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Experimental investigation into the oxidation reactivity and nanostructure of particulate matter from diesel engine fuelled with diesel/polyoxymethylene dimethyl ethers blends

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ABSTRACT

This paper focuses on oxidation reactivity and nanostructural characteristics of particulate matter (PM) emitted from diesel engine fuelled with different volume proportions of diesel/polyoxymethylene dimethyl ethers (PODEn) blends (P0, P10 and P20). PM was collected using a metal filter from the exhaust manifold. The collected PM samples were characterized using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The TGA results indicated that the PM produced by P20 had the highest moisture and volatility contents and the fastest oxidation rate of solid carbon followed by P10 and P0 derived PM. SEM analysis showed that PM generated from P20 was looser with a lower mean value than PM emitted from P10 and P0. Quantitative analysis of high-resolution TEM images presented that fringe length was reduced along with increased separation distance and tortuosity with an increase in PODEn concentration. These trends improved the oxidation reactivity. According to Raman spectroscopy data, the intensity, full width at half-maximum and intensity ratio of the bands also changed demonstrating that PM nanostructure disorder was correlated with a faster oxidation rate. The results show the use of PODEn affects the oxidation reactivity and nanostructure of PM that is easier to oxidize.

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Related in: MedlinePlus

TG and DTG curves of PM samples: (a) low load and (b) high load. Operating conditions: non-isothermal experiment, initial mass of 2 mg, ramp rate at 10 °C/min, oxidizer gas (10% O2 in N2) and purge gas (N2) flow rate at 100 mL/min.
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f1: TG and DTG curves of PM samples: (a) low load and (b) high load. Operating conditions: non-isothermal experiment, initial mass of 2 mg, ramp rate at 10 °C/min, oxidizer gas (10% O2 in N2) and purge gas (N2) flow rate at 100 mL/min.

Mentions: Pyrolysis is a basic process of thermo-chemical conversion and is the initial and associated reaction of gasification, liquefaction and combustion. Figure 1 depicts the thermogravimetric (TG) and derivative thermogravimetric (DTG) curves of PM emitted from diesel engine fuelled with P0, P10 and P20. Figure 1 shows the TG curve of moisture evaporation and volatile matter desorption at low temperature regions (60–400 °C). At low temperatures, there is no intensive chemical reaction being found. The TG curves remain relatively constant. Mass loss is insignificant at around 3%, 4% and 6% of the total mass for P0, P10 and P20 at low load, while around 1%, 3% and 5% of the total mass is loss at high load. It can be deduced that the moisture and volatile matter contents are very low in the PM samples. This may be related to the sampling method of the experiment. In the exhaust pipe where temperatures are high, most of volatile materials are found in the gas-phase and it is difficult for them to be adsorbed or coagulate onto existing PM32. The oxidation reaction of solid carbon in the PM takes place in the high temperature regions (400–750 °C). PM starts the oxidation process at lower temperatures with an increasing PODE2-4 concentration. After reaching ignition temperature, the TG curves decline rapidly. The mass loss of PM samples exceeds 95% at this stage. PM has been burnt out at 750 °C and the TG curves tend to stabilize. From Fig. 1 can also see that significant mass changes are not seen until the high temperature regions on the DTG curve. The weightlessness maximizes with increment of the PODE2-4 blending ratio. As PODE2-4 are oxygenated fuels, they may have more oxygen content in the PM which promotes oxidation. P10 and P20 show an improved oxidation rate in comparison with P013.


Experimental investigation into the oxidation reactivity and nanostructure of particulate matter from diesel engine fuelled with diesel/polyoxymethylene dimethyl ethers blends
TG and DTG curves of PM samples: (a) low load and (b) high load. Operating conditions: non-isothermal experiment, initial mass of 2 mg, ramp rate at 10 °C/min, oxidizer gas (10% O2 in N2) and purge gas (N2) flow rate at 100 mL/min.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120283&req=5

f1: TG and DTG curves of PM samples: (a) low load and (b) high load. Operating conditions: non-isothermal experiment, initial mass of 2 mg, ramp rate at 10 °C/min, oxidizer gas (10% O2 in N2) and purge gas (N2) flow rate at 100 mL/min.
Mentions: Pyrolysis is a basic process of thermo-chemical conversion and is the initial and associated reaction of gasification, liquefaction and combustion. Figure 1 depicts the thermogravimetric (TG) and derivative thermogravimetric (DTG) curves of PM emitted from diesel engine fuelled with P0, P10 and P20. Figure 1 shows the TG curve of moisture evaporation and volatile matter desorption at low temperature regions (60–400 °C). At low temperatures, there is no intensive chemical reaction being found. The TG curves remain relatively constant. Mass loss is insignificant at around 3%, 4% and 6% of the total mass for P0, P10 and P20 at low load, while around 1%, 3% and 5% of the total mass is loss at high load. It can be deduced that the moisture and volatile matter contents are very low in the PM samples. This may be related to the sampling method of the experiment. In the exhaust pipe where temperatures are high, most of volatile materials are found in the gas-phase and it is difficult for them to be adsorbed or coagulate onto existing PM32. The oxidation reaction of solid carbon in the PM takes place in the high temperature regions (400–750 °C). PM starts the oxidation process at lower temperatures with an increasing PODE2-4 concentration. After reaching ignition temperature, the TG curves decline rapidly. The mass loss of PM samples exceeds 95% at this stage. PM has been burnt out at 750 °C and the TG curves tend to stabilize. From Fig. 1 can also see that significant mass changes are not seen until the high temperature regions on the DTG curve. The weightlessness maximizes with increment of the PODE2-4 blending ratio. As PODE2-4 are oxygenated fuels, they may have more oxygen content in the PM which promotes oxidation. P10 and P20 show an improved oxidation rate in comparison with P013.

View Article: PubMed Central - PubMed

ABSTRACT

This paper focuses on oxidation reactivity and nanostructural characteristics of particulate matter (PM) emitted from diesel engine fuelled with different volume proportions of diesel/polyoxymethylene dimethyl ethers (PODEn) blends (P0, P10 and P20). PM was collected using a metal filter from the exhaust manifold. The collected PM samples were characterized using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The TGA results indicated that the PM produced by P20 had the highest moisture and volatility contents and the fastest oxidation rate of solid carbon followed by P10 and P0 derived PM. SEM analysis showed that PM generated from P20 was looser with a lower mean value than PM emitted from P10 and P0. Quantitative analysis of high-resolution TEM images presented that fringe length was reduced along with increased separation distance and tortuosity with an increase in PODEn concentration. These trends improved the oxidation reactivity. According to Raman spectroscopy data, the intensity, full width at half-maximum and intensity ratio of the bands also changed demonstrating that PM nanostructure disorder was correlated with a faster oxidation rate. The results show the use of PODEn affects the oxidation reactivity and nanostructure of PM that is easier to oxidize.

No MeSH data available.


Related in: MedlinePlus