Effect of biodiesel fuel properties and formation of NOx emissions: a review

Biodiesel is revealed as an environmentally friendly alternative fuel for a CI engine and it can palliate regulated and unregulated emissions. Biodiesel is substantially found to reduce the emissions of hydrocarbons, carbon monoxide, and particulate matter, but increasing (10–15%) oxides of nitrogen (NO_x) emissions compared with conventional diesel fuel. The accurate cause for NO_x emission is still vague. This paper reviews the effect of biodiesel properties and formation of NO_x emissions and it is classified in three sections. The first section bestows the NO_x formation mechanisms. The second edition deals with the influence of formation and biodiesel properties on NO_x emissions. Finally, a few prevailing conclusions are epitomised, and more researches are pointed out.     

Simulation of CI engine flow processes for prediction of performance and emissions with different fuels

Diesel-fuelled direct injection compression ignition engines yield high fuel conversion efficiency due to the use of high compression ratios and thus find their place in varied applications. However, tail pipe emissions of conventional diesel engines are a major source of high levels of oxides of nitrogen (NO_x) and particulate matter. Owing to stringent emission legislation, manufactures and researchers are facing tough competition to make them eco-friendly. The present paper deals with a simulation of extensive numerical experiments carried out on a single-cylinder diesel engine by varying timing of inlet valve closing (25°–55°ABDC) and fuels; rapeseed methyl esters and diesel fuel. For this purpose, a zero-dimensional thermodynamics-based model in C⁺⁺ was developed. The model takes into account the engine speed, fuel injection timing and equivalence ratio, temperature-dependent specific heat ratio and inlet valve close timing. The engine performance is evaluated in terms of thermal efficiency, in-cylinder pressure, heat release rate, and NO and soot emissions. It is observed that a significantly delayed closing of the inlet valve would result in loss of charge, and rapeseed methyl ester could be an attractive and viable alternative to petro-diesel fuel.     

Effect of heating the catalytic converter on emission characteristic of gasoline automotive vehicles

Gasoline engines have been widely used as engineering machinery, automobile and shipping power equipment due to their excellent drivability and economy. At the same time, gasoline engines are major contributors to various types of air pollutants such as carbon monoxide (CO), oxides of nitrogen (NO_x), and other harmful compounds. With the increasing concern of environment and more stringent government regulation on exhaust emissions, the reduction in engine emissions such as particulate matter and NO_x is a major research objective in engine development. In this article the effect of heating the catalytic converter on emission characteristic of automotive vehicles in its starting phase of combustion has been studied. In this work, the emission characteristic of hydrocarbons has been improved from 800 to 15 ppm, CO from 4 to 0.07 (V/V%) and NO_x from 1200 to 115 ppm.     

An experimental investigation of performance and emission characteristics of diesel engine with blends of cottonseed oil methyl ester with cold and hot EGR

An experimental investigation of diesel engine using cottonseed oil biodiesel and its blends with exhaust gas recirculation (EGR) techniques has been carried out. An optimum nozzle opening pressure of 250 bar and lower static injection timing of 20° before top dead centre (bTDC) are considered because it has been observed that these conditions only give minimum emissions. From the test results, it could be noted that there is an increasing trend of emission characteristics of HC, smoke density and NO_x for both cold and hot EGR for all blends of fuel with respect to brake power. As compared with cold EGR, the hot EGR gives lower emissions at all loads. In hot EGR, among the blends, at no-load and full-load conditions, the B100 gives the highest reduction in NO_x of 14.23% and 7.91%, respectively. However, the use of EGR leads to a rise in soot emission because of soot–NO_x trade-off for both the cases.     

Performance and emission characteristics of homogeneous charge compression ignition engine – a review

Homogeneous charge compression ignition (HCCI) engine uses a relatively new mode of combustion technology. In principle, there is no spark plug or injector to assist the combustion process, and the combustion starts at multiple spots once the mixture has reached its auto-ignition temperature. The challenges over the operation of HCCI-mode engines are the difficulties of controlling the auto-ignition of the mixture, operating range, homogeneous charge preparation, cold start, controlling knock and emissions of unburned hydrocarbon (UHC) and carbon monoxide (CO), which needed to be overcome to achieve successful operation of HCCI-mode engine. This paper reviews the working principle of HCCI-mode engine and analyse the knocking in the HCCI combustion. And it also reviews the impact of homogeneous charge on HCCI combustion parameters, such as heat-release rate and maximum pressure. Furthermore, it reviews the performance and emission characteristics of HCCI engine. For each of these parameters, the theories are discussed about successful operation of HCCI engine with comparative evaluation of performance and emission reported in the literature.     

