The influence of different driving cycles on their exhaust emissions and fuel consumption rate of gasoline passenger car was investigated in Bangkok based on the actual measurements obtained from a test vehicle drivin...The influence of different driving cycles on their exhaust emissions and fuel consumption rate of gasoline passenger car was investigated in Bangkok based on the actual measurements obtained from a test vehicle driving on a standard chassis dynamometer. A newly established Bangkok driving cycle (BDC) and the European driving cycle (EDC) which is presently adopted as the legislative cycle for testing automobiles registered in Thailand were used. The newly developed BDC is constructed using the driving characteristic data obtained from the real on-road driving tests along selected traffic routes. A method for selecting appropriate road routes for real driving tests is also introduced. Variations of keyed driving parameters of BDC with different driving cycles were discussed. The results showed that the HC and CO emission factors of BDC are almost two and four times greater than those of EDC, respectively. Although the difference in the NOx emission factor is small, the value from BDC is still greater than that of EDC by 10%. Under BDC, the test vehicle consumes fuel about 25% more than it does under EDC. All these differences are mainly attributed to the greater proportion of idle periods and higher fluctuations of vehicle speed in the BDC cycle. This result indicated that the exhausted emissions and fuel consumption of vehicles obtained from tests under the legislative modal-type driving cycle (EDC) are significantly different from those actually produced under real traffic conditions especially during peak periods.展开更多
Effects of hydrocarbon compositions on raw exhaust emissions and combustion processes were studied on an engine test bench. The optimization of gasoline hydrocarbon composition was discussed. As olefins content increa...Effects of hydrocarbon compositions on raw exhaust emissions and combustion processes were studied on an engine test bench. The optimization of gasoline hydrocarbon composition was discussed. As olefins content increased from 10.0% to 25.0% in volume, the combustion duration was shortened by about 2 degree crank angle (°CA), and the engine-out THC emission was reduced by about 15%. On the other hand, as aromatics content changed from 35.0% to 45.0%, the engine-out NOx emissions increased by 4%. An increment in olefins content resulted in a slight increase in engine-out CO emission, while the aromatics content had little effect on engine-out total hydrocarbon (THC) and CO emissions. Over the new European driving cycle (NEDC), the THC, NOx and CO emissions of fuel with 25.0% olefins and 35.0% aromatics were about 45%, 21% and 19% lower than those of fuel with 10.0% olefins and 40.0% aromatics, respectively. The optimized gasoline compositions for new engines and new vehicles have low aromatics and high olefins contents.展开更多
While Unleaded gasoline has the advantage of eliminating lead from automobile exhaust, its potential to reduce the exhaust gas and particles, merits further examination. In the present studies,the concentrations of hy...While Unleaded gasoline has the advantage of eliminating lead from automobile exhaust, its potential to reduce the exhaust gas and particles, merits further examination. In the present studies,the concentrations of hydrocarbons (HC) and earbon monoxides (CO) in emissions were analyzed on Santana engine Dynamometer under a standard test cycle, and total exhaust particles were collected from engines using leaded and unleaded gasoline. It was found that unleaded gasoline reduced the emissions of CO and HC, and decreased the quantity of vehicle exhaust particulate matters by 60%.With the unlead gasoline, only 23 kinds of organic substances, adsorbed in the particles, were identified by gas chromatography/mass spectrometer (GC/MS) while 32 components were detected using the leaded gasoline. The results of in vitro Salmonella/ microsomal test and micronucleus induction assay in CHL cells indicated that both types of gasoline increased the number of histidine-independent colonies and the frequencies of micronucleus induction; no significant differellce was found in their mutagenicity.展开更多
The working principle of a kind of compositive emission control system is inquired into, which includes exhaust heater, secondary air supplement, exhaust gas recirculation (EGR), thermal reactor and catalytic conver...The working principle of a kind of compositive emission control system is inquired into, which includes exhaust heater, secondary air supplement, exhaust gas recirculation (EGR), thermal reactor and catalytic converter, etc. The purification effect of CO, HC and NOx emission of the gasoline spark ignite (S.I.) engine is studied. The entire vehicle driving cycle tests based on the national emission standard and a series of the gasoline engine-testing bench tests including full load characteristic experiment, load characteristic experiment and idle speed experiment are done. The results show that the system has a very good emission control effect to CO, HC and NOx of gasoline engine. The construction of the system is very simple and can be mounted on the exhaust pipe conveniently without any alteration of the vehicle-use gasoline engine.展开更多
