Use of HOT EGR for NOx control in a compression ignition engine fuelled with bio-diesel from Jatropha oil

Environmental degradation and depleting oil reserves are matters of great concern round the globe. Developing countries like India depend heavily on oil import. Diesel being the main transport fuel in India, finding a suitable alternative to diesel is an urgent need. Jatropha based bio-diesel (JBD) is a non-edible, renewable fuel suitable for diesel engines and is receiving increasing attention in India because of its potential to generate large-scale employment and relatively low environmental degradation. Diesel engines running on JBD are found to emit higher oxides of nitrogen, NO_x. HOT EGR, a low cost technique of exhaust gas recirculation, is effectively used in this work to overcome this environmental penalty. Practical problems faced while using a COOLED EGR system are avoided with HOT EGR. Results indicated higher nitric oxide (NO) emissions when a single cylinder diesel engine was fuelled with JBD, without EGR. NO emissions were reduced when the engine was operated under HOT EGR levels of 5–25%. However, EGR level was optimized as 15% based on adequate reduction in NO emissions, minimum possible smoke, CO, HC emissions and reasonable brake thermal efficiency. Smoke emissions of JBD in the higher load region were lower than diesel, irrespective of the EGR levels. However, smoke emission was higher in the lower load region. CO and HC emissions were found to be lower for JBD irrespective of EGR levels. Combustion parameters were found to be comparable for both fuels.     

Effect of exhaust gas recirculation on diesel engine nitrogen oxide reduction operating with jojoba methyl ester

Jojoba methyl ester (JME) has been used as a renewable fuel in numerous studies evaluating its potential use in diesel engines. These studies showed that this fuel is good gas oil substitute but an increase in the nitrogenous oxides emissions was observed at all operating conditions. The aim of this study mainly was to quantify the efficiency of exhaust gas recirculation (EGR) when using JME fuel in a fully instrumented, two-cylinder, naturally aspirated, four-stroke direct injection diesel engine. The tests were carried out in three sections. Firstly, the measured performance and exhaust emissions of the diesel engine operating with diesel fuel and JME at various speeds under full load are determined and compared. Secondly, tests were performed at constant speed with two loads to investigate the EGR effect on engine performance and exhaust emissions including nitrogenous oxides (NO_x), carbon monoxide (CO), unburned hydrocarbons (HC) and exhaust gas temperatures. Thirdly, the effect of cooled EGR with high ratio at full load on engine performance and emissions was examined. The results showed that EGR is an effective technique for reducing NO_x emissions with JME fuel especially in light-duty diesel engines. With the application of the EGR method, the CO and HC concentration in the engine-out emissions increased. For all operating conditions, a better trade-off between HC, CO and NO_x emissions can be attained within a limited EGR rate of 5–15% with very little economy penalty.     

Study on emissions reduction of DMCC engine with oxidation catalyst

A new combustion model diesel/methanol compound combustion (DMCC) is presented, in which methanol is injected into manifold and ignited by certain amount of diesel fuel. The results showed that DMCC remarkably decreased the emission of NO_x and the smoke, but increased the emission of HC, CO and PM. However, HC, CO and NO_x were dramatically decreased with a catalytic converter, and PM was also decreased compared with that of diesel engine. The testing results illustrated that, combined with oxidation catalyst converter, DMCC could improve engine emissions. __________ Translated from Transactions of CSICE, 2006, 24(5): 402–407 [译自: 内燃机学报]     

推进特性试验下生物乳化柴油对柴油机性能的影响

在柴油机上进行柴油、三种生物乳化柴油(E10、E15和E20)和生物柴油的推进特性试验,就其燃烧特性、动力性、经济性及常规排放特性进行对比。试验结果显示:高转速时,生物乳化柴油的缸内燃烧压力和放热率略低于柴油,缸内燃烧温度有所降低;动力性相比柴油略有下降,仅E10的燃油消耗率比柴油低,B100最高;烟度和NOx排放均有显著降低,且随水和丁醇掺混比例增加而降低; CO和HC排放与柴油基本无差别,整体增加不多。表明:生物乳化柴油作为替代燃料能保证柴油机运行的稳定性,可同时降低柴油机的烟度和NOx排放,具有良好的环境效益和经济效益。     

