In-Plume Emission Test Stand 2: Emission Factors for 10- to 100-kW U.S. Military Generators

Abstract

Although emissions of air pollutants from some military tactical equipment are not subject to the emissions standards, local communities near military bases must conform to the National Ambient Air Quality Standards. Military diesel generators are widely used in training. A portable in-plume system was used to measure fuel-based emission factors (EFs) for particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HCs) for 30-, 60-, and 100-kW generators at five load levels and for cold starts. It was found that EFs depend on multiple parameters including engine size, engine load, unit age, and total running hours. The average CO EF of generators tested was 5% lower, and the average NOx EF was 63% lower than AP-42 estimates; average PM EF was 80% less than the AP-42 estimates. A 2002 model-year 60-kW engine produced 25% less PM than a 1995 engine of the same family with similar running hours. CO EFs decrease with increasing engine load, NOx EFs increase up to mid-loads and decrease slightly at high loads, PM EFs increase with loads for 30- and 60-kW engines. CO and PM have higher EFs and NOx has a lower EF during cold starts than during hot-stabilized operation. PM chemical source profiles were also examined.

Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE): Emissions of particulate matter from wood and dung cooking fires, garbage and crop residue burning, brick kilns, and other sources

“…For the diesel generator, PM 2.5 was 80% OC and 6% EC. The predominance of OC and EC in diesel generator emissions is consistent with prior studies that showed their mass contributions in excess of 83% Zhu et al, 2009). The diesel 10 generator OC-to-EC ratio of 12.7 is in the range previously observed for a diesel generator running on high sulfur diesel at a relatively low load (0-25 kW) .…”

“…PM 2.5 concentrations in the sampled smoke plume from the petrol generator were not significantly greater than background PM levels, resulting in a high uncertainty. Recent studies have shown consistently lower EF PM2.5 for US military diesel generators that exhibited an average (± standard deviation) of 1.2 ± 0.6 g kg -1 (Zhu et al, 2009). A professionally-maintained diesel generator on the ICIMOD campus in Nepal was observed to have a high MCE (0.998) (Stockwell et al, 2016) and likely a lower EF PM2.5 than the rented diesel generator from which our filter sample was collected.…”

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“…52,54 Pagels et al 36 demonstrated that charge-bearing nanoparticles deposit on the upper ELPI stages, thereby creating biases in these results. Zhu et al 55 implemented an ELPI fitting procedure 52 that accounts for these artifacts by iteratively adjusting the particle size and number concentrations for a bimodal distribution to match the current deposited on each impactor stage. This fitting algorithm is also used for IPETS ELPI measurements.…”