Engine

Previous studies examining gasoline and hydrogen engines have typically focused on factors pertaining to air to fuel ratios, their effects on an ICE performance, combustion by-products produced during the ignition cycle and its subsequent environmental effects. Alternatively, this study examines the ways in which a hydrogen engine cavitation can be enhanced by using a graphene coated layer on the cylinder combustion chamber walls. SEM micrographs for the coated surfaces' microstructure showed a uniform distribution of the graphene layer that was free from cavities and demonstrating little to no observable defects. The study's results also showed large improvements in the BTE and exhaust temperature with respect to BMEP performance. This further resulted in significantly low levels harmful gaseous emissions, with observable reductions in the emissions of CO, NOx, and hydrocarbon derived from gasoline and pure hydrogen fuel. These results are thus indicative of a significant improvement in the performance of this particular typology of engine, in contrast to other experimentation focus found in other studies.

Fuel conversion efficiency is one of the main concerns in the field of internal combustion engine systems. Although the Otto cycle delivers the maximum efficiency possible in theory, the kinematics of the slider–crank mechanism of the conventional internal combustion engines makes it difficult to reach this level of efficiency in practice. This study proposes using the unique hypocycloid gear mechanism instead of the conventional slider–crank mechanism for the internal combustion engines to increase engine efficiency and minimize frictional power losses. The hypocycloid gear mechanism engine’s kinematics provides the means for the piston-rod assembly to reciprocate in a straight-line motion along the cylinder axis besides achieving a nonlinear rate of piston movement. As a result, this characteristic allows for a true constant-volume combustion, which in turn would lead to higher work output. An in-cylinder gas volume change model of the hypocycloid gear mechanism engine was develop...

The environmental pollution in the metropolitan cities is increasing rapidly mostly because of the increased number of fossil fuel powered vehicles. Many alternative options are now being studied throughout the world. One of the alternative solutions can be a compressed air powered vehicle. The present study focuses on converting an SI engine into a compressed air engine. A two stroke single cylinder SI engine is converted to operate using compressed air because of its design simplicity. The cylinder head of the engine is modified by replacing the existing cam with a set of newly designed flank cam and an inlet-exhaust air passage. As the cylinder head of the engine is modified, the engine is tested for different timing of the valve opening and duration of opening. Three sets of valve timing are used to test the converted compressed air engine. The air pressure used in the present study is 7 bar which is obtained using a compressor. The design and experimental test result presented here can be used for further research and modification of the technique.

This paper numerically investigates the role of heat and mass transfer coefficients on the performance of automotive catalytic converters, which are employed to reduce engine exhaust emissions. The pollutant conversion performance of a converter is influenced by a number of physical and chemical processes that take place in gaseous and solid phases as the exhaust gases flow through the catalyst. A quantitative predictive understanding of these complex catalyst processes involving flow dynamics, heterogeneous surface reactions, and heat and mass transport mechanisms is important in improving the converter design. The role of convective transport phenomena becomes important at high temperature when the mass transfer becomes rate limiting to an increasing extent. The objective of the present study is to elucidate the influence of convective heat and mass transfer mechanisms. The mathematical model considers the conservation of mass, momentum and energy in both gaseous and solid phases. In addition to the heterogeneous surface reactions, the 2 model also takes into account the adsorption/desorption of oxygen in the catalyst during non-stoichiometric composition of air-fuel mixtures. The governing equations are solved by an implicit scheme using a successive line under relaxation method. The converter performance under both the steady state and the transient conditions is analyzed. Key Words engine emissions, engine exhaust after-treatment, heat and mass transfer, numerical simulations. Nomenclature C g j gas phase concentration of species j, mol/m 3 C s j surface concentration of species j, mol/m 3 c pg specific heat of gas, J/kg·K c ps specific heat of substrate, J/kg·K D h hydraulic diameter, m D j diffusion coefficient of species j, m 2 /s G a geometric surface area, m 2 /m 3 ∆H k heat of reaction of species k, J/mol h g heat transfer coefficient between flow and substrate, J/m 2 ·s·K h ∞ heat transfer coefficient between substrate and atmosphere, J/m 2 ·s·K k m j mass transfer coefficient for species j, m/s L catalyst length, m Nu Nusselt number Pr Prandtl number

Properties and desired characteristics of biogas fuel are also presented. The main aspect of stationary internal combustion engines for electrical generators use is for isolated farms and rural areas, which is now thoroughly examined through techno-economical analysis and impacts on environment.

