Common Rail Direct Injection Engine Research Articles

Effect of fuel injection pressure and injection timing of Karanja biodiesel blends on fuel spray, engine performance, emissions and combustion characteristics

In this investigation, effect of 10%, 20% and 50% Karanja biodiesel blends on injection rate, atomization, engine performance, emissions and combustion characteristics of common rail direct injection (CRDI) type fuel injection system were evaluated in a single cylinder research engine at 300, 500, 750 and 1000bar fuel injection pressures at different start of injection timings and constant engine speed of 1500rpm. The duration of fuel injection slightly decreased with increasing blend ratio of biodiesel (Karanja Oil Methyl Ester: KOME) and significantly decreased with increasing fuel injection pressure. The injection rate profile and Sauter mean diameter (D32) of the fuel droplets are influenced by the injection pressure. Increasing fuel injection pressure generally improves the thermal efficiency of the test fuels. Sauter mean diameter (D32) and arithmetic mean diameter (D10) decreased with decreasing Karanja biodiesel content in the blend and significantly increased for higher blends due to relatively higher fuel density and viscosity. Maximum thermal efficiency was observed at the same injection timing for biodiesel blends and mineral diesel. Lower Karanja biodiesel blends (up to 20%) showed lower brake specific hydrocarbon (BSHC) and carbon monoxide (BSCO) emissions in comparison to mineral diesel. For lower Karanja biodiesel blends, combustion duration was shorter than mineral diesel however at higher fuel injection pressures, combustion duration of 50% blend was longer than mineral diesel. Up to 10% Karanja biodiesel blends in a CRDI engines improves brake thermal efficiency and reduces emissions, without any requirement of hardware changes or ECU recalibration.

Combustion Cycle-by-Cycle Variations in a Common Rail Direct Injection Engine Fueled with Dimethyl Carbonate–Diesel Blend

AbstractIn consideration of the multiple split injection, heavy exhaust gas recirculation (EGR) atmosphere, high latent heat of vaporization of dimethyl carbonate (DMC), and low cetane number, the combustion variations of both diesel and D10 (a fuel blend of 10% of DMC in diesel) have been investigated with characteristic parameters of indicated mean effective pressure pmi, peak pressure pmax, and initial 10% combustion duration θd. Results show that the cyclical coefficients of variation (COVs) of three characteristic parameters are lower than 2%. This means good combustion quality thanks to the precise control of fuel injection. The COVs for diesel are much smaller than those for D10 fuel. The COVs of pmi, pmax, and θd rise with a declining center of heat release (COHR), while the COVs show visible growth with the increase in EGR rate. The anticipation of possible combustion instability due to pilot injections did not happen. Both pmax and θd have good corresponding relations with pmi. The pmi positivel...

Multi-zone phenomenological model of combustion and emission characteristics and parametric investigations for split injections and multiple injections in common-rail direct-injection diesel engines

This paper presents the formulation of a multi-zone zone phenomenological model for predicting the combustion and emission characteristics of split-injection and multiple-injection common-rail direct-injection diesel engines. In this model, the instantaneous combustion space is divided into two regions, namely the spray zones and the surrounding air. The model predictions for combustion and emissions for split injections and multiple injections are validated with the measured results on a wide range of injection schedules available in the literature. The comparisons reveal the good predictive ability of the model with reasonable accuracy and demonstrate the applicability of the multi-zone model to multiple-injection common-rail direct-injection engines. Hence, the model is used for parametric investigations to analyse the effect of split injections and multiple injections on the combustion and emission characteristics of common-rail direct-injection diesel engines. The parametric investigations show that an increase in the pilot fuel quantity increases the nitrogen oxide emissions and reduces the soot emissions while the dwell period has to be optimized for simultaneous reductions in the nitrogen oxide emissions and the soot emissions. Therefore the present model can be used to achieve an optimal injection schedule for given engine operating conditions.