Numerical and experimental investigations on a dual fuel HCCI engine by using ethanol as primary fuel and diesel as secondary fuel for NOX reduction and better performance

ABSTRACT

Achieving the new emission norms is a difficult task to today’s compression ignition (CI) engine without any exhaust gas after-treatment technologies. It is necessary to find the practical method which reduces the unsafe emission, with minor modifications of the CI engine. Dual fuel homogeneous charge compression ignition (HCCI) engine has been recognised as one of the solutions to minimise the emissions and achieve higher performance. In the present study the dual fuel HCCI engine mode of operation carried out by supply of ethanol fuel-air mixture to the engine cylinder through the carburetor and diesel fuel is directly injected at the end of compression for the initiation of ignition. Dual fuel HCCI engine is one of the most promising engines suitable for alternative fuels and lower NO_X emissions. An experimental investigation is carried out on dual fuel HCCI engine. Fuel consumption and exhaust emissions such as NO_X, CO₂, CO, HC are measured and compared with conventional CI engine. The results show that NO_X emission tends to decrease at low and moderate loads of the engine, but at full load condition it is slightly higher. Further, thermal efficiency is calculated and compared in CI engine; it is observed that there is a slight improvement in thermal efficiency at high load operation. In the dual fuel HCCI engine mode, there is a provision to use of ethanol or any other alternate fuel for better energy efficiencies and low NO_X emission.     

Performance and emission characteristics of cashew nut shell oil on the CI engine

This article is an effort to address the need for a non-cooking oil-based biodiesel. Here, the experimental work is done on a single cylinder, direct injection CI engine using cashew nut shell oil biodiesel blends under constant speed. The cashew nut shell liquid (CNSL) biodiesel is blended with the diesel fuel and used as biodiesel blend. Blends used for testing are B20, B40 and B60. The effect of the fuels on engine power, brake thermal efficiency (BTE) and exhaust gas temperature was determined by performance tests. The influences of blends on CO, CO₂, HC and NO_x emissions were investigated by emission tests. The BTE values of biodiesel are closer to diesel. Compared to diesel, all the biodiesel blends gave lesser unburnt hydrocarbon (HC), carbon monoxide (CO) and smoke emissions. Slightly higher NO_x emissions were found in CNSL biodiesel blends, which is typical of the other biodiesels.     

Influence of spark timing on the performance and emission characteristics of gasoline–hydrogen-blended high-speed spark-ignition engine

This article experimentally investigates the effect of spark timing on performance and emission characteristics of high-speed spark-ignition (SI) engine operated with different hydrogen–gasoline fuel blends. For this purpose, the conventional carbureted SI engine is modified into an electronically controllable engine, wherein an electronically controllable unit was used to control the ignition timings and injection duration of gasoline. The tests were conducted with different spark timings at the wide open throttle position and 3000 rpm engine speed. The experimental results demonstrated that brake mean effective pressure and engine brake thermal efficiency increased first and then decreased with the increase in spark advance. Peak cylinder pressure, temperature and heat release rate were increased until 20% hydrogen addition and with increased spark timings. NO_x emissions were continuously increased with the increment in both spark timings and hydrogen addition, whereas hydrocarbon emissions were increased with spark timings but decreased with hydrogen addition. CO emissions were reduced with the increase in spark timing and hydrogen addition.     

