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This study explores the influence of different driving styles and road gradient profiles on NO X emissions in a diesel passenger vehicle on urban driving. Driving dynamics parameters were correlated with cumulative NO X emissions measured during on-road driving on urban roads. In this work, the vehicle was driven on two different urban routes, one with mostly hilly roads and the other with predominately flat roads to assess the effect of road gradient on NO X emissions. Each route was driven six times, the first drive on each route was driven very timidly, each subsequent drive systematically became more aggressive with the sixth drive being very aggressive. From the vehicle speed and road gradient data, the instantaneous vehicle energy was estimated and correlated against the instantaneous NO X emission. In order to investigate for monotonic relationships, Spearmans rank correlation coefficient was used to investigate potential correlations between NO X emissions and driving parameters. A strong positive correlation was observed between instantaneous NO X emissions and instantaneous vehicle energy irrespective of the driving behaviour. The correlation of driving dynamics parameters with NO X emissions also showed a similar trend indicating that driving aggressiveness and vehicle NO X emissions have a strong relationship. Also there is evidence that the influence of road gradient on NO X emissions decreases with an increase in driving aggressiveness.

This study reports on a turbo-charged diesel engine performance, combustion and exhaust emissions when fuelled with three non-edible biodiesel blends, a neat waste cooking biodiesel (WBD100) and a neat reference diesel (D100). Waste cooking biodiesel was chosen as the non-edible biodiesel for its availability and low cost. Diethylene glycol dimethyl ether (DGM) was introduced as an additive owing to its superior ignitability and high oxygen content. The three blends tested in this investigation were 70/30/0, 70/20/10 and 70/10/20 in proportions of diesel/waste cooking biodiesel/DGM. In all cases, a commercial diesel was taken as the reference fuel for comparative discussion about parameters of the engine performance, combustion and exhaust emissions. A fully-instrumented, 4-stroke, 6-cylinder, turbocharged diesel engine was utilised for the experiments. Without significantly deteriorating engine performance, the three biodiesel blends and WBD100 reduced both particulate matter (PM) and particulate number (PN) emissions remarkably with the expected increase of nitrogen oxides (NOx) emissions.

The nonlinear dynamics of a combustion system in a modern common-rail dual-fuel engine has been studied. Using nonlinear dynamic data analysis (phase space reconstruction, recurrence plots, recurrence qualification analysis and wavelet analysis), the effect of ethanol fumigation on the dynamic behaviour of a combustion system has been examined at an engine speed of 2000 rpm with engine load rates of 50%, 75% and 100% and ethanol substitutions up to 40% (by energy) in 10% increments for each engine load. The results show that the introduction of ethanol has a significant effect on inter-cycle combustion variation (ICV) and the dynamics of the combustion system for all of the studied engine loads. For pure diesel mode and lower ethanol substitutions, the ICV mainly exhibits multiscale dynamics: strongly periodic and/or intermittent fluctuations. As the ethanol substitution is increased, the combustion process gradually transfers to more persistent low-frequency variations. At different engine loads, we can observe the bands with the strongest spectral power density that persist over the entire 4000 engine cycles. Compared to high engine loads (75% and 100%), the dynamics of the combustion system at a medium engine load (50%) was more sensitive to the introduction of ethanol. At higher ethanol substitutions, the increased ICV and the complexity of the combustion system at the medium load are attributable to the enhanced cooling caused by the excessive ethanol evaporation, while the low-frequency large-scale combustion fluctuations for the higher engine loads are likely caused by cyclic excitation oscillation during the transition of the combustion mode.

Particle emission characteristics and engine performance were investigated from an auxiliary, heavy duty, six-cylinder, turbocharged and after-cooled diesel engine with a common rail injection system using spiked fuels with different combinations of sulphur (S) and vanadium (V) spiking. The effect of fuel S content on both particle number (PN) and mass (PM) was clearly observed in this study. Higher PN and PM were observed for fuels with higher S contents at all engine load conditions. This study also found a correlation between fuel S content and nucleation mode particle number concentration which have more harmful impact on human health than larger particles. The highest PN and PM were observed at partial load conditions. In addition, S in fuel resulted in higher viscosity of spiked fuels, which led to lower engine blow-by. Fuel V content was observed in this study, evidencing that it had no clear effect on engine performance and emissions. Increased engine load also resulted in higher engine blow-by. The lower peak of in-cylinder pressure observed at both pre-mixed and diffusion combustion phases with the spiked fuels may be associated with the lower energy content in the fuel blends compared to diesel fuel.

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.

