This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for...This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for membrane desalination devices to produce fresh water.A new exhaust-gas heat exchanger of fins and tube,with a reinforced heat transfer tube section,unequal spacing fins,a mixing zone between the fin groups and four routes tube bundle,was designed.Numerical simulations were also used to provide reference information for structural design.Experiments were carried out for exhaust gas waste heat recovery from a marine diesel engine in an engine test bench utilizing the heat exchanger.The experimental results show that the difference between heat absorption by water and heat reduction of exhaust gas is less than 6.5%.After the water flow rate was adjusted,the exhaust gas waste heat recovery efficiency was higher than 70%,and the exhaust-gas heat exchanger’s outlet water temperature was 55°C–85°C at different engine loads.This means that the heat recovery from the exhaust gas of a marine diesel engine meets the requirement to drive a membrane desalination device to produce fresh water for fishers working in small and medium-sized fishing vessels.展开更多
Here a Gaussian Shell Model Array (GSMA) beam is used to investigate the propagation characteristics in the jet engine exhaust region. It has great significance to improve various optical systems for wide application ...Here a Gaussian Shell Model Array (GSMA) beam is used to investigate the propagation characteristics in the jet engine exhaust region. It has great significance to improve various optical systems for wide application in trapping cold atoms, creating gratings, and atmospheric optical communication. We calculate analytical formulas for the spectral density (SD) and the propagation factors M<sub>x</sub>2</sup> and M<sub>y</sub>2</sup> of a GSMA beam. The influence of inner scale of turbulence in the jet engine exhaust region on its power spectrum has been also analyzed. According to these results, the influence of turbulence in a jet engine exhaust on a GSMA beam has been reduced by changing the parameters of light source and turbulence. For example, it is an excellent tool for mitigation of the jet engine exhaust-induced anisotropy of turbulence to increase the source coherence length, the root-mean-squared (rms) beam width, the wavelength or reduce the outer scale of turbulence.展开更多
The effect of fin attachment on the thermal stress reduction of exhaust manifold of an off road diesel engine(Komatsu HD325-6) was investigated.For doing this,coupled thermo-fluid-solid analysis of exhaust manifold of...The effect of fin attachment on the thermal stress reduction of exhaust manifold of an off road diesel engine(Komatsu HD325-6) was investigated.For doing this,coupled thermo-fluid-solid analysis of exhaust manifold of the off road diesel engine was carried out.The thermal analysis,including thermal flow,thermal stress,and the thermal deformation of the manifold was investigated.The flow inside the manifold was simulated and then its properties including velocity,pressure,and temperature were obtained.The flow properties were transferred to the solid model and then the thermal stresses and the thermal deformations of the manifold under different operating conditions were calculated.Finally,based on the predicted thermal stresses and thermal deformations of the manifold body shell,two fin types as well as body shell thickness increase were applied in the critical induced thermal stress area of the manifold to reduce the thermal stress and thermal deformation.The results of the above modifications show that the combined modifications,i.e.the thickness increase and the fin attachment,decrease the thermal stresses by up to 28% and the contribution of the fin attachment in this reduction is much higher compared to the shell thickness increase.展开更多
Because the normal operation of the engine is located near the equilibrium manifold, the method of equilibrium mani fold nonlinear dynamic modeling is adopted for turbofan engine more than the local train modeling. Th...Because the normal operation of the engine is located near the equilibrium manifold, the method of equilibrium mani fold nonlinear dynamic modeling is adopted for turbofan engine more than the local train modeling. The method studies the sys tem characteristics near the equilibrium manifold. The modeling method can be realized through dynamic and static twostep, and for the specific parameter modeling steps and algorithm are given. The output of the test data is compared with the model output through numerical simulation, to check the model with an additional set of test data. The simulation results show that the model has reached the requirements of engineering accuracy.展开更多
Cu–Mn bimetal catalysts were prepared to remove nitrogen oxides(NOx)from diesel engine exhaust at low temperatures.At a Cu/Mn ratio of 3:2,the NOx conversions at 200°C reached 65%and 90%on Cu–Mn/ZSM‐5 and Cu–...Cu–Mn bimetal catalysts were prepared to remove nitrogen oxides(NOx)from diesel engine exhaust at low temperatures.At a Cu/Mn ratio of 3:2,the NOx conversions at 200°C reached 65%and 90%on Cu–Mn/ZSM‐5 and Cu–Mn/SAPO‐34,respectively.After a hydrothermal treatment and reaction in the presence of C3H6,the activity of Cu–Mn/SAPO‐34 was more stable than that of Cu–Mn/ZSM‐5.No obvious variations in the crystal structure or dealumination were observed,whereas the physical structure was best maintained in Cu–Mn/SAPO‐34.The atomic concentration of Cu on the surface of Cu–Mn/SAPO‐34 was quite stable,and the consumption of octahedrally coordinated Cu2+could be recovered.Conversely,the proportion of octahedrally coordinated Cu2+on the surface of Cu–Mn/ZSM‐5 significantly decreased.Therefore,besides the structure,the redox cycle between Cu+and octahedrally coordinated Cu2+played an important role in the stability of the catalysts.展开更多