Detailed analysis on injection timing retardation and simultaneous technology in a biodiesel-powered compression ignition engine

ABSTRACT

This detailed study focuses mainly on the reduction of oxides of nitrogen emissions from CI engines. It also discusses about other emissions and performance parameters. Injection timing retardation and simultaneous technology methods have been employed for controlling oxides of nitrogen emissions by many researchers. This review paper studies on injection timing retardation and simultaneous technology and its effects on various operating parameters carried out in a biodiesel-powered CI engines. The objective of this work is to find the significance of injection parameters such as retardation of injection timing and simultaneous technology on the various emission parameters. This paper also deals upon the various methods of retardation of injection timing and simultaneous technology to examine the emissions such as HC, CO, NO_x, smoke, and particulate matters. The present study showed that widespread review on CI engine emission characteristics in a CI engine fuelled with biodiesel blends.     

Artificial neural network-based prediction of performance and emission characteristics of CI engine using polanga as a biodiesel

The present work predicts the performance parameters, namely brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), peak pressure, exhaust gas temperature and exhaust emissions of a single cylinder four-stroke diesel engine at different injection timings and engine load using blended mixture of polanga biodiesel by artificial neural network (ANN). The properties of biodiesel produced from polanga were measured based on ASTM standards. Using some of the experimental data for training, an ANN model was developed based on standard back-propagation algorithm for the engine. Multi-layer perception network was used for non-linear mapping between input and output parameters. Different activation functions and several rules were used to assess the percentage error between the desired and the predicted values. It was observed that the developed ANN model can predict the engine performance and exhaust emissions quite well with correlation coefficient (R) 0.99946, 0.99968, 0.99988, 0.99967, 0.99899, 0.99941 and 0.99991 for the BSFC, BTE, peak pressure, exhaust gas temperature, NO_x, smoke and unburned hydrocarbon emissions, respectively. The experimental results revealed that the blended fuel provides better engine performance and improved emission characteristics.     

Experimental exploration on NO x diminution by the combined effect of antioxidant additives with SCR in a diesel engine powered by neem biodiesel

ABSTRACT

The use of biodiesel in diesel engines leads to the reduction of tail pipe emissions; But, several researchers portray that the use of biodiesel produces more NO_x pollution than diesel-fuelled engines, which is an hindrance for the scope of biodiesel usage. In this work, an experimental investigation of the combined effect of antioxidant additive added in the fuel as a fuel modification technique and SCR (selective catalytic reduction) as after a treatment technique on NO _x reduction in a neem biodiesel-powered compression ignition engine has been conducted. Results show that the antioxidant additive combined with the SCR technique reduces the NO _x emission significantly by 82% and there was a slight increase in UBHC and CO emission due to the addition of oxidation-suppressing additives with neem biodiesel and aqueous urea solution injection at the exhaust without a major drop in BTE and fuel consumption.     

Experimental investigation on spark ignition engine using blends of bio-ethanol produced from citrus peel wastes

The performance and pollutant emissions of a four stroke spark ignition engine operating on gasoline and bio-ethanol blends were investigated experimentally. The citrus peel wastes were grinded and subjected to simple distillation to remove d-limonene and then the remains were kept in an autoclave at a temperature of 120°C for 15 min. Finally, by doing simple distillation, bio-ethanol was extracted. From the experiments, the specific fuel consumption (SFC) was slightly increased and the brake thermal efficiency was slightly decreased. Exhaust gas emissions were measured and analysed for hydrocarbons (HC), carbon dioxide (CO₂), carbon monoxide (CO) and oxides of nitrogen (NO_x) at an engine speed of 2500?rpm. The concentration of CO and HC emissions in the exhaust pipe was found to be decreased when bio-ethanol blends were used. The concentration of CO₂ was found to be slightly increased and NO_x was reduced when ethanol blends were used.     

The effect of engine emission on canola biodiesel blends with TiO2

The role of nanoparticles and nanofluid additives for biodiesel has gained consistent position in the current trend as they contribute to increase the performance of the engine with lower emission. In addition, additives also help to increase the engine reliability and lifespan. In this work, the effects of canola biodiesel blends of 20% proportions with diesel were investigated at 100% of engine load. The fuel is tested in a multi-cylinder water-cooled direct ignition (DI) engine. There are numerous notable works on nanofluid; however, the addition of TiO₂ nanoparticle as additive to produce canola biodiesel fuel is very limited. With the addition of the TiO₂ nanoparticle on Canola biodiesel blend in the DI engine, the exhaust property of gases such as CO, HC and NO_X is reduced. Furthermore, the combustion characteristics of the engine are improved. The canola biodiesel blends also resulted in lower NO_x emission as well as low smoke.     

