Publications by authors named "Piqiang Tan"

Article Synopsis
  • This study examines the characteristics of soot particles from a heavy-duty diesel engine that uses different blends of waste cooking oil biodiesel (WCO) and petroleum diesel.
  • The findings indicate that as the percentage of biodiesel in the fuel increases, the fringe length of soot particles decreases, while their oxidation activity and oxygen-to-carbon ratio (O/C) first increase and then decrease along the exhaust treatment system.
  • Additionally, varying biodiesel blends affect the chemical composition and structure of soot, which can help in optimizing exhaust after-treatment systems for better performance.
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Fossil fuel energy crisis and environmental pollution have initiated the scientific research on alternative fuels. Biodiesel (B100), gas to liquid (G100), and coal to liquid (C100) are superb selections to be substitutes for conventional diesel. To better investigate the emission characteristics of the alternative fuels mentioned above, a portable emission measurement system (PEMS) was used to carry out this study under real-world driving conditions.

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Wall impingement, particularly liquid-wall impingement, has been demonstrated to be one of the critical causes of combustion deterioration in plateau diesel engines. Obviously, the complexity of wall impingement is exacerbated by the plateau scenario. However, fundamental studies specifically dedicated to this phenomenon are still inconclusive and insufficiently detailed, obviating the feasibility of the targeted design and optimization of diesel engines operating in regions with different altitudes.

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In this study, the effect of new and used catalyzed diesel particulate filter (CDPF) with different catalyst loadings on the particulate emissions including the particle mass (PM), particle number (PN), particle size distribution (PSD) and geometric mean diameter (GMD) from a diesel vehicle were investigated based on a heavy chassis dynamometer. Results showed that more than 97.9% of the PN and 95.

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Article Synopsis
  • Diesel engines primarily emit particulate matter (PM) and nitrogen oxides (NO), with a focus on regulating NO emissions during low load and temperature conditions.
  • Selective catalytic reduction coated on diesel particulate filter (SDPF) effectively reduces both NO and PM emissions simultaneously, particularly enhancing NO performance at lower operating conditions.
  • A study of a light-duty diesel engine showed that combining a diesel oxidation catalyst (DOC) and SDPF achieved over 90% conversion and filtration efficiency for gaseous pollutants and PM, significantly trapping PM sizes between 10 and 23 nm.
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Soot particles in engine exhaust seriously pollute the atmosphere and endanger human health. For soot oxidation, Pt and Pd precious metal catalysts are widely used and are effective. In this paper, the catalytic characteristics of catalysts with different Pt/Pd mass ratios for soot combustion were studied through X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller analysis, scanning electron microscopy, transmission electron microscopy, the temperature-programmed oxidation reaction, and thermogravimetry.

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In this study, the effects of a diesel oxidation catalyst (DOC) coupled with a catalyzed diesel particulate filter (CDPF) with different catalyst loadings on the power, fuel consumption, gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel consumption. The reduction effect of the DOC on the CO and hydrocarbon (HC) increased with the engine load.

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Used cooking oil (UCO) biodiesel may be one of the most potential alternative fuels in China to lower the dependency on crude oil for transportation. An experimental study has been conducted to assess the interactions between biodiesel produced from UCO in Shanghai and elastomer materials on high-speed marine diesel engines by immersing elastomer materials into conventional fossil diesel, 5, 10, and 20%, of a volumetric blending ratio of UCO biodiesel and pure UCO biodiesel. The test duration is 168 h at different temperatures of 25, 50, and 70 °C.

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Article Synopsis
  • Catalyzed diesel particulate filters (CDPFs) are effective for controlling emissions, but they experience aging over time, which affects their performance.
  • A study used various methods to analyze how noble metal loadings and mileage influence the aging of CDPFs, revealing that higher noble metal content can help slow down aging-related performance declines.
  • Results indicated that aging enhances the crystallinity of the CDPFs and shifts the characteristic temperatures for converting emissions, while excessive noble metals do not necessarily improve anti-aging effects.
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A comparative experiment was conducted based on a non-road diesel engine to investigate the effects of two after-treatment devices on the engine's emission characteristics as well as their power and fuel consumption performances. The first after-treatment device is a combination of a diesel oxidation catalyst (DOC) and a catalytic diesel particulate filter (CDPF). The second device is a single CDPF-coated improved noble metal catalyst.

