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Due to the demands of the market to increase efficiency and power density of large MW size gas engines, existing ignition schemes are gradually reaching their limits. These limitations initially triggered the development of laser ignition as an effective alternative, first only for gas engines and now for a much wider range of internal combustion engines revealing a number of immediate advantages like no electrode erosion or flame kernel quenching. Within this broad range investigation, laser plasmas were generated by ns Nd-YAG laser pulses and characterized by emission and Schlieren diagnostic methods. High-pressure chamber experiments with lean hydrogen- air mixtures were successfully performed and allowed the determination of essential parameters like minimum pulse energies at different ignition pressures and temperatures as well as at variable fuel air compositions. In this way, relevant parameters were acquired allowing estimation/ development of future laser ignition systems.

The scarce and rapidly depleting conventional petroleum resources have promoted research for alternative fuels for internal combustion engines. Among various possible options, fuels derived from vegetable oils present promising “greener” substitutes for fossil fuels. Vegetable oils due to their agricultural origin are able to reduce net CO2 emissions to the atmosphere along with import substitution of petroleum products. However, several operational and durability problems of using straight vegetable oils in diesel engines reported, which are because 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 with mineral diesel, thereby eliminating its effect on combustion characteristics of the engine. In the present experimental research, vegetable oil (Jatropha Curcus) was used as substitute fuel.

The Homogeneous charge compression ignition (HCCI) is the third alternative for the combustion in the reciprocating engine. HCCI a hybrid of well-known spark ignition (SI) and compression ignition (CI) engine concepts and has potential of combining the best features of both. A two cylinder, four stroke, direct injection diesel engine was modified to operate one cylinder on the compression ignition by detonation of homogeneous mixture of ethanol and air. The homogeneous mixture of the charge is prepared by port injection of ethanol in the preheated Intake air. This study presents results of experimental investigations of HCCI combustion of ethanol at intake air temperature of 120°C and at different air-fuel ratios. In this paper, the combustion parameters, pressure time history, rate of pressure rise, rate of heat release, mean temperature history in the combustion chamber is analyzed and discussed.

The development of more efficient and powerful internal combustion engines requires the use of new and advanced engine technologies. These advanced engine technologies and emission requirements for meeting stringent global emission norms have increased the power densities of engine leading to downsizing. In all these engines, cylinder head and liner are normally cooled but the piston is not cooled, making it susceptible to disintegration/ thermal damage. Material constraints restrict the increase in thermal loading of piston. High piston temperature rise may lead to engine seizure because of piston warping. So pistons are additionally cooled by oil jet impingement from the underside of the piston in heavy duty diesel engines. However, if the temperature at the underside of the piston, where the oil jet strikes the piston, is above the boiling point of the oil, it may contribute to the mist generation.

This study was set out to characterize particulate emissions from diesel engines in terms of poly aromatic hydrocarbon emissions and Benzene Soluble Organic Fraction. The characteristics of DPM vary with engine operating conditions, quality of fuel and lubricants being used. Hence the diesel exhaust for the purpose of toxicity characterization needs to be studied for Organic Matter in terms of Poly Aromatic Hydrocarbon (PAH) and Benzene Soluble Fraction (BSF). Therefore, the objectives of the present research are to characterize the diesel exhaust particulate matter for the above parameters under varying engine operating conditions/loads. Six PAHs, namely Chrysene, Benzo (k) Flouranthene, Benzo (a) Pyrene, Dibenzo (a, h) Anthracene, Benzo (g,h,i) Perylene and Indenopyrene were analyzed on High Pressure Liquid Chromatography (HPLC). PAH concentrations in the particulates of Mahindra DI engine were affected by engine loads.

The methyl esters of vegetable oils, known as biodiesel are becoming increasingly popular because of their low environmental impact and potential as a green alternative fuel for diesel engine and they would not require significant modification of existing engine hardware. Methyl ester of rice bran oil (ROME) is derived through transesterification process. Previous research has shown that ROME has comparable performance, lower bsfc in comparison to diesel. There was reduction in the emissions of CO, HC, and smoke but NOx emissions increased. Experimental investigations have been carried out to examine the combustion characteristics in a direct injection transportation diesel engine running with diesel, and 20% blend of rice bran methyl ester with diesel.

