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Homogeneous charge compression ignition (HCCI) engines are attracting attention as next-generation internal combustion engines mainly because of very low NOx and PM emission potential and excellent thermal efficiency. Particulate emissions from HCCI engines have been usually considered negligible however recent studies suggest that PM number emissions from HCCI engines cannot be neglected. This study is therefore conducted on a modified four cylinder diesel engine to investigate this aspect of HCCI technology. One cylinder of the engine is modified to operate in HCCI mode for the experiments and port fuel injection technique is used for preparing homogenous charge in this cylinder. Experiments are conducted at 1200 and 2400 rpm engine speeds using gasoline, ethanol, methanol and butanol fuels. A partial flow dilution tunnel was employed to measure the mass of the particulates emitted on a pre-conditioned filter paper.

Homogeneous Charge Compression Ignition (HCCI) offers great promise for excellent fuel economy and extremely low emissions of NOx and PM. HCCI combustion lacks direct control on the "start of combustion" such as spark timing in SI engines and fuel injection timing in CI engines. Auto ignition of a homogeneous mixture is very sensitive to operating conditions of the engine. Even small variations of the load can change the timing from "too early" to "too late" combustion. Thus a fast combustion phasing control is required since it sets the performance limitation of the load control. Crank angle position for 50% heat release is used as combustion phasing feedback parameter. In this study, a dual-fuel approach is used to control combustion in a HCCI engine. This approach involves controlling the combustion heat release rate by adjusting fuel reactivity according to the conditions inside the cylinder. Two different octane fuels (methanol and n-heptane) are used for the study.

Laser is emerging as a strong contender as an alternative ignition source for internal combustion (IC) engines. Short laser pulses of few nanoseconds duration delivered by a Q-switched laser are focused by a lens inside the engine cylinder containing combustible fuel-air mixture. If the peak intensity at the focal point exceeds threshold intensity level, breakdown of combustible gases occurs, which leads to plasma formation. If the energy of the spark generated by plasma is high enough, the mixture ignites. In this investigation, laser ignition (LI) was performed in a single cylinder engine at constant speed and wide open throttle conditions using CNG as fuel. Combustion behavior was recorded using a high speed data acquisition system. For laser ignition of the engine, a laser spark plug was designed and manufactured. Laser spark plug consists of combination of lenses and optical windows.

Indian Railways have a fleet of high-horsepower diesel-electric locomotives rated at 2310 kW. These high horsepower diesel-electric locomotives have evolved from original design of 1940 kW locomotives. Adoption of new design turbochargers was essential for this upgrading efforts and a series of new design turbochargers were evaluated on the engine test-bed before their use on the diesel locomotives. The objective was to increase engine power output, improve fuel efficiency and limit thermal loading. Test-bed evaluation of different turbochargers was carried out for comparing five different turbochargers. Each turbocharger had different size nozzle ring, diffuser, turbine blade assembly, impeller and inducer. The compressor maps of turbochargers were used to plot the engine load lines and to calculate surge margins. The tests involved measuring critical parameters for various combinations of engine speed and load for every turbocharger.

Use of alternative fuels, and reduction of particulate and NOx emissions are major challenges for making diesel engines environmentally benign. Measures adopted for reducing gravimetric particulate emissions necessarily always do not reduce particulate number concentration, which is strongly related with adverse health effects. Current emission norms in some parts of the world limit particulate number concentration along with particulate mass. In this scenario, it becomes important to investigate effect of fuel injection parameters and fuel injection strategies such as pilot injections on particulate size-number distribution. A single cylinder research engine is used to evaluate the effect of different fuel injection strategies and injection timings (for pilot and main injections) on particulate size-number distribution and total particulate numbers.

Homogeneous charge compression ignition (HCCI) is an advanced combustion concept that is developed as an alternative to diesel engines with higher thermal efficiency along with ultralow NOx and PM emissions. To study the performance of this novel technique, experiments were performed in a two cylinder engine, in which one cylinder is modified to operate in HCCI mode while other cylinder operates in conventional CI mode. The quality of homogeneous mixture of air and fuel is the key feature of HCCI combustion. Low volatility of diesel is a major hurdle in achieving HCCI combustion because it is difficult to make a homogeneous mixture of air and fuel. This problem is resolved by external mixture preparation technique in uses a dedicated diesel vaporizer with an electronic control system. All the injection parameters such as fuel quantity, fuel injection timing, injection delay etc., are controlled by the injection driver circuit.

Adverse health effects of particulate matter (PM) originating from diesel engine exhaust are largely attributed to the complex chemical composition of the exhaust species. This study was set out to characterize particulate emissions from a Euro-III-compliant modern automotive common rail direct injection (CRDI) sports utility vehicle (SUV) diesel engine operated at different loads at rated engine speed (1800 rpm), employing diesel and 20% biodiesel blends (B20) produced from Karanja oil. This study is mainly divided into two main sections, first one includes the gravimetric analysis in order to assess the amount of Benzene Soluble Organic Fraction (BSOF) and trace metals using Inductively Coupled Plasma-Optical Emission Spectrometer (ICPOES). The second section includes real-time measurements for Organic Carbon (OC), Elemental Carbon (EC) and total particle-bound Polycyclic Aromatic Hydrocarbons (PAHs).