A cascaded system of electrical discharges (non-thermal plasma) andadsorption process was investigated for the removal of oxides of Nitrogen (NO_x) and totalhydrocarbons (THC) from an actual diesel engine exhaust. The...A cascaded system of electrical discharges (non-thermal plasma) andadsorption process was investigated for the removal of oxides of Nitrogen (NO_x) and totalhydrocarbons (THC) from an actual diesel engine exhaust. The non-thermal plasma and adsorptionprocesses were separately studied first and then the cascaded process was studied. In this study,different types of adsorbents were used. The NO_x removal efficiency was higher withplasma-associated adsorption (cascaded) process compared to the individual processes and the removalefficiency was found almost invariant in time. When associated by plasma, among the adsorbentsstudied, activated charcoal and MS-13X were more effective for NO_x and THC removal respectively.The experiments were conducted at no load and at 50 % load conditions. The plasma reactor was keptat room temperature throughout the experiment, while the temperature of the adsorbent reactor wasvaried. A relative comparison of adsorbents was discussed at the end.展开更多
Reported in this paper is a feasibility study on the injection of plasma induced N radicals for the abatement of NO and NOx present in the actual diesel exhaust. The radical laden diesel exhaust was further treated by...Reported in this paper is a feasibility study on the injection of plasma induced N radicals for the abatement of NO and NOx present in the actual diesel exhaust. The radical laden diesel exhaust was further treated by discharge plasma in a dielectric barrier discharge reactor. N radicals were produced in a separate plasma reactor filled with BaTiO3 pellets and were then injected into the treatment zone, There was a significant improvement in the efficiency when the radicals were injected compared to that when there was no radical injection. The efficiency of NOx removal at 0 load with plasma alone was 14% whereas with the injection of N radicals it went up to 38%, The results of the experiments conducted at different loads are discussed,展开更多
This paper reports the studies conducted on removal of oxides ofnitrogen (NOx) from diesel engine exhaust using electrical dischargeplasma combined with adsorbing materials such as molecular sieves.This study is being...This paper reports the studies conducted on removal of oxides ofnitrogen (NOx) from diesel engine exhaust using electrical dischargeplasma combined with adsorbing materials such as molecular sieves.This study is being reported for the first time. The exhaust is takenfrom a diesel engine of 6 kW under no load conditions. Thecharacteristic behavior of a pulse energized dielectric barrierdischarge reactor in the diesel exhaust treatment is reported. TheNOx removal was not significant (36/100) when the reactor without anypacking was used.展开更多
This paper reports improved performance of discharge plasma in raw engine exhaust treatment. For the purpose of investigation, both filtered and raw diesel engine exhaust were separately treated by the discharge plasm...This paper reports improved performance of discharge plasma in raw engine exhaust treatment. For the purpose of investigation, both filtered and raw diesel engine exhaust were separately treated by the discharge plasma. In raw exhaust environment, the discharge plasma exhibits a superior performance with regard to NOx removal, energy consmnption and formation of by-products. In this study, experiments were conducted at conditions of different temperatures and loads.展开更多
Achieving simultaneous reduction of NOx,CO and unburned hydrocarbon(UHC) emissions without compromising engine performance at part loads is the current focus of dual fuel engine research.The present work focuses on an...Achieving simultaneous reduction of NOx,CO and unburned hydrocarbon(UHC) emissions without compromising engine performance at part loads is the current focus of dual fuel engine research.The present work focuses on an experimental investigation conducted on a dual fuel(diesel-natural gas) engine to examine the simultaneous effect of inlet air pre-heating and exhaust gas recirculation(EGR) ratio on performance and emission characteristics at part loads.The use of EGR at high levels seems to be unable to improve the engine performance at part loads.However,it is shown that EGR combined with pre-heating of inlet air can slightly increase thermal efficiency,resulting in reduced levels of both unburned hydrocarbon and NOx emissions.CO and UHC emissions are reduced by 24% and 31%,respectively,The NOx emissions decrease by 21% because of the lower combustion temperature due to the much inert gas brought by EGR and decreased oxygen concentration in the cylinder.展开更多
A cascaded system of electrical discharges (Non-thermal plasma), catalyst andadsorption process was investigated for the removal of oxides of nitrogen (NO_x) and carbonmonoxide (CO) from a Diesel engine raw exhaust. T...A cascaded system of electrical discharges (Non-thermal plasma), catalyst andadsorption process was investigated for the removal of oxides of nitrogen (NO_x) and carbonmonoxide (CO) from a Diesel engine raw exhaust. The three processes were separately studied first,and then the cascaded processes, namely plasma-catalyst and plasma-adsorbent, were investigated. Inthis paper main emphasis was laid on the effect of carbonaceous soot oxidation on the plasmatreatment process. While the cascaded plasma-catalyst process exhibits a higher CO removal, thecascaded plasma-adsorbent process exhibits a higher NO_x removal. The experiments were conductedunder no-load. The plasma and adsorbent reactors were kept at room temperature throughout theexperiment while the catalyst reactor was kept at 200℃ / 300℃.展开更多