This paper presents a comparative analysis between single and twin-screw propulsion systems of a bulk carrier to evaluate the ship and propeller performance in terms of fuel consumption as well as to discuss the cavit...This paper presents a comparative analysis between single and twin-screw propulsion systems of a bulk carrier to evaluate the ship and propeller performance in terms of fuel consumption as well as to discuss the cavitation and noise criteria.An optimization model is developed to select the optimum propeller geometry and operational point along the engine load diagram for the selected engines of each case.The engines are selected from the same series due to the same behaviour along the engine load diagram.The propellers are selected from the B-series as fixed-pitch propellers.It has been concluded that while the components of the single-screw propulsion system are larger than the twin-screw,the single-screw propulsion system shows a reduction in fuel consumption than the twin screw by around 19%,thus affecting the amount of exhaust emissions from the ship.This model helps the ship designers to select a suitable propeller to improve the energy efficiency of the ships.展开更多
In this study,a model is developed to simulate the dynamics of an internal combustion engine,and it is calibrated and validated against reliable experimental data,making it a tool that can effectively be adopted to co...In this study,a model is developed to simulate the dynamics of an internal combustion engine,and it is calibrated and validated against reliable experimental data,making it a tool that can effectively be adopted to conduct emission predictions.In this work,the Ricardo WAVE software is applied to the simulation of a particular marine diesel engine,a four-stroke engine used in the maritime field.Results from the bench tests are used for the calibration of the model.Finally,the calibration of the model and its validation with full-scale data measured at sea are presented.The prediction includes not only the classic engine operating parameters for a comparison with surveys but also an estimate of nitrogen oxide emissions,which are compared with similar results obtained with emission factors.The calibration of the model made it possible to obtain an overlap between the simulation results and real data with an average error of approximately 7%on power,torque,and consumption.The model provides encouraging results,suggesting further applications,such as in the study on transient conditions,coupling of the engine model with the ship model for a complete simulation of the operating conditions,and optimization studies on consumption and emissions.The availability of the emission data during the sea trial and validated simulation results are the strengths and novelties of this work.展开更多
The effects of cooled external exhaust gas recirculation (EGR) on the combustion and emission performance of diesel fuel homogeneous charge compression ignition (HCCI) are studied. Homogeneous mixture is formed by...The effects of cooled external exhaust gas recirculation (EGR) on the combustion and emission performance of diesel fuel homogeneous charge compression ignition (HCCI) are studied. Homogeneous mixture is formed by injecting fuel in-cylinder in the negative valve overlap (NVO) period. So, the HCCI combustion which has low NOx and smoke emission is achieved. Cooled external EGR can delay the start of combustion effectively, which is very useful for high cetane fuel (diesel) HCCI, because these fuels can easily self-ignition, which makes the start of combustion more early. External EGR can avoid the knock combustion of HCCI at high load which means that the EGR can expand the high load limit. HCCI maintains low smoke emission at various EGR rate and various load compared with conventional diesel engine because there is no fuel-rich area in cylinder.展开更多