An experimental and computational study of the increasingly used third generation common rail injection system with piezo actuator has been carried out. A complete characterization of the different elements of the system, both geometrically and hydraulically, has been performed in order to describe its behavior. The information obtained through the characterization has been used to create a one-dimensional model that has been implemented in the commercial software AMESim and extensively validated against experimental data. The results of the validation demonstrate the model ability to predict the injection rate of the injector with high level of accuracy, therefore constituting a powerful tool in order to carry out further studies of this type of injection systems.

The sprays from a high-pressure multi-hole nozzle injected into a constant-volume chamber have been visualized and quantified in terms of droplet velocity and diameter with a two-component phase Doppler anemometry (PDA) system at injection pressures up to 200 bar and chamber pressures varying from atmospheric to 12 bar. The flow characteristics within the injection system were quantified by means of a fuel injection equipment (FIE) onedimensional model, providing the injection rate and the injection velocity in the presence of hole cavitation, by an in-house three-dimensional computational fluid dynamics (CFD) model providing the detailed flow distribution for various combinations of nozzle hole configurations, and by a fuel atomization model giving estimates of the droplet size very near to the nozzle exit. The overall spray angle relative to the axis of the injector was found to be almost independent of injection and chamber pressure, a significant advantage relative to swirl pressure atomizers. Temporal droplet velocities were found to increase sharply at the start of injection and then to remain unchanged during the main part of injection, before decreasing rapidly towards the end of injection. The spatial droplet velocity profiles were jet-like at all axial locations, with the local velocity maximum found at the centre of the jet. Within the measured range, the effect of injection pressure on droplet size was rather small while the increase in chamber pressure from atmospheric to 12 bar resulted in much smaller droplet velocities, by up to fourfold, and larger droplet sizes by up to 40 per cent.

In the 21st century, automobile industries are increasing at an unimaginable space. A huge problem of internal combustion (IC) engines is that it is a main cause of noise pollution. That is the reason mufflers are used to reduce the noise produced. Though mufflers are not designed to serve any primary exhaust function, they are installed within the exhaust system of most IC engines. It is designed as a soundproofing device that reduces the loudness of the pressure created by the engine. But mufflers need design and geometry considering the physics behind it which is very confounded. Established muffler design has been an iterative process by trial and error method. With recent research in this area has made it possible to do it in an analytical and experimental way.
There are two types of muffler, absorption type muffler and reactive muffler. The project dealt with the complexity behind the different mufflers and finally designed and constructed an absorption type muffler. After constructing the muffler according to our design using mild steel sheet and steel wool, we compared its performance based on three cases, no muffler condition, laboratory muffler condition and our newly designed muffler condition. Each case we calculated the insertion loss, brake specific fuel consumption (BSFC) and specific fuel consumption (SFC). And finally we showed with graphical representation that, our designed muffler performed better than the laboratory muffler condition and no muffler condition.
Of course, we did not achieve our desired result, since mild steel is no longer used as the construction material anymore and the available steel wool was not quality as we expected. However, we hope using better construction material and our design will certainly reduce the sound pressure level a great deal.

Advanced combustion strategies including premixed charge compression ignition, homogeneous charge compression ignition, and lifted flame combustion are promising approaches for meeting increasingly stringent emissions regulations and improving fuel efficiency in next generation powertrains. Variable valve actuation and closed-loop control promise to play a key role in the promotion and control of these advanced combustion modes. For example, modulation of intake valve closure timing dictates the effective compression ratio and influences the total amount of charge trapped inside the cylinder, and in so doing allows manipulation of the in-cylinder reactant concentrations and temperature prior to and during the combustion process. The effort described here uses data from, and an experimentallyvalidated simulation model for, a multi-cylinder engine with variable geometry turbocharging, cooled exhaust gas recirculation, and fully flexible variable valve actuation. This effort's intent is to determine the control authority over the gas exchange process and effective compression ratio when intake valve closure timing modulation is included on a modern turbocharged diesel engine, as well as to lay the groundwork for closed-loop control design for the promotion and control of advanced combustion modes. The engine testbed at Purdue provides a unique opportunity to pursue these objectives for turbocharged engines with exhaust gas recirculation, as it is the only such engine system in academia outfitted with multi-cylinder fully-flexible valve actuation. A method to estimate in-cylinder temperature at top dead centre is also described. Candidate control architectures for both steady state and transient operation are introduced.