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The primary purpose of this study was to investigate the effect of a catalyzed continuously regenerating trap (CCRT) system composed of a diesel oxidation catalyst (DOC) and a catalyzed diesel particulate filter (CDPF) on the main gaseous and particulate emissions from an urban diesel bus, as well as the durability performance of the CCRT system. Experiments were conducted based on a heavy chassis dynamometer, and a laboratory activity test as well as X-ray photoelectron spectroscopy (XPS) test were applied to evaluate the changes of the aged CCRT catalyst. Results showed that the CCRT could reduce the CO by 71.

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Particle number is a key index for evaluating particulate emissions, and diesel oxidation catalysts (DOCs) are one of the most important technologies for controlling the particulate emissions of a diesel engine. In this paper, a novel phenomenological one-dimensional model was established to predict particle number and size distributions at a DOC outlet with the aim of investigating the effects of DOC on particle number emissions. The phenomenological model consisted of two submodels: submodel-1, a global kinetic model for calculating particle size in particle number and size distributions after particles had passed through the DOC, and submodel-2, an original global parametric model for calculating the particle number at the DOC outlet.

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A diesel bus was tested with a China City Bus Cycle (CCBC) on a heavy chassis dynamometer, and the components of the particulate emissions with different after-treatment equipment were investigated. Results showed that OC was less than EC in the particulates of the bus emissions without the use of after-treatment equipment. The organic components were mainly fatty acids (60.

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Article Synopsis
  • A study was conducted on diesel buses that meet China’s emissions standards (Ⅲ, Ⅳ, Ⅴ) using different biodiesel blends (0%, 5%, 10%) to measure particulate matter (PM) emissions during the CCBC driving cycle.
  • Results showed that China Ⅴ buses had significantly lower total PM emissions compared to China Ⅲ buses, with decreases in PM number and mass ranging from 52.7% to 68.1% across various conditions.
  • The study found that PM emissions characteristics varied by bus type; for instance, the nucleation mode PM emissions for China Ⅲ buses spiked at high speeds, while those for China Ⅳ and Ⅴ were largely produced at middle-low
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This study investigates the influence of noble metal capacity and promoter capacity in diesel oxidation catalysts (DOC) and catalyzed diesel particulate filters (CDPF) on particulate matter (PM) emissions. Four types of exhaust aftertreatments were applied to a diesel bus engine that meets the national Ⅲ emissions regulations. On-board tests were conducted respectively.

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Based on heavy chassis dynamometers, an experimental study was conducted in a diesel bus with proton transfer reaction mass spectrometry (PTR-MS). It investigated the effects of volatile organic compound (VOC) emission characteristics with three different diesel oxidation catalyst (DOC)+catalyzed diesel particulate filter (CDPF) after-treatments for a typical Chinese city bus driving cycle (CCBC). The results reveal that the major compounds from the diesel bus are OVOCs, aromatic hydrocarbons, alkenes, alkanes, nitrogenous organic compounds, and polycyclic aromatic hydrocarbons (PAH), and that the OVOCs account for more than 50%of the total VOCs.

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This work investigates the effects of lubricant sulfur contents on the morphology, nanostructure, size distribution and elemental composition of diesel exhaust particle on a light-duty diesel engine. Three kinds of lubricant (LS-oil, MS-oil and HS-oil, all of which have different sulfur contents: 0.182%, 0.

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Based on the revolving drum test bench, an experimental study was conducted in heavy-duty diesel vehicle at China Stage Ⅲ with and without DOC+CDPF to investigate the effects of DOC+CDPF on the gaseous and particle emission characteristics under C-WTVC driving cycle. The results showed that from city circulation conditions to high way circulation conditions to high-speed circulation conditions, the CO, THC, CO and PM emission factors of the test vehicle without DOC+CDPF decreased while NO and PN emission factors increased, the particle number concentration showed two peaks versus the size of the particles and accumulated particles predominated. After the test vehicle was equipped with DOC+CDPF, the emissions factors decreased and the faster the circulation speed, the greater the decreasing amplitudes of the emissions factors.

