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Adopting a low compression ratio (LCR) is a viable approach to meet the stringent emission regulations since it can simultaneously reduce the oxides of nitrogen (NOx) and particulate matter (PM) emissions. However, significant shortcomings with the LCR approach include higher unburned hydrocarbon (HC) and carbon monoxide (CO) emissions and fuel economy penalties. Further, poor combustion stability of LCR engines at cold ambient and part load conditions may worsen the transient emission characteristics, which are least explored in the literature. In the present work, the effects of implementing the low compression ratio (LCR) approach in a mass-production light-duty vehicle powered by a single-cylinder diesel engine are investigated with a major focus on transient emission characteristics.

Mass-production single-cylinder engines are generally not turbocharged due to pulsated exhaust flow. Hence, about one-third of the fuel chemical energy is wasted in the engine exhaust. To extract the exhaust energy and boost the single-cylinder engines, a novel supercharging with a turbo-compounding strategy is proposed in the present work, wherein an impulse turbine extracts energy from the pulsated exhaust gas flow. Employing an impulse turbine for a vehicular application, especially on a single-cylinder engine, has never been commercially attempted. Hence, the design of the impulse turbine assumes higher importance. A nozzle, designed as a stator part of the impulse turbine and placed at the exhaust port to accelerate the flow velocity, was included as part of the layout in the present work. The layout was analyzed using the commercial software AVL BOOST. Different nozzle exit diameters were considered to analyze their effect on the exhaust back pressure and engine performance.

A diesel engine was operated with karanja oil, bio-diesel obtained from karanja oil (BDK) and diesel as pilot fuels while LPG was used as primary fuel. LPG supply was varied from zero to the maximum value that the engine could tolerate. The engine output was kept at different constant levels of 25%, 50%, 75% and 100% of full load. The thermal efficiency improved at high loads. Smoke level was reduced drastically at all loads. CO and HC levels were reduced at full load. There was a slight increase in the NO level. Combustion parameters indicated an increase in the ignition delay. Peak pressure and rate of pressure rise were not unfavorably affected. There was an increase in the peak heat release rate with LPG induction. The amount of LPG that could be tolerated with out knock at full load was 49%, 53% and 61% on energy basis with karanja oil, BDK and diesel as pilots.

Emulsification of biodiesel with water aids in reducing oxides of nitrogen (NOx) and smoke emissions simultaneously whilst improving the engine performance. However, widespread commercial applications of biodiesel-water emulsions require cost-effective surfactants that result in stable emulsions to avoid the corrosive effects of water at high temperatures prevailing in the engine combustion systems. The current investigation explored the effect of adding water to biodiesel at 6 and 12% by weight. A novel, cost-effective surfactant Polyglycerol Polyricinoleate (PGPR), was used to stabilize the emulsions. A magnetic stirrer with a heating facility was utilized to prepare biodiesel-water emulsions that were stable for over five months. The experiments were carried out on a light-duty diesel engine at a constant rated speed and varying load conditions. The results obtained with the emulsions were compared with neat biodiesel as the reference fuel.

The diesel power train (engine and transmission) is the most significant mass contributor in a three- wheeled vehicle. High idling vibrations from the engine get transmitted to the structure and the body panels through the engine mounts. Isolation of these vibrations by proper design of rubber mounts is the most effective engineering approach to improve ride quality of vehicle. In the present study, a mathematical model of the powertrain and mount system is developed; with the engine and transmission being assumed to behave as a rigid body (6 degrees-of-freedom) and the compliance comes from the mounts. As a first step, the modes and natural frequencies are obtained. Following this the response to unbalanced inertial forces for an excitation frequency range of 20-60 Hz (1200-3600 rpm) has been obtained. The model is validated by comparing its results with results of previous published research work.

Nowadays, Direct Injection Spark Ignition (DISI) engines are very popular because of their lower fuel consumption and exhaust emissions due to lean stratified mixture operation at most of load conditions. In these engines, achieving mixture stratification plays an important role on performance and emission characteristics of the engine. Also, mixture stratification is mainly dependent on in-cylinder flows and air-fuel interaction, which in turn largely dependent on valve configurations. Therefore, understanding them is very much essential in order to improve the engine performance. In this study, a CFD analysis has been carried out on two- and four-valve four-stroke engines to analyze in-cylinder flows and air-fuel interaction at different conditions. The engines specifications considered here are taken from the literature for which experimental data is available. ‘STAR-CD’ software has been used for the CFD analysis. For meshing, polyhedral trimmed cells have been adopted.

For more than a decade there is a progressive demand for fuel efficient and high specific power output engines. Optimization of engine cooling and thermal management is one of the important activities in engine design and development. In the present paper an effort has been made to simulate the heat transfer modes of cylinder block and head for a present 4-stroke air-cooled motorcycle engine. Two and three-dimensional decoupled and conjugate heat transfer analysis has been done with commercially available computational fluid dynamics (CFD) codes. Experimental results are also presented. A complete simulation model has been developed and CFD techniques have been applied to design and optimize air cooling surfaces of cylinder head and block, for an air cooled motorcycle engine. The two dimensional analysis is an easy and fast method to predict fin surface temperature, heat transfer co-efficient and flow velocity.

