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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.

To meet the target of the CO2 regulations, it is mandatory to replace high-carbon fossil fuels with low-carbon fuels. Diesel/Natural Gas (NG) reactivity-controlled compression ignition (RCCI) can reduce CO2 emission, which stratifies two types of fuels with different reactivity. And also, RCCI produces less NOx and particulate matter emissions by reducing the in-cylinder temperature. However, RCCI must still be enhanced in terms of the thermal and combustion efficiencies at low and medium loads. In this work, a modified piston geometry was applied to improve the RCCI combustion. The piston geometry was designed to minimize heat loss and reduce flame quenching in an RCCI engine. Experiments were conducted using a single-cylinder engine with a displacement volume of 1,000 cc. Diesel was directly injected into the cylinder, and NG was fed through the intake port.

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.

In marine or stationary engines, consistent engine performance must be guaranteed for long-haul operations. A dual-fuel combustion strategy was used to reduce the emissions of particulates and nitrogen oxides in marine engines. However, in this case, the combustion stability was highly affected by environmental factors. To ensure consistent engine performance, the in-cylinder pressure measured by piezoelectric pressure sensors is generally measured to analyze combustion characteristics. However, the vulnerability to thermal drift and breakage of sensors leads to additional maintenance costs. Therefore, an indirect measurement via a reconstruction model of the in-cylinder pressure from engine block vibrations was developed. The in-cylinder pressure variation is directly related to the block vibration; however, numerous noise sources exist (such as, valve impact, piston slap, and air flowage).

The application of dual-fuel combustion in the freight transportation sectors has received considerable attention due to the capability of achieving higher fuel efficiency and less pollutant emissions than the conventional diesel engines. In this study, high-speed flame visualization was used to investigate the phenomena of natural gas/diesel dual-fuel combustion in a single-cylinder heavy-duty engine with optical access. To implement diverse fuel blending conditions, diesel injection timing and natural gas substitution ratio were varied under constant fuel energy input. A novel flame regime separation method was implemented based on color segmentation in HSV color space to characterize the spatial distributions of premixed and non-premixed flame regimes. Flame images for larger natural gas substitution showed a significant reduction in the non-premixed flame regime accompanied by flame propagation along the vaporized diesel sprays.

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.

The rising concerns of emissions have put enormous strain on the automotive industry. Industry is, therefore looking for next-generation engines and advanced combustion technologies with ultra-low emissions and high efficiency. To achieve this, more insights into the combustion and pollutant formation processes in IC engines is required. Since conventional measures have not been insightful, in-situ measurement of combustion and pollution formation through optical diagnostics is being explored. Gaining full optical access into the diesel engine combustion chamber is a challenging task. The late-compression flow dynamics is not well understood due to limited access into the engine combustion chamber. These flow structures contribute immensely to fuel-air mixing and combustion. The objective of this study is to understand the role of combustion chamber design on vertical plane air-flow structures.

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.

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.

Lean stratified combustion is a mean to dilute the fuel-air mixture leaner than stoichiometric ratio, by using stratification of fuel gradient in a spark ignition engine. Under the lean stratified combustion, differed from the stoichiometric homogeneous charge combustion, flame could propagate through extremely rich air-fuel mixture, while the global air-fuel mixture is under lean condition. The rich mixture causes considerable amount of particulate matter, but, due to large effect of efficiency improvement, the attractive point is on fuel economy compare to homogeneous charge SI combustion. The easiest way to reduce particulate matter is changing fuel to gaseous hydrocarbon, to minimize evaporating and mixing period.

Lean stratified combustion shows high potential to reduce fuel consumption because it operates without the intervention of a throttle valve. Despite its high fuel economy potential, it emits large amounts of particulate matter (PM) because the locally rich mixture is formed at the periphery of a spark plug. Furthermore, the combustion phasing angle is not realized at MBT ignition timing, which can bring high work conversion efficiency. Since PM emission and work conversion efficiency are in a trade-off relation, this research focused on reducing PM emission through achieving high work conversion efficiency. Two intake air control strategies were examined in this research; throttle operation and late intake valve closing (LIVC). The experiment was conducted in a single cylinder spray-guided direct injection spark ignition (SG-DISI) engine with liquefied petroleum gas (LPG). The injected fuel amount was fixed so as to investigate the effect of each strategy.

