Simultaneous reduction of NO–smoke–CO<Subscript>2</Subscript> emission in a biodiesel engine using low-carbon biofuel and exhaust after-treatment system

The present work focuses on the simultaneous reduction of NO–smoke–CO₂ emission in a Karanja oil methyl ester (KOME)-fueled single-cylinder compression ignition engine by using low-carbon biofuel with exhaust after-treatment system. Replacement of KOME for diesel reduced smoke emission by 3% but resulted in increase of NO emission and CO₂ emission by 13 and 35% at 100% load condition. In order to reduce CO₂ emission, tests were conducted with a blend of KOME and orange seed oil (OSO), a low-carbon fuel on equal volume basis (50–50). At the same operating conditions, compared to KOME, 27% reduction in CO₂ emission and 5% reduction in smoke emission were observed. However, a slight increase in NO emission was observed. To achieve simultaneous reduction of NO–smoke–CO₂ emissions, three catalysts, namely monoethanolamine, zeolite and activated carbon, were selected for exhaust after-treatment system and tested with optimum KOME–OSO blend. KOME–OSO + zeolite showed a great potential in simultaneous reduction of NO–smoke–CO₂ emissions. NO, smoke and CO₂ emissions were simultaneously reduced by about 15% for each emission compared to diesel at 100% load condition. The effect of exhaust after-treatment system with KOME–OSO blend on combustion, performance and other emission parameters is discussed in detail in this study. Fourier transform infrared spectrometry analysis and testing were done to identify the absorbance characteristics of zeolite material.     

Carbon particulate matter incineration in diesel engine emissions using indirect nonthermal plasma processing

One of the promising applications of nonthermal plasma (NTP) for environmental cleanup technology is low-temperature oxidation or incineration of carbon particulate matter (PM) in diesel engine emissions. In this process, NO₂ and activated radical species induced by NTP can incinerate carbon PM trapped by a diesel particulate filter (DPF) at low temperature (< 300 °C). In the present study, an experiment was carried out on indirect NTP DPF regeneration for real diesel engine emissions comprising CO₂ of several per cent, hydrocarbons of several hundreds of ppm and moisture of several tens of percentages. It was confirmed that DPF regeneration is possible for a real diesel emission at a low temperature of 280 °C. The removal energy efficiency was estimated to be 0.82 g/kW h. This electric power range is sufficient to meet the recently proposed long-term national regulation for diesel automobiles in Japan.     

Diesel emission control: Catalytic filters for particulate removal

The European diesel engine industry represents a vital sector across the Continent, with more than 2 million direct work positions and a turnover of over 400 billion Euro. Diesel engines provide large paybacks to society since they are extensively used to transport goods, services and people. In recent years increasing attention has been paid to the emissions from diesel engines which, like gasoline engine emissions, include carbon monoxide (CO), hydrocarbons (HC) and oxides of nitrogen (NO_x). Diesel engines also produce significant levels of particulate matter (PM), which consists mostly of carbonaceous soot and a soluble organic fraction (SOF) of hydrocarbons that have condensed on the soot.

Meeting the emission levels imposed for NO_x and PM by legislation (Euro IV in 2005 and, in the 2008 perspective, Euro V) requires the development of a number of critical technologies to fulfill these very stringent emission limits (e.g. 0.005 g/km for PM). This review is focused on these innovative technologies with special reference to catalytic traps for diesel particulate removal.     

Effect of EGR on the exhaust gas temperature and exhaust opacity in compression ignition engines

In diesel engines, NOx formation is a highly temperature-dependent phenomenon and takes place when the temperature in the combustion chamber exceeds 2000 K. Therefore, in order to reduce NOx emissions in the exhaust, it is necessary to keep peak combustion temperatures under control. One simple way of reducing the NOx emission of a diesel engine is by late injection of fuel into the combustion chamber. This technique is effective but increases fuel consumption by 10–15%, which necessitates the use of more effective NOx reduction techniques like exhaust gas recirculation (EGR). Re-circulating part of the exhaust gas helps in reducing NOx, but appreciable paniculate emissions are observed at high loads, hence there is a trade-off between NOx and smoke emission. To get maximum benefit from this trade-off, a paniculate trap may be used to reduce the amount of unburnt particulates in EGR, which in turn reduce the paniculate emission also. An experimental investigation was conducted to observe the effect of exhaust gas re-circulation on the exhaust gas temperatures and exhaust opacity. The experimental setup for the proposed experiments was developed on a two-cylinder, direct injection, air-cooled, compression ignition engine. A matrix of experiments was conducted for observing the effect of different quantities of EGR on exhaust gas temperatures and opacity     