Effects of octane number on exhaust emissions of a spark ignition engine

This paper deals with the experimental study that aims to examine the effects of octane number of three different fuel oxygenates on exhaust emissions of a typical spark ignition engine. Three commonly used oxygenates, namely methyl tertiary butyl ether (MTBE), methanol, and ethanol, which were blended with a base unleaded fuel in three ratios (10, 15 and 20 vol%), were investigated. The engine emissions of CO, HC, and NO_x were measured under a variety of engine operating conditions using an engine dynamometer set‐up. It is found that generally as the octane number of the fuel increases the CO and HC emissions decrease but the NO_x emission increases for all three blends. Further, for the leaded fuel (RON of 92), as the speed of the engine increases the CO and NO_x emissions decrease but the HC emission decreases. A similar trend was found for MTBE blends also. These emission results are presented in terms of octane number and their effects are discussed in this paper. Copyright © 2002 John Wiley & Sons, Ltd.     

Hydrogen enriched waste oil biodiesel usage in compression ignition engine

In the present study, hydrogen enrichment for biodiesel-diesel blends was evaluated to investigate the performance and emission characteristics of a compression ignition engine. Biodiesel was obtained from waste oil and blended to pure diesel fuel by volume fraction of 0%, 10% and 20%. After that, pure hydrogen was introduced through the intake air at different flow rates. Effects of pure hydrogen on performance and emission characteristics were investigated by evaluating power, torque, specific fuel consumption, CO, CO₂ and NO_x emissions. Experimental study revealed that waste oil biodiesel usage deteriorated performance and emission parameters except CO emissions. However, the enrichment test fuels with hydrogen fuel can improve performance characteristics and emission parameters, whereas it increased NO_x emissions. Brake thermal efficiency and specific fuel consumption were improved when the test fuels enriched with hydrogen gas. Because of absence of carbon atoms in the chemical structure of the hydrogen fuel, hydrogen addition dropped CO and CO₂ emissions but increment in cylinder temperature caused rising in NO_x emissions.     

Performance and emission characteristics of a diesel engine using isobutanol–diesel fuel blends

The aim of this study is to investigate the suitability of isobutanol–diesel fuel blends as an alternative fuel for the diesel engine, and experimentally determine their effects on the engine performance and exhaust emissions, namely break power, break specific fuel consumption (BSFC), break thermal efficiency (BTE) and emissions of CO, HC and NO_x. For this purpose, four different isobutanol–diesel fuel blends containing 5, 10, 15 and 20% isobutanol were prepared in volume basis and tested in a naturally aspirated four stroke direct injection diesel engine at full -load conditions at the speeds between 1200 and 2800 rpm with intervals of 200 rpm. The results obtained with the blends were compared to those with the diesel fuel as baseline. The test results indicate that the break power slightly decreases with the blends containing up to 10% isobutanol, whereas it significantly decreases with the blends containing 15 and 20% isobutanol. There is an increase in the BSFC in proportional to the isobutanol content in the blends. Although diesel fuel yields the highest BTE, the blend containing 10% isobutanol results in a slight improvement in BTE at high engine speeds. The results also reveal that, compared to diesel fuel, CO and NO_x emissions decrease with the use of the blends, while HC emissions increase considerably.     

Effect of hydrogen and LPG addition on the efficiency and emissions of a dual fuel diesel engine

This paper presents some experimental investigations on dual fuel operation of a 4 cylinder (turbocharged and intercooled) 62.5 kW gen-set diesel engine with hydrogen, liquefied petroleum gas (LPG) and mixture of LPG and hydrogen as secondary fuels. Results on brake thermal efficiency and emissions, namely, un-burnt hydrocarbon (HC), carbon monoxide (CO), NO_x and smoke are presented here. The paper also includes vital information regarding performances of the engine at a wide range of load conditions with different gaseous fuel substitutions. When only hydrogen is used as secondary fuel, maximum enhancement in the brake thermal efficiency is 17% which is obtained with 30% of secondary fuel. When only LPG is used as secondary fuel, maximum enhancement in the brake thermal efficiency (of 6%) is obtained with 40% of secondary fuel. Compared to the pure diesel operation, proportion of un-burnt HC and CO increases, while, emission of NO_x and smoke reduces in both cases. On the other hand, when 40% of mixture of LPG and hydrogen is used (in the ratio 70:30) as secondary fuel, brake thermal efficiency enhances by 27% and HC emission reduces by 68%. Further, shortcoming of low efficiency at lower load condition in a dual fuel operation is removed when a mixture of hydrogen and LPG is used as the secondary fuel at higher than 10% load condition.     