An engine basically is defined as a device which converts chemical energy of the fuel into heat energy and further into mechanical output. Based on classifications there are variety of engines based on the size, position of piston, and farther classification, consideration of various parameters is important so as for the efficient working of an engine. One of them being the heat dissipation. Heat dissipation is an important factor because overheating the engine may not just only reduce its overall performance but may develop thermal stresses, fatigue and over all reduce in the working life cycle of an engine. The paper tries to investigate the thermal distribution of a v8 turbo charge engine block and tries to analyze the cooling effect of air by CFD

Increase in energy demand, stringent emission norms and depletion of oil resources have led the researchers to find alternative fuels for internal combustion engines. On the other hand, waste oils pose a very serious environment challenge because of their disposal problems all over the world. In this context, waste oils are currently receiving renewed interest. The properties of the oil derived from waste plastics, cooking and engines oils were analyzed and compared with the petroleum products and found that it has properties similar to that of diesel. This paper gives a brief review about using waste oil of these three types of oil as a fuel for diesel engines. The conversion process of each type of waste oil is presented. The results obtained from the experimental studies on a diesel engine are discussed.

Pulse detonation is a propulsion technology that involves detonation of fuel to produce thrust more efficiently than current engine systems. By literature survey and library research it is shown that Pulse Detonation Engine (PDE) technology is more efficient than current engine types by virtue of its mechanical simplicity and thermodynamic efficiency. As the PDE produces a higher specific thrust than comparable ramjet, scramjet engines at speeds of up to approximately Mach 2.3 to Mach 5, it is suitable for use as part of a multi-stage propulsion system. The PDE can provide static thrust for a ramjet or scramjet engine, or operate in combination with turbofan systems. As such, it sees potential applications in many sectors of the aerospace, aeronautic, and military industries. However, there remain engineering challenges that must be overcome before the PDE can see practical use. Current methods for initiating the detonation process need refinement. To this end, many government research bodies and a few private organizations around the world are working on PDS research & further development.

Performance and emission characteristics of compression ignition (C.I.) engines were reviewed in this work. This study was conducted by reviewing works that were carried out using biodiesel derived from the oils of: cotton seed, mahua, rice-bran, canola, Shea butter and Jatropha; and biodiesel from waste frying oil, waste palm oil, blend of ethanol and biodiesel, and diesel-biodiesel-ethanol fuel blend. The results showed that while using biodiesel and its blends; brake power was reduced by 4-5% and brake specific fuel consumption increased by 5-10%. CO 2 emissions were reduced by 5-8% and NOx increased by 11-22%. Neat biodiesel was better up in CO 2 reduction by about 22.5% at higher loads when compared to B20. However, the increase in NOx emission and power losses resulting from neat biodiesel suggest that low blend biodiesel such as B20 has the potential of becoming optimum blend. The works under review revealed that biodiesel exhibits similar performance on diesel engine when compared to fossil diesel and possesses better emission characteristics. These findings identified biodiesel as a renewable and prospective future fuel that will protect our environment.

In this paper, computational modelling of the exhaust system of two types of large-bore, multicylinder, two-stroke engine is performed. The airflow performance of a four-cylinder V-bank Cooper GMV-4TF engine and a six-cylinder in-line Clark TLA engine is simulated. The simulation includes the computation of pressure wave propagation in the exhaust manifold. Using a modified method of the steepest ascent numerical technique, tuned exhaust manifolds are designed for each engine with the objective of reduced NO emissions. The NO reduction is accomplished by increasing the trapped cylinder mass and correspondingly reducing the peak combustion temperature. The simulations predict NO reductions in the range 10-30 per cent as a result of exhaust tuning.

