Influence of retarded injection timing on thermal performance and emission characteristics of a diesel engine fuelled with an optimized pyrolytic blend

The enormous rise in plastic waste leads to severe environmental issues and complete removal is a quiet challenge. The entire world focuses on finding new alternate for traditional conventional fuel. The waste low-density polyethylene is chosen as feedstock for the preparation of fuel from thermo-catalytic pyrolysis, considering the silica–alumina catalyst at a reaction temperature of 500 °C. From our previous study, the lower blends of waste low-density polyethylene exhibit a similar performance to diesel. However, brake thermal efficiency and oxides of nitrogen are not encouraging. Further improving combustion behaviour, the present research is carried out at different injection timings. The investigation is carried on standard injection timing of 23°bTDC and three retarded injection timings, namely, 21°bTDC, 19°bTDC and 17°bTDC. Retarded injection timing exhibits higher performance and lower unburned hydrocarbon, oxides of nitrogen and carbon monoxide emissions. However, smoke emission is increased due to the reduced heat release at all the considered test parameters. The result divulges that reduced performance and increased smoke at 17°bTDC due to the lack of burning rate. The combustion behaviour of 20% waste low-density polyethylene by volume at 19°bTDC is similar to that of diesel at 23°bTDC. Hence, the injection timing of 19°bTDC is preferred as an optimized condition for the test fuel 20% waste low-density polyethylene by volume.

Effects of Gasoline-Diesel Ratio on Combustion and Emission Characteristics of a Dual-Fuel CI Engine: A CFD Simulation

Recently, considerable efforts are made by the engine researches all over the world, focusing primarily on achieving ultra-low emissions of NOx (nitrogen oxides) and soot without any compromise to high thermal efficiency from dual-fuel engine. In this study, combustion performance and engine-out emission of a single cylinder gasoline-diesel dual-fuel engine are numerically investigated by employing a commercial computation fluid dynamics (CFD) software, especially developed for internal combustion engines modeling. Here, gasoline-diesel relative ratio has been varied to find its impacts on performance of a dual-fuel engine. The results show that, in-cylinder pressure, in-cylinder temperature and rate of heat release (ROHR) are increased with gradual increment in diesel relative to gasoline. Injecting higher amount of diesel directly inside the combustion chamber as pilot fuel might have facilitated the auto-ignition process by reducing the ignition delay and accelerated the premixed gasoline-air flame propagation. These led to shorter main combustion duration which is quite desirable to suppress the knock in dual-fuel engines. In addition, NOx emission is found to decrease with relatively higher percentage of diesel. On the other hand, with increasing gasoline ratio relative to diesel, combustion duration is prolonged significantly and led to incomplete combustion, thereby increasing unburned hydrocarbon (UHC) and carbon monoxide (CO).

Investigation and Optimization of Diesel Engine Outputs under Undi Biodiesel-Diesel Strategies

The present investigation accentuates the impact of Undi biodiesel blended Diesel on combustion, performance, and exhaust fume profiles of a single-cylinder, four-stroke Diesel engine. Five Undi biodiesel-Diesel blends were prepared and tested at four variable loads over a constant speed of 1500 (±10) rpm. The Undi biodiesel incorporation to Diesel notably improves the in-cylinder pressure and heat release rate of the engine. The higher amount of Undi biodiesel addition enhances the brake thermal efficiency and brake specific energy consumption of the engine. In addition, the Undi biodiesel facilitates to reduce the major pollutants, such as brake specific unburned hydrocarbon, brake specific carbon monoxide, and brake specific particulate matter emissions with slightly higher brake specific oxides of nitrogen emissions of the engine. To this end, a trade-off study was introduced to locate the favorable Diesel engine operating conditions under Undi biodiesel-Diesel strategies. The optimal Diesel engine outputs were found to be 32.65% of brake thermal efficiency, 1.21 g/kWh of brake specific cumulated oxides of nitrogen and unburned hydrocarbon, 0.94 g/kWh of brake specific carbon monoxide, and 0.32 g/kWh of brake specific particulate matter for 50% (by volume) Undi biodiesel share blend at 5.6 bar brake mean effective pressure with a relative closeness value of 0.978, which brings up the pertinence of the trade-off study in Diesel engine platforms.