In order to assess the performance of a new cleansing and combustion-improving gasoline additive (MAZ), and to explore the evaluation methods of additives, two engines with the same model number and performance indi...In order to assess the performance of a new cleansing and combustion-improving gasoline additive (MAZ), and to explore the evaluation methods of additives, two engines with the same model number and performance indices, fueled with and without the MAZ gasoline additive respectively, are carried through 100 h strenuous tests on a bench. The results obtained in full load characteristic and load characteristics of different operational modes are compared. It indicates that the power, economy and emission of the engine fueled with the MAZ additive all have obvious improvement in comparison with the engine without adding the additive: the power increasing by 16.43%, specific fuel consumption (SFC) decreasing 5.39%, and the emission of CO, HC and NOx falling by 28.61%, 54.38% and 10.1% respectively. Wear and tear of the engine cylinder is weakened, and sediment of combustion chamber inner side is reduced. In addition, no negative effect on the catalytic conversion device is found.展开更多
Energy shortage and environmental pollution are becoming more serious,biodiesel is regarded as the most promising alternative fuel for diesel engines due to its environmentally friendly and renewable characteristics.I...Energy shortage and environmental pollution are becoming more serious,biodiesel is regarded as the most promising alternative fuel for diesel engines due to its environmentally friendly and renewable characteristics.In this study,the biodiesel-ethanol blends were used in a diesel engine,and the purpose of the study was to simultaneously control the NOx and soot emissions of the diesel engine by adjusting the injection strategy and EGR rate.A turbocharged,six-cylinder,common rail direct injection(CRDI)engine model was established using GT-Power.The effects of the main-post injection strategy and post injection coupled with exhaust gas recirculation(EGR)on combustion and emission characteristics were investigated at a maximum torque speed and a medium load.The results show that when the main-post injection strategy is employed,the combustion duration of the main injection is shortened with an increase in the main-post injection interval(MPI).When the MPI increased to more than 18℃A,the heat release of post injection could be observed clearly from the curve of the heat release rate,NOx emissions decreased by 5.70%and 7.12%,respectively,and soot emissions decreased by 25.56%and 30.20%,respectively.Moreover,with the increasing post injection quantity,the combustion duration of the main injection shortened,and the peak heat release rate(PHRR)of the post injection increased.When the fuel quantity for the post injection increased from 2 to 6 mg,NOx emissions decreased from 2.33%to 9.80%,and soot emissions decreased from 16.10%to 34.97%.The effect of post injection quantity on emissions was more significant than that of the MPI.In addition,with increasing EGR rate,the ignition delay is prolonged,the peak cylinder pressure,PHRR,peak combustion temperature and NOx emissions decrease,whereas soot emissions increase gradually.Main-post injection can improve the NO-soot trade-off,the optimal EGR rate is 22.86%under a post injection quantity of 4 mg and a MPI of 22℃A.展开更多
The present research focuses on addressing the faster depletion of fossil fuels and environmental pollution in addition to the energy crisis that hinders the progress of a nation.In the current research,waste banana l...The present research focuses on addressing the faster depletion of fossil fuels and environmental pollution in addition to the energy crisis that hinders the progress of a nation.In the current research,waste banana leaves were considered as substrates for biogas production.Biogas is taken as the primary fuel in dual fuel(DF)operations to maximize possible diesel savings.The performance and combustion assessment were executed in a low heat rejection(LHR)engine using 5%diethyl ether by volume blended with diesel(5DEE)as pilot fuel.The combustion attributes of the engine reveal that the apex of net heat release rate(NHRR)curve retarded a bit as compared to apex of base result.The peak cylinder pressure was noted to be 6.19 MPa in the LHR engine running with 5DEE+biogas at 11.7°crank angle(CA)after top dead center(aTDC)compared to 5.23 MPa for the diesel alone operation at the same position.The apex point for NHRR was observed to be 54.51 J(°)^(−1)for 5DEE+biogas in LHR engine positioned at 3.2°aTDC.The brake thermal efficiency at full engine load operation decreased by 12.7%and 5.2%for biogas substitutions of 0.8 kg h^(−1)with diesel and 5DEE,respectively,compared to the base result.The smoke opacity and nitric oxide emissions were reduced during the DF run accompanied by diethyl ether as a fuel additive.展开更多
