Effect of injection timing and EGR on engine-out-responses of a common-rail diesel engine fueled with neat biodiesel

Nowadays, diesel-powered engines are becoming attractive worldwide due to their superior fuel economy, higher efficiency and excellent reliability. Biodiesel can be considered as the most promising and in demand alternative fuel because it is a non-toxic, biodegradable and renewable fuel. This work attempts to simultaneously reduce the BSNOx and smoke from the levels of fossil diesel by using palm methyl ester (PME) biodiesel. In addition, this paper describes the conversion of a common-rail injection system with a custom-made electronic control system, focusing on hardware development, the engine control unit and fuel delivery system development. Parametric studies dealing with injection timing and exhaust gas recirculation (EGR) variation using neat palm biodiesel were performed and compared with baseline diesel. The tests were performed at a constant speed and load of 1500 rpm and 0.4 MPa, respectively. Firstly, the start of injection (SOI) timing was varied from TDC to -25° ATDC to demonstrate the flexible control of the custom-made engine controller. Later, the SOI timing was kept at an optimum of -11°ATDC and the EGR rates were adjusted (i.e. 0-50%). The experimental results indicated that both the injection timing and EGR variation had a prominent effect on the engine performance, emissions and combustion characteristics for an engine operating with baseline diesel or neat biodiesel. Based on the highest brake thermal efficiency (BTE) and a reasonable NOx level, the optimum injection timing is found to be at -11°ATDC for both the baseline diesel and biodiesel operation. A wider range of EGR rates from 0% to 50% were investigated to bring down the NOx levels from the EURO II limit to meet with more stringent EURO limits. It was found that with the PME fuel, engine operation at 30% EGR resulted in the optimum trade-off between BSNOx and smoke emissions. In fact, simultaneous BSNOx and smoke reduction from the levels of fossil diesel is possible with the use of PME biodiesels in parallel with the implementation of late SOI timing or a higher EGR rate in diesel engines

Comparative assessment of performance, emissions and combustion characteristics of gasoline/diesel and gasoline/biodiesel in a dual-fuel engine

In recent years, rapid growth in population, development, and industrialization have led to a high demand for energy worldwide. Biofuels from bio-based products can be considered an alternative to fossil fuels used in the transport sector. However, the use of biodiesel in conventional diesel combustion engines has usually caused lower thermal efficiency and higher specific fuel consumption. Using alternative fuels and switching to promising combustion technologies such as low temperature combustion (LTC) are reliable approaches to address this issue. This research aims to use biofuels as an alternative energy source for engines operating in dual-fuel combustion mode. The effects of diesel/biodiesel strategies on dual-fuel combustion were investigated. This dual-fuel combustion mode proposes port fuel injection of gasoline and direct injection of diesel/biodiesel fuel with rapid in-cylinder fuel blending. The results of engine performance, emissions, and cylinder pressure were recorded and analyzed. The results showed that engines operating under dual-fuel combustion mode could achieve high efficiency with near zero nitrogen oxide (NOx) and smoke emissions. The biodiesel-gasoline dual-fuel combustion mode showed lower hydrocarbon (HC) and carbon monoxide (CO) emissions than the diesel-gasoline dual-fuel combustion mode. The oxygen content in biodiesel is especially useful in limiting locally fuel rich regions, resulting in improved combustion and thereby reducing HC and CO emissions simultaneously

Experimental Investigation of Performance, Emission and Combustion Characteristics of a Common-Rail Diesel Engine Fuelled with Bioethanol as a Fuel Additive in Coconut Oil Biodiesel Blends

In the present study, the effects of adding of bioethanol as a fuel additive to a coconut biodiesel-diesel fuel blend on engine performance, exhaust emissions, and combustion characteristics were studied in a medium-duty, high-pressure common-rail turbocharged four-cylinder diesel engine under different torque conditions. The test fuels used were fossil diesel fuels, B20 (20% biodiesel blend), B20E5 (20% biodiesel + 5% bioethanol blend), and B20E10 (20% biodiesel + 10% bioethanol blend). The experimental results demonstrated that there was an improvement in the brake specific energy consumption (BSEC) and brake thermal efficiency (BTE) of the blends at the expense of brake specific fuel consumption (BSFC) for each bioethanol blend. An increment in nitrogen oxide (NOx) across the entire load range, except at low load conditions, was found with a higher percentage of the bioethanol blend. Also, it was found that simultaneous smoke and carbon monoxide (CO) emission reduction from the baseline levels of petroleum diesel fuel is attainable by utilizing all types of fuel blends. In terms of combustion characteristics, the utilization of bioethanol blended fuels presented a rise in the peak in-cylinder pressure and peak heat release rate (HRR) at a low engine load, especially for the B20E10 blend. Furthermore, the B20E10 showed shorter combustion duration, which reduced by an average of 1.375 °CA compared to the corresponding baseline diesel. This study therefore showed that the B20E10 blend exhibited great improvements in the diesel engine, thus demonstrating that bioethanol is a feasible fuel additive for coconut biodiesel-diesel blends