The development of thermal stress in the exhaust manifold of a gasoline engine is considered.The problem is addresses in the frame of a combined approach wherefluid and structure are coupled using the GT-POWER and STA...The development of thermal stress in the exhaust manifold of a gasoline engine is considered.The problem is addresses in the frame of a combined approach wherefluid and structure are coupled using the GT-POWER and STAR-CCM+software.First,the external characteristic curve of the engine is compared with a one-dimen-sional simulation model,then the parameters of the model are modified until the curve matches the available experimental values.GT-POWER is then used to transfer the inlet boundary data under transient conditions to STAR-CCM+in real-time.The temperature profiles of the inner and outer walls of the exhaust manifold are obtained in this way,together with the thermal stress and thermal deformation of the exhaust manifold itself.Using this information,the original model is improved through the addition of connections.Moreover,the local branch pipes are optimized,leading to significant improvements in terms of thermal stress and thermal deforma-tion of the exhaust manifold(a 7%reduction in the maximum thermal stress).展开更多
The problem with fixed valve timing that the valve train is set by the automaker for peak efficiency running at a specific point in the engine’s operating range. When the vehicle is moving slower or faster than this ...The problem with fixed valve timing that the valve train is set by the automaker for peak efficiency running at a specific point in the engine’s operating range. When the vehicle is moving slower or faster than this ideal operating point the engine’s combustion cycle fails to properly burn the air/fuel mixture leading to considerably compromised engine performance and wastes fuel. Variable Valve Timing (VVT) is a solution developed to overcome this engine deficiency, dynamically altering the valve's opening and closing for optimal performance at any speed. The intension in this work is to contribute towards pursuing the development of variable valve timing (VVT) for improving the engine performance. This investigation covers the effect of exhaust valve opening (EVO), and closing (EVC) angle on engine performance and emissions. The aim is to optimize engine power and brake specific fuel consumption (BSFC) where the effect of engine speed has also been considered. Power, BMEP, BSFC, NO, and CO were calculated and presented to show the effect of varying valve timing on them for all the valve timing cases. The calculations of engine performance were carried out using the simulation and analysis engineering software: LOTUS”, and engine emissions were calculated using “ZINOX” program. Sensitivity analysis shows that the reduction of 10% of (EVO) angle gave a reduction of around 2.5% in power and volumetric efficiency, also a slight increase in nitrogen oxide (NO) and carbon monoxide (CO), while a 10% decrease in (EVC) causes around 1% improvement in Power. The effects of different (VVT) from the simulations are analyzed and compared with those in the reviewed literature.展开更多
Improved performance of plasma in raw engine exhaust treatment is reported. A new type of reactor referred to as of cross-flow dielectric barrier discharge （DBD） was used, in which the gas flow is perpendicular to t...Improved performance of plasma in raw engine exhaust treatment is reported. A new type of reactor referred to as of cross-flow dielectric barrier discharge （DBD） was used, in which the gas flow is perpendicular to the corona electrode. In raw exhaust environment, the cross-flow （radial-flow） reactor exhibits a superior performance with regard to NOx removal when compared to that with axial flow of gas. Experiments were conducted at different flow rates ranging from 2 L/min to 25 L/min. The plasma assisted barrier discharge reactor has shown encouraging results in NOx removal at high flow rates.展开更多
Diesel engines meeting the latest emission regulations must be equipped with exhaust gas aftertreatment system,including diesel oxidation catalysts(DOC),diesel particulate filters(DPF),and selective catalytic reductio...Diesel engines meeting the latest emission regulations must be equipped with exhaust gas aftertreatment system,including diesel oxidation catalysts(DOC),diesel particulate filters(DPF),and selective catalytic reduction(SCR).However,before the final integration of the aftertreatment system(DOC+DPF+SCR)and the diesel engine,a reasonable structural optimization of the catalytic converters and a large number of bench calibration tests must be completed,involving large costs and long development cycles.The design and optimization of the exhaust gas aftertreatment system for a heavy-duty diesel engine was proposed in this paper.Firstly,one-dimensional(1D)and threedimensional(3D)computational models of the exhaust gas aftertreatment system accounting for the structural parameters of the catalytic converters were established.Then based on the calibrated models,the effects of the converter’s structural parameters on their main performance indicators,including the conversion of various exhaust pollutants and the temperatures and pressure drops of the converters,were studied.Finally,the optimal design scheme was obtained.The temperature distribution of the solid substrates and pressure distributions of the catalytic converters were studied based on the 3D model.The method proposed in this paper has guiding significance for the optimization of diesel engine aftertreatment systems.展开更多