This paper is concerned with engine experiments and spectroscopic analysis of premixed mixture ignition in the end-gas region (PREMIER) combustion in a pilot fuel ignited, natural gas dual-fuel engine. The results reveal the characteristics and operating parameters that induce and affect this combustion mode. The PREMIER combustion is followed by natural gas flame propagation. Pilot-injected diesel fuel ignites the natural gas/air mixture, and the flame propagates before the natural gas/air mixture is autoignited in the end-gas region. This combustion cycle differs from a knocking cycle in terms of combustion and emission characteristics. The PREMIER combustion can be controlled by pilot fuel injection timing, the equivalence ratio, and the exhaust gas recirculation (EGR) rate, and can be used as an effective method for high load extension on a dual-fuel engine. An analysis of the relationship between the maximum in-cylinder pressure and its crank angle (CA) is used to compare combustion dynamics during conventional, PREMIER, and knocking combustion. In PREMIER combustion, the heat release gradually transforms from the slower first-stage flame rate to the faster second-stage rate. During PREMIER combustion, the maximum indicated mean effective pressure (IMEP) and thermal efficiency increase by about 25 per cent compared with those of conventional combustion, and low carbon monoxide (CO) and total hydrocarbon (HC) emissions can be achieved. However, nitrogen oxide (NO x ) emissions increase. Spectroscopic analysis shows that the intensity of the OH* emissions in the end-gas region increases as the combustion mode transforms from conventional to PREMIER to knocking. In all three modes, emission fluctuations above 650 nm can be observed in the end-gas region. These emissions are attributed to the luminosity from soot particles formed during the concurrent diesel fuel combustion.

This paper presents experimental results of a new compressed natural gas direct injection (CNG-DI) engine that has been developed from modification of a multi cylinder gasoline port injection (PI) engine. The original gasoline-PI engine was also modified to a CNG bi-fuel system. The test results obtained from CNG fuel using two different systems (i.e. bi-fuel and DI) have been investigated and compared with the original gasoline engine. The objective of this investigation is to compare the test results between CNG-DI, with CNG-BI and gasoline-PI engines with the same displacement volume. It was found that the CNG-DI engine produces similar brake power at 6000 rpm and wide open throttle (WOT) but produces higher brake power at part load condition as compared to the original gasoline. The CNG-BI engine produces 23% lower brake power than the CNG-DI engine. The average brake specific fuel consumption (BSFC) of the CNG-DI engine was 0.28% and 8% lower than gasoline-PI and CNG-BI engines respectively. The CNG-DI engine reduces 42% NOx emission as compared to the base engine. However, the CNG-DI engine produces higher HC and CO emissions as compared to the base engine. This paper discusses a review on the direct injection (DI) natural gas engine with new information along with other investigations.

The combustion of fuel inside the internal combustion engine lead to form many by-products like CO2, CO, Exhaust hydrocarbons, various oxides of nitrogen and compound like soot basically known as carboneous deposits. To sustain the engine performance and emission control, this soot must be clean out. This literature contains various mechanical and chemical methods for carbon deposits cleaning, also the formation and adverse effect of soot formation on internal combustion engine. The conventional methods show their performance appreciably on various parameters, but still there is need of a cleaning system that can vanish out all the battle-necks of conventional methods. This literature will also give review about the automated system which will overcome all the drawbacks of conventional methods.

This paper uses a multi-dimensional computational fluid dynamics (CFD) code coupled with detailed chemistry, the KIVA-CHEMKIN code, to provide guidelines for solving problems with premixed combustion strategies, namely, lack of combustion phasing control, excessive pressure rise rate, and spray wall impingement due to early injections. A multiple injection concept is used to control combustion phasing and reduce the rate of peak pressure rise. To address spray-wall impingement, an adaptive injection strategy (AIS) using twoinjection pulses at different injection pressures is employed.

Two direct injection spark ignition (DISI) engines with identical combustion chamber geometries and fuel injection systems were used to investigate fuel economy, exhaust emissions, the in-cylinder flow field, the fuel spray behaviour and combustion characteristics with early inlet valve closure (EIVC) strategies aimed at reducing parasitic induction work owing to throttling. One engine had extensive optical access through a transparent piston crown and transparent cylinder liner, while the other all-metal engine allowed continuous running. Engine running focused at low and intermediate engine loads (, 3 and , 6 bar indicated mean effective pressure) and two engine speeds (2000 and 3500 r/min). The results show that the indicated specific fuel consumption (ISFC) could be reduced by almost 6 per cent without significant deterioration in gaseous exhaust pollutant emissions. The results also show that the in-cylinder bulk flow and turbulence and the thermodynamic conditions during combustion are affected significantly by EIVC operation.