Light-duty diesel vehicles contribute significantly to urban air pollution. Laboratory-based standard driving test cycles do not take into account external driving factors, which greatly impact the vehicle emissions compared to the real-world driving emission (RDE) measurements. This results in higher emission levels obtained by RDE tests, compared to the standard approaches. In the current study, an RDE measurement campaign has been conducted in Brisbane city traffic using a portable emission measurement system (PEMS). Thirty drivers with a wide variety of driving experiences participated using a Hyundai iLoad van in a custom test route. RDEs and driving parameters were recorded during each trip. Principal component analysis (PCA) was applied to investigate the relationship between driving dynamics and vehicle emissions. Also, the impact of different trips, driving time, and driving experience on driving behaviour and emissions. Route familiarity, traffic density, and driving experience have a strong impact on driving behaviour and emissions. The driver's response to changing traffic, unknown routes, and vehicles significantly vary among different drivers which results in a high volume of transient events (frequent acceleration and deceleration). Transient events are very common in city driving which has a strong correlation to vehicle emissions.

Presented is a comprehensive evaluation of thermodynamic techniques used for the determination of top dead centre (TDC) in an internal combustion engine (ICE). This work thoroughly explores the assumptions made in thermodynamic calibration and assesses the impact these have through a rigorous sensitivity analysis, not previously attempted in any other study. The results of this work are presented as kernel density estimates (KDEs), an estimate of the probability density function (pdf), in order to offer both qualitative and quantitative assessments of the loss angle and the influence of the assumptions underpinning the loss angles determination. Thermodynamic loss angles ranging between-0.5CA and-0.6CA have been found for the engine under investigation.

Using a six-cylinder turbocharged common rail compression ignition engine, this study investigated the effect of oxygenated fuels on transient and steady-state performance. This paper considers the effect of oxygenated fuels on both cold- and hot-start operation. A range of fuel oxygen contents between 0% and 13.57% was derived from diesel, waste cooking biodiesel and two other blends, containing triacetin as a fuel additive. A custom test was designed to investigate engine performance parameters using acceleration, load increase and steady-state modes of operation. For each fuel, the cold-start test was conducted after an overnight engine-off time. In this study, different parameters related to engine performance were studied, such as engine coolant and lubricant temperatures and their rise rate, boost pressure, injected fuel, turbocharger lag, engine speed and torque, start of injection, maximum in-cylinder pressure, maximum rate of pressure rise, cyclic variability, FMEP, mechanical and thermal efficiencies, and BSFC. In comparison with hot-start, the cold-start results indicated a higher injected fuel, indicated torque, maximum in-cylinder pressure, maximum rate of pressure rise, FMEP, BSFC and CoV of IMEP, and a lower SOI, ME and BTE. During cold-start, using oxygenated fuels, instead of diesel, resulted in a lower rate of lubricant temperature rise and a higher BSFC, while decreasing the FMEP. Using oxygenated fuels, instead of diesel, during the idle and transient modes resulted in lower indicated torque and maximum in-cylinder pressure under cold-start whilst, under hot-start, it resulted in higher indicated torque and maximum in-cylinder pressure, because during hot-start, the fuel oxygen is significantly influential in torque build-up during turbocharger lag. While, during cold-start there are some other influential factors. In addition, oxygenated fuels—compared to diesel—experienced higher CoV of IMEP during cold-start while, during hot-start, they had lower values.

© 2019 Elsevier Ltd 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.

In the transportation sector, the share of biofuels such as biodiesel is increasing and it is known that such fuels significantly affect NOx emissions. In addition to NOx emission from diesel engines, which is a significant challenge to vehicle manufacturers in the most recent emissions regulation (Euro 6.2), this study investigates NO2 which is a toxic emission that is currently unregulated but is a focus to be regulated in the next regulation (Euro 7). This manuscript studies how the increasing share of biofuels affects the NO2, NOx, and NO2/NOx ratio during cold-start (in which the after-treatment systems are not well-effective and mostly happens in urban areas). Using a turbocharged cummins diesel engine (with common-rail system) fueled with diesel and biofuel derived from coconut (10 and 20% blending ratio), this study divides the engine warm-up period into 7 stages and investigates official cold- and hot-operation periods in addition to some intermediate stages that are not defined as cold in the regulation and also cannot be considered as hot-operation. Engine coolant, lubricating oil and exhaust temperatures, injection timing, cylinder pressure, and rate of heat release data were used to explain the observed trends. Results showed that cold-operation NOx, NO2, and NO2/NOx ratio were 31–60%, 1.14–2.42 times, and 3–8% higher than the hot-operation, respectively. In most stages, NO2 and the NO2/NOx ratio with diesel had the lowest value and they increased with an increase of biofuel in the blend. An injection strategy change significantly shifted the in-cylinder pressure and heat release diagrams, aligned with the sudden NOx drop during the engine warm-up. The adverse effect of cold-operation on NOx emissions increased with increasing biofuel share.