Analysis of ethanol blends on spark ignition engines

The objective of this investigation was to find the effect of ethanol–gasoline blends as fuel on the performance and exhaust emission of a spark ignition (SI) engine. A four-stroke three-cylinder SI engine was used for this study. Performance tests were conducted for the three blends E5 (5% ethanol), E10 (10% ethanol) and E15 (15% of ethanol) as well as E0(100% gasoline) to evaluate their brake thermal efficiency, specific fuel consumption and mechanical efficiency, while exhaust emissions were also analysed for carbon monoxide (CO), hydrocarbons (HC), carbon dioxide (CO₂) and oxides of nitrogen (NO_x) with varying torque conditions and constant speed of the engine. The results showed that blends of gasoline and ethanol increased the brake power, brake thermal efficiency and the fuel consumption. The CO and HC emissions concentration in the engine exhaust decreased while the NO_x concentration increased.     

Investigation on the combustion,performance and emissions of a diesel engine fuelled by biodiesel and its blends with different oxygenated organic compounds

An experimental investigation is carried out to evaluate the effects of biodiesel–ethanol (BE) blends, biodiesel–dimethyl carbonate (BC) blends and biodiesel–diglyme (BG) blends on the combustion, performance and emission characteristics of a diesel engine operated at different loads and constant engine speed. Compared with biodiesel, for a specific engine load, the BE and BC blends have lower peak cylinder pressure at full load, while the BG blends show a slight variation in the peak cylinder pressure. In comparison with biodiesel, the BE, BC and BG blends have slightly higher brake thermal efficiency. Drastic reduction in smoke is observed with BE, BC and BG blends at higher engine loads. The BSNO_x emissions are found slightly lower for BE, BC and BG blends almost at all loads. The BE and BC blends have a slight variation in the BSCO and BSHC emissions, while the BG blends have lower BSCO and BSHC emissions.     

Emission reduction potential of using gas-to-liquid and dimethyl ether fuels on a turbocharged diesel engine

A study of engine performance characteristics and both of regulated (CO, HC, NO_x, and smoke) and unregulated (ultrafine particle number, mass concentrations and size distribution) emissions for a turbocharged diesel engine fueled with conventional diesel, gas-to-liquid (GTL) and dimethyl ether (DME) fuels respectively at different engine loads and speeds have been carried out. The results indicated that fuel components significantly affected the engine performance and regulated/unregulated emissions. GTL exhibited almost the same power and torque output as diesel, while improved fuel economy. GTL significantly reduced regulated emissions with average reductions of 21.2% in CO, 15.7% in HC, 15.6% in NO_x and 22.1% in smoke in comparison to diesel, as well as average reductions in unregulated emissions of total ultrafine particle number (N_tot) and mass (M_tot) emissions by 85.3% and 43.9%. DME can significantly increase torque and power, compared with the original diesel engine, as well as significantly reduced regulated emissions of 40.1% in HC, 48.2% in NO_x and smoke free throughout all the engine conditions. However, N_tot for DME is close to that for diesel. The reason is that the accumulation mode particle number emissions for DME are very low due to the characteristics of oxygen content and no C-C bond, which promotes the processes of nucleation and condensation of the semi-volatile compounds in the exhaust gas, as a result, a lot of nucleation mode particles produce.     

A comprehensive study on reduction of NOx emission applying EGR technique in a diesel engine using biodiesel (POME) as fuel with ether-based additives