Nowadays, due to stringent emission regulations, it is imperative to incorporate modeling efforts with experiments. This paper presents the development of a phenomenological model to investigate the effects of various in-cylinder strategies on combustion and emission characteristics of a common-rail direct-injection (CRDI) diesel engine. Experiments were conducted on a single-cylinder, supercharged engine with displacement volume of 0.55 l at different operating conditions with various combinations of injection pressure, number of injections involving single injection and multiple injections with two injection pulses, and EGR. Data obtained from experiments was also used for model validation. The model incorporated detailed phenomenological aspects of spray growth, air entrainment, droplet evaporation, wall impingement, ignition delay, premixed and mixing-controlled combustion rates, and emissions of nitrogen oxides (NOx) and diesel soot.

Gasoline direct injection (GDI) engines are now trending in automobile field because of good fuel economy and low exhaust emissions over their port fuel injection (PFI) counter parts. They operate with a lean stratified mixture in most of conditions. However, their performance is dependent on mixture stratification which in-turn depends on fuel injection pressure, timing and strategy. But, the main challenge to GDI engines is soot and particulate matter (PM) emissions. However, they can be reduced by employing multi-stage fuel injection strategy. Therefore, in the present work, an effort has been made to study the effect of fuel injection parameters on soot emissions of a GDI engine using the CFD analysis. In addition, the study is also extended to evaluate the performance, combustion and other emission characteristics of the engine. First the engine is modelled using the PRO-E software. The geometrical details of the engine are obtained from the literature.

Achieving stable combustion without misfire and knocking is challenging in premixed charge compression ignition (PCCI) especially in small bore, air cooled diesel engines owing to lower power output and inefficient cooling system. In the present study, a single cylinder, air cooled diesel engine used for agricultural water pumping applications is modified to run in PCCI mode by replacing an existing mechanical fuel injection system with a flexible common rail direct injection system. An advanced start of fuel injection (SOI) and exhaust gas recirculation (EGR) are required to achieve PCCI in the test engine. Parametric investigations on SOI, EGR and fuel injection pressure are carried out to identify optimum parameters for achieving maximum brake thermal efficiency. An SOI sweep of 12 to 50 deg. CA bTDC is done and for each SOI, EGR is varied from 0 to 50% to identify maximum efficiency points. It was found that EGR helps in extending the load range from 20 to 40% of rated load.

Over the years, much progress has been made in automotive vehicle technology to achieve high efficiency and clean combustion. Reactivity controlled compression ignition (RCCI) is one of the most widely studied high-efficiency, clean combustion strategies. However, complex dual-fuel injection systems and associated controls, high unburned hydrocarbon (UHC), and carbon monoxide (CO) emissions limit RCCI use in practical applications. Recently, single fuel RCCI strategies are gaining more attention as the above shortcomings are effectively addressed. Homogeneous charge with direct injection (HCDI) is a single fuel RCCI strategy that results in high thermal efficiency and lower UHC and CO emissions. In HCDI, the port-injected diesel fuel vapour and air are inducted during the intake stroke and ignited with direct-injected diesel fuel near the end of the compression stroke. However, high oxides of nitrogen (NOx) make HCDI less viable for practical applications.

The classical trade-off between NOx and soot emissions from conventional diesel engines has been a limiting factor in meeting ever stringent emission norms. The electronic control of fuel injection in diesel engines emerged as an important strategy for their simultaneous reduction. The high pressure multiple-injection in a common rail direct injection system has been promising in this regard. While, the effects of pilot injection or multiple pulses of CRDI injection schedule on simultaneous reduction of NOx and soot have been widely investigated and reported, the investigations concerning three and more injection pulses have been limited. In this paper, the ability of a predictive model, developed by the authors, in providing optimal multiple-injection schedule is demonstrated through parametric investigations. The effects of pilot and post fuel quantity and dwell between the injection pulses on NOx and soot emissions are discussed.

Cold formed carbon steel C sections are often employed as load carrying structural members in heavy commercial trucks. The cold forming operations employed during the making of these members generate certain amount of residual stresses throughout the sections. As the residual stresses play a significant role in determining the structural behavior of truck frame rail members, a careful assessment of residual stresses resulting from cold forming operation is needed. In the present investigation, residual stresses in frame rail corner sections were numerically predicted with the help of non-linear Finite Element (FE) analysis in ABAQUS and compared with the experimentally measured residual stress values using X-ray diffraction technique. It has been observed that the numerically predicted residual stresses are in agreement with the experimentally measured residual stresses in forming direction.