Injection Strategy in Natural Gas–Diesel Dual-Fuel Premixed Charge Compression Ignition Combustion under Low Load Conditions

Dual-fuel premixed charge compression ignition (DF-PCCI) combustion has been proven to be a viable alternative to conventional diesel combustion in heavy-duty compression ignition engines due to its low nitrogen oxides (NO_x) and particulate matter (PM) emissions. When natural gas (NG) is applied to a DF-PCCI engine, its low reactivity reduces the maximum pressure rise rate under high loads. However, the NG–diesel DF-PCCI engine suffers from low combustion efficiency under low loads. In this study, an injection strategy of fuel supply (NG and diesel) in a DF-PCCI engine was investigated in order to reduce both the fuel consumption and hydrocarbon (HC) and carbon monoxide (CO) emissions under low load conditions. A variation in the NG substitution and diesel start of energizing (SOE) was found to effectively control the formation of the fuel–air mixture. A double injection strategy of diesel was implemented to adjust the local reactivity of the mixture. Retardation of the diesel pilot SOE and a low fraction of the diesel pilot injection quantity were favorable for reducing the combustion loss. The introduction of exhaust gas recirculation (EGR) improved the fuel economy and reduced the NO_x and PM emissions below Euro VI regulations by retarding the combustion phasing. The combination of an NG substitution of 40%, the double injection strategy of diesel, and a moderate EGR rate effectively improved the combustion efficiency and indicated efficiency, and reduced the HC and CO emissions under low load conditions.     

Effect of compression ratio on performance,emission and combustion characteristics of diesel–acetylene-fuelled single-cylinder stationary CI engine

The present investigation aims to depict the effect of compression ratio on performance, emission and combustion characteristics of diesel–acetylene-fuelled stationary compression ignition engine. The optimum values for compression ratio, injection timing and injection pressure for diesel were experimentally found, and baseline data were established as 20, 23° before top dead centre and 210 bar, respectively. In order to investigate the effect of acetylene fuelling, acetylene gas was inducted at four different flow rates of 60, 120, 180 and 240 litres per hour at compression ratio 20. It was observed that the flow rate of 120 litres per hour gave the best performance with highest brake thermal efficiency of 25.09%. In order to find the optimum compression ratio for acetylene fuelling at 120 litres per hour, experimentation was done at different compression ratios of 18, 19, 20, 21 and 22. Experimental results showed that highest brake thermal efficiency of 25.72% was achieved at compression ratio 21 for diesel–acetylene fuelling which was much higher than 23.32% for pure diesel. Carbon monoxide, hydrocarbon and smoke emissions were also measured and found to be lower, while the NOx emissions were higher at optimized values in dual-fuel mode as compared to those for pure diesel. Peak cylinder pressure and net heat release rate were also calculated and found to be higher in dual-fuel mode compared to diesel mode.     

Experimental analysis of fuel from fish processing industry waste in a diesel engine

In the present work, biofuel derived from industrial fish processing industry waste is used in diesel engines to study its suitability . Biofuel from industry fish waste is produced through catalytic cracking, and its quality has been improved through distillation. A single cylinder 4.5 kW at 1500 rpm was used to find the suitability of biofuel and undistilled biofuel in diesel engine. Experimental results show that the brake thermal efficiency of biofuel and undistilled biofuel is similar. Brake thermal efficiency for diesel, undistilled biofuel and biofuel is 29.98, 32.12 and 32.4%, respectively, at 80% load. Carbon monoxide, unburnt hydrocarbons, particulate matter and oxides of nitrogen emissions increase with undistilled biofuel compared to biofuel. There is a small reduction in carbon dioxide emission with undistilled biofuel compared to biofuel. Even though the cylinder pressure is high with undistilled biofuel, the intensity of premixed combustion is lower than distilled biofuel. The ignition delay and combustion duration increase with undistilled biofuel. Finally, it is concluded that the fuel derived from fish processing industry waste can be used as a fuel for diesel engine after distillation.     

