Volatile Organic Fraction Research Articles

Effect of plant roots on the radiocarbon age of loess deposits in arid central Asia

Radiocarbon and OSL dating are the two main approaches used to date aeolian deposits in arid central Asia (ACA). Previous results showed that, compared with OSL dating, the 14C ages of loess deposits in ACA are underestimated when the loess age is beyond ∼25 ka. However, the cause of this radiocarbon age underestimation has not been adequately addressed. In this study, we measured the 14C ages of different dating materials, including pyrolysis volatile (Py-V), pyrolysis residue (Py-R), humin, and total organic carbon fractions from two loess sections in ACA (the Hoalin section in the western Pamir Mountains, and the TLD16 section in the northern Tianshan Mountains). The results show that different dating material yielded different 14C ages for all the loess samples, and all the radiocarbon ages obtained are younger than their corresponding OSL ages. Based on these results, together with a regional comparison of 78 14C ages from ACA with their corresponding OSL ages, we propose that the 14C age underestimation is mainly due to the contamination by the deep penetration of the extended root systems of the plants that grow in arid areas, whereas this effect is less significant in the summer monsoon–dominated Chinese Loess Plateau.

Chemical recycling of PVC-containing plastic waste for recycling of critical metals

Chemical recycling of polyvinyl chloride containing plastic waste to recover critical metals is a promising way to solve two important problems (polyvinyl chloride disposal and critical metal recovery) in waste management and is being transferred on a larger scale in the “CHM-Technology” project. Various polyvinyl chloride containing plastic wastes were pyrolyzed to generate a hydrogen chloride rich vapor. This hydrogen chloride rich vapor is used in a second step to chlorinate indium in liquid crystal displays. Indium chloride has a lower boiling point than indium-tin-oxide and evaporates. This is cooled down and generates a metal concentrate together with the decomposed volatile materials from liquid crystal displays. The chlorine content in the polyvinyl chloride containing plastic waste residues is reduced. The products solid, oil, hydrochloric acid and gas can be used for new products. For metal purification the metal concentrate is mixed with water, filtrated, distilled and an electrolysis is carried out to recover metallic indium. Nine waste containing PVC were used with significant differences: when more hydrochloric acid and less volatile organic fraction was produced, more indium was transferred to the metal concentrate. The best recovery of indium (78% purity after electrolysis) was 39 wt-% from LCD panels containing 83 mg In/kg.

Lignite Upgradation of Mae Moh Power Plant Thailand via Low – Temperature Pyrolysis

The lignite at Mae Mo mine in Lampang Thailand, which is the focus of this study is ranked as the lowest class in coal classification. The lignite is currently burned directly in boilers for electricity production, resulting in inefficiencies. The objective is to use low-temperature pyrolysis to improve the lignite. Lab-scale experiments were conducted using different lignite particle sizes (2.36 mm, 1.00 mm, and 0.25 mm) at temperatures ranging from 250-600°C and retention times of 0-60 mins. The best quality lignite was achieved processing a particle size of 2.36 mm at a temperature of 350°C and a retention time of 20 mins. The gross calorific value, fixed carbon, and char content increased with higher operating temperatures. Weight loss occurred between 300-600°C due to the degradation of volatile organic fractions and char formation. Ash and sulfur constituents increased in smaller coal sizes. The average gross calorific value of char was 23.04-27.19 MJ/kg. Lower operating temperatures, larger coal sizes, and sufficient retention time are recommended for the pyrolysis process to achieve optimal results.

Evolution of physicochemical characteristics of soot in a single coal combustion flame

This study experimentally investigated the evolution of the nanomorphology, graphite crystals, oxidation reactivity, and functional groups of soot in a single coal combustion flame. Nascent (sample #1), young (sample #2), and mature (sample #3) soot were collected from a Shenhua single coal combustion flame. The soot samples were then tested and analyzed using high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy to determine their physicochemical characteristics. The results showed that the nascent soot was an individual particle, the mature soot was a highly agglomerated soot aggregate, and the young soot was a transitional particle. The primary particles of sample #1 comprised several randomly orientated individual polycyclic aromatic hydrocarbon (PAH) crystal sheets, whereas the primary particles of samples #2 and #3 were typical core-shell graphite structures. The sp2/sp3 content, volatile organic fraction, and oxidation rate constant of samples #1, #2, and #3 decreased, resulting in successively weakened reactivity. The infrared spectrum absorption of 2800–3000 and 1700–900 cm−1 indicated that the hydrogen in the three coal-derived soot samples was mainly aromatic rather than aliphatic. Furthermore, the proportion of solo and duo aromatic out-of-plane (OPLA) CH bending in samples #1, #2, and #3 increased, whereas the proportion of trio-quatro OPLA CH bending decreased.