Influence of engine operating variable on combustion to reduce exhaust emissions using various biodiesels blend

This study focused mainly on the behavior of biodiesel operated under various operating conditions. The experiment was conducted with B20 of three potential biodiesel sources, namely, rice bran, Moringa and sesame oil. A significant outcome was observed from the test results, which showed that the brake thermal efficiency of the biodiesel blend was about 3.4% lower under constant speed running conditions than constant torque operating conditions. Similarly, about 6.5% lower exhaust gas temperatures under constant speed running conditions with lower peak pressure were found than under constant torque testing conditions. On the subject of emission, it is seen that the testing conditions also have an influence on exhaust emission. For instance, under constant speed running conditions, the engine produces about 19.5% lower NO and 19% higher HC than under constant torque running conditions. A similar influence was also found in the pressure and heat release rate. However, there is a clear variation found in the results under different operating conditions. Therefore, it is necessary to test the fuel under various operating conditions, such as constant torque, constant speed, variable injection timing, for the optimal use of biodiesel

Evaluation of a novel biofuel from unwanted waste and its impact on engine performance, emissions, and combustion characteristics in a diesel engine

The effect of a new biofuel source derived from waste palm oil mill effluent (POME) addition to diesel on engine performance, emissions, and combustion characteristics was investigated in a single-cylinder diesel engine under six different speed operations and at full load conditions. The experimental results suggested that there are some penalties in engine torque, brake power, brake specific fuel consumption (BSFC), and brake specific nitrogen oxide (BSNOx) with the presence of Biopro Diesel™ fuel in the blend. Moreover, there is an improvement in exhaust emissions with lower brake specific hydrocarbons (BSHC), brake specific carbon monoxide (BSCO) and smoke emissions by using Biopro Diesel™ fuel blends across all engine speeds. Besides, the tip surfaces of the injectors running with Biopro Diesel™ blends were found to be cleaner than that of an injector running with fossil diesel. Moreover, there is an improvement in the combustion process with a shorter total burning angle for Biopro Diesel™ fuel blends than that of diesel at all engine speeds. Overall, the results suggested that biofuel derived from waste POME blended with fossil diesel can be used satisfactorily in an unmodified diesel engine

Effect of antioxidant on the oxidation stability and combustion-performance-emission characteristics of a diesel engine fueled with diesel-biodiesel blend

Alexandrian laurel or Calophyllum inophyllum oil is recently considered one of the most anticipated nonconsumable or nonedible biodiesel sources. An attempt has been made in this study to increase the oxidation stability and investigate the engine performance, emission, and combustion characteristics of a diesel engine by adding 1% (by vol.) of two antioxidants, such as 2,6-Di-tert.-butyl-4-methylphenol and 2,2'-methylenebis (4-methyl-6-tert-butylphenol), in higher percentages of C. inophyllum biodiesel (CB30) with diesel fuel (B0). The experiment was performed on a single-cylinder, water-cooled, direct-injection diesel engine for this purpose. The addition of both antioxidants increased the oxidation stability without significantly changing other physicochemical properties. Results also show that the antioxidants enhanced the start of combustion of biodiesel, which resulted in a short ignition delay. The peak pressure and the peak heat release rate during premixed combustion phase of pure CB30 and its modified blend with antioxidant were higher than those of B0. Both antioxidant blends showed higher brake power, higher brake thermal efficiency, and lower brake specific fuel consumption than pure CB30. Both antioxidants significantly reduced NOX emission; however, CO, HC, and smoke opacity were slightly higher than those of CB30. Based on this study, Alexandrian laurel or C inophyllum biodiesel blend (CB30) with antioxidant can be used as an alternative fuel in a diesel engine without modifications. (C) 2015 Elsevier Ltd. All rights reserved