T{(NPI), 1999 #117}his research compares the effects of oxygenated fuels on engine blow-by during engine cold and hot start operation using a common rail, turbocharged diesel engine. Diesel, waste cooking biodiesel and a highly oxygenated additive, triacetin, were used to make a range of fuel oxygen contents (0–13.57%). This study investigated engine blow-by and its correlation with indicated, brake and friction power; and blow-by normalised by different parameters. Result showed that neat diesel produces higher blow-by during cold start than the oxygenated fuels. There was a strong correlation between blow-by and indicated power, and the fuel calorific value was identified as a leading factor. To further analyse the results, this study normalised the engine blow-by by power to reveal the other influences on engine blow-by. The result verified the strong influence of power. This study also furthered the analysis by normalising the blow-by data by exhaust flow rate, intake air flow rate and injected fuel flow rate. It was discovered that oxygenated fuels perform better between hot and cold start, when compared to diesel. The blow-by inhibited properties of oxygenated fuels, such as higher lubricity and viscosity may be the cause for better performance of oxygenated fuels during cold start.

In this paper, a four-component reduced mechanism (methane, n-dodecane, methylcyclohexane and toluene) with 150 species and 847 reactions was proposed for predicting the combustion characteristics and emissions from natural gas-diesel dual fuel engines. Equivalence ratio (ϕ) from 0.5 to 2.0, pressure (P) from 30 to 90 bar, temperature (T) from 500 to 1700 K and ϕ from 0.5 to 2.0, P from 1 to 10 bar, T from 298 to 550 K were set as the reaction conditions for two reaction models respectively. The detailed mechanisms were reduced using the directed relation graphs (DRG), directed relation graphs with error propagation (DRGEP) and full species sensitivity analysis (FSSA) methods. The validation of the reduced mechanism was performed based on the ignition delay and the laminar flame speed data available in the literature. Then the effects of cross-reactions on the oxidation of diesel were further studied, associated with the reaction flux, concentration and sensitivity analysis. Finally, the reduced mechanisms were verified at a reactivity controlled compression ignition (RCCI) combustion mode at 25% and 75% loads, the maximum validation error is 3.3%. It was found that the effects of cross-reactions on ignition were more pronounced in medium and low temperatures. Ignition was also enhanced by an increase in the equivalence ratio, but was not found to be sensitive to pressure. Under lower temperatures, adding cross-reactions can better reveal the formation of diesel intermediates. However, at higher temperatures, the addition of cross-reactions did not significantly increase the reaction speeds of the intermediate products.

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.

As biofuels are increasingly represented in the fuel market, the use of these oxygenated fuels should be evaluated under various engine operating conditions, such as cold-start. However, to-date quantification has been mostly done under hot-start engine operation. By using a custom test designed for this study, a comparative investigation was performed on exhaust emissions during cold- and hot-start with diesel and three oxygenated fuels based on waste cooking biodiesel and triacetin. This study used a six-cylinder, turbocharged, after-cooled diesel engine with a common rail injection system. The results during cold-start with diesel showed lower NOx (up to 15.4%), PN (up to 48%), PM1 (up to 44%) and PM2.5 (up to 63%). However, the oxygenated fuels during cold-start showed a significant increase in NOx (up to 94%), PN (up to 27 times), PM1 (up to 7.3 times) and PM2.5 (up to 5 times) relative to hot-start. The use of oxygenated fuels instead of diesel during hot-start decreased the PN, PM2.5 and PM1 (up to 91%) while, during cold-start, it only decreased PM1 and PM2.5 at some engine operating modes and increased PN significantly up to 17 times. In both cold- and hot-start, the use of oxygenated fuels resulted in an increase in NOx emission. For cold-start this was up to 125%, for hot-start it was up to 13.9%. In comparison with hot-start, the use of oxygenated fuels during cold-start increased nucleation mode particles significantly, which are harmful. This should be taken into consideration, since cold-start operation is an inevitable part of the daily driving schedule for a significantly high portion of vehicles, especially in cities.

Owing to the increasing share of biofuels in combustion engines, use of these oxygenated fuels instead of diesel should be evaluated under different engine operating conditions. This paper studies the influence of oxygenated fuels on engine performance parameters under transient, compared to steady-state, operation on a six-cylinder, turbocharged, compression-ignition engine with a common rail injection system. The fuels used in this study were diesel, waste cooking biodiesel, and triacetin (as a highly oxygenated additive). A custom test was used to investigate different engine performance parameters during acceleration, load increase, and steady-state modes of operation. Additionally, a legislative transient cycle (NRTC), composed of many discrete transient modes, was used to study engine performance during a whole transient cycle. In this paper, different engine performance-related parameters were investigated, such as IMEP, BMEP, FMEP, turbocharger lag, air-to-fuel ratio, engine speed and torque, star...

