Application of multi-criteria decision making methods to compression ignition engine efficiency and gaseous, particulate and greenhouse gas emissions

Compression ignition (CI) engine design is subject to many constraints which presents a multi-criteria optimisation problem that the engine researcher must solve. In particular, the modern CI engine must not only be efficient, but must also deliver low gaseous, particulate and life cycle greenhouse gas emissions so that its impact on urban air quality, human health, and global warming are minimised. Consequently, this study undertakes a multi-criteria analysis which seeks to identify alternative fuels, injection technologies and combustion strategies that could potentially satisfy these CI engine design constraints. Three datasets are analysed with the Preference Ranking Organization Method for Enrichment Evaluations and Geometrical Analysis for Interactive Aid (PROMETHEE-GAIA) algorithm to explore the impact of 1): an ethanol fumigation system, 2): alternative fuels (20 % biodiesel and synthetic diesel) and alternative injection technologies (mechanical direct injection and common rail injection), and 3): various biodiesel fuels made from 3 feedstocks (i.e. soy, tallow, and canola) tested at several blend percentages (20-100 %) on the resulting emissions and efficiency profile of the various test engines. The results show that moderate ethanol substitutions (~20 % by energy) at moderate load, high percentage soy blends (60-100 %), and alternative fuels (biodiesel and synthetic diesel) provide an efficiency and emissions profile that yields the most “preferred” solutions to this multi-criteria engine design problem. Further research is, however, required to reduce Reactive Oxygen Species (ROS) emissions with alternative fuels, and to deliver technologies that do not significantly reduce the median diameter of particle emissions.

The effect of triacetin as a fuel additive to waste cooking biodiesel on engine performance and exhaust emissions

This study investigates the effect of oxygenated fuels on engine performance and exhaust emission under a custom cycle using a fully instrumented 6-cylinder turbocharged diesel engine with a common railinjection system. A range of oxygenated fuels based on waste cooking biodiesel with triacetin as an oxygenated additive were studied. The oxygen ratio was used instead of the equivalence ratio, or air to fuelratio, to better explain the phenomena observed during combustion. It was found that the increased oxygen ratio was associated with an increase in the friction mean effective pressure, brake specific fuel consumption, CO, HC and PN. On the other hand, mechanical efficiency, brake thermal efficiency, CO2, NOx and PM decreased with oxygen ratio. Increasing the oxygen content of the fuel was associated with a decrease in indicated power, brake power, indicated mean effective pressure, brake mean effective pressure, friction power, blow-by, CO2, CO (at higher loads), HC, PM and PN. On the other hand, the brakespecific fuel consumption, brake thermal efficiency and NOx increased by using the oxygenated fuels. Also, by increasing the oxygen content, the accumulation mode count median diameter moved toward the smaller particle sizes. In addition to the oxygen content of fuel, the other physical and chemical properties of the fuels were used to interpret the behavior of the engine.

Characterising vehicle emissions from the burning of biodiesel made from vegetable oil

Biodiesel manufactured from canola oil was blended with diesel and used as fuel in two diesel vehicles. This study aimed to test the emissions of diesel engines using blends of 100%, 80%, 60%, 40% , 20% biodiesel and 100% petroleum diesel, and characterise the particulate matter and gaseous emissions, with particular attention to levels of polycyclic aromatic hydrocarbons (PAHs) which are harmful to humans. A real time dust monitor was also used to monitor the continuous dust emissions during the entire testing cycle. The ECE(Euro 2) drive cycle was used for all emission tests. It was found that the particle concentration was up to 33% less when the engine burnt 100% biodiesel, compared to 100% diesel. Particle emission reduced with increased percentages of biodiesel in the fuel blends. Reductions of NOx, HC and CO were limited to about 10% when biodiesel was burned. Levels of CO2 emissions from the use of biodiesel and diesel were similar. Eighteen EPA priority PAHs were targeted, with only 6 species detected in the gaseous phase from the samples . 9 PAHs were detected in particulate phases at much lower levels than gaseous PAHs. Some marked reductions were observed for less toxic gaseous PAHs such as naphthalene when burning 100% biodiesel, but the particulate PAH emissions, which have more implications to adverse health effects, were virtually unchanged and did not show a statistically significant reduction. These findings are useful to gain an understanding of the emissions and environmental impacts of biodiesel.