The nitrogen oxide(NOx)release of diesel engines can be reduced using water in diesel emulsion fuel without any engine modification.In the present paper,different formulations of water in diesel emulsion fuels were pr...The nitrogen oxide(NOx)release of diesel engines can be reduced using water in diesel emulsion fuel without any engine modification.In the present paper,different formulations of water in diesel emulsion fuels were prepared by ultrasonic irradiation.The water droplet size in the emulsion,polydisperisty index,and the stability of prepared fuel was examined,experimentally.Afterwards,the performance characteristics and exhaust emission of a single cylinder air-cooled diesel engine were investigated using different water in diesel emulsion fuels.The effect of water content(in the range of 5%-10% by volume),surfactant content(in the range of 0.5%-2% by volume),and hydrophilic-lipophilic balance(HLB)(in the range of 5-8)was examined using Box-Behnken design(BBD)as a subset of response surface methodology(RSM).Considering multi-objective optimization,the best formulation for the emulsion fuel was found to be 5%water,2% surfactant,and HLB of 6.8.A comparison was made between the best emulsion fuel and the neat diesel fuel for engine performance and emission characteristics.A considerable decrease in the nitrogen oxide emission(-18.24%)was observed for the best emulsion fuel compared to neat diesel fuel.展开更多
In the present article we characterized the emissions at the exhaust of a Common Rail (CR) diesel engine, representative of lightduty class, equipped with a catalyzed diesel particulate filter (CDPF) in controlled...In the present article we characterized the emissions at the exhaust of a Common Rail (CR) diesel engine, representative of lightduty class, equipped with a catalyzed diesel particulate filter (CDPF) in controlled environment. The downstream exhausts were directly analyzed (for PM, CO, CO/, Oz, HCs, NOx) by infrared and electrochemical sensors, and SEM-EDS microscope; heavy metals were chemically analyzed using mosses and lichens in bags, and glass-fibre filters all exposed at the engine exhausts. The highest particle emission value was in the 7-54 nm size range; the peak concentration rose until one order of magnitude for the highest load and speed. Particle composition was mainly carbonaceous, associated to noticeable amounts of Fe and silica fibres. Moreover, the content of Cu, Fe, Na, Ni and Zn in both moss and lichen, and of A1 and Cr in moss, was significantly increased. Glass-fibre filters were significantly enriched in A1, B, Ba, Cu, Fe, Na, and Zn. The role of diesel engines as source of carbonaceous nanoparticles has been confirmed, while further investigations in controlled environment are needed to test the catalytic muffler as a possible source of silica fibres considered very hazardous for human health.展开更多
Efficient mixing and thermal control are important in the flow reactor for obtaining a high product yield and selectivity.Here,we report a heterogeneous chemical kinetic study of propene oxidation within a newly desig...Efficient mixing and thermal control are important in the flow reactor for obtaining a high product yield and selectivity.Here,we report a heterogeneous chemical kinetic study of propene oxidation within a newly designed catalytic jet-stirred reactor(CJSR).To better understand the interplay between the catalytic performances and properties,the CuO thin films have been characterized and the adsorbed energies of propene on the adsorbed and lattice oxygen were calculated using density functional theory(DFT)method.Structure and morphology analyses revealed a monoclinic structure with nano-crystallite size and porous microstructure,which is responsible for holding an important quantity of adsorbed oxygen.The residence time inside the flow CJSR(1.12–7.84 s)makes it suitable for kinetic study and gives guidance for scale-up.The kinetic study revealed that using CJSR the reaction rate increases with O_2concentration that is commonly not achievable for catalytic flow tube reactor,whereas the reaction rate tends to increase slightly above 30%of O_2due to the catalyst surface saturation.Moreover,DFT calculations demonstrated that adsorbed oxygen is the most involved oxygen,and it has found that the pathway of producing propene oxide makes the reaction of C_3H_6over CuO surface more likely to proceed.Accordingly,these findings revealed that CJSR combined with theoretical calculation is suitable for kinetic study,which can pave the way to investigate the kinetic study of other exhaust gases.展开更多
Cetane improvers reduce the ignition delay, which in turn reduces the combustion temperatures thereby reduce NOx emissions. Exhaust gas recirculation (EGR) proved to be an effective way to reduce the NOx emissions. ...Cetane improvers reduce the ignition delay, which in turn reduces the combustion temperatures thereby reduce NOx emissions. Exhaust gas recirculation (EGR) proved to be an effective way to reduce the NOx emissions. In this present experimental work, a combination of exhaust gas recirculation and cetane improver ethyl hexyl nitrate (EHN) is used to investigate the performance and exhaust emissions of a single cylinder four stroke naturally aspirated direct injection and air cooled diesel engine. Test results show that the brake thermal efficiency increases with the increase in the percentage of EGR which is accompanied by a reduction in brake specific fuel consumption and exhaust gas temperatures, and that bio- diesel with cetane improver under 20% EGR reduces NOx emissions by 33% when compared to baseline fuel without EGR. However carbon monoxide (CO), hydro carbon (HC) and smoke emissions increase with an increase in percentage of EGR.展开更多
