In-use emission measurements were made from twenty-seven pieces of construction equipment, which included four backhoes, six wheel loaders, four excavators, two scrapers (one with two engines), six bulldozers, and four graders. This is the largest study of off-road equipment emissions using 40 CFR part 1065 compliant PEMS equipment for all regulated gaseous and particulate emissions. The large variability in emissions, especially for NO x and PM, could have important implications for developing accurate emissions inventories and models. This variability is primarily due to differences in engine load factors for different types of work and combinations of work and idle time and the displacement of the engines. a b s t r a c t Gaseous and particle emissions from construction engines contribute an important fraction of the total air pollutants released into the atmosphere and are gaining increasing regulatory attention. Robust quantification of nitrogen oxides (NO x ) and particulate matter (PM) emissions are necessary to inventory the contribution of construction equipment to atmospheric loadings. Theses emission inventories require emissions factors from construction equipment as a function of equipment type and modes of operation. While the development of portable emissions measurement systems (PEMS) has led to increased studies of construction equipment emissions, emissions data are still much more limited than for on-road vehicles. The goal of this research program was to obtain accurate in-use emissions data from a test fleet of newer construction equipment (model year 2002 or later) using a Code of Federal Requirements (CFR) compliant PEMS system. In-use emission measurements were made from twenty-seven pieces of construction equipment, which included four backhoes, six wheel loaders, four excavators, two scrapers (one with two engines), six bulldozers, and four graders. The engines ranged in model year from 2003 to 2012, in rated horsepower (hp) from 92 to 540 hp, and in hours of operation from 24 to 17,149 h. This is the largest study of off-road equipment emissions using 40 CFR part 1065 compliant PEMS equipment for all regulated gaseous and particulate emissions. a r t i c l e i n f oPublished by Elsevier Ltd.
In-lab and on-road emission comparisons are made between AVL's M.O.V.E GAS PEMS 493 system and the UCR mobile emissions laboratory (MEL), which served as a Federal Reference Method (FRM) for comparison and validation. These comparisons are made for three different heavyduty engines with NO x emission certification levels ranging from 0.27 g/kWh (0.2 g/hph) to 5.4 g/kWh (4.0 g/hph). The brake-specific emissions during the Not-To-Exceed (NTE) engine operating zone are compared between the FRM and portable emission measurement systems (PEMS) to quantify the measurement uncertainty of the new commercial PEMS. Overall, the PEMS shows good correlation to the FRM and demonstrate its ability to measure a wide variety range of emission levels. The PEMS brake-specific NO x (bsNO x) measurement is well-behaved with +5 to −10 % relative error over the 1.0 to 7.0-g/kWh range. Further, the relative NO x error ranged from a +15 to −15 % over the 0.1 to 1-g/kWh range. The relative NO x error increases sharply below 0.1 g/kWh from 15 % to more than 50 % at 0.02 g/kWh. The relative error below 0.10 g/kWh is high due to the very low NO x emission rates that approach the detection limit of both the raw PEMS and dilute FRM measurement methods. The PEMS bsCO 2 average bias is observed to be slightly higher than the MEL reference laboratory at 2 % overall. The PEMS NMHC and CO emissions were on average −11.8 and −3.6 % compared to the MEL for the 2006 engine, respectively. The main purpose of this study was to determine the measurement uncertainty of recently released PEMS in comparison with legacy and ultra-low emission modern heavy-duty vehicles.
Hybrid engine technology is a potentially important strategy for reduction of tailpipe greenhouse gas (GHG) emissions and other pollutants that is now being implemented for off-road construction equipment. The goal of this study was to evaluate the emissions and fuel consumption impacts of electric-hybrid excavators using a Portable Emissions Measurement System (PEMS)-based methodology. In this study, three hybrid and four conventional excavators were studied for both real world activity patterns and tailpipe emissions. Activity data was obtained using engine control module (ECM) and global positioning system (GPS) logged data, coupled with interviews, historical records, and video. This activity data was used to develop a test cycle with seven modes representing different types of excavator work. Emissions data were collected over this test cycle using a PEMS. The results indicated the HB215 hybrid excavator provided a significant reduction in tailpipe carbon dioxide (CO) emissions (from -13 to -26%), but increased diesel particulate matter (PM) (+26 to +27%) when compared to a similar model conventional excavator over the same duty cycle.
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