This research studies the influence of oxygenated fuels on transient and steady-state engine performance and emissions using a fully instrumented, 6-cylinder, common rail turbocharged compression ignition engine. Beside diesel, the other tested fuels were based on waste cooking biodiesel (primary fuel) with triacetin (highly oxygenated additive). A custom test was designed for this study to investigate the engine performance and emissions during steady-state, load acceptance and acceleration operation modes. Furthermore, to study the engine performance and emissions during a whole transient cycle, a legislative cycle (NRTC), which contains numerous discrete transient modes, was utilised. In this paper, the turbocharger lag, engine power, NOx, PM, PN and PN size distribution were investigated. During NRTC the brake power, PM and PN decreased with fuel oxygen content. During steady-state operation, compared to diesel, the oxygenated fuels showed lower indicated power, while they showed higher values during acceleration and turbocharger lag. During acceleration and load increase modes, NOx, PM and PN peaked over the steady-state counterpart, also, the accumulation mode count median diameter moved toward the larger particle sizes. Increasing the fuel oxygen content increased the indicated specific NOx and PN maximum overshoot, while engine power, PM, PN and PM maximum overshoot decreased. Also, the accumulation mode count median diameter moved toward the smaller particle sizes.

Emissions from ships at berth are small compared to the total ship emissions; however, they are one of the main contributors to pollutants in the air of densely-populated areas, consequently heavily affecting public health. This is due to auxiliary marine engines being used to generate electric power and steam for heating and providing services. The present study has been conducted on an engine representative of a marine auxiliary, which was a heavy duty, six-cylinder, turbocharged and after-cooled engine with a high pressure common rail injection system. Engine performance and emission characterisations during cold start are the focus of this paper, since cold start is significantly influential. Three tested fuels were used, including the reference diesel and two IMO (International Maritime Organization) compliant spiked fuels. The research engine was operated at a constant speed and 25% load condition after 12 h cooled soak. Results show that during cold start, significant heat generated from combustion is used to heat the engine block, coolant and lubricant. During the first minute, compared to the second minute, emissions of particle number (PN), carbon monoxide (CO), particulate matter (PM), and nitrogen oxides (NO x) were approximately 10, 4, 2 and 1.5 times higher, respectively. The engine control unit (ECU) plays a vital role in reducing engine emissions by changing the engine injection strategy based on the engine coolant temperature. IMO-compliant fuels, which were higher viscosity fuels associated with high sulphur content, resulted in an engine emission increase during cold start. It should be taken into account that auxiliary marine diesel engines, working at partial load conditions during cold start, contribute considerably to emissions in coastal areas. It demonstrates a need to implement practical measures, such as engine pre-heating, to obtain both environmental and public health advantages in coastal areas.

The importance of the in-cylinder pressure transducer has been proven in revealing the information about combustion and exhaust pollution formation, as well as for its capability to classify knock. Due to their high price, they are not used commercially for engine health monitoring, which is of significant importance. Hence, this study will investigate the reconstruction of the in-cylinder pressure trace using a structure-borne acoustic emission (AE) sensor, which are relatively low cost sensors. As shown in the literature, AE indicators show a strong correlation with in-cylinder pressure parameters in both time and crank angle domain. In this study, to avoid the effect of engine speed fluctuations, the reconstruction is done in the crank angle domain by means of the Hilbert transform of AE. Complex cepstrum signal processing analysis with a feed-forward neural network is used to generate a reconstruction regime. Furthermore, the reconstructed signals are used to determine some of the important in-cylinder parameters such as peak pressure (PP), peak pressure timing (PPT), indicated mean effective pressure (IMEP) and pressure rise rate. Results showed that the combination of cepstrum analysis with neural network is capable of reconstructing pressure using AE, regardless of engine load, speed and fuel type. The reconstructed pressure can be used to reliably determine PP and PPT. IMEP can be estimated as well in a reasonable range.

The present study focuses on the synthesis of novel catalytic nanoparticles and their effect on combustion, performance, and emission characteristics of a diesel engine. For this purpose, Mg cations were doped into a Fe3O4 lattice to form MgxFe(3-x)O4 (x = 0.25, 0.5, 0.75, and 1) using a solution combustion method. Comprehensive characterization studies were carried out to assess the oxygen storage capacity (OSC) and the properties of final powders. These synthesized samples were dispersed in a diesel-biodiesel blend fuel with a concentration of 90 ppm. Assessment of the structure of the samples proved the formation of MgFe2O4 structures, suggesting that Mg cations were embedded into the Fe3O4 and formed appropriate structures. The OSC was reduced from 8661 μmol/g (Mg0·25Fe2·75O4) to 7069 μmol/g (MgFe2O4) by introducing additional Mg cations. When run on a six-cylinder diesel engine, the fuel mixed from the synthesized samples did not significantly influence the indicated power (IP), brake specific fuel consumption (BSFC) or the brake thermal efficiency (BTE). In addition to the obtained result for the OSC of the sample, which declined by increasing the Mg concentration in the Fe3O4 lattice, using the sample with the highest concentration of Mg cations, a considerable reduction was detected in the major exhaust emissions such as HC (56.5%), PM1 (35%), and PN (37%) and a slight decrease occurred in CO (7%) compared to the engine fueled by pure fuel. Based on the experimental engine results, the MgFe2O4 sample can be considered as a useful nanocatalyst for mixing in the fuels for emissions reduction.