Proper design of exhaust systems in marine high-power turbocharged diesel engines can contribute to improve the low-speed performance of these engines and make the working conditions of the cylinders more uniform.Here...Proper design of exhaust systems in marine high-power turbocharged diesel engines can contribute to improve the low-speed performance of these engines and make the working conditions of the cylinders more uniform.Here a high-power marine 16-cylinder V-type turbocharged diesel engine is simulated using the GT-Power software.The results reveal the differences induced by different exhaust system structures,such as an 8-cylinder-inpipe exhaust system with single/double superchargers and a 4-cylinder-in-pipe exhaust system with a single supercharger.After a comparative analysis,the 8-cylinder type with double superchargers is determined to be the optimal solution,and the structure of the exhaust system is further optimized.The simulations show that the optimized maximum exhaust temperature difference among cylinders is reduced by 66%.Finally,the simulation results and the optimized performance of the designed exhaust system are verified through experiments.展开更多
The engine performance and exhaust emissions of biodiesel produced from peanut oil must be evaluated to assess its potential as an alternative diesel fuel. In this study, two diesel engines rated at 14.2 kW (small) an...The engine performance and exhaust emissions of biodiesel produced from peanut oil must be evaluated to assess its potential as an alternative diesel fuel. In this study, two diesel engines rated at 14.2 kW (small) and 60 kW (large) were operated on pure peanut oil biodiesel (PME) and its blends with a reference diesel (REFDIESEL). Results showed that comparable power and torque were delivered by both the small and large engines when ran on pure PME than on REFDIESEL while brake-specific fuel consumption (BSFC) was found to be higher in pure PME. Higher exhaust concentrations of nitrogen oxides (NOx), carbon dioxide (CO2) and total hydrocarbons (THC) and lower carbon monoxide (CO) emissions were observed in the small engine when using pure PME. Lower CO2, CO and THC emissions were obtained when running the large engine with pure PME. Blends with low PME percentage showed insignificant changes in both engine performance and exhaust emissions as compared with the reference diesel. Comparison with soybean biodiesel indicates similar engine performance. Thus, blends of PME with diesel may be used as a supplemental fuel for steady-state non-road diesel engines to take advantage of the lubricity of biodiesel as well as contributing to the goal of lowering the dependence to petroleum diesel.展开更多
A one-dimensional pipe flow model of single-cylinder diesel engine is established to investigate the intake and exhaust flow characteristics of diesel engine in the condition of high power density(HPD).A space-lime co...A one-dimensional pipe flow model of single-cylinder diesel engine is established to investigate the intake and exhaust flow characteristics of diesel engine in the condition of high power density(HPD).A space-lime conservation element and solution element(CE/SE)method is used to derive the discrete equations of the partial differential equation for the intake and exhaust systems.The performance parameters of diesel engine with speed of 2100 r/min are simulated.The simulated results are in accordance with the experimental data.The effect of increased power density on charging coefficient is analyzed using a validated model.The results show that the charging coefficient is slowly improved with the increase in intake pressure,and is obviously reduced with the increase in engine speed.展开更多
Diesel engine exhaust(DEE) and crystalline silica exposures occur simultaneously in the mining industry,and occupational sampling campaigns can be time-and cost-consuming. The authors evaluated a dualport system for s...Diesel engine exhaust(DEE) and crystalline silica exposures occur simultaneously in the mining industry,and occupational sampling campaigns can be time-and cost-consuming. The authors evaluated a dualport system for simultaneous sampling of DEE and crystalline silica in laboratory and field conditions.Laboratory tests evaluated the operation of pumps during 8 h sampling and the intensity of the flow variation for various filter loading conditions and for different modes of operation. Field validation was performed in an underground mine. Pumps operated in constant flow or constant pressure modes.Tests in constant flow mode showed that when the flowrate increased on one side of the system, it decreased on the opposite side according to the loading intensity. Tests in constant pressure mode showed that flowrates systematically decreased when using loaded cassettes. However, the higher the backpressure setting, the lower the flow variation was. Flow variations during field tests were generally within the acceptable ±5% range. However, significant flow variations were identified in higher concentrations. A significant negative correlation was found between flowrate variation and total carbon concentration. While the majority of tests support the use of the dual-port for evaluating concomitant exposures, results highlight the possibility of filter overloading as a cause of flowrate changes.展开更多