Experimental study of the performances of a modified diesel engine operating in homogeneous charge compression ignition (HCCI) combustion mode versus the original diesel combustion mode

Homogeneous charge compression ignition (HCCI) combustion mode provides very low NO_x and soot emissions; however, it has some challenges associated with hydrocarbon (HC) emissions, fuel consumption, difficult control of start of ignition and bad behaviour to high loads. Cooled exhaust gas recirculation (EGR) is a common way to control in-cylinder NO_x production in diesel and HCCI combustion mode. However EGR has different effects on combustion and emissions, which are difficult to distinguish. This work is intended to characterize an engine that has been modified from the base diesel engine (FL1 906 DEUTZ-DITER) to work in HCCI combustion mode. It shows the experimental results for the modified diesel engine in HCCI combustion mode fueled with commercial diesel fuel compared to the diesel engine mode. An experimental installation, in conjunction with systematic tests to determine the optimum crank angle of fuel injection, has been used to measure the evolution of the cylinder pressure and to get an estimate of the heat release rate from a single-zone numerical model. From these the angle of start of combustion has been obtained. The performances and emissions of HC, CO and the huge reduction of NO_x and smoke emissions of the engine are presented. These results have allowed a deeper analysis of the effects of external EGR on the HCCI operation mode, on some engine design parameters and also on NO_x emission reduction.     

Role of hydrogen in improving performance and emission characteristics of homogeneous charge compression ignition engine fueled with graphite oxide nanoparticle-added microalgae biodiesel/diesel blends

The development of low-temperature combustion models combined with the use of biofuels has been considered as an efficient strategy to reduce pollutant emissions like CO, HC. NO_x, and smoke. Indeed, Homogeneous Charge Compression Ignition (HCCI) is the new approach to drastically minimize NO_x emissions and smoke owing to the lower cylinder temperature and a higher rate of homogeneous A/F mixture as compared to compression ignition (CI) engines. The present research deal with the behavior analysis of a CI engine powered by diesel, Euglena Sanguinea (ES), and their blends (ES20D80, ES40D60, ES60D40, ES80D20). The experimental results revealed the highest brake thermal efficiency for ES20D80 although it decreased by 4.1% compared to diesel at normal mode. The average drop in HC, CO, and smoke was 2.1, 2.3, and 5.7% for ES20D80 as opposed to diesel fuel. Therefore, in the next stage, ES20D80 with various concentrations of graphite oxide (GO) nanoparticle (20, 40, 60, and 80 ppm) was chosen to carry out experiments in the HCCI mode, in which hydrogen gas was induced along with air through the intake pipe at a fixed flow rate of 3 lpm for the enrichment of the air-fuel mixture. As a result, the combination of hydrogen-enriched gas and GO-added ES20D80 in the HCCI mode showed similar performance to the CI engine but registered a major reduction of NO_x and smoke emissions, corresponding to 75.24% and 53.07% respectively, as compared to diesel fuel at normal mode.     

Performance and exhaust emission of turpentine oil powered direct injection diesel engine