Controlling automotive exhaust emissions: successes and underlying science

Photochemical reactions of vehicle exhaust pollutants were responsible for photochemical smog in many cities during the 1960s and 1970s. Engine improvements helped, but additional measures were needed to achieve legislated emissions levels. First oxidation catalysts lowered hydrocarbon and carbon monoxide, and later nitrogen oxides were reduced to nitrogen in a two-stage process. By the 1980s, exhaust gas could be kept stoichiometric and hydrocarbons, carbon monoxide and nitrogen oxides were simultaneously converted over a single 'three-way catalyst'. Today, advanced three-way catalyst systems emissions are exceptionally low. NOx control from lean-burn engines demands an additional approach because NO cannot be dissociated under lean conditions. Current lean-burn gasoline engine NOx control involves forming a nitrate phase and periodically enriching the exhaust to reduce it to nitrogen, and this is being modified for use on diesel engines. Selective catalytic reduction with ammonia is an alternative that can be very efficient, but it requires ammonia or a compound from which it can be obtained. Diesel engines produce particulate matter, and, because of health concerns, filtration processes are being introduced to control these emissions. On heavy duty diesel engines the exhaust gas temperature is high enough for NO in the exhaust to be oxidised over a catalyst to NO2 that smoothly oxidises particulate material (PM) in the filter. Passenger cars operate at lower temperatures, and it is necessary to periodically burn the PM in air at high temperatures.     

An experimental investigation on the performance,combustion and emission characteristics of a variable compression ratio diesel engine using diesel and palm stearin methyl ester

An attempt has been made to use biodiesel prepared from non-edible portion of palm oil as fuel of a conventional mono-cylinder compression ignition engine. The present experimental investigation takes into account the combined effect of using blends of diesel–palm stearin biodiesel as fuels and the compression ratio on different performance, combustion and emission characteristics of the said engine. The experiments have been carried out on a single-cylinder, direct injection diesel engine at varying compression ratio of 16:1–18:1 in four steps. It is observed that the brake thermal efficiency reduces by 7.9% when neat biodiesel is used instead of diesel. But, it increases with the increase in compression ratio for all the blends. Brake specific fuel consumption and exhaust gas temperature increase with the addition of biodiesel to diesel and also with the increase in compression ratio. Heat release rate decreases with biodiesel, and it is minimum at the rated compression ratio of 17.5:1 for all the fuels considered here. On the other hand, ignition delay is found to be more with neat diesel, and it increases with the decrease in compression ratio. Significant reductions in emissions of carbon monoxide (CO), hydrocarbon (HC) and smoke are observed with biodiesel, while the emissions of oxides of nitrogen (NO_x) and carbon dioxide (CO₂) increase. The decrease in compression ratio increases the emissions of CO, HC and smoke, but the emissions of NO_x and CO₂ decrease with the decrease in compression ratio.     

Combustion performance of rubber seed methyl ester using aromatic and phenolic antioxidants in a multi-cylinder diesel engine

This paper analyzes the effect of antioxidants on engine combustion performance of a multi-cylinder diesel engine fueled with rubber seed biodiesel blends. Four antioxidants, namely 2-tert-butylbenzene-1,4-diol, N,N′-diphenyl-1,4-phenylenediamine, 2(3)-tert-Butyl-4-methoxyphenol and N-phenyl-1,4-phenylenediamine, were added at concentrations of 1000 and 2000 ppm to rubber seed biodiesel blends. Antioxidants blends increased the brake power by 4.21% and decreased the brake-specific fuel consumption by 6.82% compared to base biodiesel blends. The NO emissions reduction percentage for antioxidants fuels was 9.78% compared to base line biodiesel. However, the treated biodiesel blends increased carbon monoxide, hydrocarbon and smoke opacity up to 32.20, 42.15 and 43.92%, respectively, compared to non-treated blends. Compared to diesel fuel, antioxidants fuels decreased the brake power and increased the brake-specific fuel consumption, cylinder pressure and heat release rate. But compared to biodiesel blends, the cylinder pressure and heat release rate with antioxidants were reduced by 4.17 and 6.87%, respectively. It can be concluded that antioxidants addition is effective in increasing the oxidation stability and controlling the NO emissions of rubber seed biodiesel fueled diesel engines.     