<strong>Objective:</strong> To assess the association between circulating C-reactive protein (CRP), and CRP polymorphisms in the diesel engine exhaust (DEE)-exposed workers. <strong>Methods:</stro...<strong>Objective:</strong> To assess the association between circulating C-reactive protein (CRP), and CRP polymorphisms in the diesel engine exhaust (DEE)-exposed workers. <strong>Methods:</strong> In 137 DEE-exposed workers and 127 unexposed comparable control workers, six urinary mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and serum CRP levels were assayed. Genotyping of four CRP single-nucleotide polymorphisms (SNPs) was measured. <strong>Results: </strong>Serum CRP levels increased in exposed versus control workers (all p < 0.001). In the DEE-exposed workers, two CRP polymorphisms were associated with serum CRP levels, the subjects of rs1205 TT genotype had lower serum CRP levels (p < 0.05 compared to TC or CC). <strong>Conclusions: </strong>Our findings suggest that polymorphisms in CRP and circulating CRP involved in the inflammatory process may play significant roles in human sensitivity to lung function injury caused by DEE exposure. This study will help investigate the underlying mechanisms of adverse respiratory effects induced by DEE.展开更多
基金supported by the National Key Research and Development Program of China[Grant No.2017YFE0116100]the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China[Grant No.KYCX20_2821].
文摘This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for membrane desalination devices to produce fresh water.A new exhaust-gas heat exchanger of fins and tube,with a reinforced heat transfer tube section,unequal spacing fins,a mixing zone between the fin groups and four routes tube bundle,was designed.Numerical simulations were also used to provide reference information for structural design.Experiments were carried out for exhaust gas waste heat recovery from a marine diesel engine in an engine test bench utilizing the heat exchanger.The experimental results show that the difference between heat absorption by water and heat reduction of exhaust gas is less than 6.5%.After the water flow rate was adjusted,the exhaust gas waste heat recovery efficiency was higher than 70%,and the exhaust-gas heat exchanger’s outlet water temperature was 55°C–85°C at different engine loads.This means that the heat recovery from the exhaust gas of a marine diesel engine meets the requirement to drive a membrane desalination device to produce fresh water for fishers working in small and medium-sized fishing vessels.
文摘Here a Gaussian Shell Model Array (GSMA) beam is used to investigate the propagation characteristics in the jet engine exhaust region. It has great significance to improve various optical systems for wide application in trapping cold atoms, creating gratings, and atmospheric optical communication. We calculate analytical formulas for the spectral density (SD) and the propagation factors M<sub>x</sub>2</sup> and M<sub>y</sub>2</sup> of a GSMA beam. The influence of inner scale of turbulence in the jet engine exhaust region on its power spectrum has been also analyzed. According to these results, the influence of turbulence in a jet engine exhaust on a GSMA beam has been reduced by changing the parameters of light source and turbulence. For example, it is an excellent tool for mitigation of the jet engine exhaust-induced anisotropy of turbulence to increase the source coherence length, the root-mean-squared (rms) beam width, the wavelength or reduce the outer scale of turbulence.
文摘The effect of fin attachment on the thermal stress reduction of exhaust manifold of an off road diesel engine(Komatsu HD325-6) was investigated.For doing this,coupled thermo-fluid-solid analysis of exhaust manifold of the off road diesel engine was carried out.The thermal analysis,including thermal flow,thermal stress,and the thermal deformation of the manifold was investigated.The flow inside the manifold was simulated and then its properties including velocity,pressure,and temperature were obtained.The flow properties were transferred to the solid model and then the thermal stresses and the thermal deformations of the manifold under different operating conditions were calculated.Finally,based on the predicted thermal stresses and thermal deformations of the manifold body shell,two fin types as well as body shell thickness increase were applied in the critical induced thermal stress area of the manifold to reduce the thermal stress and thermal deformation.The results of the above modifications show that the combined modifications,i.e.the thickness increase and the fin attachment,decrease the thermal stresses by up to 28% and the contribution of the fin attachment in this reduction is much higher compared to the shell thickness increase.
文摘Because the normal operation of the engine is located near the equilibrium manifold, the method of equilibrium mani fold nonlinear dynamic modeling is adopted for turbofan engine more than the local train modeling. The method studies the sys tem characteristics near the equilibrium manifold. The modeling method can be realized through dynamic and static twostep, and for the specific parameter modeling steps and algorithm are given. The output of the test data is compared with the model output through numerical simulation, to check the model with an additional set of test data. The simulation results show that the model has reached the requirements of engineering accuracy.