This paper presents the results of experimental work carried out to evaluate the combustion performance and exhaust emission characteristics of turpentine oil fuel (TPOF) blended with conventional diesel fuel (DF) fueled in a diesel engine. Turpentine oil derived from pyrolysis mechanism or resin obtained from pine tree dissolved in a volatile liquid can be used as a bio-fuel due to its properties. The test engine was fully instrumented to provide all the required measurements for determination of the needed combustion, performance and exhaust emission variables. The physical and chemical properties of the test fuels were earlier determined in accordance to the ASTM standards.ResultsIndicated that the engine operating on turpentine oil fuel at manufacture's injection pressure – time setting (20.5 MPa and 23° BTDC) had lower carbon monoxide (CO), unburned hydrocarbons (HC), oxides of nitrogen (NO_x), smoke level and particulate matter. Further the results showed that the addition of 30% TPOF with DF produced higher brake power and net heat release rate with a net reduction in exhaust emissions such as CO, HC, NO_x, smoke and particulate matter. Above 30% TPOF blends, such as 40% and 50% TPOF blends, developed lower brake power and net heat release rate were noted due to the fuels lower calorific value; nevertheless, reduced emissions were still noted.     

The emission analysis of an IDI diesel engine fueled with methyl ester of waste frying palm oil and its blends

In this study, the exhaust emissions of an unmodified diesel engine fueled with methyl ester of waste frying palm-oil (biodiesel) and its blends with petroleum based diesel fuel (PBDF) were investigated at the full load-variable speed condition. The relationships between the fuel properties and the air–fuel equivalence ratio, fuel line pressure, start of injection (SOI) timing, and ignition delay were also discussed to explain their effects on the emissions. The obtained test results were compared with the reference values which were determined by using PBDF. The results showed that when biodiesel was used in the test engine, the fuel line pressure increased while air–fuel equivalence ratio and ignition delay decreased. These behaviors affected the combustion phenomena of biodiesel which caused to reduction 57% in carbon monoxide (CO) emission, about 40% in unburned hydrocarbon (HC) emission and about 23% in smoke opacity when compared with PBDF. However, NO_x and CO₂ emissions of the biodiesel have showed different behaviors in terms of the engine speed.     

A study on the effect of hydrogen enriched intake air on the characteristics of a diesel engine fueled with ethanol blended diesel

This work aims to replace conventional diesel fuel with low and no carbon fuels like ethanol and hydrogen to reduce the harmful emission that causes environmental degradation. Pursuant to this objective, this study investigated the performance, combustion, and emission characteristics of the diesel engine operated on dual fuel mode by ethanol-diesel blends with H₂ enriched intake air at different engine loads with a constant engine speed of 1500 rpm. The results were compared to sole diesel operation with and without H₂ enrichment. The ethanol/diesel was blended in v/v ratios of 5, 10, and 15% and tested in a diesel engine along with a 9 lpm H₂ flow rate at the intake manifold. The results revealed that 10% ethanol with 9 lpm H₂ combination gives the maximum brake thermal efficiency, which is 1% and 4.8% higher than diesel with and without H₂ enrichment, respectively. The brake specific fuel consumption of the diesel-ethanol blends with H₂ flow increased with increasing ethanol ratio in the blend. When the ethanol ratio increased from 5 to 10%, in-cylinder pressure and heat release rate were increased, whereas HC, CO, and NO_x emissions were decreased. At maximum load, the CO and HC emission of 10% ethanol blend with 9 lpm H₂ case decreased by about 50% and 28.7% compared to sole diesel. However, NO_x emission of the same blend was 11.4% higher than diesel. From the results, the study concludes that 10% ethanol blended diesel with a 9 lpm H₂ flow rate at the intake port is the best dual-fuel mode combination that gives the best engine characteristics with maximum diesel replacement.     

Effects of Fischer-Tropsch diesel fuel on combustion and emissions of direct injection diesel engine

Effects of Fischer-Tropsch (F-T) diesel fuel on the combustion and emission characteristics of a single-cylinder direct injection diesel engine under different fuel delivery advance angles were investigated. The experimental results show that F-T diesel fuel exhibits shorter ignition delay, lower peak values of premixed burning rate, lower combustion pressure and pressure rise rate, and higher peak value of diffusion burning rate than conventional diesel fuel when the engine remains unmodified. In addition, the unmodified engine with F-T diesel fuel has lower brake specific fuel consumption and higher effective thermal efficiency, and presents lower HC, CO, NO _x and smoke emissions than conventional diesel fuel. When fuel delivery advance angle is retarded by 3 crank angle degrees, the combustion duration is obviously shortened; the peak values of premixed burning rate, the combustion pressure and pressure rise rate are further reduced; and the peak value of diffusion burning rate is further increased for F-T diesel fuel operation. Moreover, the retardation of fuel delivery advance angle results in a further significant reduction in NO _x emissions with no penalty on specific fuel consumption and with much less penalty on HC, CO and smoke emissions. __________ Translated from Chinese Internal Combustion Engine Engineering, 2007, 28(2): 19–23 [译自: 内燃机工程]     