Thermal loading of diesel engine pistons has increased dramatically in recent years due to applications of various advanced technologies to meet low emission and high power requirements. Control of piston temperatures by cooling of pistons has become one of the determining factors in a successful engine design. The pistons are cooled by oil jets fired at the underside from the crankcase. Any undesirable piston temperature rise may lead to engine seizure because of piston warping. However, if the temperature at the underside of the piston, where oil jet strikes the piston, is above the boiling point of the oil being used, it may contribute to the mist generation. This mist significantly contribute to the non-tail pipe emissions in the form of unburnt hydrocarbons (UBHC's), which has unfortunately not been looked into so seriously, as the current stress of all the automobile manufacturers is on meeting the tail pipe emission legislative limits.

This paper deals with the evaluation of steel cap pistons for up-gradation of diesel electric locomotives for Indian Railways. These engines are four stroke, medium speed compression ignition engines (CR 12.5: 1) with output of 121 kW per cylinder on series 1 and 167 kW per cylinder on series 2. The series 1 engine uses single piece aluminum pistons, with rating of 0.295 kW/cm2 of piston crown area. A higher version of the series 1 engine with higher fuel efficiency and improvement in lube oil consumption was developed. As part of this improvement program, a composite steel cap piston with forged aluminum skirt was used. The whole engine up-gradation kit including the higher capacity turbocharger, higher fuel delivery pressure fuel pump, modified cam shaft, larger after-cooler along with the steel cap piston were evaluated for performance.

This experimental study was undertaken to investigate the use of vegetable oil derivatives to substitute mineral diesel fuel. Straight vegetable oils pose some problems like injector coking, carbon deposits etc., when used as a fuel in an engine. These problems are due to high viscosity, low volatility and polyunsaturated character of vegetable oils. Transesterified vegetable oil derivative called “biodiesel” appear to be most convenient way of utilizing vegetable oil as a substitute fuel in diesel engines. In present investigation, rice bran oil (non-edible) was transesterified to methyl ester and reaction conditions for transeterifcation process for rice bran oil were optimized. Various properties like viscosity, density, flash point of the biodiesel thus prepared are comparable to diesel and found to be in acceptable range as per ASTM norms (ASTM D6751). Experimental investigations were carried out on a four stroke, four cylinders, transportation DI diesel engine.

Several experimental studies have been conducted for evaluating coefficient of friction and wear in simulated engine conditions using a piston ring segment and a liner piece rubbing against each other in reciprocating mode under load and lubricated conditions. In the present experimental investigation, a non-firing engine simulator has been developed in order to simulate engine conditions to a much closer extent. This machine can operate at similar linear speed, stroke, and load and can simulate almost similar engine operating conditions except firing pressures. This machine can also be used for comparing liners with different surface properties and the effects of surface texture on wear and oil consumption. One cylinder liner has been used for experimentation and the wear and surface properties behaviour were evaluated at several locations in the liner. Surface profile, roughness parameters are evaluated at several locations in the liner and at the top compression ring.

Thermal loading of diesel engine pistons has increased dramatically in recent years due to applications of various technologies to meet low emission and high power requirements. Control of piston temperatures by cooling of these pistons has become one of the determining factors in a successful engine design. The pistons are cooled by oil jets fired at the underside from the crankcase. Any undesirable piston temperature rise may lead to engine seizure due to piston warping. However, if the temperature at the underside of the piston, where the oil jet strikes the piston, is above the boiling point of the oil being used, it may contribute to the mist generation. This mist may significantly contribute to the non-tail pipe emissions in the form of unburnt hydrocarbons (UBHC). The problem of non-tail pipe emissions has unfortunately not been looked into so seriously, as the current stress of all the automobile manufacturers is on meeting the tail -pipe emission legislative limits.

Increased environmental awareness and depletion of fossil fuel resources are driving industry to develop alternative fuels that are environmentally more acceptable. Vegetable oils are potential alternative fuels. Vegetable oils in India are produced from numerous oil-seed crops. While all vegetable oils have high energy content, most require some processing to ensure safe usage in internal combustion engines. Most detrimental properties of oils are its high viscosity, low volatility and polyunsaturated character. The most widely used method is to convert vegetable oils into biodiesel. Biodiesel fuels are primary esters, which are produced by transesterifcation of vegetable oils. Several vegetable oil esters have been investigated so far in different parts of the world and found suitable to be used in diesel engines.