基金supported by the National Natural Science Foundation of China(51008277)the Natural Science Foundation of Zhejiang Province(LY14E080001)the Key Project of Zhejiang Provincial Science and Technology Program(2012C03003-4)~~
文摘Cu–Mn bimetal catalysts were prepared to remove nitrogen oxides(NOx)from diesel engine exhaust at low temperatures.At a Cu/Mn ratio of 3:2,the NOx conversions at 200°C reached 65%and 90%on Cu–Mn/ZSM‐5 and Cu–Mn/SAPO‐34,respectively.After a hydrothermal treatment and reaction in the presence of C3H6,the activity of Cu–Mn/SAPO‐34 was more stable than that of Cu–Mn/ZSM‐5.No obvious variations in the crystal structure or dealumination were observed,whereas the physical structure was best maintained in Cu–Mn/SAPO‐34.The atomic concentration of Cu on the surface of Cu–Mn/SAPO‐34 was quite stable,and the consumption of octahedrally coordinated Cu2+could be recovered.Conversely,the proportion of octahedrally coordinated Cu2+on the surface of Cu–Mn/ZSM‐5 significantly decreased.Therefore,besides the structure,the redox cycle between Cu+and octahedrally coordinated Cu2+played an important role in the stability of the catalysts.
文摘A cascaded system of electrical discharges (non-thermal plasma) andadsorption process was investigated for the removal of oxides of Nitrogen (NO_x) and totalhydrocarbons (THC) from an actual diesel engine exhaust. The non-thermal plasma and adsorptionprocesses were separately studied first and then the cascaded process was studied. In this study,different types of adsorbents were used. The NO_x removal efficiency was higher withplasma-associated adsorption (cascaded) process compared to the individual processes and the removalefficiency was found almost invariant in time. When associated by plasma, among the adsorbentsstudied, activated charcoal and MS-13X were more effective for NO_x and THC removal respectively.The experiments were conducted at no load and at 50 % load conditions. The plasma reactor was keptat room temperature throughout the experiment, while the temperature of the adsorbent reactor wasvaried. A relative comparison of adsorbents was discussed at the end.
文摘Reported in this paper is a feasibility study on the injection of plasma induced N radicals for the abatement of NO and NOx present in the actual diesel exhaust. The radical laden diesel exhaust was further treated by discharge plasma in a dielectric barrier discharge reactor. N radicals were produced in a separate plasma reactor filled with BaTiO3 pellets and were then injected into the treatment zone, There was a significant improvement in the efficiency when the radicals were injected compared to that when there was no radical injection. The efficiency of NOx removal at 0 load with plasma alone was 14% whereas with the injection of N radicals it went up to 38%, The results of the experiments conducted at different loads are discussed,
文摘This paper reports the studies conducted on removal of oxides ofnitrogen (NOx) from diesel engine exhaust using electrical dischargeplasma combined with adsorbing materials such as molecular sieves.This study is being reported for the first time. The exhaust is takenfrom a diesel engine of 6 kW under no load conditions. Thecharacteristic behavior of a pulse energized dielectric barrierdischarge reactor in the diesel exhaust treatment is reported. TheNOx removal was not significant (36/100) when the reactor without anypacking was used.
文摘This paper reports improved performance of discharge plasma in raw engine exhaust treatment. For the purpose of investigation, both filtered and raw diesel engine exhaust were separately treated by the discharge plasma. In raw exhaust environment, the discharge plasma exhibits a superior performance with regard to NOx removal, energy consmnption and formation of by-products. In this study, experiments were conducted at conditions of different temperatures and loads.
文摘Achieving simultaneous reduction of NOx,CO and unburned hydrocarbon(UHC) emissions without compromising engine performance at part loads is the current focus of dual fuel engine research.The present work focuses on an experimental investigation conducted on a dual fuel(diesel-natural gas) engine to examine the simultaneous effect of inlet air pre-heating and exhaust gas recirculation(EGR) ratio on performance and emission characteristics at part loads.The use of EGR at high levels seems to be unable to improve the engine performance at part loads.However,it is shown that EGR combined with pre-heating of inlet air can slightly increase thermal efficiency,resulting in reduced levels of both unburned hydrocarbon and NOx emissions.CO and UHC emissions are reduced by 24% and 31%,respectively,The NOx emissions decrease by 21% because of the lower combustion temperature due to the much inert gas brought by EGR and decreased oxygen concentration in the cylinder.