With the development of China automotive industry, the total quantity of motor vehicles is increasing constantly. But the air pollution caused by motor vehicles is becoming a serious problem. The control of exhaust em...With the development of China automotive industry, the total quantity of motor vehicles is increasing constantly. But the air pollution caused by motor vehicles is becoming a serious problem. The control of exhaust emissions from motor vehicles has been a concern of government authority.展开更多
基金funded by the Energy Policyand Planning Office (EPPO) of Thailand
文摘The influence of different driving cycles on their exhaust emissions and fuel consumption rate of gasoline passenger car was investigated in Bangkok based on the actual measurements obtained from a test vehicle driving on a standard chassis dynamometer. A newly established Bangkok driving cycle (BDC) and the European driving cycle (EDC) which is presently adopted as the legislative cycle for testing automobiles registered in Thailand were used. The newly developed BDC is constructed using the driving characteristic data obtained from the real on-road driving tests along selected traffic routes. A method for selecting appropriate road routes for real driving tests is also introduced. Variations of keyed driving parameters of BDC with different driving cycles were discussed. The results showed that the HC and CO emission factors of BDC are almost two and four times greater than those of EDC, respectively. Although the difference in the NOx emission factor is small, the value from BDC is still greater than that of EDC by 10%. Under BDC, the test vehicle consumes fuel about 25% more than it does under EDC. All these differences are mainly attributed to the greater proportion of idle periods and higher fluctuations of vehicle speed in the BDC cycle. This result indicated that the exhausted emissions and fuel consumption of vehicles obtained from tests under the legislative modal-type driving cycle (EDC) are significantly different from those actually produced under real traffic conditions especially during peak periods.
基金supported by the Beijing Municipal Science & Technology Commission(No. D0405002040221)
文摘Effects of hydrocarbon compositions on raw exhaust emissions and combustion processes were studied on an engine test bench. The optimization of gasoline hydrocarbon composition was discussed. As olefins content increased from 10.0% to 25.0% in volume, the combustion duration was shortened by about 2 degree crank angle (°CA), and the engine-out THC emission was reduced by about 15%. On the other hand, as aromatics content changed from 35.0% to 45.0%, the engine-out NOx emissions increased by 4%. An increment in olefins content resulted in a slight increase in engine-out CO emission, while the aromatics content had little effect on engine-out total hydrocarbon (THC) and CO emissions. Over the new European driving cycle (NEDC), the THC, NOx and CO emissions of fuel with 25.0% olefins and 35.0% aromatics were about 45%, 21% and 19% lower than those of fuel with 10.0% olefins and 40.0% aromatics, respectively. The optimized gasoline compositions for new engines and new vehicles have low aromatics and high olefins contents.
文摘While Unleaded gasoline has the advantage of eliminating lead from automobile exhaust, its potential to reduce the exhaust gas and particles, merits further examination. In the present studies,the concentrations of hydrocarbons (HC) and earbon monoxides (CO) in emissions were analyzed on Santana engine Dynamometer under a standard test cycle, and total exhaust particles were collected from engines using leaded and unleaded gasoline. It was found that unleaded gasoline reduced the emissions of CO and HC, and decreased the quantity of vehicle exhaust particulate matters by 60%.With the unlead gasoline, only 23 kinds of organic substances, adsorbed in the particles, were identified by gas chromatography/mass spectrometer (GC/MS) while 32 components were detected using the leaded gasoline. The results of in vitro Salmonella/ microsomal test and micronucleus induction assay in CHL cells indicated that both types of gasoline increased the number of histidine-independent colonies and the frequencies of micronucleus induction; no significant differellce was found in their mutagenicity.
基金This project is supported by Provincial Natural Science Foundation of Guangdong, China and Provincial Environmental Protection Science Foundation of Guangdong, China(No.320-D38000).