Preservation of bioactive compounds occurring in fresh pasta fortified with artichoke bracts and tomato powders obtained with a novel pre-treatment

Over the years, the need to recover agro-industrial by-products has become a global concern, due to their environmental and economic impact. In this work, two different powders obtained from artichoke bracts and tomato by an innovative, non-thermal, and non-invasive technology (patent nr. 001,426,984) were added to the formulation of fresh Tagliatelle pasta. The fate of bioactive compounds before and after the cooking process was analyzed following the total polyphenolic content and the antioxidant activity. The addition of vegetable powders led to an increase in the above-mentioned parameters (110.0 mg of Gallic Acid/100 g pasta and 36.4 μmol TEAC/100 g pasta for Artichoke-LP-Raw Pasta; 120.1 mg of Gallic Acid/100 g pasta and 55.3 μmol TEAC/100 g pasta for Tomato-LP-Raw Pasta), and a mutual protection between polyphenolic compounds and proteins was observed, minimizing the bioactive compounds degradation along cooking process. The volatile organic fraction and the rate of starch digestion with related predicted glycaemic index were also investigated in fortified Tagliatelle samples, showing differences among them, demonstrating that the type of vegetable added characterized the aroma of both raw and cooked pasta. This functional pasta has proved to retain an antioxidant activity higher than the one obtained with the addition of traditional dehydrated vegetables.

Candying process for enhancing pre-waste watermelon rinds to increase food sustainability

This work describes two alternative laboratory methods 'candying fruit' methods of fresh mesocarp of Crimson sweet watermelon, a typical waste and unappetizing material. Our experimental candying process was conducted by slow osmosis, lasting 24 weeks at room temperature. It was activated with granular sucrose according to our two alternative laboratory methods, WET and DRY. Fresh watermelon rinds were transformed into candied fruit with excellent flavor and aromas. The aromatic profile of all the materials was characterized with HS-SPME-GC–MS technique. The results highlighted some significant differences in the Volatile Organic Compounds fraction, probably attributable both to the cultivar and to the two candying methods, as verified also by a panel test. The class of alcohols remains almost constant in all the samples. Terpenoids are highly present in FRESH samples, while they disappear in DRY candied ones. Acetate esters are absent in FRESH rinds, they reach the maximum level in WET, and stop at the middle in DRY samples. The trend of the values ​​relating to the class of acids is opposite: absent in the FRESH aromatic profile, maximum and average for DRY and WET samples, respectively.

Effect of ethanol blends, E10, E25 and E85 on sub-23 nm particle emissions and their volatile fraction at exhaust of a high-performance GDI engine over the WLTC

This study was aimed to characterize the effect of ethanol blends on sub-23 nm particles and on their volatile organic fraction from a turbocharged 1.8 L direct injection spark ignition engine. Tests were performed on the Worldwide Harmonized Light Vehicles Test Cycle. Engine was fueled with three different blends: 10, 25 and 85 %v/v of ethanol content, gasoline was used as reference fuel. An Engine Exhaust Particle Sizer was used to measure the particle number and size in the range 5.6–560 nm. Particle measure was carried out by diluting the sample gas through both a single diluter and the Dekati Engine Exhaust Diluter. The number and diameter of particles emitted from ethanol blends as well as the presence of volatiles are affected from both the specific phase of the cycle and the fuel properties. A large fraction of volatiles in the sub-23 nm range, especially in the low and extra-high phases of the test cycle, was observed whatever the fuel. Anyway, the percentage of sub-23 m particles increases as the ethanol content in the blends increases except for E85. For this blend, the greater decrease of temperature due to the stronger charge cooling effect ascribable to the larger ethanol content, deteriorates the combustion evolution contributing to the formation of large soot particles. The addition of ethanol to gasoline fuel increases the volatile organic fraction whatever the blend ratio.

