"Improving air quality is one of TxDOT's five core goals, and this grant helps us to accomplish that mission," TxDOT Deputy Executive Director Steve Simmons said. "We look forward to working with the University of Houston, as well as the Environmental Protection Agency, to continue to find ways to reduce emissions from construction equipment."
UH's researchers will supervise the installation of Nett Technologies' BlueMAXTM selective catalytic reduction system, which is classified by the EPA as an emerging technology, on five TxDOT nonroad vehicles. They then will do testing and analysis on the BlueMAX's ability to reduce emissions, which will provide the EPA with real-world performance data.
"Houston is an ideal urban area to obtain maximum benefits from diesel retrofits, because it has a high population density, poor air quality and is not meeting ozone standards due in large part to the nitrogen oxides emitted by diesel-powered vehicles and equipment," explained professor Mike Harold, co-principal investigator of the Texas Diesel Testing and Research Center. "Over half of total mobile-source NOx emissions are attributed to diesel engines in the greater Houston area."
The team will do what Harold calls "a baseline emissions assessment" of each vehicle before the BlueMAX unit is installed. After the installation, the team will monitor the unit's performance using a portable emission measurement system, which is connected to the vehicle during operation in the field.
UH's diesel-testing facility, established in 2003 to carry out evaluation, technology development and research of heavy-duty diesel emissions devices and new fuels, is equipped with a heavy-duty chassis dynamometer, on which one of the TxDOT vehicles will undergo more thorough testing.
Located in Mississauga, Ontario, Canada, Nett Technologies specializes in emission-control products for engines, vehicles and machinery used in the mining, material handling and construction industries. The company's wide range of products includes catalytic converters for diesel, natural gas, liquefied petroleum gas and gasoline engines, diesel particulate filters and fume diluters.
The Nett BlueMAX selective catalytic reduction (SCR) system is designed to control nitrogen oxide emissions from medium- and heavy-duty diesel engines, using a control strategy that relies on a NOx concentration measurement by a sensor positioned upstream of the SCR catalyst.
"The NOx sensor-based control strategy makes the system very suitable for retrofit applications," said M.A. Mannan, business manager for Nett Technologies. "No time-consuming calibration, such as through engine mapping, is necessary, and the system can be installed on a wide range of diesel engines, including mechanical engines."
The system also controls diesel particulate matter, hydrocarbons and carbon monoxide, Mannan said.
"Selective-catalytic reduction, which was first developed for the abatement of NOx from power plants, is considered to have the best NOx-removal potential and durability for heavy-duty diesel vehicles," Harold said.
The specifications for the vehicles to be tested vary, Harold said, but all have Caterpillar engines with model years between 1998 and 2004 and horsepower between 120 and 305. Therefore, he said, the emissions reductions from each vehicle will vary.
"There is only one retrofit for nonroad vehicles on the EPA's emerging technology list that results in NOx reduction," Harold said. "Currently, the only other option for reducing NOx from this class of equipment is to purchase a new engine. Installing retrofits is a much more cost-effective option as opposed to buying brand new engines."
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