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The influence of engine load and fuel premixing ratio (PMR) on unregulated emission from a methanol-diesel dual-fuel RCCI (MD-RCCI) engine is examined in this study. The study focuses on assessing the adverse effects of unregulated emissions (saturated HC, unsaturated HC, carbonyl compounds, aromatic hydrocarbon, NH3, and SO2) on the health of human beings and the environment. To quantify the effect on the environment, the greenhouse gas potential (GWPs), Eutrophication potential (EP), Acidification potential (AP), and Ozone forming potential (OFP) are calculated and presented. The cancer risk potential (CRP) of the carbonyl compounds (HCHO and CH3CHO) is calculated and presented to see the effect on human health. The results demonstrate that at lower engine load, with an increase in PMR, the OFP and CRP for MD-RCCI operation increase significantly, whereas AP, EP, and GWPs decrease. Additionally, with a rise in the load at a constant PMR, the AP, EP and OFP decrease significantly.

Di-ethyl ether (DEE) belongs to the family of oxygenated fuels, which have been investigated as an alternative to conventional diesel. However, increasing the proportion of DEE in DEE-diesel blends changes its physicochemical properties. This work shows the non-evaporating and non-reacting spray characteristics of diesel, DEE20 (20% v/v DEE and 80% v/v diesel), and DEE40 (40% v/v DEE and 60% v/v diesel) were investigated. The effect of fuel injection pressure (FIP: 500 and 800 bar) on the spray morphology and droplet size distribution at different axial locations along the spray axis was done. FIP of 800 bar showed a reduction in Sauter mean diameter (SMD) of spray droplets with increasing axial distance due to improved spray atomisation because of the drag forces of the surrounding air on the fuel droplets. DEE20 showed a higher number of droplets having a smaller diameter than DEE40. DEE20 and DEE40 showed superior spray atomisation characteristics than diesel.

Considering the demand for sustainable transport, alternative fuels are a keen research topic for IC engine researchers. Among various alternative fuels being explored, Di-ethyl ether (DEE) is gaining popularity off-late for compression-ignition (CI) engines owing to its high cetane rating, oxygen presence in its molecular structure, and lower carbon content. This study explores the suitability of DEE blends in tractor engines. DEE blends [15% and 30% (v/v)] with diesel were compared with baseline diesel for combustion, and emission characterisation, keeping all parameters identical, including the fuel injection timings. Results were analysed for different engine loads at 1500 rpm. Delayed combustion was observed with DEE blends with diesel, possibly due to a higher cooling effect from DEE vaporisation and retarded dynamic fuel injection due to its higher compressibility. However, the DEE blend fuelled engine performance was comparable to baseline diesel.

Diesel engines are lucrative in terms of high thermal efficiency and low specific fuel consumption. The major drawbacks of these engines are high NOx and particulate matter (PM) emissions due to heterogeneous combustion. In the current emissions norms (BS-VI), a limit for particle number concentration is also introduced. There are few numerical studies investigating the soot particle size and number characteristics at different engine operating conditions. In this work, a parametric numerical study is conducted to investigate the effect of engine operating parameters on PM characteristics such as number density, size, and volume fraction. Simulations were performed using the Reynolds Averaged Navier Stokes equation with renormalization group K-ε turbulence model available in ANSYS FORTE CFD software.

The potential for simultaneous reduction of soot and NOx emissions and higher fuel conversion efficiency has already been demonstrated for reactivity-controlled compression ignition (RCCI) engines. The RCCI engine has a relatively higher peak pressure rise rate (PPRR) and cyclic variations compared to the conventional diesel engine. The upper and lower operating load boundaries of the RCCI engine are restricted by higher PPRR and cyclic variations, respectively. The cyclic variations in the air-fuel ratio are one of the main factors which govern the variations in combustion parameters. The cyclic variations in combustion need to be controlled for stable engine operation. The present study estimates the cyclic air-fuel ratio from the measured in-cylinder pressure data for the RCCI engine. The RCCI experiments are performed on a modified single-cylinder compression ignition (CI) engine equipped with a development ECU.

Engine design and selection of fuels for automotive applications are required to minimize noise and exhaust emissions without compromising fuel economy. The knocking combustion investigation is essential as it directly affects the performance and durability as well as the thermal efficiency of the engine. Several fuel additives were suggested in the previous studies to mitigate the knocking combustion in spark ignition (SI) engines. The present study reviews the effect of antiknock fuel additives such as ethanol, methanol, prenol, n-butanol, furan mixtures, etc., on knocking behavior in SI engines. Additionally, this paper aims to present a systematic review of the studies conducted to investigate the effect of EGR on the knocking in SI engines. The EGR is often considered an effective means to suppress knocking in SI engines. The thermal effect of EGR in controlling the knocking is well known as EGR affects the temperature and pressure history of the combustion chamber.