Development of Aircraft propulsion systems over the years has simultaneously given rise to the increase of air pollution. Several attempts have been made to reduce the polluting gases which are emitted by the exhaust jet. The core focus of the paper is ideally placed on the analysis of the CAD model of the Open Rotor Engine and an ordinary jet engine for which the correlated results are condensed. Moreover the numerical calculations, based on the results of the analysis prove that the reduction of Specific Fuel Consumption (SFC) and CO 2 emission with a significant increase in thrust are sufficed. The open rotor engines although controls the air pollution, fails to moderate the noise pollution by producing high decibel of sound. This paper work also proposes a conceptual idea of employing the piezo electric vibration absorbers to reduce the noise while still getting a good fuel burn performance.

The paper describes the development and validation of a quasi-dimensional combustion model, applicable to any type of HSDI Diesel engines. In this model, the fundamental in-cylinder processes are taken into account, including turbulence, fuel injection, spray dynamics, ignition and combustion. In comparison to similar models presented in literature, a more physical description of average in-cylinder turbulence properties and their interaction with spray dynamics is introduced, as well as a detailed modeling of fuel jet wall impingement. Some experimental measures available in literature and CFD-3D simulations have been considered to calibrate the modeling parameters. These improved submodels make results accuracy less dependent on the calibration carried out on each engine, so that the same parameters setting can be successfully applied to different combustion chamber configurations. The model is first applied to a small HSDI turbocharged Diesel engine. The specific calibration was supported by both experiments and simulation results, the latest being obtained from 3D-CFD analyses. Then, a different Diesel engine has been simulated, adopting the same set-up of the model parameters. For both engines, the comparison between experiments and simulation shows a very good agreement in terms of in-cylinder pressures and heat release rates, as well as of average in-cylinder turbulence properties. It is worth to mention that the two engines, have a quite different unit displacement, i.e. 312 and 697 cc, respectively.

Hosseini, V.; Neill, W. S.; Guo, H.; Chippior, W. L.; Fairbridge, C.; Mitchell, K. Contact us / Contactez nous: [email protected]. http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=fr L'accès à ce site Web et l'utilisation de son contenu sont assujettis aux conditions présentées dans le site Web page / page Web http://dx.

Turbochargers are finding increasing appliincreasingly more stringent emission standards. This cation to automotive diesel engines as cost effective means paper is part of an extensive experimental profor improving their power output and efficiency, and gramme focused on turbine design technology for reducing exhaust emissions; these requirements have led vehicle applications aiming to (a) explore available to the need for highly loaded turbocharger turbines. A means to modify the turbine operating characteristics mixed-flow turbine is capable of achieving its peak isen-in order to improve the engine/turbocharger matchtropic efficiency at reduced velocity ratios compared to a ing and (b) improve the transfer of energy from the typical radial inflow turbine; it is therefore possible to pulsating exhaust gases to the turbine. In order to improve the turbocharger/engine matching. These turbines achieve these aims, the project is centred on mixeddiffer from the commonly used radial turbines in that the flow turbine rotors as opposed to radial rotors comflow approaches the rotor in the non-radial direction; in monly used in automotive turbochargers. This choice the extreme a mixed-flow turbine would become an axial overcomes one of the principal limitations of the machine. The steady and unsteady performances of a radial inflow turbine, where stress and material conmixed-flow turbocharger turbine with a constant blade siderations dictate that the blade angle must be zero inlet angle have been investigated. The steady flow results to maintain radial blade sections and to keep the indicated that the mixed-flow turbine obtains a peak centrifugal load in the blades purely tensile. A efficiency (total-to-static) of 75 per cent at a velocity ratio mixed-flow geometry permits the use of a non-zero of 0.61, compared with that of a typical radial-inflow turblade angle without departure from the above bine which peaks at a velocity ratio of 0.7. The performance requirement and introduces an extra degree of freeand flow characteristics were found to deviate significantly dom into the rotor design, which has particular from the equivalent steady state values commonly used in implications for the range of operation of the turbine, turbocharger turbine design.

Eaton has developed an aftertreatment system for medium-and heavy-duty diesel engines in response to the US 2010 regulations. This system consists of a fuel reformer, a lean NO x trap (LNT), and an ammonia selective catalytic reduction (SCR) catalyst in series. A transient, one-dimensional model of the system was developed to improve system performance, reduce experimental testing, and optimize system design. In this paper, the LNT portion of this model is presented. The model simulates flow, heat transfer, and chemical reactions in the LNT catalyst. A global LNT chemical kinetic mechanism was developed to simulate the key catalytic processes with the minimum number of reactions. The model can be used to predict LNT catalyst performance over a range of operating conditions and driving cycles.