文摘The working principle of a kind of compositive emission control system is inquired into, which includes exhaust heater, secondary air supplement, exhaust gas recirculation (EGR), thermal reactor and catalytic converter, etc. The purification effect of CO, HC and NOx emission of the gasoline spark ignite (S.I.) engine is studied. The entire vehicle driving cycle tests based on the national emission standard and a series of the gasoline engine-testing bench tests including full load characteristic experiment, load characteristic experiment and idle speed experiment are done. The results show that the system has a very good emission control effect to CO, HC and NOx of gasoline engine. The construction of the system is very simple and can be mounted on the exhaust pipe conveniently without any alteration of the vehicle-use gasoline engine.
文摘This paper presents a comparative analysis between single and twin-screw propulsion systems of a bulk carrier to evaluate the ship and propeller performance in terms of fuel consumption as well as to discuss the cavitation and noise criteria.An optimization model is developed to select the optimum propeller geometry and operational point along the engine load diagram for the selected engines of each case.The engines are selected from the same series due to the same behaviour along the engine load diagram.The propellers are selected from the B-series as fixed-pitch propellers.It has been concluded that while the components of the single-screw propulsion system are larger than the twin-screw,the single-screw propulsion system shows a reduction in fuel consumption than the twin screw by around 19%,thus affecting the amount of exhaust emissions from the ship.This model helps the ship designers to select a suitable propeller to improve the energy efficiency of the ships.
基金Open access funding provided by Universita degli Studi di Napoli Federico II within the CRUI-CARE Agreement.
文摘In this study,a model is developed to simulate the dynamics of an internal combustion engine,and it is calibrated and validated against reliable experimental data,making it a tool that can effectively be adopted to conduct emission predictions.In this work,the Ricardo WAVE software is applied to the simulation of a particular marine diesel engine,a four-stroke engine used in the maritime field.Results from the bench tests are used for the calibration of the model.Finally,the calibration of the model and its validation with full-scale data measured at sea are presented.The prediction includes not only the classic engine operating parameters for a comparison with surveys but also an estimate of nitrogen oxide emissions,which are compared with similar results obtained with emission factors.The calibration of the model made it possible to obtain an overlap between the simulation results and real data with an average error of approximately 7%on power,torque,and consumption.The model provides encouraging results,suggesting further applications,such as in the study on transient conditions,coupling of the engine model with the ship model for a complete simulation of the operating conditions,and optimization studies on consumption and emissions.The availability of the emission data during the sea trial and validated simulation results are the strengths and novelties of this work.
基金This project is supported by National Basic Research Program of China (973Program, No. 2001CB209205)National Natural Science Foundation ofChina (No. 50406016)
文摘The effects of cooled external exhaust gas recirculation (EGR) on the combustion and emission performance of diesel fuel homogeneous charge compression ignition (HCCI) are studied. Homogeneous mixture is formed by injecting fuel in-cylinder in the negative valve overlap (NVO) period. So, the HCCI combustion which has low NOx and smoke emission is achieved. Cooled external EGR can delay the start of combustion effectively, which is very useful for high cetane fuel (diesel) HCCI, because these fuels can easily self-ignition, which makes the start of combustion more early. External EGR can avoid the knock combustion of HCCI at high load which means that the EGR can expand the high load limit. HCCI maintains low smoke emission at various EGR rate and various load compared with conventional diesel engine because there is no fuel-rich area in cylinder.
基金This project is supported by Provincial Natural Science Foundation of Guangdong, China and Provincial Environmental Protection Science Foundation of Guangdong, China(No.320-D3800).
文摘In order to assess the performance of a new cleansing and combustion-improving gasoline additive (MAZ), and to explore the evaluation methods of additives, two engines with the same model number and performance indices, fueled with and without the MAZ gasoline additive respectively, are carried through 100 h strenuous tests on a bench. The results obtained in full load characteristic and load characteristics of different operational modes are compared. It indicates that the power, economy and emission of the engine fueled with the MAZ additive all have obvious improvement in comparison with the engine without adding the additive: the power increasing by 16.43%, specific fuel consumption (SFC) decreasing 5.39%, and the emission of CO, HC and NOx falling by 28.61%, 54.38% and 10.1% respectively. Wear and tear of the engine cylinder is weakened, and sediment of combustion chamber inner side is reduced. In addition, no negative effect on the catalytic conversion device is found.