Premixed Charge Compression Ignition (PCCI) is a promising LTC strategy to reduce NOx and soot emissions without relying on after-treatment devices. One major drawback of PCCI is high HC and CO emissions resulting from fuel-wall impingement due to early injection of diesel. Narrow-angle direct injection (NADI) helps reduce the wall wetting of fuel. But it is effective only at lower loads. At mid and higher loads, it increases soot and CO emissions in small-bore engines due to the formation of fuel-rich pockets in the piston bowl region. This problem is addressed using a split injection strategy in the present work. A 3-D CFD model is developed and validated with experimental data at two load conditions. Simulations are performed using CONVERGE CFD software. Split injection strategies are explored using wide (148 deg) and narrow (88 deg) spray included angles.

Unsaturated methyl esters in biodiesel make it susceptible to oxidation and fuel quality degradation upon long-term storage. It is almost impossible to use biodiesel for commercial applications immediately after production. The lead time between biodiesel production and usage is generally high, causing auto-oxidation and fuel quality degradation. Hence any onsite improvement in fuel quality should be tested with aged biodiesel. To avoid the food versus fuel debate, non-edible oil feedstocks are preferable for producing biodiesel. However, biodiesel from non-edible oil sources has more unsaturated methyl ester constituents. The traditional trade-off between oxides of nitrogen (NOx) and soot emissions in conventional diesel combustion is reduced to a more severe NOx problem with biodiesel. In the present study, NOx mitigation through fuel modifications is studied for oxidized biodiesel produced from a non-edible oil, Karanja.

The distribution of fuel-air mixture inside the engine cylinder strongly influences the combustion process. Planar laser-induced fluorescence (PLIF) is commonly used for fuel distribution measurement, however, it is mostly reported on moderate- to large-sized engines. In the present work, PLIF is applied to measure the fuel distribution inside the cylinder of a small, four-stroke, port-fuel-injection (PFI), spark-ignition engine with displacement volume of 110 cm3. Iso-octane was used as the base fuel, and 3-pentanone (15% by volume) was added as a fluorescent tracer in the base fuel. The effect of equivalence ratio, considering ϕ = 1.2, 1.0, and 0.8, on in-cylinder fuel distribution was studied with low throttle opening of 25% at 1200 rpm. PLIF images were recorded at different crank angle degrees during both intake and compression strokes over a swirl measurement plane located at the TDC position.

Engine modelling aims at studying the combustion related phenomenon occurring in Internal Combustion (IC) engines. In this regard, a low dimensional mathematical model using first principles has been developed to study Spark Ignited (SI) engines. The resulting equations are Ordinary Differential Equations (ODE) (for volume, pressure, torque, speed and work done) and Partial Differential Equations (PDEs) for temperature and species conservation equations (fuel, CO, CO2, NO). This model utilizes simplified reaction kinetics for the oxidation of fuel in the combustion chamber. A two-step mechanism for the combustion of fuel and the classical Zeldovich Mechanism are used to predict the amount of NO formed during combustion. The model is solved in FORTRAN using LSODE subroutine (for stiff equations) with lumped parameters for thermal properties and diffusion, and invoking the ideal gas assumption.

Single-cylinder engines in mass production are generally not turbocharged due to the pulsated and intermittent exhaust gas flow into the turbocharger and the phase lag between the intake and exhaust stroke. The present work proposes a novel approach of decoupling the turbine and the compressor and coupling them separately to the engine to address these limitations. An impulse turbine is chosen for this application to extract energy during the pulsated exhaust flow. Commercially available AVL BOOST software was used to estimate the overall engine performance improvement of the proposed novel approach compared to the base naturally aspirated (NA) engine. Two different impulse turbine layouts were analyzed, one without an exhaust plenum and the second layout having an exhaust plenum before the power turbine. The merits and limitations of both layouts are compared in the present study.

Despite the advantages of turbocharging in improved engine performance and reduced exhaust emissions, commercial single-cylinder engines used for automotive applications remain naturally aspirated (NA) and are not generally turbocharged. This is due to the shortcomings with pulsated and intermittent exhaust gas flow into the turbine and the phase lag between the intake and exhaust stroke. In the present study, experimental investigations are initially carried out with a suitable turbocharger closely coupled to a single-cylinder diesel engine. Results indicated that the engine power dropped significantly by 40% for the turbocharged engine compared to the NA version even though the air mass flow rate was increased by at least 1.5 times with turbocharging. A novel approach of decoupling the turbine and the compressor and coupling them separately to the engine is proposed to address these limitations.

Currently, alternative fuels produced from waste resources are gaining much attention to replace depleting fossil fuels. The disposal of waste plastic poses severe environmental problems across the globe. The energy embodied in waste plastics can be converted into liquid fuel by pyrolysis. The present work explores the possibility of utilizing waste plastic oil (WPO) produced from municipal plastic wastes and waste cooking oil (WCO) biodiesel produced from used cooking oil in a dual fuel reactivity-controlled compression ignition (RCCI) mode. A single-cylinder light-duty diesel engine used for agricultural water pumping applications is modified to run in RCCI through suitable intake and fuel injection systems modifications. Alternative fuel blends, viz. WPO and WCO biodiesel with 20 vol. % in gasoline and diesel is used as a port and direct-injected fuels in RCCI. The premixed ratio and direct-injected fuel timings are optimized to achieve maximum thermal efficiency.