Using renewable alternative fuels and studying their impact on the performance and emissions of compression ignition engines

This practical study examined the effect of engine torque on engine performance and emissions. The most important parameters of engine performance are thermal efficiency, brake power (BP), and specific fuel consumption. As for exhaust emissions, the most important of which are hydrocarbons (HCs), carbon monoxide (CO), and nitrogen oxides (NO_x). The experiment was conducted for a single-cylinder, four-stroke compression ignition engine. Mixtures (B0, B10, B20, B30, and B40) were taken from biodiesel prepared from sunflower oil by the esterification method. The engine speed was fixed at 1700 rpm, and torque variable was from 0 to 10 N m. The results indicated a decrease in engine BP by an average of 19.5 W, a decrease in thermal efficiency by an average of 1.058%, while an increase in fuel consumption by an average of 0.095 kg/kW h⁻¹ compared to diesel. As for exhaust emissions, HC emissions decreased by 5.8 ppm, while CO decreased by 0.0207%, and NO_x emissions increased by 138.5 ppm compared to diesel, due to changes in the properties of biodiesel, such as high density, viscosity, and low calorific value compared to the properties of regular diesel     

Performance and exhaust emission characteristics of a CI engine fueled with Pongamia pinnata methyl ester (PPME) and its blends with diesel

Transport vehicles greatly pollute the environment through emissions such as CO, CO₂, NO_x, SO_x, unburnt or partially burnt HC and particulate emissions. Fossil fuels are the chief contributors to urban air pollution and major source of green house gases (GHGs) and considered to be the prime cause behind the global climate change. Biofuels are renewable, can supplement fossil fuels, reduce GHGs and mitigate their adverse effects on the climate resulting from global warming. This paper presents the results of performance and emission analyses carried out in an unmodified diesel engine fueled with Pongamia pinnata methyl ester (PPME) and its blends with diesel. Engine tests have been conducted to get the comparative measures of brake specific fuel consumption (BSFC), brake specific energy consumption (BSEC) and emissions such as CO, CO₂, HC, NO_x to evaluate the behaviour of PPME and diesel in varying proportions. The results reveal that blends of PPME with diesel up to 40% by volume (B40) provide better engine performance (BSFC and BSEC) and improved emission characteristics.     

Emission characteristics of a turbocharged diesel engine fueled with gas-to-liquids

Emission characteristics of a turbocharged, intercooled, heavy-duty diesel engine operating on neat gas-to-liquids (GTL) and blends of GTL with conventional diesel were investigated and a comparison was made with those of diesel fuel. The results show that nitrogen oxides (NO _x ), smoke, and particulate matter (PM) emissions can be decreased when operating on GTL and diesel-GTL blends. Engine emissions decrease with an increase of GTL fraction in the blends. Compared with diesel fuel, an engine operating on GTL can reduce NO _x , PM, carbon monoxide (CO), and hydrocarbon (HC) by 23.7%, 27.6%, 16.6% and 12.9% in ECE R49 13-mode procedure, respectively. Engine speed and load have great influences on emissions when operating on diesel-GTL blends and diesel fuel in the turbocharged diesel engine. The study indicates that GTL is a promising alternative fuel for diesel engines to reduce emissions. Translated from Transactions of CSICE, 2006, 24(6): 489–493 [译自: 内燃机学报]     

Optimization of port injection of n-decanol in a PCCI engine using response surface methodology