Mixture formation in GDI engine is considered crucial in determining combustion and emissions characteristics, which mainly depend on fuel spray quality. However, spray characteristics change with variations in control parameters such as fuel injection parameters, fuel injection strategy, engine operating conditions, and fuel properties. Growing research interest in the use of methanol as an additive with gasoline has motivated the need for deeper investigations of spray characteristics of these fuels. Although, it can be noted that sufficient literature is available in the area of spray characterization under several independent influencing factors, however, comparative analysis of gasohol spray behavior under different ambient conditions is hardly studied.

Automotive engines produce pollutant species which has the potential to damage human health as well as the environment. The toxicity potential of these species depends on the concentration, route, and exposure time. Toxicity studies are required in the current scenario due to increased pollution levels by vehicles used for transportation. This study is a review focused on the toxicity analysis of particulate, elemental (particle associated as soot), and organic carbon (organic fraction, PAHs) emission from the internal combustion engine with conventional and alternative fuels like biodiesel and alcohol. The study is focused on the formation, characterization, and quantification of particulate matter, elemental and organic carbon, and their effect on human health. The other part of the study is focused on mutagenicity (mutation in DNA) and cytotoxicity (cell toxicity) of the particulate emitted from the engines.

Cyclic variations are inherent in the combustion of internal combustion engines. However, extreme cyclic combustion variations limit the operation of spark-ignition (SI) engines, particularly at highly lean and diluted charge operation. Lean charge operation is desired due to its expected benefits in fuel efficiency and engine-out NOx and HC emissions. Studies suggested the existence of the low-dimensional deterministic nature of cyclic variations, which is essential from the perspective of designing a high-frequency controller. The lean limit of a SI engine operation may be extended by controlling the deterministic component of cyclic variations to meet the future strict emissions and fuel economy regulations. This paper presents a review of the evolution of the experimental and analytical understanding of cyclic combustion variations of spark-ignition engines.

Petroleum products are used to power internal combustion engines (ICEs). Emissions and depletion of petroleum reserves are important questions that need to be answered to ensure existence of ICEs. Indian Railways (IR) operates diesel locomotives, which emit large volume of pollutants into the environment. IR is looking for an alternative to diesel for powering the Locomotives. Methanol has emerged as a replacement for petroleum fuels because it can be produced from renewable resources as well as from non-renewable resources in large quantities on a commercially viable scale. It has similar/superior physico-chemical properties, which reduce tailpipe emissions significantly. It is therefore necessary to understand the in-cylinder phenomenon in methanol fueled engines before its implementation on a large-scale.

Alternative fuels, coupled with advanced engine technologies, are potential solutions to overcome energy crisis and environmental degradation challenges, that transport sector faces. Methanol has emerged as a potential candidate as an alternate fuel due to adequate availability of indigenous feedstocks, such as coal, biomass, and municipal solid waste (MSW). Policy makers of several countries are focusing on developing roadmap for methanol fueled vehicles, especially in developing countries like China and India. These countries have the largest two-wheeler market globally; therefore, methanol adaptability on 2-wheeler engine becomes important national priority. This study is aimed at feasibility assessment of methanol (M100) fueled two-wheeler engine using simulations. Present study was divided into four different phases.

In the present work, the in-cylinder tumble/swirl flow and its effect on the homogeneity, turbulence, and combustion of methane are investigated in a canted valve engine using ANSYS. The study is focused on the impact of initial swirl and tumble on the charge preparation, turbulent kinetic energy, and combustion of methane. The flow simulation was performed in ANSYS using hybrid mesh for cold flow simulation to study the tumble/swirl flow variation. For combustion simulation, a 2D axisymmetric model was used with an initial swirl and tumble ratio for studying the effect on premixed combustion. The flow simulation was performed for suction and compression to see the variation in the swirl and tumble with crank position and engine speed. The combustion simulation was performed only for compression and power stroke to save the computation time. The results depict that the flow inside the cylinder plays a significant role in the preparation of a homogeneous charge.

In this study, the influence of fuel premixing ratio (PMR) on the performance, combustion, and emission characteristics of dual-fuel operation in the compression ignition (CI) engine have been investigated. For dual fuel operation in CI-engine, two fuels of different reactivity are utilized in the same combustion cycle. In this study, low reactivity fuels (gasoline/butanol) is injected into the intake manifold, and high reactivity fuel (diesel) is directly injected into the cylinder. To operate the conventional CI engine in dual-fuel mode, the intake manifold of the engine was modified and a solenoid based port fuel injector was installed. A separate port fuel injector controller was used for injecting the gasoline or butanol. Suitable instrumentation was used to measure in-cylinder pressure and exhaust gas emissions. Experiments were performed by maintaining the constant fuel energy at different fuel PMR for different engine loads at constant engine speed.

