• Energy Research

One of the most important sources of air pollution, especially in urban areas, is the exhaust emissions from passenger cars. New European emissions regulations, to minimize the gap between manufacturer-reported emissions and those emitted on the road, require new vehicles to undergo emission testing on public roads during the certification process. Outlined in the new regulation are specific boundary conditions to which the route on which the vehicle is driven must comply during a legal test. These boundary conditions, as they relate to the design and subsequent driving of a compliant route, are discussed in detail. The practicality of designing a compliant route is discussed in the context of developing a route on the Gold Coast in Queensland, Australia, in a prescriptive manner. The route itself was driven 5 times and the results compared against regulation boundary conditions.

Rising concerns over environmental and health issues of internal combustion engines, along with growing energy demands, have motivated investigation into alternative fuels derived from biomasses, such as biodiesel. Investigating engine and exhaust emission behaviour of such alternative fuels is vital in order to assess suitability for further utilisation. Since many parameters are relevant, an effective multivariate analysis tool is required to identify the underlying factors that affect the engine performance and exhaust emissions. This study utilises principal component analysis (PCA) to present a comprehensive correlation of various engine performance and emission parameters in a compression ignition engine using diesel, biodiesel and triacetin. The results show that structure-borne acoustic emission is strongly correlated with engine parameters. Brake specific NOx, primary particle diameter and fringe length increases by increasing the rate of pressure rise. Longer ignition delay and higher engine speeds can increase the nucleation particle emissions. Higher air-fuel equivalence ratio can increase the oxidative potential of the soot by increasing fringe distance and tortuosity. The availability of oxygen in the cylinder, from the intake air or fuel, can increase soot aggregate compactness. Fuel oxygen content reduces particle mass and particle number in the accumulation mode; however, they increase the proportion of oxygenated organic species. PCA results for particle chemical and physical characteristics show that soot particles reactivity increases with fuel oxygen content.

This chapter studied the effect of ethanol fumigation on engine performance using a modern compression ignition engine. Performance-related parameters were investigated at ethanol substitutions of 0, 10, 20, 30, and 40% (by energy) under 25, 50, 75, and 100% load at 1500 and 2000 rpm. Using E10 and E20 in some of the operating modes decreased FMEP and BSFC; while using E40 increased FMEP and BSFC. The mechanical efficiency improved with the use of E10 in half of the operating modes; however, in general there was a decreasing trend associated with increasing ethanol substitution. While ethanol improved the thermal efficiency, lower substitutions performed better. At lower loads, thermal efficiency decreased with higher substitutions, while at higher loads, it increased with higher substitutions. Increasing the ethanol substitution increased the maximum in-cylinder pressure. The maximum rate of pressure rise was minimally impacted at low substitutions, although it increased significantly at high substitutions (>20%). At 1500 rpm, increasing the ethanol substitution decreased the CoV of IMEP, especially with E30 and E40. However, at 2000 rpm, using higher substitutions slightly increased the CoV of IMEP (~2%) at higher loads. Under 25% load, increasing the ethanol substitution increased the maximum apparent heat release rate. Under 50 and 75% loads, by increasing the ethanol substitution there was a tendency toward having double peaks in the heat release diagram. Also, increasing the substitution rate increased the peak values. Under full load, the first peak values increased and the second peak diminished as the ethanol rate increased.

This paper builds on previous work using surrogate fuel to investigate advanced internal combustion engine fuels. To date, a surrogate fuel of this nature has not been used for microalgae hydrothermal liquefaction (HTL) biocrude. This research used five different chemical groups found in microalgae HTL biocrude to design a surrogate fuel. Those five chemical groups constitute around 65% (by weight) of a microalgae biocrude produced by HTL. Weight percentage of the microalgae HTL biocrude chemical compounds were used to design the surrogate fuel, which was miscible with diesel at all percentages. The engine experiments were conducted on a EURO IIIA turbocharged common-rail direct-injection six-cylinder diesel engine to test engine performance and emissions. Exhaust emissions, including particulate matter and other gaseous emissions, were measured with the surrogate fuel and a reference diesel fuel. Experimental results showed that without significantly deteriorating engine performance, lower particulate mass, particulate number and CO emissions were observed with a penalty in NOx emissions for all surrogate blends compared to those of the reference diesel.

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.

Nitrogen (N) content in algae hydrothermal liquefaction (HTL) biocrude is high (5–8 wt%) and generally presumed to result in high NOx emissions during combustion. However, to our knowledge a very limited previous work on diesel engine performance and emissions of N-containing fuels. In order to investigate this issue, pyridine, an N-heterocyclic compound commonly found in algae biocrude, was blended with diesel fuel. This study investigated the influence of N in fuels, using a surrogate fuel to simulate algal biocrude, to determine the combustion behavior and emissions profile of an industrial multi-cylinder diesel engine. The presence of N in the fuel affected its physical properties. Density was slightly higher than neat diesel, while the viscosity, the flash point and the higher heating value (HHV) of the N-containing fuels reduced with increasing N content. The flash point of N-containing fuels were reduced, which affects the storage and transportation of the fuel. The engine load between 25 and 75% was observed to have an effect on engine performance parameters. Compared to diesel, N-containing fuels emitted both lower carbon monoxide (CO) and unburned hydrocarbons (HC). Increasing nitrogen oxides (NOx) emissions were observed with increasing N content in the fuels. At 50% and 75% loads, NOx emissions from N0.1 (0.1 wt% N), N0.5 (0.5 wt% N) and N2 (2 wt% N) were lower than for EUROIII. Particulate matter (PM) was lower for N-containing fuels compared to diesel fuel except for N0.1.

In this study, an LPG fumigation system was fitted to a Euro III compression ignition (CI) engine to explore its impact on performance, and gaseous and particulate emissions. LPG was introduced to the intake air stream (as a secondary fuel) by using a low pressure fuel injector situated upstream of the turbocharger. LPG substitutions were test mode dependent, but varied in the range of 14-29% by energy. The engine was tested over a 5 point test cycle using ultra low sulphur diesel (ULSD), and a low and high LPG substitution at each test mode. The results show that LPG fumigation coerces the combustion into pre-mixed mode, as increases in the peak combustion pressure (and the rate of pressure rise) were observed in most tests. The emissions results show decreases in nitric oxide (NO) and particulate matter (PM2.5) emissions; however, very significant increases in carbon monoxide (CO) and hydrocarbon (HC) emissions were observed. A more detailed investigation of the particulate emissions showed that the number of particles emitted was reduced with LPG fumigation at all test settings – apart from mode 6 of the ECE R49 test cycle. Furthermore, the particles emitted generally had a slightly larger median diameter with LPG fumigation, and had a smaller semi-volatile fraction relative to ULSD. Overall, the results show that with some modifications, LPG fumigation systems could be used to extend ULSD supplies without adversely impacting on engine performance and emissions.

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