Impact of sulfur functional groups on physicochemical properties and oxidation reactivity of diesel soot particles

Soot particles with sulfur functional groups (SFGs) are one of the main concerns from shipping emissions, especially when they are produced from fuel combustion with high fuel sulfur content (FSC). The present study investigates the physicochemical characteristics of soot particles generated from different FSC fuels on a marine auxiliary diesel engine. A comprehensive set of experimental techniques including Fourier transform infrared (FT-IR), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) are employed to characterize SFGs, chemical elements, morphology, nanostructure, volatile organic fraction (VOF) content and oxidation behavior, respectively. Results reveal that, FSC has negligible influences on combustion performance, yet its high content increases the concentrations of SFGs (–SH, C–S–S, C–S, SO42−) and sulfur element VOF content and primary particle size (dp) of soot particles. Linear correlations between soot fringe length (La), oxidation activation energy (Ea) and relative concentrations of –SH and C–S are observed, respectively. Higher relative concentration of C–S bond corresponds to shorter La. The relative amounts of –SH and C–S could improve soot oxidation reactivity, associated with lower Ea. In addition, metal-sulfates are formed from the combination of SO42− with metal elements contained in fuel or lube oils, among which CaSO4 is shown an enhancing factor for soot oxidation.

Impact of fuel aromatic content on soot particle physicochemical properties of marine auxiliary diesel engine.

Fuel aromatic content (AC) is one of the main reasons for PM (particulate matter) emissions from ocean-going ships. The present study investigates the influence of AC on physicochemical characteristics of soot particles from marine auxiliary diesel engine. The TEM (transmission electron microscopy), Raman spectroscopy, FTIR (Fourier transform infrared spectroscopy), and TGA (thermalgravimetric analyzer) are employed to jointly characterize samples. The results reveal that soot particles from high-AC fuel have bigger dp (primary particle size), longer fringe length (La), and higher graphitization degree, all of which have significant impacts on chemical properties such as more VOF (volatile organic fraction), higher concentrations of aromatic C-H and C=C groups. These are mainlydue to several aromatic rings decomposed from aromatic components could promote the growth of carbon layer, and incomplete pyrolysis productions arealso present in soot particles. The relative amounts of aromatic C-H and C=C are well correlated with dp and La, respectively.

Understanding the role of exhaust gas recirculation in gasoline/diesel dual-fuel combustion soot features

Exhaust gas recirculation (EGR) can not only mitigate the pressure rise rate but also reduce the NO x emissions in dual-fuel combustion, especially at high loads. With the introduction of EGR, the thermal, chemical, and dilution effects may alter the soot oxidation reactivity and related features. However, little research has been conducted on the effect of EGR on dual-fuel combustion soot features. The paper targets this gap by assessing the oxidation reactivity, morphology and nanostructure, and oxygenated surface functional groups of particulates from dual-fuel combustion with various EGR ratios. The results from thermogravimetric analysis showed that increasing EGR ratios decreased the mass distribution of volatile organic fraction and soot oxidation reactivity under the operating point. This indicated that introducing EGR in dual-fuel combustion would increase the regeneration temperature of diesel particulate filters. Owing to the dilution and thermal effects, mean primary particle diameter gradually increased with the increasing EGR ratio. Soot particulates produced by higher EGR ratios tended to a more graphitic structure, characterized by longer fringe length but smaller tortuosity from high resolution transmission electron micrograph (HRTEM) images. The Raman results also verified the observations from HRTEM. In addition, the concentration of C-OH slightly reduced with increasing EGR ratio, while that of C=O showed no clear trend.

Volatile Organic Compounds, Indole, and Biogenic Amines Assessment in Two Mediterranean Irciniidae (Porifera, Demospongiae).

Solid phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was employed for the headspace determination of the volatile organic fraction emitted by two of the most common Mediterranean demosponges, Ircinia variabilis and Sarcotragus spinosulus, and of indole and some biogenic amines released by sponges in an aqueous medium. A total of 50/30 µm divinylbenzene/carboxen/polydimethylsiloxane and 75 µm carboxen/polydimethylsiloxane fibers were used for the headspace extraction of low molecular weight sulfur compounds from a hermetically sealed vial containing sponge fragments, while the direct immersion determination of indole and biogenic amines was performed. The biogenic amines were extracted after in-solution derivatization with isobutyl chloroformate. All analytical parameters (linearity, limits of detection, and quantification, precision, and recovery) were evaluated for indole and biogenic amines. SPME-GC-MS proved to be a reliable means of highlighting the differences between molecules released by different sponges, principally responsible for their smell. The combined approaches allowed the identification of several volatile compounds in the headspace and other molecules released by the sponges in an aqueous medium, including indole and the BAs cadaverine, histamine, isobutylamine, isopentylamine, propylamine, 2-phenylethylamine, putrescine and tryptamine. The results obtained represent a further contribution to the picture of odoriferous molecules secreted by sponges.