This paper presents the experimental investigation of combustion stability and nano-particle emissions from the CNG-diesel RCCI engine. A modified automotive diesel engine is used to operate in RCCI combustion mode. An open ECU is used to control the low and high reactivity fuel injection events. The engine is tested for fixed engine speed and two different engine load conditions. The tests performed for various port-injected CNG masses and diesel injection timings, including single and double diesel injection strategy. Several consecutive engine cycles are recorded using in-cylinder combustion pressure measurement system. Statistical and return map techniques are used to investigate the combustion stability in the CNG-diesel RCCI engine. Differential mobility spectrometer is used for the measurement of particle number concentration and particle-size and number distribution. It is found that advanced diesel injection timing leading to higher cyclic combustion variations.

Depleting fossil-fuels and increasing harmful emissions by the combustion of fossil fuels in IC engine is a matter of great concern. It is necessary to explore solutions complying with the prevailing emission norms in different sectors. Methanol has the potential amongst all primary alcohols for widespread use in transport sector due to its clean-burning, high octane rating, sources of production like high ash coal, and biomass. The addition of methanol to gasoline can significantly reduce engine-out emissions. Gasoline-Methanol blends (Gasohols) can be used to reduce dependence of the transport sector on fossil fuels. This study deals with investigation of spray characteristics of methanol-gasoline blends as it affects engine performance and emissions characteristics to a great extent.

This study presents the experimental investigation of performance, combustion, gaseous and nano-particle emission characteristics of conventional compression ignition (CI) engine fueled with neat diesel and butanol/diesel blends. The experiments were conducted for neat diesel, 10%, 20% and 30% butanol/diesel blend on the volume basis at different engine loads. Combustion characteristics were investigated on the basis of in-cylinder pressure measurement and heat release analysis. The in-cylinder combustion pressure traces were recorded for 2000 consecutive engine combustion cycles for computation of heat release and different combustion parameters. Combustion stability analysis is conducted by analyzing the coefficient of variation of in indicated mean effective pressure (IMEP) and total heat release (THR). Wavelet analysis is also used for analyzing the temporal variations in IMEP data series.

Ethanol fuelled homogenous charge compression ignition engine (HCCI) offers a better alternative to tackle the problems of achieving higher engine efficiency and lower emissions. Numerical simulations were carried out for a HCCI engine fueled with ethanol by stochastic reactor model using newly developed reduced ethanol oxidation mechanism consists of 47 species and 272 reactions. Reduced mechanism used in this study is validated by measured engine cylinder pressure curves and measured ignition delays in constant volume reactors in the previous study. Simulations are conducted for engine speeds ranging from 1000 to 3000 rpm at different intake temperatures (range 365-465 K) by varying the air-fuel ratio. Parametric study for combustion and emission characteristics is conducted and engine maps are developed at most efficient inlet temperatures. The HCCI operating range is defined using combustion efficiency (>85%) and maximum pressure rise rate (<5 MPa/ms).

Fuel atomization and air-fuel mixing processes play a dominant role on engine performance and emission characteristics in a direct injection compression ignition engine. Understanding of microscopic spray characteristics is essential to predict combustion phenomena. The present work investigated near nozzle flow and atomization characteristics of biodiesel fuels in a constant volume chamber. Waste cooking oil, Jatropha, and Karanja biodiesels were applied and the results were compared with those of conventional diesel fuel. The tested fuels were injected by a solenoid injector with a common-rail injection system. A high-speed camera with a long distance microscopic lens was utilized to capture the near nozzle flow. Meanwhile, Sauter mean diameter (SMD) was measured by a phase Doppler particle analyzer to compare atomization characteristics.

Premixed charge compression ignition (PCCI) combustion is an advanced combustion technique, which has the potential to be operated by alternative fuels such as alcohols. PCCI combustion emits lower oxides of nitrogen (NOx) and particulate matter (PM) and results thermal efficiency similar to conventional compression ignition (CI) engines. Due to extremely high heat release rate (HRR), PCCI combustion cannot be used at higher engine loads, which make it difficult to be employed in production grade engines. This study focused on development of an advanced combustion engine, which can operate in both combustion modes such as CI combustion as well as PCCI combustion mode. This Hybrid combustion system was controlled by an open engine control unit (ECU), which varied the fuel injection parameters for mode switching between CI and PCCI combustion modes.

In this study, macroscopic spray characteristics of Waste cooking oil (WCO), Jatropha oil, Karanja oil based biodiesels and baseline diesel were compared under simulated engine operating condition in a constant volume spray chamber (CVSC). The high pressure and high temperature ambient conditions of a typical diesel engine were simulated in the CVSC by performing pre-ignition before the fuel injection. The spray imaging was conducted under absence of oxygen in order to prevent the fuels from igniting. The ambient pressure and temperature for non-evaporating condition were 3 MPa and 300 K. Meanwhile, the spray tests were performed under the ambient pressure and temperature of 4.17 MPa and 804 K under evaporating condition. The fuels were injected by a common-rail injection system with injection pressure of 80 MPa. High speed Mie-scattering technique was employed to visualize the evaporating sprays.