Heuristic methods have been a successful tool for optimizing engine parameters in both simulation and experimental testing. An improved hybrid method applying both the particle swarm optimization method and genetic algorithm was developed, tested, and compared with a basic particle swarm method for improving engine emissions and performance. A computational comparison between the particle swarm optimization–genetic algorithm hybrid, basic particle swarm optimization, and basic genetic algorithm was done using standard test problems. Computational results indicated improvements in both the efficiency and effectiveness of the present hybrid method. Engine testing was performed under steady-state conditions at 1400 r/min at 4.15 bar brake mean effective pressure. The basic particle swarm optimization and the hybrid particle swarm optimization–genetic algorithm method were applied to the test apparatus and used to locate the optimum neighborhood of the engine operation. A single-objecti...

Increase in energy demand, stringent emission norms and depletion of oil resources have led the researchers to find alternative fuels for internal combustion engines. On the other hand, waste oils pose a very serious environment challenge because of their disposal problems all over the world. In this context, waste oils are currently receiving renewed interest. The properties of the oil derived from waste plastics, cooking and engines oils were analyzed and compared with the petroleum products and found that it has properties similar to that of diesel. This paper gives a brief review about using waste oil of these three types of oil as a fuel for diesel engines. The conversion process of each type of waste oil is presented. The results obtained from the experimental studies on a diesel engine are discussed.

Hydrodynamic similarity of cavitation flows in nozzles of different scales has been observed experimentally. In this paper a model of cavitation has been developed, taking into account the bubbly nature of cavitation and assuming local homogeneity of the vapour-liquid flow. The model of cavitation is built from correlations for evaporation and condensation, based on bubble dynamics theory, and an equation for the number density of cavitation bubbles, derived by assuming hydrodynamic similarity of cavitation flows. Compared with conventional models of cavitation, which fix the number density of cavitation bubbles, the present model takes into account the effect of liquid tension on the number density of active cavitation nuclei. The model has been implemented within the VECTIS computational fluid dynamics code and applied to the simulation of cavitating flows in nozzles.

Heat transfer is one of the major factors affecting the performance, efficiency, and emissions of internal combustion engines. As convection heat transfer is dominant in engine heat transfer, accurate modelling of the boundary layer heat transfer is required. In engine computational fluid dynamics (CFD) simulations, the wall function approach has been widely used to model the near-wall flow and temperature field. The present paper suggests a modified wall function approach to model heat transfer in internal combustion engines. Special emphasis has been placed on introducing the effect of variable density and variable viscosity in the model formulation. A non-dimensional temperature corrector is suggested to incorporate the variable density effect on the wall function approach. The suggested model is applied in KIVA-3V and is validated against experimental data of a homogeneous charge compressionignition engine, showing improved predictions for pressure and emissions compared with the standard wall function model.

The emissions of oxides of nitrogen (NO x ) from biodiesel blended fuels reported in the literature vary from an NO x increase to an NO x decrease relative to the neat petroleum diesel fuel (PDF). To explain these NO x differences, three PDFs with varying fuel properties were admixed with a neat soy-derived biodiesel at 10 per cent and 20 per cent volume ratios and evaluated using a heavy-duty diesel engine exercised over transient and steady-state cycles. The PDFs with 'low' and 'medium' cetane numbers led to a change in combustion phasing when blended with the neat biodiesel, resulting in reduced NO x emissions at low engine power. The B100 blended with the 'high'-cetane-number PDF showed minimal change in combustion phasing and resulted in an NO x increase at all engine loads. The derived peak incylinder gas temperature variation correlated with the brake-specific NO x emissions indicating that the thermal NO x formation responds to the addition of biodiesel. The biodiesel blends had an NO x -particulate matter trade-off, also suggesting a thermal NO x effect. The increase in NO x emissions of the biodiesel blends also had a strong correlation with the level of saturated hydrocarbons at high engine power.