The energy consumption is increasing rapidly due to population growth, improved living standards and industrialisation. A significant amount of fossil fuels is consumed by the transportation sector, which causes the fast depletion of fossil fuels and environmental pollution. These problems can be overcome by using Biodiesel. This research work aims to reduce the NO_x emission in diesel engines. The literature survey reveals that the use of a fuel additive reduces the emissions by oxygenating the fuel. Among oxygenates, ether proves to behave better than alcohols. Hence, for this present work, two different types of ethers were selected which were not used in earlier occasions. DGME (Diethylene Glycol Monomethyl Ether) and DGMB (Diethylene Glycol Monobutyl Ether) are the two additives selected from the ether group and used as additives with palm oil methyl ester (POME) biodiesel in various proportions and tested in a direct injection compression ignition engine which reduced the emissions. To start with, the engine was run with diesel and subsequently with biodiesel and with the additives. The performance tests were carried out in a single-cylinder, four-stroke, water-cooled engine with and without exhaust gas recirculation (EGR). This engine is coupled with eddy current dynamometer. The use of biodiesel in conventional diesel engines results in substantial reduction in emission of carbon monoxide, particulates and unburned hydrocarbons, but increases NO_x emission. This review focuses on reduction of NO_x emission. Combustion and performance analysis of the engine have also been evaluated.     

Influence of injection timing on engine performance,emission characteristics of Mimusops Elangi methyl ester

ABSTRACT

The improvement in engine performance and exhaust emissions reduction are the major important issues in developing a more efficient engine. The injection timing is one the major parameters that affect the engine performance and emissions for a diesel engine. The present work focused on characterising the in?uence of injection timing on engine performance and exhaust emissions. This has been critically investigated for B20?+?25?ppm (20% Mimusops Elangi methyl ester-80% diesel fuel?+?25?ppm of TiO₂ nanoparticle) additive as alternative fuel. The B20?+25 ppm TiO₂ nanoparticle additive produces more HC and CO emission, but reduce NO_X emission when injection timing is retarded. Advancement in injection timing for B20?+25?ppm TiO₂ nanoparticle additive results in an increase of brake thermal efficiency, decreases brake specific fuel consumption and giving out less HC, CO, smoke emissions but the marginal increase in the NO_X emission.     

Effect of CNG flow rate on the performance and emissions of a Mullite-coated diesel engine under dual-fuel mode

On the diesel engines that are used to generate power in transportation and industries, many researchers have to deal with major problems of smoke emissions while extracting higher efficiency. There are many studies which reported the exhaust emission reduction strategies from diesel engines by applying new combustion methods that are capable of mitigating the formation of harmful emissions. One of the methods to reduce the exhaust emissions in diesel engines is to use the dual-fuel combustion mode. In this study, an attempt has been made to evaluate the effect of thermal barrier coating (TBC) on the dual-fuel engine and for this, experiments are carried out on a single-cylinder direct-injection diesel engine under dual-fuel and low heat rejection mode with compressed natural gas (CNG) as gaseous fuel. Engine components that are exposed to the combustion are coated with Mullite (3Al₂O₃-2SiO₂) TBC. Diesel at 200 bar injector opening pressure was used as pilot fuel and CNG at different flow rates (5, 10 and 15 litres per minute) was inducted into the combustion chamber through inlet manifold as main fuel. Experimental results show that the coating of TBC on the engine components has a positive effect on the performance emissions of the dual-fuel test engine. Brake specific fuel consumption (BSFC) was found improved significantly at all flow rates of CNG with coated engine. Emissions on the other hand were also noticed to be on the lower side with the coated engine except NO_x. Smoke emissions were significantly reduced with coated CNG operation of the test engine at all flow rates.     

Experimental investigations of direct injection compression ignition engine by using Coconut,and Karanja biodiesel fuels with emulsions of microalgae based antioxidant

The Compression Ignition (CI) engines are playing vital role in the transportation sector; because of their lower maintenance cost even. The practice of Diesel or biodiesel is increasing Green House Gases (GHG) such as NO_x, particulate matter in the environment. Among all GHG emissions, NO_x is most harmful to human, environment. The use of additives in Diesel, biodiesel their blends in CI engine is very well practicing fuel modification technique to reduce GHG emissions. The higher cost of phenol, amine-based antioxidants are causing to increase CI engine operating cost. In this work, to investigate unmodified Direct Injection Compression Ignition engine characteristics. The Mixed culture Microalgae (MCM) biomass particles used as an antioxidant additive in pure Coconut, Karanja biodiesel. The brake thermal efficiency improved because of the explosion of MCM particles. The NO_x emissions reduced due to the absorption of heat from the combustion chamber by microalgae particle.