Using wavelet and fractal theories, cycle-to-cycle variations (CCVs) in a common-rail compression ignition (CI) engine have been investigated at engine loads of 25% and 50%, biodiesel blend level was from 0% to 100%. Wavelet power spectrums and singularity spectra were calculated to identify the dominant oscillatory combustion modes and multifractal complexity. Reaction paths and component consumption sensitivity of n-heptane and methyl decanoate were studied to reveal the effect of biodiesel blend level on the combustion process of diesel fuel. Results reveal that the effect of biodiesel blend level on the CCVs is more significant at a low load, even when biodiesel blend level increases to 20%, the coefficients of variation decreases from 3.99% to 1.57%. The CCVs exhibit multiscale dynamics for all tested cases, and persistent high-frequency oscillations appear around a 16-cycle period persisting over the entire or several hundred of the engine cycles. As the biodiesel blend level increases, the periodic bands with the highest power were interrupted and combined with lower-frequency and high-frequency intermittent fluctuations. However, for the higher load, the dynamics of CCVs are mainly displayed in an intermittent fashion. The larger broadness of singularity spectra at higher engine loads suggests a higher degree of multifractality. For all of the tested cases, the dynamics of the CCVs behave like antipersistent walks. As a oxygenated fuel, biofuel substitution leads to increase of c7h15-1 concentration and radicals such as OH, O and H2O2, which are beneficial to decrease ignition delay and accelerate the chemical reaction rate of diesel fuel, and therefore inhibit the CCVs.

This study aims to investigate the effect of the port injection of ammonia on performance, knock and NOx emission across a range of engine speeds in a gasoline/ethanol dual-fuel engine. An experimentally validated numerical model of a naturally aspirated spark-ignition (SI) engine was developed in AVL BOOST for the purpose of this investigation. The vibe two zone combustion model, which is widely used for the mathematical modeling of spark-ignition engines is employed for the numerical analysis of the combustion process. A significant reduction of ~50% in NOx emissions was observed across the engine speed range. However, the port injection of ammonia imposed some negative impacts on engine equivalent BSFC, CO and HC emissions, increasing these parameters by 3%, 30% and 21%, respectively, at the 10% ammonia injection ratio. Additionally, the minimum octane number of primary fuel required to prevent knock was reduced by up to 3.6% by adding ammonia between 5 and 10%. All in all, the injection of ammonia inside a bio-fueled engine could make it robust and produce less NOx, while having some undesirable effects on BSFC, CO and HC emissions.

NOx emissions from diesel engines are a concern from both environmental and health perspectives. Recently this attention has targeted cold-start emissions highlighting that emission after-treatment systems are not effective in this period. Using a 6-cylinder, turbocharged, common-rail diesel engine, the current research investigates NOx emissions during cold-start using different engine performance parameters. In addition, it studies the influence of waste lubricating oil on NOx emissions introducing it as a fuel additive (1 and 5% by volume). To interpret the NOx formation, this study evaluates different parameters: exhaust gas temperature, engine oil temperature, engine coolant temperature, start of injection/combustion, in-cylinder pressure, heat release rate, maximum in-cylinder pressure and maximum rate of pressure rise. This study clarified how cold-start NOx increases as the engine is warming up while in general cold-start NOx is higher than hot-start. Results showed that in comparison with warmed up condition, during cold-start NOx, maximum in-cylinder pressure and maximum rate of pressure rise were higher; while start of injection, start of combustion and ignition delay were lower. During cold-start increased engine temperature was associated with decreasing maximum rate of pressure rise and peak apparent heat release rate. During cold-start NOx increased with temperature and it dropped sharply due to the delayed start of injection. This study also showed that using waste lubricating oil decreased NOx and maximum rate of pressure rise; and increased maximum in-cylinder pressure. NOx had a direct correlation with the maximum rate of pressure rise; and an inverse correlation with the maximum in-cylinder pressure.