DOC+DPF在防爆柴油机上的应用研究

在某型防爆柴油机加装DOC+DPF后处理装置上进行台架实验,结果表明,PY03型装置不会增大防爆柴油机系统的排气背压,对CO平均转化效率达96%,对颗粒物有较高的捕集和再生效率,不透光烟度平均转化效率为82.7%;PY02型装置因尺寸较小,热负荷较高,与该排放状况不匹配。为提高装置的利用率和使用寿命,通过对耦合的DOC+DPF孔道进行可燃性气体CO组分输运和颗粒物离散相数值模拟。结果表明:随着废气流速的增大,DOC+DPF出口废气中CO浓度升高,转化效率下降;15 m/s的气流速度是发动机该排放水平下转化效率最高的最大速度;孔道入口速度增大,颗粒物向孔道后端壁面沉积;DOC+DPF装置在防爆柴油机上实用可行。     

Advances in biodiesel fuel for application in compression ignition engines

The importance of biodiesel as a renewable and economically viable alternative to fossil diesel for applications in compression ignition (CI) engines has led to intense research in the field over the last two decades. This is predominantly due to the depletion of petroleum resources, and increasing awareness of environmental and health impacts from the combustion of fossil diesel. Biodiesel is favoured over other biofuels because of its compatibility with present day CI engines, with no further adjustments required to the core engine configurations when used in either neat or blended forms. Studies conducted to date on various CI engines fuelled with varying biodiesel types and blends under numerous test cycles have shown that key tailpipe pollutants, such as carbon monoxide, aromatics, sulphur oxides, unburnt hydrocarbons and particulate matters are potentially reduced. The effects of biodiesel on nitrogen oxides emission require further tests and validations. The improvement in most of the diesel emission species comes with a trade-off in a reduction of brake power and an increase in fuel consumption. Biodiesel’s lubricating properties are generally better than those of its fossil diesel counterpart, which result in an increased engine life. These substantial differences in engine-out responses between biodiesel and fossil diesel combustion are mainly attributed to the physical properties and chemical composition of the fuels. Despite the purported benefits, widespread adoption of biodiesel usage in CI engines is hindered by outstanding technical challenges, such as low temperature inoperability, storage instabilities, in-cylinder carbon deposition and fuel line corrosion. It is imperative that these issues are addressed appropriately to ensure that long-term biodiesel usage in CI engines does not negatively affect the overall engine durability. Possible solutions range from biodiesel fuel reformulation through feedstock choice and production technique, to the simple addition of fuel additives. This calls for a more strategic and comprehensive research effort internationally, with an overarching approach for co-ordinating sustainable exploitation and utilisation of biodiesel. This review examines the combustion quality, exhaust emissions and tribological impacts of biodiesel on CI engines, with specific focus on the influence of biodiesel’s physico-chemical properties. Ongoing efforts in mitigating problems related to engine operations due to biodiesel usage are addressed. Present day biodiesel production methods and emerging trends are also identified, with specific focus on the conventional transesterification process wherein factors affecting its yield are discussed.     

Study on the effect of exhaust gas-based fuel preheating device on ethanol–diesel blends operation in a compression ignition engine

