet emissions. The method is based on the use of
representative real-world measurements of construction vehicles obtained by
means of a portable emissions measurement system (PEMS). Recommendations are made about
development and practical applications of emissions inventories for
construction fleet management.
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Dr. Frey and collaborators have recently published in Environmental Science and Technology
a methodology for estimating high-resolution, regional on-road vehicle emissions
and the associated reductions in air pollutant emissions from vehicles that
utilize alternative fuels or propulsion technologies. The fuels
considered are gasoline, diesel, ethanol, biodiesel, compressed natural
gas, hydrogen, and electricity. The technologies considered are internal
combustion or compression engines, hybrids, fuel cell, and electric. Road
link-based emission models are developed using modal fuel use and emission
rates applied to facility- and speed-specific driving cycles. The methodology makes use of
second-by-second data from field measurements using Portable Emission
Measurement Systems (PEMS) in order to develop correction factors for
real-world driving cycles.
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In addition to previous studies in Dr. Frey’s group that
compared energy use and emissions of dump trucks and construction vehicles fueled with B20 biodiesel versus petroleum
diesel, we have recently published a similar study in Transportation Research – Part D that focuses on eight cement mixers. These three studies include a combined
total of 35 vehicles that were tested for approximately one day on each of
the two fuels. In general, these
studies support the finding from dynamomter tests that substitution of B20
for petroleum diesel leads to reductions in tailpipe emissions of carbon
monoxide, hydrocarbons, and particulate matter. While there are differences in the effect
of B20 on the emissions of nitrogen oxides from one vehicle to another, on
average there was little change.
These studies also establish duty cycles for multiple types of
vehicles, including dump trucks, cement mixers, front-end loaders,
backhoes, and motor graders. The
newly measured duty cycles, coupled with modal emission rates obtained from
in-use measurements using Portable Emission Measurement Systems, enable
estimation of the effect of variations in vehicle operations on emissions.
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Dr. Frey’s father passed away on March 30, 2010. The Washington
Post has written a news obituary for Henry
Richard Frey, who had a 40+ year career in ocean sciences and related
fields. The late Dr. Frey, who
served in the U.S. Marine Corps during the Korean Conflict, will be inurned
at Arlington National Cemetery.
News Archive
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