Diesel engines are very efficient prime movers in their power range. Fuel is directly injected into the combustion chamber. Performance and emission characteristics of diesel engines are highly influenced by the fuel spray parameters and atomization of the injected fuel. As the emission regulations become stringent, it is very important to optimize the combustion in internal combustion engines for different fuels including alternative fuels. Spray visualization using optical techniques play a very important role to analyze macroscopic spray parameters and fuel atomization behavior. In the present experimental study, an important alternative CI engine fuel, Karanja oil and its blends with diesel have been investigated for their spray parameters and fuel atomization relative to mineral diesel. These parameters are different for the two fuels because of difference in the viscosity and density of the fuels.

The homogeneous charge compression ignition (HCCI) combustion process is capable of providing both high ‘diesel-like’ efficiencies and very low NOx and particulate emissions. However, among several technical challenges, controlling the combustion phasing, particularly during transients is a major issue, which must be resolved to exploit its commercial applications. This study is focused on the experimental investigations of behavior of combustion timing and other combustion parameters during startup and load transients. The study is conducted on a gasoline fuelled HCCI engine by varying intake air temperature and air-fuel ratio at different engine speeds. Port fuel injection technique is used for preparing homogeneous mixture of gasoline and air. For fueling startup transient test, fuel injection was turned off, and the engine was motored for several minutes until the fire-deck, intake and exhaust temperatures stabilized.

New combustion concepts developed in internal combustion engines such as homogeneous charge compression ignition (HCCI) have attracted serious attention due to the possibilities to simultaneously achieve higher efficiency and lower emissions, which will impact the environment positively. The HCCI combustion concept has potential of ultra-low NOX and particulate matter (PM) emission in comparison to a conventional gasoline or a diesel engine. Environmental Legislation Agencies are becoming increasingly concerned with particulate emissions from engines because the health and environmental effects of particulates emitted are now known and can be measured by sophisticated instruments. Particulate emissions from HCCI engines have been usually considered negligible, and the measurement of mass emission of PM from HCCI combustion systems shows their negligible contribution to PM mass. However some recent studies suggest that PM emissions from HCCI engines cannot be neglected.

Poor oxidation stability is the central problem associated with the commercial acceptance of the biodiesel. The EU standard (EN14214) specifies a minimum value of 6 h for biodiesel induction period at 110°C, measured with Rancimat instrument. Most of the freshly prepared biodiesel generally have lower induction periods than prescribed by the standards. Anti-oxidants are therefore added to enhance the oxidation/ storage stability of biodiesel. Oxidation is an exothermic process, and the reaction heat evolved makes it possible to use thermo gravimetric analysis (TGA). In the present study, the oxidation stability of methyl esters derived from Karanja oil and Neem oil, stabilized with anti-oxidant pyrogalol (PY) was studied by DSC. Onset temperature of freshly prepared Karanja biodiesel (KOME) and Neem biodiesel (NOME) was observed to be 148 and 153°C respectively. The stability increases with increasing anti-oxidant dosage.

Mono alkyl esters of long-chain fatty acids derived from renewable lipid feedstock, such as vegetable oils or animal fats, also known as biodiesel are well positioned to replace mineral diesel. The outstanding technical problem with biodiesel is that it is more susceptible to oxidation owing to its exposure to oxygen present in the air and high temperature. This happens mainly due to the presence of varying numbers of double bonds in the free fatty acid molecules. The chemical reactivity of esters can therefore be divided into oxidative and thermal instability, which can be determined by the amount and configuration of the olefinic unsaturation in the fatty acid chains. Many of the plant-derived fatty oils contain polyunsaturated fatty acids that are more prone to oxidation. Increasing production of biodiesel from vegetable oils (edible) places strain on food production, availability and price and leads to food versus fuel conflict.

Due to the increasingly stricter emission legislations and growing demand for lower fuel consumption, there have been significant efforts to improve combustion efficiency, while satisfying the emission requirements. Homogenous Charge Compression Ignition (HCCI) combustion offers significant efficiency improvements compared to conventional gasoline engines. However, due to the nature of HCCI, fully homogeneous charge HCCI combustion can be realized only in a limited operating range. Control of HCCI engines to obtain the desirable operation requires understanding of how different charge variables influence the cyclic variations in HCCI combustion. Under certain operating conditions, HCCI engines exhibit large cyclic variations in ignition timing. Cyclic variability ranging from stochastic to deterministic patterns can be observed. One important design goal for engine development is to minimize cyclic variability.