Rapid depletion of fossil fuels and stringent emission regulations compel the scientific community to search for alternative energy sources for the internal combustion engines. Among many alternative biofuels, ethanol is getting worldwide attention for compression ignition engine either in the form of partial substitute or complete replacement for diesel fuel. Ethanol fuel has certain undesirable properties like poor flammability limit which results in cold starting issues and higher hydrocarbon emission which restricts their use in compression ignition engine. This issue can be easily overcome by preheating of ethanol fuel before it gets admitted inside the engine cylinder. In the present study, a standard preheating device is designed and fabricated in accordance with engine specifications and simulations were carried out under various operating conditions to evaluate its performance. Furthermore, experimental investigations were carried out in a compression ignition engine fueled with ethanol blends of 20 and 30% with diesel by volume and the fuel blends were preheated using burned exhaust gases. In addition, a comparative study has been carried out for preheated and non-preheated blends of E20 (20% of ethanol and 80% of diesel) and E30 with baseline diesel. The experimental results show that the preheated E20 (20% of ethanol and 80% of diesel) blend has higher brake thermal efficiency of 36.28% with a significant reduction in brake specific fuel consumption when compared with all the other blends. Moreover, the preheated E20 blend reduces the carbon monoxide, unburned hydrocarbon and smoke emissions by 49, 48 and 10%, respectively. However, the NOx emission is increased by 6% as compared to the non-preheating effect. It is also noted that the preheating of ethanol blends produced better combustion results with a significant reduction in the ignition delay period. Hence, it can be concluded that the ethanol fuel can be effectively used in a diesel engine by means of preheating using exhaust gases and could be a viable option for diesel engine applications.     

Knock characteristics of dual-fuel combustion in diesel engines using natural gas as primary fuel

This paper investigates the combustion knock characteristics of diesel engines running on natural gas using pilot injection as means of initiating combustion. The diesel engines knock under normal operating conditions but the knock referred to in this paper is an objectionable one. In the dual-fuel combustion process we have the ignition stage followed by the combustion stage. There are three types of knock: diesel knock, spark knock and knock due to secondary ignition delay of the primary fuel (erratic knock). Several factors have been noted to feature in defining knock characteristics of dual-fuel engines that include ignition delay, pilot quantity, engine load and speed, turbulence and gas flow rate     

Influence of ethanol-diesel blended fuels on diesel exhaust emissions and mutagenic and genotoxic activities of particulate extracts

This study was aimed at evaluating the influence of ethanol addition on diesel exhaust emissions and the toxicity of particulate extracts. The experiments were conducted on a heavy-duty diesel engine and five fuels were used, namely: E0 (base diesel fuel), E5 (5%), E10 (10%), E15 (15%) and E20 (20%), respectively. The regulated emissions (THC, CO, NOx, PM) and polycyclic aromatic hydrocarbon (PAH) emissions were measured, and Ames test and Comet assay, respectively, were used to investigate the mutagenicity and genotoxicity of particulate extracts. From the point of exhaust emissions, the introduction of ethanol to diesel fuel could result in higher brake specific THC (BSTHC) and CO (BSCO) emissions and lower smoke emissions, while the effects on the brake specific NOx (BSNOx) and particulate matters (BSPM) were not obvious. The PAH emissions showed an increasing trend with a growth of ethanol content in the ethanol-diesel blends. As to the biotoxicity, E20 always had the highest brake specific revertants (BSR) in both TA98 and TA100 with or without metabolizing enzymes (S9), while the lowest BSR were found in E5 except that of TA98-S9. DNA damage data showed a lower genotoxic potency of E10 and E15 as a whole.     

SNH4100型柴油机排放控制的试验研究

主要论述了SNH4100型柴油机排放控制方法及理论依据,通过对喷油泵、喷油器、高压油管内径和活塞顶部燃烧室的性能匹配试验,使SNH4100型柴油机排放水平得到较好的控制;同时,为今后其他机型的开发提供了理论依据和经验。     

Influence of air intake pipe on engine exhaust emission

The exhaust emissions of a four-cylinder four-stroke petrol engine have been measured. Tests have been conducted at engine speeds ranges from 1000 to 4000 rpm and at air intake pipe diameters of 20, 25, 30, 35, 40 and 63 mm. The results demonstrate that the concentrations of the hydrocarbon (HC) and that of the carbon monoxide (CO) are relatively high at small air intake pipe diameter of 20 mm and at low engine speed of about 1000 rpm. Both pollutants have a minimum at large air intake pipe diameter of about 63 mm and at high engine speed of about 4000 rpm. The exhaust emissions HC and CO increase also as the ambient pressure decreases and as the altitude of the engine increases. The values of carbon dioxide (CO₂) and the oxygen (O₂) remain relatively constant at a wide range of different operating conditions. Therefore the knowledge about the effect of the above parameters could lead to improve the emission control technology as well as the engine performance on engine development and design.     

