“We have invented a drive-through Streamlined Heavy-duty Emissions Test (SHED) which measures all the pollutants of importance in mass emissions units—the current government standard,” says Donald Stedman, John Evans Professor in the Department of Chemistry and Biochemistry at Denver. “The test allows the truck to simply accelerate in its normal way with its normal load.”
University of Denver
The new SHED test for truck emissions is more accurate and less costly.
The SHED technique measures realistic truck exhaust emissions in 20 seconds or less and the truck does not even have to stop. The system basically places a 50-foot long tent roof over the roadway which captures some of the exhaust. “Under the roof,” says Stedman, “is a perforated sampling tube with suction provided by an in-line blower. The perforations are designed to accelerate the air sample down the tube at about the same speed as the truck accelerates under the roof.”
The result is a measurement that is closely comparable to federal emissions standards.
That is an upgrade to existing testing practices in two ways. First, the current method tests only for how much or little light (opacity) a truck’s exhaust lets in. This actually has little correlation with the government standard for pollution which is measured in units of smoke mass. Oxides of nitrogen, an important part of diesel exhaust, are not measured at all.
Second, the test now in place is time-consuming which drives up transportation costs. The truck must be pulled over and stopped with the engine idling. The tester mounts an opacity monitor on the hot exhaust pipe, then has the driver floor the accelerator to allow the motor to go to its maximum RPM. “This is something that never occurs under normal circumstances,” Stedman says.
The SHED testing technique has undergone two successful tests. The first was done in collaboration with researchers at Texas A&M University. The second took place in Vancouver, British Columbia. In the latter test, more than 1,000 heavy-duty truck emissions were measured. The results were presented in April at the Coordinating Research Council On-Road Mobile Source Emissions Conference. See http://www.metrovancouver.org/about/publications/Publications/2013_RSD_HDV_Study.pdf
Stedman says that practical applications of the SHED test include “improved estimates of the impact of truck emissions on air quality and fast emission screening at selected drive-through locations such as weigh stations, transit terminals and border crossings.”
The SHED test could also help The United States fulfill an unmet part of the North American Free Trade Agreement (NAFTA), he notes. NAFTA allows trucks from Mexico to deliver directly to destinations in the U.S. But in practice that doesn’t happen, in part because of fears that the Mexican trucks might be more polluting than the better-regulated U.S. fleet.
“Border crossing loads now are emptied from one truck and refilled into another,” says Stedman, “significantly increasing the cost and time of transportation.”
Earlier work by Stedman and University of Denver colleagues resulted in a technique that enabled an emissions test for cars that, by using remote sensing, could be carried out in about one second as the car drove by. That resulted in on-road emission monitoring being made a part of the 1990 U.S. Clean Air Act Amendments, although that mandate has been more or less ignored, except in Colorado. In Colorado, almost 300,000 drivers each year get a postcard from Air Care Colorado stating that they have passed their emission test by means of remote sensing during the course of their normal driving and thus do not have to report for their biennial emission test.
Stedman is hopeful that his new truck test will take off in the USA as successfully as his car test has been accepted in Colorado.
Donald Stedman | Newswise
Species may appear deceptively resilient to climate change
24.11.2017 | University of California - Davis
Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University
High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons
The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
24.11.2017 | Physics and Astronomy
24.11.2017 | Health and Medicine
24.11.2017 | Earth Sciences