Research on alternative fuels is increasing due to environmental concerns and diminishing fossil fuel reserves. Biodiesel is one of the best renewable replacements for petroleum-based fuels. This paper examines the potential of biodiesel obtained from Jatropha curcas and Moringa oleifera oils. The physico-chemical properties of J. curcas and M. oleifera methyl esters were presented, and their 10% by volume blends (JB10 and MB10) were compared with diesel fuel (B0). The performance of these fuels and their emissions were assessed in a fully loaded multi-cylinder diesel engine at various engine speeds. The properties of J. curcas and M. oleifera biodiesels and their blends agreed with ASTM D6751 and EN 14214 standards. Engine performance test results indicated that the JB10 and the MB10 fuels produced slightly lower brake powers and higher brake specific fuel consumption values compared to diesel fuel over the entire range of speeds. Engine emission results indicated that the JB10 and MB10 fuels reduced the average emissions of carbon monoxide by 14 and 11%, respectively; and hydrocarbons by 16 and 12%, respectively. However, the JB10 and MB10 fuels slightly increased nitrous oxides emissions by 7 and 9%, respectively, and carbon dioxide by 7 and 5%, respectively compared to B0. In conclusion, J. curcas and M. oleifera are potential feedstock for biodiesel production, and the JB10 and MB10 blends can replace diesel fuel without modifying engines to produce cleaner exhaust emissions.

Samples of commercial diesel were subjected to forty hours of intense cavitation flow across a diesel injector in a specially designed high-pressure recirculation flow rig. In the high pressure part of the rig, diesel samples were compressed to 550 bar using a continuous flow high pressure pump. In the low pressure part of the rig, the diesel samples were maintained at 70 o C using a temperature control system in conjunction with a heat exchanger.

This paper reports the computer simulation based theoretical and the test rig based experimental investigations for improving the performance and emission characteristics of a two stroke cycle spark ignition engine. Computer simulation was carried out using a standard software. Models were prepared for the carburettor and gasoline direct injection modes. Using the design and operating data of a standard commercial two stroke cycle spark ignition engine results were generated in the carburettor and gasoline direct injection modes. Different parameters like brake power, BSFC, CO and HC emissions, exhaust and spark plug temperatures, peak cylinder gas pressure and its cyclic variations were studied in the carburettor and GDI modes. There was improvement in engine power and reduction in BSFC in the GDI mode as compared to carburettor mode. The CO and HC emissions were reduced in the GDI mode due to better atomization and reduced scavenging loses.

This paper presents experimental results of a new compressed natural gas direct injection (CNG-DI) engine that has been developed from modification of a multi cylinder gasoline port injection (PI) engine. The original gasoline-PI engine was also modified to a CNG bi-fuel system. The test results obtained from CNG fuel using two different systems (i.e. bi-fuel and DI) have been investigated and compared with the original gasoline engine. The objective of this investigation is to compare the test results between CNG-DI, with CNG-BI and gasoline-PI engines with the same displacement volume. It was found that the CNG-DI engine produces similar brake power at 6000. rpm and wide open throttle (WOT) but produces higher brake power at part load condition as compared to the original gasoline. The CNG-BI engine produces 23% lower brake power than the CNG-DI engine. The average brake specific fuel consumption (BSFC) of the CNG-DI engine was 0.28% and 8% lower than gasoline-PI and CNG-BI engines respectively. The CNG-DI engine reduces 42% NOx emission as compared to the base engine. However, the CNG-DI engine produces higher HC and CO emissions as compared to the base engine. This paper discusses a review on the direct injection (DI) natural gas engine with new information along with other investigations. © 2011 Elsevier Ltd.
http://ac.els-cdn.com/S0360544211002349/1-s2.0-S0360544211002349-main.pdf?_tid=c2bf5f32-a9c6-11e3-b389-00000aab0f01&acdnat=1394615868_af9452d9cda4f71e98e5cd80760b3339 
http://www.sciencedirect.com/science/article/pii/S0360544211002349

The name itself shows that this engine is a cycle of six strokes where two strokes are the power strokes. This is additionally a reciprocating sort of engine with twofold progression of charge and it very well may be both internal and external ignition. It totally differ with the 2 stroke and 4 stroke engine because of its thermodynamic cycle. This type of engine consist of a “modified cylinder head” with “with two supplementary chambers” one is combustion chamber and the other one is an air heating chamber and both the chambers are totally independent from the cylinder. The design analysis of this type of engine is quite easy because of separated cylinder and combustion chamber. In this type of engine two valves are added with comparison of four stroke engine and both the valves are operated by an arrangement of piston. This engine is more efficient thermodynamically because the volume change in power stroke is more than the compression stroke and intake stroke. The leading advantage of this engine is “the reduction in fuel consumption by 40%”, there are two power stroke in the cycle of six strokes, and it is also less polluting type of engine. Six stroke engine's selection by the vehicle industry would tremendously affect the earth and world economy.