Most internal combustion engine makers have adopted after-treatment systems, such as selective catalytic reduction (SCR), diesel particulate filter (DPF), and diesel oxidation catalyst (DOC), to meet emission regulations. However, as the emission regulations become stricter, the size of the after-treatment systems become larger. This aggravates the price competitiveness of engine systems and causes fuel efficiency to deteriorate due to the increased exhaust pressure. Dual-fuel premixed charge compression ignition (DF-PCCI) combustion, which is one of the advanced combustion technologies, makes it possible to reduce nitrogen oxides (NOx) and particulate matter (PM) during the combustion process, while keeping the combustion phase controllability as a conventional diesel combustion (CDC). However, DF-PCCI combustion produces high amounts of hydrocarbon (HC) and carbon monoxide (CO) emissions due to the bulk quenching phenomenon under low load conditions as a huddle of commercialization.

Knocking combustion limits the downsized gasoline engines’ potential for improvement with regard to fuel economy. The high in-cylinder pressure and temperature caused by the adaptation of a turbocharger aggravates the tendency of the end-gas to autoignite. Thus, the knocking combustion does not allow for further advancing of the combustion phase. In this research, the effects of the ignition and valve timings on knocking combustion were investigated under steady-state conditions. Moreover, the optimal ignition and valve timings for the transient operations were derived with the aim of a greater fuel economy improvement, based on the steady-state analysis. A 2.0 liter turbocharged gasoline direct injection engine with continuously variable valve timing (CVVT), was utilized for this experiment. 2, 10, and 18 bar brake mean effective pressure (BMEP) load conditions were used to represent the low, medium, and high load operations, respectively.

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.

The spray and combustion of diesel fuel were investigated to provide a better understanding of the evaporation and combustion process under the simulated cold-start condition of a diesel engine. The experiment was conducted in a constant volume combustion chamber and the engine cranking period was selected as the target ambient condition. Mie scattering and shadowgraph techniques were used to visualize the liquid- and vapor-phase of the fuel under evaporating non-combustion conditions (oxygen concentration=0%). In-chamber pressure and direct flame visualization were acquired for spray combustion conditions (oxygen concentration=21%). The fuel was injected at an injection pressure of 30 MPa, which is the typical pressure during the cranking period.

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.

This paper investigated the influence of the injector nozzle geometry on fuel consumption and exhaust emission characteristics of a light-duty diesel engine with 250 MPa injection. The engine used for the experiment was the 0.4L single-cylinder compression ignition engine. The diesel fuel injection equipment was operated under 250MPa injection pressure. Three injectors with nozzle hole number of 8 to 10 were compared. As the nozzle number of the injector increased, the orifice diameter decreased 105 μm to 95 μm. The ignition delay was shorter with larger nozzle number and smaller orifice diameter. Without EGR, the particulate matter(PM) emission was lower with larger nozzle hole number. This result shows that the atomization of the fuel was improved with the smaller orifice diameter and the fuel spray area was kept same with larger nozzle number. However, the NOx-PM trade-offs of three injectors were similar at higher EGR rate and higher injection pressure.

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.

Biodiesel made from Jatropha oil by transesterification process has viscosity and other important physical properties comparable to mineral diesel hence it can be used as an alternate fuel in conventional diesel engines. It is important to investigate the spray characteristics of biodiesel because emissions from the engines are dependent on fuel atomization process and resulting fuel-air mixing. This study focuses on the Jatropha biodiesel spray investigations using Phase Doppler Interferometry (PDI) for measurement of various microscopic spray parameters such as Sauter mean diameter (SMD) and spray droplet size and velocity distributions. The spray and engine experiments were carried out for Jatropha biodiesel (JB100) and their 20% blends (JB20) with mineral diesel as baseline. Fuel injection pressure during the spray experiments was maintained at 200 bars for all tests, quite similar to small horse power agricultural engines, and the fuel injection quantity was varied.