Effect of Fuel Auto-Ignition Quality on Particle Size Distribution and Particulates Morphology in a Direct Injection Diesel Engine

The effect of fuel auto-ignition quality on particle size distribution and particulates morphology were investigated for the purpose of revealing the relationship between cetane number and particles emission. Experiments were conducted on common-rail direct injection engine under steady-state operating condition. Two basic diesel-like fuels were used in this study, hydrogenation diesel and straight-run diesel. The test fuels which have various cetane number were made up of these two basic ones. The results indicate that with increasing the fuel cetane number, a significant decrease of nucleation mode particles is found. For particle number size classification, the percentage of SOF has the same trend as the number of nucleation mode particles which size below 22nm and similar result is found between the percentage of dry soot and particles above 50nm.

Experimental study on combustion and particle size distribution of a common rail diesel engine fueled with GTL/diesel blends

The effect of GTL/diesel blends on combustion and particle size distribution were experimentally investigated in a turbocharged intercooled common-rail direct injection (CRDI) engine under steady-state and transient-state operating conditions. The experiments include six fuels: fossil diesel (G0), G10, G20, G30, G60 and G100 (GXX means a blend of XX vol% GTL in diesel). Particle size distribution was measured by TSI EEPS 3090 through a two-stage dilution tunnel. The engine was tested without exhaust gas recirculation (EGR) in all modes. The results indicate that the majority of particles are in the diameter region of 10–200 nm with GTL under middle speed. Compared with fossil diesel, the GTL/diesel blends shorten the ignition delay and reduce the proportion of premixed burning. With the proportion of GTL increasing in blends, the heat-release rate and pressure-rise rate of premixed burning drop. Increasing blend ratio is also found to reduce the nucleation mode particle number and favor the accumulation mode particles formation, while total particle number concentration increases. A relativity is also found between size range and blend ratio. For transient-state condition, a higher nucleation mode particle number and accumulation mode particle number are found; the effect on PSD with GTL is less sensitive than that with fossil diesel. Besides, it is of benefit to decrease the total particle number and nucleation mode particle number with the ratio of GTL become larger in the blends fuel under transient cycle.

A Comparative Morphological Study of Primary and Aged Particles Emitted from a Biodiesel (B20) vis-à;-vis Diesel Fuelled CRDI Engine

A comparative morphological analysis was performed on the exhaust particles emitted from a common rail direct injection (CRDI) sports utility vehicle (SUV) engine for primary and aged particulates. In this study, soot particles were collected from the CRDI engine fuelled with mineral diesel and 20% biodiesel blend (B20). The engine was operated at a constant speed of 1800 rpm for five different loads (0%, 25%, 50%, 75%, 100% rated load) for primary and aged particulate collection. Primary particulate samples were collected on pre-conditioned quartz filter papers from the exhaust stream after partial dilution. For collection of aged particles, the diluted exhaust was passed through a customized photochemical chamber with 2 hour retention time. This allowed photochemical reactions to proceed in presence of ultraviolet light leading to particulate aging in simulated daylight conditions and particulates were collected downstream of the photochemical chamber. Particulate laden filters were observed by scanning electron microscopy (SEM). It was observed that B20 emitted significantly lower primary particulates in comparison to mineral diesel for all the loads. B20 emitted lower particulates at lower load conditions for aged samples. At higher engine loads (75% and 100%), this reduction in aged particulates for B20 compared to mineral diesel was quite significant.

Assessment of toxic potential of primary and secondary particulates/aerosols from biodiesel vis-à-vis mineral diesel fuelled engine

Toxicity of engine out emissions from primary and secondary aerosols has been a major cause of concern for human health and environmental impact. This study aims to evaluate comparative toxicity of nanoparticles emitted from a modern common rail direct injection engine (CRDI) fuelled with biodiesel blend (B20) vis-à-vis mineral diesel. The toxicity and potential health hazards of exhaust particles were assessed using various parameters such as nanoparticle size and number distribution, surface area distribution, elemental and organic carbon content and polycyclic aromatic hydrocarbons adsorbed onto the particle surfaces, followed by toxic equivalent factor assessment. It was found that biodiesel particulate toxicity was considerably lower in comparison to mineral diesel.

