Search

The share of biofuels in the transportation sector is increasing. Previous studies revealed that the use of biofuels decreases the size of particles (which is linked to an increase in particulate toxicity). Current emission regulations do not consider small particles (sub-23 nm); however, there is a focus in future emissions regulations on small particles. These and the fact that within cold-start emissions are higher than during the warmed-up operation highlight the importance of a research that studies particulate matter emissions during cold-start. This research investigates the influence of biofuel on PN and PM concentration, size distribution, median diameter and cumulative share at different size ranges (including sub-23 nm and nucleation mode) during cold-start and warm-up operations using diesel and 10, 15 and 20% mixture (coconut biofuel blended with diesel). During cold-start, between 19 and 29% of total PN and less than 0.8% of total PM were related to the nucleation mode (sub-50 nm). Out of that, the share of sub-23 nm was up to 9% for PN while less than 0.02% for PM. By using biofuel, PN increased between 27 and 57% at cold-start; while, the increase was between 4 and 19% during hot-operation. The median diameter also decreased at cold-start and the nucleation mode particles (including sub-23 nm particles) significantly increased. This is an important observation because using biofuel can have a more adverse impact within cold-start period which is inevitable in most vehicles’ daily driving schedules.

In numerous epidemiological studies, exposure to particulate matter (PM) has been associated with negative health outcomes. It has been established so far that the detrimental health effects of particles cannot be explained by a single parameter, such as particle mass, as the complexity of chemical composition and reactivity of particles are not always represented by the mass loadings. The oxidative potential (OP) of aerosol particles represents a promising indicator of their potential toxicity. To develop strategies and regulations at improving the air quality, an increasing number of studies are focused on the application of source apportionment (SA) of PM., while a limited number of SA investigations have been applied to OP. In this review previous research of SA of atmospheric PM oxidative potential and proposed guidelines for future studies are summarized. Most of the research studies were carried out in an urban area and focused on PM2.5, while few studies examined other PM fractions. It was noted that the three dominant contributors to OP were biomass burning (9-97%), secondary aerosols (6-67%) and traffic/vehicles (16-88%). The presence of other factors that contributed to the increase of OP to a lesser extent depended on the location and season. Further, a considerable discrepancy in the contribution of various OP vs. PM sources was discovered using SA models. Because of this, the use of SA is not equivalent when considering the mass of PM and its toxicity.

A comprehensive analysis of combustion behaviour during cold, intermediately cold, warm and hot start stages of a diesel engine are presented. Experiments were conducted at 1500 rpm and 2000 rpm, and the discretisation of engine warm up into stages was facilitated by designing a custom drive cycle. Advanced injection timing, observed during the cold start period, led to longer ignition delay, shorter combustion duration, higher peak pressure and a higher peak apparent heat release rate (AHRR). The peak pressure was ~30% and 20% and the AHRR was ~2 to 5% and ±1% higher at 1500 rpm and 2000 rpm, respectively, during cold start, compared to the intermediate cold start. A retarded injection strategy during the intermediate cold start phase led to shorter ignition delay, longer combustion duration, lower peak pressure and lower peak AHRR. At 2000 rpm, an exceptional combustion behaviour led to a ~27% reduction in the AHRR at 25% load. Longer ignition delays and shorter combustion durations at 25% load were observed during the intermediately cold, warm and hot start segments. The mass fraction burned (MFB) was calculated using a single zone combustion model to analyse combustion parameters such as crank angle (CA) at 50% MFB, AHRR@CA50 and CA duration for 10–90% MFB.

This study investigates the effect of engine temperature during cold start and hot start engine operation on particulate matter emissions and engine performance parameters. In addition to a fundamental study on cold start operation and the effect of lubricating oil during combustion, this research introduces important knowledge about regulated particulate number emissions and particulate size distribution during cold start, which is an emerging area in the literature. A further aspect of this work is to introduce waste lubricating oil as a fuel. By using diesel and two blends of diesel with 1 and 5% waste lubricating oil in a 6-cylinder turbocharged engine on a cold start custom test, this investigation studied particle number (PN), friction losses and combustion instability with diesel and waste lubricating oil fuel blends. In order to understand and explain the results the following were also studied: particle size distribution and median diameter, engine oil, coolant and exhaust gas temperatures, start of injection, friction mean effective pressure (FMEP), mechanical efficiency, coefficient of variation (CoV) of engine speed, CoV of indicated mean effective pressure (IMEP) and maximum rate of pressure rise were also studied. The results showed that during cold start the increase in engine temperature was associated with an increase in PN and size of particles, and a decrease in FMEP and maximum rate of pressure rise. Compared to a warmed up engine, during cold start, PN, start of injection and mechanical efficiency were lower; while FMEP, CoV of IMEP and maximum rate of pressure rise were higher. Adding 5% waste lubricating oil to the fuel was associated with a decrease in PN (during cold start), decreased particle size, maximum rate of pressure rise and CoV of IMEP and was associated with an increase in PN and nucleation mode particles (during hot start) and FMEP.