文摘A cascaded system of electrical discharges (Non-thermal plasma), catalyst andadsorption process was investigated for the removal of oxides of nitrogen (NO_x) and carbonmonoxide (CO) from a Diesel engine raw exhaust. The three processes were separately studied first,and then the cascaded processes, namely plasma-catalyst and plasma-adsorbent, were investigated. Inthis paper main emphasis was laid on the effect of carbonaceous soot oxidation on the plasmatreatment process. While the cascaded plasma-catalyst process exhibits a higher CO removal, thecascaded plasma-adsorbent process exhibits a higher NO_x removal. The experiments were conductedunder no-load. The plasma and adsorbent reactors were kept at room temperature throughout theexperiment while the catalyst reactor was kept at 200℃ / 300℃.
基金supported by the Basic Ability Improvement Project for Young and Middle-Aged Teachers in Guangxi Universities,Project No.2021KY0792.
文摘The development of thermal stress in the exhaust manifold of a gasoline engine is considered.The problem is addresses in the frame of a combined approach wherefluid and structure are coupled using the GT-POWER and STAR-CCM+software.First,the external characteristic curve of the engine is compared with a one-dimen-sional simulation model,then the parameters of the model are modified until the curve matches the available experimental values.GT-POWER is then used to transfer the inlet boundary data under transient conditions to STAR-CCM+in real-time.The temperature profiles of the inner and outer walls of the exhaust manifold are obtained in this way,together with the thermal stress and thermal deformation of the exhaust manifold itself.Using this information,the original model is improved through the addition of connections.Moreover,the local branch pipes are optimized,leading to significant improvements in terms of thermal stress and thermal deforma-tion of the exhaust manifold(a 7%reduction in the maximum thermal stress).
文摘The problem with fixed valve timing that the valve train is set by the automaker for peak efficiency running at a specific point in the engine’s operating range. When the vehicle is moving slower or faster than this ideal operating point the engine’s combustion cycle fails to properly burn the air/fuel mixture leading to considerably compromised engine performance and wastes fuel. Variable Valve Timing (VVT) is a solution developed to overcome this engine deficiency, dynamically altering the valve's opening and closing for optimal performance at any speed. The intension in this work is to contribute towards pursuing the development of variable valve timing (VVT) for improving the engine performance. This investigation covers the effect of exhaust valve opening (EVO), and closing (EVC) angle on engine performance and emissions. The aim is to optimize engine power and brake specific fuel consumption (BSFC) where the effect of engine speed has also been considered. Power, BMEP, BSFC, NO, and CO were calculated and presented to show the effect of varying valve timing on them for all the valve timing cases. The calculations of engine performance were carried out using the simulation and analysis engineering software: LOTUS”, and engine emissions were calculated using “ZINOX” program. Sensitivity analysis shows that the reduction of 10% of (EVO) angle gave a reduction of around 2.5% in power and volumetric efficiency, also a slight increase in nitrogen oxide (NO) and carbon monoxide (CO), while a 10% decrease in (EVC) causes around 1% improvement in Power. The effects of different (VVT) from the simulations are analyzed and compared with those in the reviewed literature.
文摘Improved performance of plasma in raw engine exhaust treatment is reported. A new type of reactor referred to as of cross-flow dielectric barrier discharge （DBD） was used, in which the gas flow is perpendicular to the corona electrode. In raw exhaust environment, the cross-flow （radial-flow） reactor exhibits a superior performance with regard to NOx removal when compared to that with axial flow of gas. Experiments were conducted at different flow rates ranging from 2 L/min to 25 L/min. The plasma assisted barrier discharge reactor has shown encouraging results in NOx removal at high flow rates.
基金Projects(2017YFC0211202,2017YFC0211301)supported by the National Key R&D Program of China。
文摘Diesel engines meeting the latest emission regulations must be equipped with exhaust gas aftertreatment system,including diesel oxidation catalysts(DOC),diesel particulate filters(DPF),and selective catalytic reduction(SCR).However,before the final integration of the aftertreatment system(DOC+DPF+SCR)and the diesel engine,a reasonable structural optimization of the catalytic converters and a large number of bench calibration tests must be completed,involving large costs and long development cycles.The design and optimization of the exhaust gas aftertreatment system for a heavy-duty diesel engine was proposed in this paper.Firstly,one-dimensional(1D)and threedimensional(3D)computational models of the exhaust gas aftertreatment system accounting for the structural parameters of the catalytic converters were established.Then based on the calibrated models,the effects of the converter’s structural parameters on their main performance indicators,including the conversion of various exhaust pollutants and the temperatures and pressure drops of the converters,were studied.Finally,the optimal design scheme was obtained.The temperature distribution of the solid substrates and pressure distributions of the catalytic converters were studied based on the 3D model.The method proposed in this paper has guiding significance for the optimization of diesel engine aftertreatment systems.