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The gaseous emissions of stage Ⅲ standard City bus with and without DOC+CDPF after-treatment fueled with biodiesel blends on real road in steady-state and transient conditions were studied using OBS-2200 gaseous portable emission measurement. The results showed that B20 led to a decrease of CO and THC emission rates compared with those of B0. In steady-state condition, CO and THC average mass emission rates of B20 decreased by 26.

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Based on heavy chassis dynamometer, an experimental study was conducted in diesel bus with China Stage Ⅲ, which investigated the effects of gaseous emission characteristics under CCBC driving cycle, such as carbon monoxide (CO), total hydrocarbons (THC), nitric oxide (NO), nitrogen dioxide (NO), nitrogen oxides (NO) and carbon dioxide (CO) with the fresh/aged oxidized catalyst (DOC) and oxidation catalysts coupled catalyzed particulate trap (DOC+CDPF, referred CCRT). The results showed that using fresh and aged DOC/CCRT, the diesel bus could reduce CO, THC and NO emissions, meanwhile increase NO emissions, but NO and CO emissions remained basically unchanged. In idle speed, acceleration, deceleration and constant speed of working conditions, the diesel bus using the fresh DOC had better oxidation efficiency of the CO and THC emissions than the bus using the aged DOC.

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Article Synopsis
  • The study used the Engine Exhaust Particle Sizer (EEPS) to analyze particle emissions from a China-IV diesel bus running on various biodiesel blends, including blends with 5%, 10%, 20%, and 50% biodiesel from restaurant waste oil.
  • It found that as bus speed and acceleration increased, both particulate number (PN) and mass (PM) emissions also rose, but increasing the biodiesel content led to a decrease in overall particulate emissions.
  • Particulate size distribution varied with bus performance, showing a shift from bimodal to unimodal patterns during acceleration, with higher biodiesel blends resulting in reduced PN emissions and smaller particle sizes.
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The emission characteristics of polycyclic aromatic hydrocarbons (PAHs) in exhaust particles from a diesel car were studied. In the experiment, pure diesel fuel and B10 fuel with a biodiesel blend ratio of 10% were chosen. The gaseous emissions of HC, CO and NO(x) under New European Driving Cycle (NEDC) were measured, and exhaust particulate matter (PM) samples were analyzed by gas chromatography-mass spectrometry.

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A Santana gasoline car with multi-port fuel injection (PFI) system was used as the research prototype and an engine exhaust particle sizer (EEPS) was employed to investigate the exhaust ultrafine particle number and size distribution characters of the tested vehicle in new European driving cycle (NEDC). The tested results showed that the vehicle's nuclear particle number, accumulation particle number, as well as the total particle number emission increased when the car drove in accelerated passage, and the vehicle's particle number emission was high during the first 40 seconds after test started and when the speed was over 90 km x h(-1) in extra urban driving cycle (EUDC) in NEDC. The ultrafine particle distribution of the whole NEDC showed a single peak logarithmic distribution, with diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameter was 24 nm.

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According to the first type test cycle of China national standard GB 18352.3-2005, the CO, NO(x), HC, PM and CO2 emission characteristics of a PASSAT diesel car fueled with Shanghai local IV diesel, coal based Fischer-Tropsch (F-T) diesel, and the blends of coal based F-T diesel and Shanghai local IV diesel up to 10% and 50% by volume were analyzed respectively. And the environmental impacts such as decreased air quality, health impact, photochemical ozone, global warming, and acidification that could be caused by CO, NO(x), HC, PM and CO2 emission of the diesel car were also assessed.

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Biodiesel, as one of the most promising alternative fuels, has received more attention because of limited fossil fuels. A comparison of biodiesel and petroleum diesel fuel is discussed as regards engine unregulated exhaust emissions. A diesel fuel, a pure biodiesel fuel, and fuel with 20% V/V biodiesel blend ratio were tested without engine modification The present study examines six typical unregulated emissions by Fourier transform infrared spectroscopy (FTIR) method: formaldehyde (HCHO), acetaldehyde (C2 H4 O), acetone (C3 H6 O), toluene (C7 H8), sulfur dioxide (SO2), and carbon dioxide (CO2).

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