BDF Application in a Common Rail Direct Injection Engine

BDF Application in a Common Rail Direct Injection Engine

Phenomenological modeling of combustion and emissions for multiple-injection common rail direct injection engines

The high-pressure multiple injections in common rail direct injection diesel engines offer a possibility of simultaneous reduction of exhaust smoke and oxides of nitrogen. The purpose of the present work is to develop a phenomenological model to enable parametric understanding of the combustion and emission characteristics of multiple-injection common rail direct injection engines. The model is based on a two-zone formulation comprising of fuel–air spray and the surrounding air. The model predictions for combustion and emissions are validated with measured results of different multiple-injection schedules available in the published literature. The effect of parametric variations of multiple-injection scheduling on emission characteristics are predicted using the proposed model. It is observed that the simultaneous reduction of oxides of nitrogen and smoke is possible with an optimized pilot fuel quantity and dwell between the injection pulses.

Composition and comparative toxicity of particulate matter emitted from a diesel and biodiesel fuelled CRDI engine

Abstract There is a global concern about adverse health effects of particulate matter (PM) originating from diesel engine exhaust. In the current study, parametric investigations were carried out using a CRDI (Common Rail Direct Injection) diesel engine operated at different loads at two different engine speeds (1800 and 2400 rpm), employing diesel and 20% biodiesel blends (B20) produced from Karanja oil. A partial flow dilution tunnel was employed to collect and measure the mass of the primary particulates from diesel and biodiesel blend collected on a 47 mm quartz substrate. The collected PM (particulate matter) was subjected to chemical analyses in order to assess the amount of Benzene Soluble Organic Fraction (BSOF) and trace metals using Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). For both diesel and biodiesel, BSOF results showed decreasing levels with increasing engine load. B20 showed higher BSOF as compared to those measured with diesel. The concentration of different trace metals analyzed also showed decreasing trends with increasing engine loads. In addition, real-time measurements for Organic Carbon (OC), Elemental Carbon (EC) and total particle-bound Polycyclic Aromatic Hydrocarbons (PAHs) were carried out on the primary engine exhaust coming out of the partial flow dilution tunnel. Analysis of OC/EC data suggested that the ratio of OC to EC decreases with corresponding increase in engine load for both fuels. A peak in PAH concentration was observed at 60% engine load at 1800 rpm and 20% engine load at 2400 rpm engine speeds almost identical for both kinds of fuels. Comparison of chemical components of PM emitted from this CRDI engine provides new insight in terms of PM toxicity for B20 vis-a-vis diesel.

Prediction of the Rate of Heat Release of Mixing-Controlled Combustion in a Common-Rail Engine with Pilot and Post Injections

A one-dimensional model for the prediction of the rate of heat release (ROHR) in common-rail direct-injection diesel engines with pilot, main, and post injections is developed. The model is an improvement on the previously developed mixing-controlled combustion model extended by including the effect of the wall jet. The decay of the ROHR curve has been improved in the second regime of combustion. It was observed that the input kinetic energy of the wall spray is retarded only after the growth of spray along the bowl wall exceeds the diameter of the spray cone. It is shown that this model can be extended for engines with multiple injections, i.e. pilot, main, and post injections. The ROHR was modelled as a function of the turbulence kinetic energy of the fuel mass and the dissipation rate of this energy in different stages of spray propagation. The inputs required for the model are the nozzle discharge coefficient, the injection pressure, the injection timing, and the injected fuel quantity for each injection stage that are readily controlled in common-rail engines. The predicted heat release histories corresponding to the pilot injection, the main injection, and the post injection were found to be in agreement with the experiments.