Root Cause Analysis of Failed Diesel Engine Aluminum Pistons

Root cause analysis was performed to determine the cause of failure of numerous cast aluminum pistons used in high speed diesel engines over ~7 months. The analysis consisted of metallurgical and engine systems evaluations. The metallurgical evaluation of two of the initial failed pistons showed failure by exposure to incompletely atomized and combusted fuel droplets that melted and eroded the piston crown outer diameters. The initial suspected root cause of the uncombusted fuel droplets was the presence of fuel-tank biological growth. The tanks were cleaned and the engines restored to service, but there were additional piston failures after only a short time back on-line, including piston seizures that fractured the pistons and cylinder liners. A subsequent, much more detailed engine system evaluation showed that the true root cause explaining all the failures was incorrect fuel injection timing. Two key points to be taken from this analysis are: (1) determination of the true root cause in this case required continuous and close interaction among metallurgical and engine systems personnel throughout an extended analysis process; (2) getting to the true root cause may require tenacious ‘detective’ work to track down and eliminate all other potential causes.     

A novel hydrophobic adsorbent of electrospun SiO<Subscript>2</Subscript>@MUF/PAN nanofibrous membrane and its adsorption behaviour for oil and organic solvents

With increasing oil spill accidents, the development of effective and low-cost adsorbents with good hydrophobicity is highly desirable. To cope with the clean-up of oil spill, a hydrophobic adsorbent was synthesized by electrospinning using inexpensive raw materials. By ingeniously combining melamine with polyacrylonitrile (PAN) as well as SiO₂ nanoparticles, a novel composite nanoadsorbent named SiO₂@MUF/PAN nanofibrous membrane was prepared and characterized. The adsorbents were conducted based on uniform nanofibre networks and were abundant with narrow slit-like pores, which are significant for the retention of oil and organic solvents. The hydrophobicity of the as-prepared membranes was enhanced with an increasing amount of SiO₂, and the highest water contact angle was 128.3°. Furthermore, the combination of SiO₂ and melamine increased the thermal stability of the membranes. With the unique pore structures and hydrophobicity, the membranes were able to selectively remove not only oil but also organic solvents from water surface. The adsorption capacities of the membranes with SiO₂ nanoparticles (0.9 wt%) were the highest and that for peanut oil, diesel, pump oil and engine oil were 19.09, 13.12, 18.48 and 22.67 g g^?1, respectively, while that for organic solvents ranged from 12.92 to 22.16 g g^?1. After 10 adsorption–regeneration cycles, the adsorption capacity was still around 35% of the initial value. Due to its high oil adsorption capacity, excellent reusability and the cost-effective hydrophobic, SiO₂@MUF/PAN have a great potential for oil spill clean-up.     

Numerical prediction of the performance,combustion and emission characteristics of a CI engine using different biodiesels

An attempt has been made to investigate numerically the energetic, combustion and environmental performances of a single-cylinder naturally aspirated direct injection diesel engine using the commercial software, Diesel-RK. Diesel and five different biodiesels, namely jatropha biodiesel, soybean biodiesel, palm stearin biodiesel, karanja biodiesel and rapeseed biodiesel, are used separately as fuels in this study. Experiments have also been conducted with diesel and palm stearin biodiesel to validate the predicted results. The experimental and the numerical results match both qualitatively and quantitatively with slight deviations. The analysis of the numerical results shows that the engine performance deteriorates with the use of different biodiesels as fuels. Brake thermal efficiency decreases by 3% (maximum) in case of palm stearin biodiesel. On the other hand, brake specific fuel consumption and brake specific energy consumption increase and the maximum values are found to be 25.8 and 3.6%, respectively. Among the biodiesels, jatropha biodiesel showed the best performance and palm stearin biodiesel showed the worst. When the combustion characteristics were compared, it was noted that both the ignition delay period and the heat release rate decrease to some extent for different biodiesels compared to diesel. The use of biodiesel gives a cleaner exhaust compared to that of diesel, and jatropha biodiesel gives the cleanest exhaust in terms of particulate matter and smoke emissions. However, the formation of nitrogen oxides increases with the use of biodiesels and the maximum increase was noted with rapeseed biodiesel.