Exploration of sustainable fuels and their influence on reductions in diesel emissions are nowadays a challenge for the engine and fuel researchers. This study investigates the role of fuel-borne oxygen on engine performance and exhaust emissions with a special emphasis on diesel particulate and nitric oxide (NO) emissions. A number of oxygenated-blends were prepared with waste cooking biodiesel as a base oxygenated fuel. Triacetin, a derivative from transesterified biodiesel was chosen for its high oxygen content and superior fuel properties. The experimental campaign was conducted with a 6-cylinder, common rail turbocharged diesel engine equipped with highly precise instruments for nano and other size particles and other emissions. All experiments were performed in accordance with European Stationary Cycle (ESC 13-mode). A commercial diesel was chosen as a reference fuel with 0% oxygen and five other oxygenated blends having a range of 6.02–14.2% oxygen were prepared. The experimental results revealed that the oxygenated blends having higher a percentage of fuel-borne oxygen reduced particulate matter (PM), particle number (PN), unburned hydrocarbon (UBHC) and carbon monoxide (CO) emissions to a significantly low level with a slight penalty of NO emissions. The main target of this study was to effectively utilise triacetin as an additive for waste cooking biodiesel and suppress emissions without deteriorating engine performance. The key finding of this investigation is the significant reductions in both particle mass and number emissions simultaneously without worsening engine performance with triacetin-biodiesel blends. Reductions in both particle mass and number emissions with a cost-effective additive would be a new dimension for the fuel and engine researchers to effectively use triacetin as an emission suppressor in the future.

Highlights - Oxygen ratio was used instead of the equivalence ratio. - Oxygen ratio decreases with engine load, but increases with engine speed. - IMEP, BMEP, friction power, CO2, HC, PM and PN decreased with oxygenated fuels. - BSFC, BTE and NOx increased with oxygenated fuels. - Accumulation mode count median diameter decreased with oxygenated fuels. Abstract 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 rail injection 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 fuel ratio, 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 brake specific 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.

Presented in this paper is an in-depth analysis of the impact of engine start during various stages of engine warm up (cold, intermediate, and hot start stages) on the performance and emissions of a heavy-duty diesel engine. The experiments were performed at constant engine speeds of 1500 and 2000 rpm on a custom designed drive cycle. The intermediate start stage was found to be longer than the cold start stage. The oil warm up lagged the coolant warm up by approximately 10 &deg, C. During the cold start stage, as the coolant temperature increased from ~25 to 60 &deg, C, the brake specific fuel consumption (BSFC) decreased by approximately 2% to 10%. In the intermediate start stage, as the coolant temperature reached 70 &deg, C and the injection retarded, the indicated mean effective pressure (IMEP) and the brake mean effective pressure (BMEP) decreased by approximately 2% to 3%, while the friction mean effective pressure (FMEP) decreased by approximately 60%. In this stage, the NOx emissions decreased by approximately 25% to 45%, while the HC emissions increased by approximately 12% to 18%. The normalised FMEP showed that higher energy losses at lower loads were most likely contributing to the heating of the lubricating oil.

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.

There are tons of waste tyres produced each year globally. Production of oil from the waste tyre not only manages the wastes but also produces fuels for compression ignition engines. In this investigation, a novel approach developed by Green Distillation Technologies in Australia was used to convert whole end of life tyres (ELTs) into carbon, steel, and tyre oil. The physicochemical properties of the tyre oil are similar to diesel fuel, and the fuel is miscible with diesel in any blended ratio. An engine experiment was conducted on a EURO IIIA diesel engine. All experiments were performed at constant speed and four different engine loads. Two blends (10% and 20%) of tyre oil were compared to reference diesel fuel. Exhaust emissions, including gaseous emissions, particulate matter (PM) and particulate number (PN) were investigated. The results indicate simultaneous reductions in both diesel PM and nitrogen oxides (NOx) emissions with the tyre oil blends when compared to diesel. NOx emissions were reduced by approximately 30% with both blends with respect to diesel. The reduction in PM and PN emissions were in the range of 35–60% and 5–20%, respectively. Carbon monoxide (CO) were increased by ∼ 10% compared to the reference diesel except at quarter load. Insignificant change in brake power (BP), brake mean effective pressure (BMEP) and brake thermal efficiency (BTE) were observe with the tyre oil blends. The engine remained compliant with its EURO IIIA guidelines during the use of the tyre oil blends. Based on the engine performance and emission result, the tyre oil could be alternative to traditional diesel fuel.

The disposal of waste rubber and scrap tyres is a significant issue globally; disposal into stockpiles and landfill poses a serious threat to the environment, in addition to creating ecological problems. Fuel production from tyre waste could form part of the solution to this global issue. Therefore, this paper studies the potential of fuels derived from waste tyres as alternatives to diesel. Production methods and the influence of reactor operating parameters (such as reactor temperature and catalyst type) on oil yield are outlined. These have a major effect on the performance and emission characteristics of diesel engines when using tyre derived fuels. In general, tyre derived fuels increase the brake specific fuel consumption and decrease the brake thermal efficiency. The majority of studies indicate that NOx emissions increase with waste tyre derived fuels; however, a few studies have reported the opposite trend. A similar increasing trend has been observed for CO and CO2 emissions. Although most studies reported an increase in HC emission owing to lower cetane number and higher density, some studies have reported reduced HC emissions. It has been found that the higher aromatic content in such fuels can lead to increased particulate matter emissions.

