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H. Christopher Frey

 

Professor

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Department of Civil,

Construction, and

Environmental Engineering

 

North Carolina State University
Raleigh, NC 27695-7908

Telephone: (919) 515-1155

Email:  frey (at) ncsu.edu

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Research Interests

Teaching

Publications

Current and Recent Projects

Past Projects

Computer Laboratory

Frey Research Group

Professional Activities

Real-World Vehicle Emissions

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:

 

·   Brandon Graver, an MS student working with Dr. Frey, was featured in the Southeastern Transportation Center’s Summer 2010 Research Spotlight for his work on measuring the activity, energy use, and emissions of passenger railroad locomotives.

·   Dr. Frey is starting a new collaborative research project, with Co-PI Dr. Nagui M. Rouphail, that will focus on the linkage between travel simulation and vehicle emissions models and their application to evaluation of traffic management strategies and emissions impacts.  The new project is sponsored by the U.S. Environmental Protection Agency and was selected via a scientific peer review process under the STAR grants program.  The project will be administered as a cooperative agreement with the U.S. EPA.

·   Dr. Frey’s group has recently 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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·   Brandon Graver, an MS student working with Dr. H. Christopher Frey, received the firstplace Masterslevel platform paper award at the 2010 Annual Meeting of the Air & Waste Management Association.

·   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. 

·   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.

·   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 dynamometer 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.

News Archive

 

 



Disclaimers
Portions of this web site are based upon work supported by the
National Science Foundation under Grant No. 9701502.

Any opinions, findings, and conclusions or recommendations expressed in this web site
are those of the author(s) and do not necessarily reflect the views of the
National Science Foundation.