The world energy demand has witnessed uncertainties in two dimensions. The scarcity and depletion of conventional petroleum sources are causes of great concern worldwide. Combustion of fossil fuels has led to unprecedented rise in the global CO2 level, leading to global warming. Therefore, efforts are underway in several countries to search for suitable alternative fuels that are environment friendly. Vegetable oils of non-edible nature are such alternative fuels, which can form part of potential solution. Vegetable oils, due to their agricultural origin, are able to reduce CO2 emissions to the atmosphere along with import substitution of petroleum products In the present research, experiment were designed to study the effect of reducing Neem oil's high viscosity by increasing the fuel temperature and thereby its effect on combustion and emission characteristics of the engine.

Environmental concerns have increased significantly world over in the past decade. Regulatory agencies are becoming increasingly concerned with particulate emissions as the health and environmental effects are getting understood better due to rapid development in instrumentation. Biodiesel is one of the most promising alternative diesel fuels, which is getting global acceptability among the automotive/ engine manufactures as well as users due to numerous benefits it offers over the conventional diesel. While much of literature is available on particulate emitted by diesel fuelled engine, little is known by particulate emissions from biodiesel fuelled compression ignition (CI) engine. This study concentrates on the characterization of particulate emissions from mineral diesel vis-à-vis biodiesel (B100) and its optimum blend (20%, B20) with mineral diesel.

The development of vehicles continues to be determined by increasingly stringent emissions standards including CO2 emissions and fuel consumption. To fulfill the simultaneous emission requirements for near zero pollutant and low CO2 levels, which are the challenges of future powertrains, many research studies are currently being carried out world over on new engine combustion process, such as Controlled Auto Ignition (CAI) for gasoline engines and Homogeneous Charge Compression Ignition (HCCI) for diesel engines. In HCCI combustion engine, ignition timing and combustion rates are dominated by physical and chemical properties of fuel/air/residual gas mixtures, boundary conditions including ambient temperature, pressure, and humidity and engine operating conditions such as load, speed etc.

Vegetable oils have energy content suitable to be used as compression ignition (CI) engine fuel. However, several operational and durability problems of using straight vegetable oils in CI engines are reported in the literature, which are primarily caused by their higher viscosity and low volatility compared to mineral diesel. The viscosity can be brought in acceptable range by (i) chemical process of transesterification, (ii) blending of oil with mineral diesel or (iii) by heating the vegetable oil using exhaust gas waste heat. Reduction of viscosity by blending or exhaust gas heating saves the chemical processing cost of transesterification. Present experimental investigations were carried out for evaluating combustion, performance and emission behavior of Jatropha oil blends in unheated conditions in a direct injection CI engine at different load and constant engine speed (1500 rpm).

Biodiesel is mono alkyl ester derived from vegetable oils through transesterification reaction and can be used as an alternative to mineral diesel. In the present research, methyl ester of rice-bran oil (ROME) is produced through transesterification of rice-bran oil using methanol in presence of sodium hydroxide (NaOH) catalyst. Various properties like viscosity, density, flash point, calorific value of the biodiesel thus prepared are characterized and found comparable to diesel. On the basis of previous research for performance, emission and combustion characteristics, a 20% blend of ROME (B20) was selected as optimum biodiesel blend for endurance test. Endurance test of 100 hours was conducted on a medium duty direct injection transportation diesel engine. Tests were conducted under predetermined loading cycles in two phases: engine operating on mineral diesel and engine fuelled with 20% biodiesel blend.

Vegetable oils are produced from numerous oil seed crops. While all vegetable oils have high energy content, most require some processing to assure safe use in internal combustion engines. Some of these oils already have been evaluated as substitutes for diesel fuels. However, several operational and durability problems of using straight vegetable oils in diesel engines are reported in the literature, caused by of their higher viscosity and low volatility compared to mineral diesel. In the present research, experiments were designed to study the effect of reducing Jatropha oil's viscosity by blending it with mineral diesel and thereby eliminating the effect of high viscosity and poor volatility on combustion characteristics of the engine. Experimental investigations have been carried out to examine the combustion characteristics of an indirect injection transportation diesel engine running with diesel, and jatropha oil blends with diesel.

Biodiesel (fatty acid methyl ester) is a non-toxic and biodegradable alternative fuel that is obtained from renewable sources. A major hurdle in the commercialization of biodiesel from virgin oil, in comparison to petroleum-based diesel, is its cost of production, primarily the raw material cost. Used cooking oils or waste cooking oils are economical sources for biodiesel production, which can help in commercialization of biodiesel. However, the products formed during cooking/frying (such as free fatty acids and various polymerized triglycerides) affect the transesterification reaction and the biodiesel properties. In present experimental investigations, wastecooking oil obtained from restaurant was used to produce biodiesel through transesterification process and the chemical kinetics of biodiesel production was studied. Biodiesel was blended with petroleum diesel in different proportions.