基金funded by the Key Research and Development Program of Shaanxi Province (2021GY-291)the Key Laboratory of Shaanxi Province for Development and Application of New Transportation Energy (CHD300102221508)+1 种基金the Fundamental Research Funds for the Central Universities in Chang'an University (300102220105)the Youth Innovation Team of Shaanxi Universities (Energy Saving and New Energy Automobile)。
文摘Energy shortage and environmental pollution are becoming more serious,biodiesel is regarded as the most promising alternative fuel for diesel engines due to its environmentally friendly and renewable characteristics.In this study,the biodiesel-ethanol blends were used in a diesel engine,and the purpose of the study was to simultaneously control the NOx and soot emissions of the diesel engine by adjusting the injection strategy and EGR rate.A turbocharged,six-cylinder,common rail direct injection(CRDI)engine model was established using GT-Power.The effects of the main-post injection strategy and post injection coupled with exhaust gas recirculation(EGR)on combustion and emission characteristics were investigated at a maximum torque speed and a medium load.The results show that when the main-post injection strategy is employed,the combustion duration of the main injection is shortened with an increase in the main-post injection interval(MPI).When the MPI increased to more than 18℃A,the heat release of post injection could be observed clearly from the curve of the heat release rate,NOx emissions decreased by 5.70%and 7.12%,respectively,and soot emissions decreased by 25.56%and 30.20%,respectively.Moreover,with the increasing post injection quantity,the combustion duration of the main injection shortened,and the peak heat release rate(PHRR)of the post injection increased.When the fuel quantity for the post injection increased from 2 to 6 mg,NOx emissions decreased from 2.33%to 9.80%,and soot emissions decreased from 16.10%to 34.97%.The effect of post injection quantity on emissions was more significant than that of the MPI.In addition,with increasing EGR rate,the ignition delay is prolonged,the peak cylinder pressure,PHRR,peak combustion temperature and NOx emissions decrease,whereas soot emissions increase gradually.Main-post injection can improve the NO-soot trade-off,the optimal EGR rate is 22.86%under a post injection quantity of 4 mg and a MPI of 22℃A.
基金The authors acknowledge the support received from the Alternative Fuel and Energy Lab of S‘O’A deemed to be University.
文摘The present research focuses on addressing the faster depletion of fossil fuels and environmental pollution in addition to the energy crisis that hinders the progress of a nation.In the current research,waste banana leaves were considered as substrates for biogas production.Biogas is taken as the primary fuel in dual fuel(DF)operations to maximize possible diesel savings.The performance and combustion assessment were executed in a low heat rejection(LHR)engine using 5%diethyl ether by volume blended with diesel(5DEE)as pilot fuel.The combustion attributes of the engine reveal that the apex of net heat release rate(NHRR)curve retarded a bit as compared to apex of base result.The peak cylinder pressure was noted to be 6.19 MPa in the LHR engine running with 5DEE+biogas at 11.7°crank angle(CA)after top dead center(aTDC)compared to 5.23 MPa for the diesel alone operation at the same position.The apex point for NHRR was observed to be 54.51 J(°)^(−1)for 5DEE+biogas in LHR engine positioned at 3.2°aTDC.The brake thermal efficiency at full engine load operation decreased by 12.7%and 5.2%for biogas substitutions of 0.8 kg h^(−1)with diesel and 5DEE,respectively,compared to the base result.The smoke opacity and nitric oxide emissions were reduced during the DF run accompanied by diethyl ether as a fuel additive.
文摘The nitrogen oxide(NOx)release of diesel engines can be reduced using water in diesel emulsion fuel without any engine modification.In the present paper,different formulations of water in diesel emulsion fuels were prepared by ultrasonic irradiation.The water droplet size in the emulsion,polydisperisty index,and the stability of prepared fuel was examined,experimentally.Afterwards,the performance characteristics and exhaust emission of a single cylinder air-cooled diesel engine were investigated using different water in diesel emulsion fuels.The effect of water content(in the range of 5%-10% by volume),surfactant content(in the range of 0.5%-2% by volume),and hydrophilic-lipophilic balance(HLB)(in the range of 5-8)was examined using Box-Behnken design(BBD)as a subset of response surface methodology(RSM).Considering multi-objective optimization,the best formulation for the emulsion fuel was found to be 5%water,2% surfactant,and HLB of 6.8.A comparison was made between the best emulsion fuel and the neat diesel fuel for engine performance and emission characteristics.A considerable decrease in the nitrogen oxide emission(-18.24%)was observed for the best emulsion fuel compared to neat diesel fuel.