基金the High-Tech Ship Scientific Research Project[MC-201501-D01-01].
文摘Proper design of exhaust systems in marine high-power turbocharged diesel engines can contribute to improve the low-speed performance of these engines and make the working conditions of the cylinders more uniform.Here a high-power marine 16-cylinder V-type turbocharged diesel engine is simulated using the GT-Power software.The results reveal the differences induced by different exhaust system structures,such as an 8-cylinder-inpipe exhaust system with single/double superchargers and a 4-cylinder-in-pipe exhaust system with a single supercharger.After a comparative analysis,the 8-cylinder type with double superchargers is determined to be the optimal solution,and the structure of the exhaust system is further optimized.The simulations show that the optimized maximum exhaust temperature difference among cylinders is reduced by 66%.Finally,the simulation results and the optimized performance of the designed exhaust system are verified through experiments.
文摘The engine performance and exhaust emissions of biodiesel produced from peanut oil must be evaluated to assess its potential as an alternative diesel fuel. In this study, two diesel engines rated at 14.2 kW (small) and 60 kW (large) were operated on pure peanut oil biodiesel (PME) and its blends with a reference diesel (REFDIESEL). Results showed that comparable power and torque were delivered by both the small and large engines when ran on pure PME than on REFDIESEL while brake-specific fuel consumption (BSFC) was found to be higher in pure PME. Higher exhaust concentrations of nitrogen oxides (NOx), carbon dioxide (CO2) and total hydrocarbons (THC) and lower carbon monoxide (CO) emissions were observed in the small engine when using pure PME. Lower CO2, CO and THC emissions were obtained when running the large engine with pure PME. Blends with low PME percentage showed insignificant changes in both engine performance and exhaust emissions as compared with the reference diesel. Comparison with soybean biodiesel indicates similar engine performance. Thus, blends of PME with diesel may be used as a supplemental fuel for steady-state non-road diesel engines to take advantage of the lubricity of biodiesel as well as contributing to the goal of lowering the dependence to petroleum diesel.
文摘A one-dimensional pipe flow model of single-cylinder diesel engine is established to investigate the intake and exhaust flow characteristics of diesel engine in the condition of high power density(HPD).A space-lime conservation element and solution element(CE/SE)method is used to derive the discrete equations of the partial differential equation for the intake and exhaust systems.The performance parameters of diesel engine with speed of 2100 r/min are simulated.The simulated results are in accordance with the experimental data.The effect of increased power density on charging coefficient is analyzed using a validated model.The results show that the charging coefficient is slowly improved with the increase in intake pressure,and is obviously reduced with the increase in engine speed.
基金financially supported by the Fonds de recherche du Québec-Nature et Technologies (No. RQT00043)
文摘Diesel engine exhaust(DEE) and crystalline silica exposures occur simultaneously in the mining industry,and occupational sampling campaigns can be time-and cost-consuming. The authors evaluated a dualport system for simultaneous sampling of DEE and crystalline silica in laboratory and field conditions.Laboratory tests evaluated the operation of pumps during 8 h sampling and the intensity of the flow variation for various filter loading conditions and for different modes of operation. Field validation was performed in an underground mine. Pumps operated in constant flow or constant pressure modes.Tests in constant flow mode showed that when the flowrate increased on one side of the system, it decreased on the opposite side according to the loading intensity. Tests in constant pressure mode showed that flowrates systematically decreased when using loaded cassettes. However, the higher the backpressure setting, the lower the flow variation was. Flow variations during field tests were generally within the acceptable ±5% range. However, significant flow variations were identified in higher concentrations. A significant negative correlation was found between flowrate variation and total carbon concentration. While the majority of tests support the use of the dual-port for evaluating concomitant exposures, results highlight the possibility of filter overloading as a cause of flowrate changes.
文摘<strong>Objective:</strong> To assess the association between circulating C-reactive protein (CRP), and CRP polymorphisms in the diesel engine exhaust (DEE)-exposed workers. <strong>Methods:</strong> In 137 DEE-exposed workers and 127 unexposed comparable control workers, six urinary mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and serum CRP levels were assayed. Genotyping of four CRP single-nucleotide polymorphisms (SNPs) was measured. <strong>Results: </strong>Serum CRP levels increased in exposed versus control workers (all p < 0.001). In the DEE-exposed workers, two CRP polymorphisms were associated with serum CRP levels, the subjects of rs1205 TT genotype had lower serum CRP levels (p < 0.05 compared to TC or CC). <strong>Conclusions: </strong>Our findings suggest that polymorphisms in CRP and circulating CRP involved in the inflammatory process may play significant roles in human sensitivity to lung function injury caused by DEE exposure. This study will help investigate the underlying mechanisms of adverse respiratory effects induced by DEE.