The Influence of Cycle-to-Cycle Hydrocarbon Emissions On Cyclic NO:NO2 Ratio from a HSDI Diesel Engine

Knowledge of the NO:NO2 ratio emitted from a diesel engine is particularly important for ensuring the highest performance of SCR NOx aftertreatment systems. As real driving emissions from vehicles increase in importance, the need to understand the NO:NO2 ratio emitted from a diesel engine during transient operation similarly increases. In this study, crank-angle resolved NO and NO2 measurements using fast response CLD (for NO) and a new fast LIF instrument (for NO2) have been taken from a single cylinder diesel engine at three different speed and load points including a point with and without EGR. In addition, crank-angle resolved unburned hydrocarbon (UHC) measurements have been taken simultaneously using a fast FID. A variation of the NO:NO2 ratio through the engine's exhaust stroke is also observed indicative of in-cylinder stratification of NO and NO2. A new link between the NO:NO2 ratio and the UHC emissions from an individual engine cycle is observed - the results show that where there are higher levels of UHC emissions in the first part of the exhaust stroke (blowdown), the proportion of NO2 emitted from that cycle is increased. This effect is observed and analysed across all test points and with and without EGR. The performance of the new fast LIF analyser has also been evaluated, in comparison with the previous state-of-the-art and standard "slow" emissions measurement apparatus showing a reduction in the noise of the measurement by an order of magnitude.

Immersion temperature effects on light-duty gasoline vehicles’ fuel consumption under world-wide harmonized light-duty test cycle (WLTC)

Basing on the experimental study of fuel consumbtion in World-wide Harmonized Light-duty Test Cycle (WLTC ), this paper conducted the effects of using different immersion temperature on the fuel consumption of a light-duty gasoline vehicle. The study mainly studied the first phase of WLTC with three gaseous pollutant emissions: carbon dioxide, carbon monoxide and unburned hydrocarbon(CO2, CO and HC )which is measured to caculate the fuel consumption of Light-duty Gasoline Vehicles. It appears that with the increase of time the working condition of the vehicle tends to be stable resulting in the similar emission of the gaseous pollutant in the different test. Which means the immersion temperature mainly effects gaseous pollutant emissions in low-speed phase in WLTC. Besides, the cold start of engine had generated a large quantity of carbon monoxide and unburned hydrocarbon, but it is different for the carbon dioxide which was generated continuously in the first whole phase. The study also found that the use of a higher immersion temperatures (26℃) is more favorable than a lower immersion temperatures (23℃) in the typy of testing vehicle’s fuel consumption in the WLTC test cycle.

Performance and Emission Characteristics of CI Engine Fuelled with Jatropha and Pongamia Biodiesel along with Alumina Nano particles

In this study an experimental investigation has been carried out on compression ignition engine to understand the engine behaviour like its performance and emission characteristics while using Aluminium oxide (Al2O3) nano particle as additive with a blend of diesel and biodiesel sourced from Jatropha and Pongamia vegetable oil. The Alumina nano particles are characterized by X- ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis. The biodiesel is made engine ready with adoptable properties by carrying out standard alkali transesterification process. The alumina nano particles are blended with jatropha in the mass fractions of 50, 100, 150 ppm and with Pongamia biodiesel in the mass fractions of 40, 60 ppm using an ultrasonicator. The experiments are carried out in single cylinder four stroke variable compression ratio diesel engine by varying the load using eddy current dynamometer. The experimental results reveal that there is a significant improvement in the performance characteristics like brake thermal efficiency (BTHE) and brake specific fuel consumption (BSFC) and reduction in the emission constituents like carbon monoxide (CO) and unburned hydrocarbon (HC) but in turn increase in nitric oxide (NOx) emissions were observed.