文摘In the present article we characterized the emissions at the exhaust of a Common Rail (CR) diesel engine, representative of lightduty class, equipped with a catalyzed diesel particulate filter (CDPF) in controlled environment. The downstream exhausts were directly analyzed (for PM, CO, CO/, Oz, HCs, NOx) by infrared and electrochemical sensors, and SEM-EDS microscope; heavy metals were chemically analyzed using mosses and lichens in bags, and glass-fibre filters all exposed at the engine exhausts. The highest particle emission value was in the 7-54 nm size range; the peak concentration rose until one order of magnitude for the highest load and speed. Particle composition was mainly carbonaceous, associated to noticeable amounts of Fe and silica fibres. Moreover, the content of Cu, Fe, Na, Ni and Zn in both moss and lichen, and of A1 and Cr in moss, was significantly increased. Glass-fibre filters were significantly enriched in A1, B, Ba, Cu, Fe, Na, and Zn. The role of diesel engines as source of carbonaceous nanoparticles has been confirmed, while further investigations in controlled environment are needed to test the catalytic muffler as a possible source of silica fibres considered very hazardous for human health.
基金financial support from the Ministry of Science and Technology of China (2017YFA0402800)the National Natural Science Foundation of China (51476168 and 91541102)+1 种基金Recruitment Program of Global Youth Expertsthe support of Chinese Academy of Sciences for senior international scientists within the framework of PIFI program (2017PE0009)
文摘Efficient mixing and thermal control are important in the flow reactor for obtaining a high product yield and selectivity.Here,we report a heterogeneous chemical kinetic study of propene oxidation within a newly designed catalytic jet-stirred reactor(CJSR).To better understand the interplay between the catalytic performances and properties,the CuO thin films have been characterized and the adsorbed energies of propene on the adsorbed and lattice oxygen were calculated using density functional theory(DFT)method.Structure and morphology analyses revealed a monoclinic structure with nano-crystallite size and porous microstructure,which is responsible for holding an important quantity of adsorbed oxygen.The residence time inside the flow CJSR(1.12–7.84 s)makes it suitable for kinetic study and gives guidance for scale-up.The kinetic study revealed that using CJSR the reaction rate increases with O_2concentration that is commonly not achievable for catalytic flow tube reactor,whereas the reaction rate tends to increase slightly above 30%of O_2due to the catalyst surface saturation.Moreover,DFT calculations demonstrated that adsorbed oxygen is the most involved oxygen,and it has found that the pathway of producing propene oxide makes the reaction of C_3H_6over CuO surface more likely to proceed.Accordingly,these findings revealed that CJSR combined with theoretical calculation is suitable for kinetic study,which can pave the way to investigate the kinetic study of other exhaust gases.
文摘Cetane improvers reduce the ignition delay, which in turn reduces the combustion temperatures thereby reduce NOx emissions. Exhaust gas recirculation (EGR) proved to be an effective way to reduce the NOx emissions. In this present experimental work, a combination of exhaust gas recirculation and cetane improver ethyl hexyl nitrate (EHN) is used to investigate the performance and exhaust emissions of a single cylinder four stroke naturally aspirated direct injection and air cooled diesel engine. Test results show that the brake thermal efficiency increases with the increase in the percentage of EGR which is accompanied by a reduction in brake specific fuel consumption and exhaust gas temperatures, and that bio- diesel with cetane improver under 20% EGR reduces NOx emissions by 33% when compared to baseline fuel without EGR. However carbon monoxide (CO), hydro carbon (HC) and smoke emissions increase with an increase in percentage of EGR.
文摘With the development of China automotive industry, the total quantity of motor vehicles is increasing constantly. But the air pollution caused by motor vehicles is becoming a serious problem. The control of exhaust emissions from motor vehicles has been a concern of government authority.