Introduced in this paper is a Bayesian model for isolating the resonant frequency from combustion chamber resonance. The model shown in this paper focused on characterising the initial rise in the resonant frequency to investigate the rise of in-cylinder bulk temperature associated with combustion. By resolving the model parameters, it is possible to determine: the start of pre-mixed combustion, the start of diffusion combustion, the initial resonant frequency, the resonant frequency as a function of crank angle, the in-cylinder bulk temperature as a function of crank angle and the trapped mass as a function of crank angle. The Bayesian method allows for individual cycles to be examined without cycle-averaging|allowing inter-cycle variability studies. Results are shown for a turbo-charged, common-rail compression ignition engine run at 2000 rpm and full load.

An experimental study has been performed to investigate the ignition delay of a modern heavy-duty common-rail diesel engine run with fumigated ethanol substitutions up to 40% on an energy basis. The ignition delay was determined through the use of statistical modelling in a Bayesian framework this framework allows for the accurate determination of the start of combustion from single consecutive cycles and does not require any differentiation of the in-cylinder pressure signal. At full load the ignition delay has been shown to decrease with increasing ethanol substitutions and evidence of combustion with high ethanol substitutions prior to diesel injection have also been shown experimentally and by modelling. Whereas, at half load increasing ethanol substitutions have increased the ignition delay. A threshold absolute air to fuel ratio (mole basis) of above ~110 for consistent operation has been determined from the inter-cycle variability of the ignition delay, a result that agrees well with previous research of other in-cylinder parameters and further highlights the correlation between the air to fuel ratio and inter-cycle variability. Numerical modelling to investigate the sensitivity of ethanol combustion has also been performed. It has been shown that ethanol combustion is sensitive to the initial air temperature around the feasible operating conditions of the engine. Moreover, a negative temperature coefficient region of approximately 900{1050 K (the approximate temperature at fuel injection) has been shown with for n-heptane and n-heptane/ethanol blends in the numerical modelling. A consequence of this is that the dominate effect influencing the ignition delay under increasing ethanol substitutions may rather be from an increase in chemical reactions and not from in-cylinder temperature. Further investigation revealed that the chemical reactions at low ethanol substitutions are different compared to the high (> 20%) ethanol substitutions.

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. © 2014 Elsevier Ltd. All rights reserved.

With the advent of alternative fuels, such as biodiesels and related blends, it is important to develop an understanding of their effects on inter-cycle variability which, in turn, influences engine performance as well as its emission. Using four methanol trans-esterified biomass fuels of differing carbon chain length and degree of unsaturation, this paper provides insight into the effect that alternative fuels have on inter-cycle variability. The experiments were conducted with a heavy-duty Cummins, turbo-charged, common-rail compression ignition engine. Combustion performance is reported in terms of the following key in-cylinder parameters: indicated mean effective pressure (IMEP), net heat release rate (NHRR), standard deviation of variability (StDev), coefficient of variation (CoV), peak pressure, peak pressure timing and maximum rate of pressure rise. A link is also established between the cyclic variability and oxygen ratio, which is a good indicator of stoichiometry. The results show that the fatty acid structures did not have a significant effect on injection timing, injection duration, injection pressure, StDev of IMEP, or the timing of peak motoring and combustion pressures. However, a significant effect was noted on the premixed and diffusion combustion proportions, combustion peak pressure and maximum rate of pressure rise. Additionally, the boost pressure, IMEP and combustion peak pressure were found to be directly correlated to the oxygen ratio. The emission of particles positively correlates with oxygen content in the fuel as well as in the air-fuel mixture resulting in a higher total number of particles per unit of mass.

This study uses the first and second laws of thermodynamics to investigate the effect of 18 oxygenated fuels on the quality and quantity of energy in a turbo-charged, common-rail six19 cylinder diesel engine. This work was performed using a range of fuel oxygen content based 20 on diesel, waste cooking biodiesel, and a triacetin. The experimental engine performance and 21 emission data was collected at 12 engine operating modes. Energy and exergy parameters were 22 calculated, and results showed that the use of oxygenated fuels can improve the thermal 23 efficiency leading to lower exhaust energy loss. Waste cooking biodiesel (B100) exhibited the 24 lowest exhaust loss fraction and highest thermal efficiency (up to 6% higher than diesel). 25 Considering the exergy analysis, lower exhaust temperatures obtained with oxygenated fuels 26 resulted in lower exhaust exergy loss (down to 80%) and higher exergetic efficiency (up to 27 10%). Since the investigated fuels were oxygenated, this study used the oxygen ratio (OR) 28 instead of the equivalence ratio to provide a better understanding of the concept. The OR has 29 increased with decreasing engine load and increasing engine speed. Increasing the OR 30 decreased the fuel exergy, exhaust exergy and destruction efficiency. With the use of B100, 31 there was a very high exergy destruction (up to 55%), which was seen to decrease with the 32 addition of triacetin (down to 29%).