Toxicity of Ozonated Wastewater to HepG2 Cells: Taking Full Account of Nonvolatile, Volatile, and Inorganic Byproducts.

Wastewater ozonation forms various toxic byproducts, such as aldehydes, bromate, and organic bromine. However, there is currently no clear understanding of the overall toxicity changes in ozonated wastewater because pretreatment with solid phase extraction cannot retain inorganic bromate and volatile aldehydes, yet contributions of known ozonation byproducts to toxicity are unknown. Moreover, compared with bromate, organic bromine did not receive widespread attention. This study evaluated the toxicity of ozonated wastewater by taking aldehydes, bromate, and organic bromine into consideration. In the absence of bromide, formaldehyde contributed 96-97% cytotoxicity and 92-95% genotoxicity to HepG2 cells among the detected known byproducts, while acetaldehyde, propionaldehyde, and glyoxal had little toxicity. Both formaldehyde and dibromoacetonitrile drove toxicity among the known byproducts when bromide was present. Toxicity assays in HepG2 cells showed that when secondary effluents contained no bromide, the cytotoxicity of the nonvolatile organic fraction (NVOF) was reduced by 56-70%, and genotoxicity was completely removed after ozonation. However, the formed aldehydes (volatile organic fraction, VOF) led to increased overall toxicity. In the presence of bromide, compared with the secondary effluent, ozonation increased the cytotoxicity of the NVOFBr from 3.4-4.0 mg phenol/L to 10.3-13.9 mg phenol/L, possibly due to the formation of organic bromine. In addition, considering the toxicity of VOFBr (VOF in the presence of bromide, including aldehydes, tribromomethane, etc.), the overall cytotoxicity and genotoxicity became much higher than those of the secondary effluent. Although bromate had a limited impact on cytotoxicity and genotoxicity, it caused an increase in oxidative stress in HepG2 cells. Therefore, when taking full account of nonvolatile, volatile, and inorganic fractions, ozonation generally increases the toxicity of wastewater.

Experimental investigation into the oxidation reactivity, morphology and graphitization of soot particles from diesel/n-octanol mixtures

Aiming to investigate the impacts of n-octanol addition on the oxidation reactivity, morphology and graphitization of diesel exhaust particles, soot samples were collected from a four-cylinder turbocharged diesel engine fueled with D100 (neat diesel fuel), DO15 (85% diesel and 15% n-octanol, V/V) and DO30 (70% diesel and 30% n-octanol, V/V). All tests were conducted at two engine speeds of 1370 and 2150 r/min under a fixed torque of 125 N·m. The soot properties were characterized by thermogravimetric analyzer (TGA), transmission electron microscopy (TEM) and Raman spectroscopy (RS). The higher volatile organic fraction content, lower soot oxidation temperatures and lower activation energy from TGA results indicated that both the increasing n-octanol concentration and engine speed enhanced the soot oxidation reactivity. Additionally, quantitative analysis of TEM images showed that the soot derived from DO30 had the smallest primary particle diameters and fractal dimension, followed by those of soot produced by DO15 and D100. The RS results demonstrated that the n-octanol addition and higher engine speed led to a larger D1-FWHM (D1-full width at half maximum), AD1/AT (area ratio of D1 band and the total spectral) and AD3/AT (area ratio of D3 band and the total spectral) as well as a smaller La (crystallite width), revealing a lower degree of graphitization. Furthermore, the correlations between characterization parameters of soot properties and reactivity were nonlinear.

Oxidation and nanostructural characterization of exhaust particulates from gasoline/diesel dual-fuel combustion

It is commonly accepted that gasoline/diesel dual-fuel combustion is an effective path to simultaneously reduce particulate matter and nitrogen oxides. However, how such a combustion mode affects soot oxidation reactivity and related features is not well known. This work focused on physicochemical characteristics of carbonaceous particulates emitted by a gasoline/diesel dual-fuel engine with 20% and 40% gasoline premixed substitutions (G20 and G40, respectively), under different engine speeds. Thermogravimetric (TG) results showed that under both engine speeds, particles from dual-fuel combustion were easier to be oxidized and had higher volatile organic fraction (VOF) than diesel particles, following the order G40 > G20 > diesel. Also, particles at lower engine speed exhibited higher oxidation reactivity and VOF. Samples from dual-fuel combustion exhibited a disordered nanostructure, characterized by shorter fringe length but larger tortuosity from high-resolution transmission electron micrograph images and higher ID1/IG and AD1/AG values from Raman spectroscopy. The structure–property relationship showed that more amorphous nature in the nanostructure of dual-fuel soot brought about the increase in oxidative reactivity. However, surface oxygen content obtained by X-ray photoelectron spectroscopy was not a significant indicator affecting soot oxidation reactivity in this work.