Solar versus fossil fuels : A net energy analysis of domestic solar hot water systems in Australia

It is commonly assumed that solar hot water systems save energy and reduce greenhouse gas emissions compared to conventional electric and gas hot water systems. Very rarely has the life-cycle energy requirements (including the embodied energy of manufacture) of solar hot water systems been analysed. The extent to which solar hot water systems can save energy compared to conventional electric or gas hot water systems can be shown through a comparative net energy analysis. This method determines the ‘energy payback period’, including consideration of the difference in operational energy savings and energy embodied in the devices relative to a base case. Dr Robert Crawford, Deakin University, Australia presents the results of a net energy analysis that compared solar and conventional hot water systems for a southern (Melbourne) and a northern (Brisbane) Australian climate.

Fuels of the future : the challenge of new fuel types

Landscape disturbances associated with human activities result in many changes in vegetation structure and floristics. These changes include invasion of native vegetation by both introduced and native species, which leads to the development of 'new' vegetation types. These new vegetation types are often associated with greatly increased fuel loads, and increased levels of fire hazard. Two of these 'new' fuel types are dense thickets of woody weeds, such as Coyote Bush (Baccharis pilularis) and swards of exotic grasses with very high fuel loads, such as Buffel Grass (Cenchrus ciliaris) and Para Grass (Urochloa mutica). The 'new' fuel types which can now be recognized have significant implications for the accuracy of fire behaviour prediction and modelling. For example, modelling fire behaviour in areas invaded by exotic grasses in Australia is problematic, as current grassland fire behaviour models do not allow for the input ofthe high fuel loads associated with these invasive grasses. In forest, McArthur Forest Fire Danger Meters may not be appropriate for forests with significant levels of elevated fuels. Two case studies from southeastern Australia are discussed: the invasion of native vegetation in the urban interface by the woody shrub Burgan (Kunzea ericoides) and invasion of native grasslands by Phalaris (Phalaris aquatica).

Biodiesel breathes better

It is long-established that car exhaust fumes cause respiratory disease, and more recently the particulate matter in diesel exhaust has been implicated in the death of human airway cells.  However, new research reveals that biodiesel is a safer alternative.

Nanobiotechnology as a novel paradigm for enzyme immobilisation and stabilisation with potential applications in biodiesel production

Nanobiotechnology is emerging as a new frontier of biotechnology. The potential applications of nanobiotechnology in bioenergy and biosensors have encouraged researchers in recent years to investigate new novel nanoscaffolds to build robust nanobiocatalyt

Distilled technical cashew nut shell liquid (DT-CNSL) as an effective biofuel and additive to stabilize triglyceride biofuels in diesel

We report distilled technical cashew nut shell liquid (DT-CNSL) as a non-transesterified biofuel and also as an additive to convert triglycerides to biofuel, without the need for the formation of methyl esters. DT-CNSL blends of diesel obey physico-chemical parameters of diesel. DT-CNSL offers stability to blends of straight vegetable oil (SVO) and tallow oil in diesel. Fluorescence studies using charge transfer probes show that the blend of DT-CNSL, triglycerides and diesel is a uniform solution, and fluorescence behavior is similar to that of diesel. The economics for the cultivation of cashew (Anacardium occidentale), its industrial use and rich carbon sink properties indicate that DT-CNSL could complement or replace traditional biodiesel crops like Jatropha and improve income for farmers. © 2014 Elsevier Ltd.

Deficient cognitive control fuels children's exuberant false allegations.

In eyewitness studies as in actual investigations, a minority of children generate numerous false (and sometimes incredulous) allegations. To explore the characteristics of these children, we reinterviewed and administered a battery of tasks to 61 children (ages 4-9 years) who had previously participated in an eyewitness study where a man broke a "germ rule" twice when he tried to touch them. Performance on utilization, response conflict (Luria tapping), and theory of mind tasks predicted the number of false reports of touching (with age and time since the event controlled) and correctly classified 90.16% of the children as typical witnesses or exuberant (more than 3) false reporters. Results of a factor analysis pointed to a common process underlying performance on these tasks that accounted for 49% of the variability in false reports. Relations between task performance and testimony confirmed that the mechanisms underlying occasional intrusions are different from those that drive persistent confabulation and that deficient cognitive control fuels young children's exuberant false reports.