A novel in-cylinder pressure method for determining ignition delay has been proposed and demonstrated. This method proposes a new Bayesian statistical model to resolve the start of combustion, defined as being the point at which the band-pass in-cylinder pressure deviates from background noise and the combustion resonance begins. Further, it is demonstrated that this method is still accurate in situations where there is noise present. The start of combustion can be resolved for each cycle without the need for ad hoc methods such as cycle averaging. Therefore, this method allows for analysis of consecutive cycles and inter-cycle variability studies. Ignition delay obtained by this method and by the net rate of heat release have been shown to give good agreement. However, the use of combustion resonance to determine the start of combustion is preferable over the net rate of heat release method because it does not rely on knowledge of heat losses and will still function accurately in the presence of noise. Results for a six-cylinder turbo-charged common-rail diesel engine run with neat diesel fuel at full, three quarters and half load have been presented. Under these conditions the ignition delay was shown to increase as the load was decreased with a significant increase in ignition delay at half load, when compared with three quarter and full loads.

The effects of ethanol fumigation on the inter-cycle variability of key in-cylinder pressure parameters in a modern common rail diesel engine have been investigated. Specifically, maximum rate of pressure rise, peak pressure, peak pressure timing and ignition delay were investigated. A new methodology for investigating the start of combustion was also proposed and demonstrated—which is particularly useful with noisy in-cylinder pressure data as it can have a significant effect on the calculation of an accurate net rate of heat release indicator diagram. Inter-cycle variability has been traditionally investigated using the coefficient of variation. However, deeper insight into engine operation is given by presenting the results as kernel density estimates; hence, allowing investigation of otherwise unnoticed phenomena, including: multi-modal and skewed behaviour. This study has found that operation of a common rail diesel engine with high ethanol substitutions (>20% at full load, >30% at three quarter load) results in a significant reduction in ignition delay. Further, this study also concluded that if the engine is operated with absolute air to fuel ratios (mole basis) less than 80, the inter-cycle variability is substantially increased compared to normal operation.

Compression ignition (CI) engine design is subject to many constraints, which present a multicriteria optimization 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 is minimized. Consequently, this study undertakes a multicriteria analysis, which seeks to identify alternative fuels, injection technologies, and combustion strategies that could potentially satisfy these CI engine design constraints. Three data sets are analyzed 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 multicriteria 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. © 2013 American Chemical Society.

A time series method for the determination of combustion chamber resonant frequencies is outlined. This technique employs the use of Markov-chain Monte Carlo (MCMC) to infer parameters in a chosen model of the data. The development of the model is included and the resonant frequency is characterised as a function of time. Potential applications for cycle-by-cycle analysis are discussed and the bulk temperature of the gas and the trapped mass in the combustion chamber are evaluated as a function of time from resonant frequency information.

Computational optimisation of clinically important electrocardiogram signal features, within a single heart beat, using a Markov-chain Monte Carlo (MCMC) method is undertaken. A detailed, efficient data-driven software implementation of an MCMC algorithm has been shown. Initially software parallelisation is explored and has been shown that despite the large amount of model parameter inter-dependency that parallelisation is possible. Also, an initial reconfigurable hardware approach is explored for future applicability to real-time computation on a portable ECG device, under continuous extended use.

The feasibility of real-time calculation of parameters for an internal combustion engine via reconfigurable hardware implementation is investigated as an alternative to software computation. A detailed in-hardware field programmable gate array (FPGA)-based design is developed and evaluated using input crank angle and in-cylinder pressure data from fully instrumented diesel engines in the QUT Biofuel Engine Research Facility (BERF). Results indicate the feasibility of employing a hardware-based implementation for real-time processing for speeds comparable to the data sampling rate currently used in the facility, with acceptably low level of discrepancies between hardware and software-based calculation of key engine parameters.

For clinical use, in electrocardiogram (ECG) signal analysis it is important to detect not only the centre of the P wave, the QRS complex and the T wave, but also the time intervals, such as the ST segment. Much research focused entirely on qrs complex detection, via methods such as wavelet transforms, spline fitting and neural networks. However, drawbacks include the false classification of a severe noise spike as a QRS complex, possibly requiring manual editing, or the omission of information contained in other regions of the ECG signal. While some attempts were made to develop algorithms to detect additional signal characteristics, such as P and T waves, the reported success rates are subject to change from person-to-person and beat-to-beat. To address this variability we propose the use of Markov-chain Monte Carlo statistical modelling to extract the key features of an ECG signal and we report on a feasibility study to investigate the utility of the approach. The modelling approach is examined with reference to a realistic computer generated ECG signal, where details such as wave morphology and noise levels are variable.