This manuscript details the application of a profluorescent nitroxide (PFN) for the online quantification of radical concentrations on particulate matter (PM) using an improved Particle Into Nitroxide Quencher (PINQ). A miniature flow-through fluorimeter developed specifically for use with the 9,10-bis(phenylethynyl)anthracene-nitroxide (BPEAnit) probe was integrated into the PINQ, along with automated gas phase corrections through periodic high efficiency particle arrestor (HEPA) filtering. The resulting instrument is capable of unattended sampling and was operated with a minimum time resolution of 2.5 min. Details of the fluorimeter design and examples of data processing are provided, and results from a chamber study of side-stream cigarette smoke and ambient monitoring campaign in Guangzhou, China are presented. Primary cigarette smoke was shown to have both short-lived (t1/2 = 27 min) and long-lived (t1/2 = indefinite) PM-bound reactive oxygen species (ROS) components which had previously only been observed in secondary organic aerosol (SOA).

Waste management cost for Australia is increasing every year, and thus, it is important to find alternative ways to use the waste. For example, essential oil has a significant waste stream that can be utilized in vehicles of their producers. However, some of the essential oils contain oxygen which considerably affects engine performance, emission, and combustion characteristics of diesel engines. Thus, this research paper will try to evaluate the essential oils as a replacement of diesel fuel to operate a multicylider diesel engine. For this study, two essential oils are selected which contain different oxygenated functional groups, tea tree oil (5.4% oxygen) and eucalyptus oil (8.4% oxygen), with an aim to evaluate the effect of these functional groups on engine performance and emission parameters. These oils were blended with neat diesel (0% oxygen) to obtain a blend cotaining 2.2% oxygen by weight. The blends produced similar brake power; however, brake-specific fuel consumption (BSFC) increased for eucalyptus oil blends (2.4–3.7%) and tea tree oil blends (3.9–5.3%). Essential oil–diesel blends resulted in less CO and increased NOX emission, produced similar peak pressure, and indicated mean effective pressure. The results then lead to the conclusion that oxygenated essential oils can have a role to reduce dependency of agricultural sector on diesel in the near future.

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) will be the third leading cause of death world-wide by 2020. Prolonged exposure to particulate matter is associated with COPD progression and mortality. Diesel emissions are a major contributor to particulate matter pollution. In this study we test a therapeutic antioxidant, N-acetylcysteine (NAC), for its ability to protect bronchial epithelial cells (pHBECs) from patients with COPD from adverse effects of diesel emission exposure. METHODS: pHBECs from patients with or without COPD were cultured at air-liquid interface (ALI). Cells were exposed to diesel emissions for 30 min with or without 3-h post-exposure treatment with 5 mM N-acetylcysteine (NAC). Filtered laboratory air was tested as a negative control. Cell responses (cell viability, inflammation and oxidative stress) and gene expression profiles for intracellular and immune signaling were assessed. RESULTS: Diesel emissions exposure increased IL-8 secretion and production, antioxidant production, and cytochrome P450 1a1 (CYP1a1) mRNA expression and suppressed superoxide dismutase-1 (SOD1) mRNA expression in bronchial epithelial cells from COPD patients. Treatment with N-acetyl cysteine attenuated the suppression of SOD1. Nanostring gene expression profiling of the filtered air controls showed COPD epithelial cells have increased expression of MHC class II and an interferon signaling profile. CONCLUSIONS: This study indicates that bronchial epithelial cells from COPD patients may be vulnerable to diesel emission exposure due to reduced antioxidant capacity, and elevated CYP1a1 mRNA expression. NAC did not appear to offer protection. Future research will be needed to explore other means of recovering oxidant capacity in COPD airways.

Oxidative stress caused by generation of free radicals and related reactive oxygen species (ROS) at the sites of deposition has been proposed as a mechanism for many of the adverse health outcomes associated with exposure to particulate matter (PM). Recently, a new profluorescent nitroxide molecular probe (BPEAnit) developed at QUT was applied in an entirely novel, rapid and non-cell based assay for assessing the oxidative potential of particles (i.e. potential of particles to induce oxidative stress). The technique was applied on particles produced by several combustion sources, namely cigarette smoke, diesel exhaust and wood smoke. One of the main findings from the initial studies undertaken at QUT was that the oxidative potential per PM mass significantly varies for different combustion sources as well as the type of fuel used and combustion conditions. However, possibly the most important finding from our studies was that there was a strong correlation between the organic fraction of particles and the oxidative potential measured by the PFN assay, which clearly highlights the importance of organic species in particle-induced toxicity.