Evolution of structure and oxidation reactivity from early-stage soot to mature soot sampled from a laminar coflow diffusion flame of ethylene

This work investigated the structure and oxidation reactivity of soot sampled from a laminar coflow diffusion flame of ethylene. A capillary-nozzle-hybrid sampling method was developed to extract soot from five sampling positions along flame axis, covering both early-stage and mature soot samples. The results reveal that residence time plays an important role in modifying surface functional groups. Oxygenated and aliphatic groups gradually disappear, soot structure becomes more organized. As a consequence, the rate of mass losses is impaired during thermo-chemical conversion. The derivative thermogravimetry (DTG) results show that oxidation of early-stage soot can be separated into low-temperature (low-T) conversion and carbonaceous substances oxidation processes. The former process including both volatile organic fraction (VOF) releasing and early oxidation reactions generates the first maximum mass loss rate at about 510 °C, while the latter forms the second maximum mass loss rate at about 600 °C. Recognizing that the two processes are partially merged, the distributed activation energy model (DAEM) was introduced to decouple the bimodal behavior of DTG curves. The DAEM results reveal that with increased degree of soot maturity, relative contribution from low-T conversion process decreases abruptly, and DTG curve eventually becomes unimodal and can be well simulated by considering only carbonaceous substances oxidation process.

Experimental Simulation of the Volatile Hydrocarbons Generated by the Long-UV Photoprocessing of (C6H6) Ices with Relevance to Titan's Southern Stratospheric Ice Clouds

Abstract Ice clouds containing benzene (C6H6) have recently been detected in the stratosphere at the south pole of Titan. Their subsequent aging process induced by long-UV solar photons could lead to a photoreactivity that may release some volatile organic compounds in the gas phase. The characterization of this volatile organic fraction coming from the photoprocessing (λ > 230 nm) of such icy C6H6 has been characterized by a gas chromatograph coupled to a mass spectrometer. Complex molecular diversity is observed through the identification of C3 to C8 photoproducts, which belong to the alkane, alkene, and alkyne families and aromatic derivatives. Thereafter, these hydrocarbons will potentially be transported down to the surface, as condensed ices. Because the energy of solar UV photons decrease with altitude, most of these solid-state hydrocarbons will not be photochemically degraded and may contribute at the end to the organic layer that covers Titan’s surface. As these materials would be probed by DraMS, the mass spectrometer on board the future Dragonfly mission, these analyses could serve as benchmarks for future molecule detection on Titan’s surface.

Investigation on sub-23 nm particles and their volatile organic fraction (VOF) in PFI/DI spark ignition engine fueled with gasoline, ethanol and a 30 %v/v ethanol blend

Growing interest of the European Union to introduce new emission regulations seeking to lower the particle cut-off size down to the current limit set at 23 nm, has made crucial to achieve an extensive comprehension on their nature. In this regard, it is necessary to deepen their knowledge under different engine technologies, operating conditions, fuel properties and after-treatment devices and how their measure is affected by the sampling and dilution procedure. This paper provides a study on the sub-23 nm particles emitted from a small direct/port fuel injection, spark ignition engine fueled with gasoline, ethanol and a 30% v/v ethanol/gasoline blend, at different operating conditions. Particles were measured both upstream and downstream of a three-way catalyst. The conditions of the sampling were changed in order to investigate the volatile organic fraction. For this purpose, the exhaust gas sample was diluted through a Particulate Measurement Programme compliant system. The temperature of the first dilution stage and of evaporation chamber were changed to discriminate the volatile compounds by enhancing the condensation and the nucleation processes. An engine Exhaust Particle Sizer was used for the sizing and the counting of the particles in the range 5.6–560 nm. The results show a strong dependence of the sub-23 nm particle emissions from the engine operating condition and the fuel type. A moderate impact of the three-way catalyst was instead observed. Moreover, a significant effect of the dilution parameters in the sampling system was noted pointing out the importance to define an appropriate protocol for the measurement of the sub-23 nm particles.

Valorizing Plastic-Contaminated Waste Streams through the Catalytic Hydrothermal Processing of Polypropylene with Lignocellulose.