This work aims to define the optimum n-decanol fraction in the inlet port and the corresponding engine load for the better emissions and performance characteristics of a partially premixed charged compression ignition (PCCI) engine by response surface methodology (RSM). The numerical model based on multi-linear regression was established using experimental data. For this, the influence of various proportions of n-decanol through intake port including 10%, 20%, 30%, and 40% were experimentally investigated besides the primary injection of neem oil biodiesel in the volumetric ratio of 80% diesel and 20% neem biodiesel, namely NB20. The optimization using RSM is exploited to capitalize the brake thermal efficiency (BTE) and diminish the emissions including oxides of nitrogen (NO_x), carbon monoxide (CO) emission, smoke opacity, and hydrocarbon (HC) emission. The n-decanol fraction in the port injection of 31.43% and the engine load in terms of brake power of 2.950 kW were found to be optimum parameters with the maximum desirability of 0.752. The optimal responses for brake-specific fuel consumption (BSFC), BTE, CO, HC, smoke, and NO_x under these operating conditions were found to be 0.305 kg/kWh, 28.8%, 0.145%, 19.61%, 54.85 ppm, and 837.7 ppm, respectively. Likewise, the correlation coefficient R² values for BSFC, BTE, CO, HC, smoke and NO_x have been found to be 99.85%, 99.95%, 93.58%, 90.32%, 99.97%, and 99.93%, respectively. According to the study's findings, the RSM is a realistic method for calculating and enhancing a diesel engine's emission and performance values operating in PCCI mode and using n-decanol and NB20 as fuels.     

Combustion performance and emission reduction characteristics of automotive DME engine system

This article is a condensed overview of a dimethyl ether (DME) fuel application for a compression ignition diesel engine. In this review article, the spray, atomization, combustion and exhaust emissions characteristics from a DME-fueled engine are described, as well as the fundamental fuel properties including the vapor pressure, kinematic viscosity, cetane number, and the bulk modulus. DME fuel exists as gas phase at atmospheric state and it must be pressurized to supply the liquid DME to fuel injection system. In addition, DME-fueled engine needs the modification of fuel supply and injection system because the low viscosity of DME caused the leakage. Different fuel properties such as low density, viscosity and higher vapor pressure compared to diesel fuel induced the shorter spray tip penetration, wider cone angle, and smaller droplet size than diesel fuel. The ignition of DME fuel in combustion chamber starts in advance compared to diesel or biodiesel fueled compression ignition engine due to higher cetane number than diesel and biodiesel fuels. In addition, DME combustion is soot-free since it has no carbon–carbon bonds, and has lower HC and CO emissions than that of diesel combustion. The NO_x emission from DME-fueled combustion can be reduced by the application of EGR (exhaust gas recirculation). This article also describes various technologies to reduce NO_x emission from DME-fueled engines, such as the multiple injection strategy and premixed combustion. Finally, the development trends of DME-fueled vehicle are described with various experimental results and discussion for fuel properties, spray atomization characteristics, combustion performance, and exhaust emissions characteristics of DME fuel.     

Experimental investigation of control of NOx emissions in biodiesel-fueled compression ignition engine

Biodiesel is an alternative fuel consisting of the alkyl esters of fatty acids from vegetable oils or animal fats. Vegetable oils are produced from numerous oil seed crops (edible and non-edible), e.g., rapeseed oil, linseed oil, rice bran oil, soybean oil, etc. Research has shown that biodiesel-fueled engines produce less carbon monoxide (CO), unburned hydrocarbon (HC), and particulate emissions compared to mineral diesel fuel but higher NO_x emissions. Exhaust gas recirculation (EGR) is effective to reduce NO_x from diesel engines because it lowers the flame temperature and the oxygen concentration in the combustion chamber. However, EGR results in higher particulate matter (PM) emissions. Thus, the drawback of higher NO_x emissions while using biodiesel may be overcome by employing EGR. The objective of current research work is to investigate the usage of biodiesel and EGR simultaneously in order to reduce the emissions of all regulated pollutants from diesel engines. A two-cylinder, air-cooled, constant speed direct injection diesel engine was used for experiments. HCs, NO_x, CO, and opacity of the exhaust gas were measured to estimate the emissions. Various engine performance parameters such as thermal efficiency, brake specific fuel consumption (BSFC), and brake specific energy consumption (BSEC), etc. were calculated from the acquired data. Application of EGR with biodiesel blends resulted in reductions in NO_x emissions without any significant penalty in PM emissions or BSEC.