| 1. |
- Hao, Lijun, et al.
(author)
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Assessment of Heavy-Duty Diesel Vehicle NOx and CO2 Emissions Based on OBD Data
- 2023
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In: Atmosphere. - 2073-4433. ; 14:9
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Journal article (peer-reviewed)abstract
- Controlling NOx and CO2 emissions from heavy-duty diesel vehicles (HDDVs) is receiving increasing attention. Accurate measurement of HDDV NOx and CO2 emissions is the prerequisite for HDDV emission control. Vehicle emission regulations srecommend the measurement of NOx and CO2 emissions from vehicles using an emission analyzer, which is expensive and unsuitable to measure a large number of vehicles in a short time. The on-board diagnostics (OBD) data stream of HDDVs provides great convenience for calculating vehicle NOx and CO2 emissions by providing the engine fuel flow rate, NOx sensor output, and air mass flow. The calculated vehicle NOx and CO2 emissions based on the OBD data were validated by testing a heavy-duty truck’s emissions on the chassis dynamometer over the CHTC-HT driving cycle, showing that the calculated NOx and CO2 emissions based on the OBD data are consistent with the measured results by the emission analyzer. The calculated vehicle fuel consumptions based on the OBD data were close to the calculated results based on the carbon balance method and the measured results by the fuel flowmeter. The experimental results show that accessing vehicle NOx and CO2 emissions based on the OBD data is a convenient and applicable method.
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| 2. |
- Wang, Yachao, et al.
(author)
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A new method to assess vehicle airborne non-exhaust particles : Principle, application and emission evaluation
- 2023
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In: Applied Energy. - 0306-2619. ; 352
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Journal article (peer-reviewed)abstract
- A method that could assess the whole vehicle non-exhaust particle (NEP) emission from the whole vehicle level was proposed by combining sealed housing with the chassis dynamometer. The intake and exhaust systems were connected to the out of the chamber to avoid possible effects on NEP emissions. The most distinguishing feature of the proposed method is the whole vehicle assessment of the NEP. Based on the proposed method, three vehicles were tested under various conditions. The results proved that the total NEP from the US06 cycle could be four orders of magnitude higher than that of the WLTC cycle due to the higher thermal load. The transient NEP concentration is highly associated with the friction pairs' temperature, and there are two critical temperatures respectively for volatile particles and solid particles. Mechanical friction-dominated test (WLTC) tends to produce larger particles, while thermal process-dominated tests (US06) tend to emit smaller particles. Solid particles occupy <10% of the total particles, and solid particle is dominated with the size at 10– 23 nm. The higher the brake temperature, the higher the solid particle emissions (both concentration and portion). NEP emission decreases when vehicle miles travelled increase. Total NEP number emission factors could be two orders of magnitude higher than the current PN limit for exhaust particles (6*1011#/km). The solid particle emission factor could also be ten times higher than the current PN limit. O and Fe element distribution matches well with the SEM image, which means the proposed method could successfully sample the brake particles. The carbon element weight is dominated by the organic carbon, which might mean that it's the mechanical abrasion dominate the carbon mass. The top 5 dominant element during ICP/MS analysis is Si, Na, Mg, Zn, and Al.
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| 3. |
- Wang, Yachao, et al.
(author)
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China 6 EGR gasoline vehicles without a GPF may struggle to meet the potential SPN10 limit
- 2023
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In: Environment International. - 0160-4120. ; 181
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Journal article (peer-reviewed)abstract
- Particles larger than 10 nm from engine exhaust are gaining global concerns. In light of this, to investigate how EGR affects gasoline vehicle SPN10 (solid particles larger than 10 nm) emissions, seven gasoline vehicles (hybrid or conventional) were studied experimentally. The results revealed that EGR vehicles risk failing the current limit (6 * 1011 #/km) more than those without EGR if the cut-off size was tightened from 23 nm to 10 nm. More specifically, during the WLTC test, EGR increased the SPN10 emission factors by 2 ∼ 3 times depending on vehicle powertrains (conventional or hybrid). Notably, SPN10 emissions increased significantly when EGR was actively engaged but showed a decrease when the EGR rate remained constant. EGR and the enriched fuel–air mixture are the critical reasons for the increased SPN10.
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