Food waste is a promising resource for the production of fuels and chemicals. However, increasing plastic contamination has a large impact on the efficiency of conversion for the more established biological routes such as anaerobic digestion or fermentation. Here, we assessed a novel route through the hydrothermal liquefaction (HTL) of a model waste (pistachio hulls) and polypropylene (PP). Pure pistachio hulls gave a biocrude yield of 34% (w/w), though this reduced to 16% (w/w) on the addition of 50% PP in the mixture. The crude composition was a complex blend of phenolics, alkanes, carboxylic acids, and other oxygenates, which did not change substantially on the addition of PP. Pure PP does not breakdown at all under HTL conditions (350 °C, 15% solids loading), and even with biomass, there is only a small synergistic effect resulting in a conversion of 19% PP. This conversion was enhanced through using typical HTL catalysts including Fe, FeSO4·7H2O, MgSO4·H2O, ZnSO4·7H2O, ZSM-5, aluminosilicate, Y-zeolite, and Na2CO3; the conversion of PP reached a maximum of 38% with the aluminosilicate, for example. However, the PP almost exclusively broke down into a solid-phase product, with no enhancement of the biocrude fraction. The mechanism was explored, and with the addition of the radical scavenger butylated hydroxytoluene (BHT), the conversion of plastic reduced substantially, demonstrating that radical formation is necessary. As a result, the plastic conversion was enhanced to over 50% through the addition of the co-solvent and hydrogen donor, formic acid, and the radical donor, hydrogen peroxide. The addition of formic acid also changed the crude composition, including more carboxylic acids and oxygenated species than the conversion of the biomass alone; however, the majority of the carbon distributed to the volatile organic gas fraction producing an array of short-chain volatile hydrocarbons, which potentially could be repolymerized as a polyolefin or combined with the biocrude for further processing. Catalytic HTL was therefore shown to be a promising method for the valorization of polyolefins with biomass under typical HTL conditions.

The Inventory of Pollutants Hazardous to the Health of Living Organisms, Emitted by Road Transport in Poland between 1990 and 2017

The paper provides the results of the inventory of pollutants hazardous to the health of living organisms, emitted by road transport in Poland between 1990 and 2017. For estimating pollutant emissions from road transport, a standardized methodology was applied, consistent with the guidance of EEA/EMEP Emission Inventory Guidebook 2019 and the COPERT 5 software. The following substances were analyzed: carbon monoxide (CO), non-methane volatile organic compounds (NMVOC), nitrogen oxides (NOx) and particulate matter size fractions (total suspended particles—TSP, PM10, PM2.5). For the pollutants, emission values averaged over the distance travelled by the road fleet (average specific distance emission) were determined. The results obtained indicated that between 1990 and 2017 the annual pollutant emissions from road vehicles in Poland had an increasing trend concerning TSP (74%), PM10 (64%), PM2.5 (52%) and NOx (25%), while the corresponding emissions had a decreasing trend for CO (−117%) and NMVOC (−85%). However, a clear downward trend was found for the average specific distance emissions of all substances throughout the subsequent inventory years: TSP (−28%), PM10 (−100%), PM2.5 (−91%), NOx (−84%), CO (−208%) and NMVOC (−173%), which is due to the dynamic progress in the technological advancement of road vehicles.

Study on influencing factors of particle emissions from a RCCI engine with variation of premixing ratio and total cycle energy

Relevant researches have shown that the prolonged Ignition Delay (ID) is always directly related to the reduction in accumulation mode particle (AMP) and the increase in nucleation mode particle (NMP) emission of Reactivity Controlled Compression Ignition (RCCI) engines. However, seemingly opposite results were discovered in our recent experiments. It appears that ID has no decisive effect on particulate emissions in RCCI engines. To study other main factors which together determine particulate emissions, further detailed experiments were carried out in the RCCI engine with variation of premixing ratio (Rp) and total cycle energy (Etotal). The results show that the formation of engine particles should be divided into in-cylinder and out-of-cylinder processes. Soot agglomerates are mainly formed during in-cylinder process, while the complex materials, finally collected by the particle analyzer, are mainly formed during out-of-cylinder process. Besides, the influencing factors in both in-cylinder and out-of-cylinder processes together determine the formation of particles, such as the maximum combustion temperature (Tmax), one in-cylinder impact factor, the exhaust gas temperature and the volatile organic fraction (VOF) concentration, two out-of-cylinder impact factors that conspire to produce a decrease in NMP emission and an increase in AMP emission.