Stability of Cu-Mn bimetal catalysts based on different zeolites for NO_x removal from diesel engine exhaust

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.

DeNOx Study in Diesel Engine Exhaust Using Barrier Discharge Corona Assisted by V_2O_5/TiO_2 Catalyst

A plasma-assisted catalytic reactor was used to remove nitrogen oxides (NOx)from diesel engine exhaust operated under different load conditions. Initial studies were focused onplasma reactor (a dielectric barrier discharge reactor) treatment of diesel exhaust at varioustemperatures. The nitric oxide (NO) removal efficiency was lowered when high temperature exhaust wastreated using plasma reactor. Also, NO removal efficiency decreased when 45% load exhaust wastreated. Studies were then made with plasma reactor combined with a catalytic reactor consisting ofa selective catalytic reduction (SCR) catalyst, V_2O_5/TiO_2. Ammonia was used as a reducing agentfor SCR process in a ratio of 1:1 to NOx. The studies were focused on temperatures of the SCRcatalytic reactor below 200℃. The plasma-assisted catalytic reactor was operated well to remove NOxunder no-load and load conditions. For an energy input of 96 J/l, the NOx removal efficienciesobtained under no-load and load conditions were 90% and 72% respectively at an exhaust temperatureof 100 ℃.

Effect of fin attachment on thermal stress reduction of exhaust manifold of an off road diesel engine

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.

Injection of N-Radicals into Diesel Engine Exhaust Treated by Plasma for Improved NO_x Removal: A Feasibility Study

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,

Removal of Nitrogen Oxides in Diesel Engine Exhaust by Plasma Assisted Molecular Sieves

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.

Unfiltered Diesel Engine Exhaust Treatment by Discharge Plasma: Effect of Soot Oxidation

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℃.

Study of Pulsed Plasma in a Crossed Flow Dielectric Barrier Discharge Reactor for Improvement of NO_x Removal in Raw Diesel Engine Exhaust

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.

Design and optimization of exhaust gas aftertreatment system for a heavy-duty diesel engine

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.

Optimizing the Exhaust System of Marine Diesel Engines to Improve Low-speed Performances and Cylinder Working Conditions

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.

Non-Conventional Plasma Assisted Catalysts for Diesel Exhaust Treatment: A Case Study

This paper reports the application of pulse discharges along with catalysts in treat- ing the exhaust gas at higher temperatures. In the present work a plasma reactor, filled with catalysts, called as plasma catalytic reactor, is studied for removal of oxides of nitrogen, total hydrocarbons and carbon monoxide. The experiments are conducted on an actual diesel engine exhaust at no-load and at different temperatures starting from room temperature to 300°C. The removal efficiencies of these pollutants are studied. The experiments are carried out with both con- ventional and non-conventional catalysts. The idea is to explore the pollutant removal efficiency characteristics by non-conventional catalysts. The efficiency results are compared with that of conventional catalysts. The experiments are carried out at a constant pulse repetition rate of 120 pps. Both pellet and honeycomb type catalysts are used in the study.

Application of Space-time Conservation Element and Solution Element Method in Intake and Exhaust Flows of High Power Density Diesel Engine

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.

Determination of arsenic in air particulates and diesel exhaust particulates by spectrophotometry

A method was developed for the determination of trace arsenic by spectrophotometry. The proposed method is rapid, simple, and inexpensive. This method can be used for sensitive determination of trace arsenic in environmental samples and especially in air particulates. The results obtained by this method as a proposed method were compared with those obtained by hydride generation atomic absorption spectrometry as a popular reported method for the determination of arsenic and an excellent agreement was found between them. The method was also used for determination of arsenic associated with airborne particulate matter and diesel exhaust particulates. The results showed that considerable amount of arsenic are associated with diesel engine particulates. The variation in concentration of arsenic was also investigated. The atmospheric concentration of arsenic was different in different sampling stations was dependent to the traffic density.

Present Situation of Purification Technologies for Automotive Exhaust in China

It is presented that eliminating and controlling the current automotive exhaust emission should be important and urgent in China, and the Chinese state emission standards have been getting stricter and stricter. Also the present purification technologies for automotive exhaust are elucidated. It is indicated that the development and the commercialization of Rare Earth based on three way catalytic converters is pretty necessary and urgent to address the current harsh automotive exhaust emission problems in China. In addition, the future automotive exhaust purification technologies are prospected.

Parallel personal measurements of diesel engine exhaust and crystalline silica using dual sampling port

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.

Sensitivity of Lichens to Diesel Exhaust under Laboratory Conditions

Lichen vegetation reacts very sensitively to a variety of air pollutants including increased nitrogen concentrations as well as to traffic exhaust in general, which makes lichens reliable monitoring organisms for atmospheric pollution. Recent environmental studies have shown that decreasing abundance of acidophytic lichen species and the increase of nitrophytic lichens can be explained by elevated levels of atmospheric nitric-compounds adsorbed onto nanoparticles. One major source of these atmospheric compounds amongst a wider pollution inventory is diesel exhaust—a mixture of gases and particle matter. This study aimed to shed light on the impact of diesel exhaust on the viability of six differently sensitive lichen species. Diesel exhaust particle concentrations in the laboratory experiments resembled those at a local highway during rush hour. By incubation in a closed stainless steel chamber we could exclude influences from other pollutants than diesel exhaust providing explicit data about the effects of diesel exhaust on lichens. The investigations revealed effects on the photosynthesis of the lichen photobionts and hence the lichen vitality. The conclusions of this study are that 1) the photobiont is affected stronger as the mycobiont and 2) older parts of the lichen are damaged first. Another remarkable result of this study is that 3) these lichens are regenerating to some extent during incubation-free periods—unless the organism is not damaged too much to restore photosynthetic activity. To our knowledge this is the first study evaluating the impact of diesel exhaust on lichens under laboratory conditions separate from other interfering pollutants.

C-Reactive Protein Gene Polymorphisms Correlated with Serum CRP Levels of Diesel Engine Exhaust-Exposed Workers

Objective: To assess the association between circulating C-reactive protein (CRP), and CRP polymorphisms in the diesel engine exhaust (DEE)-exposed workers. Methods: 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. Results: 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). Conclusions: 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.

Diesel generator exhaust heat recovery fully-coupled with intake air heating for off-grid mining operations:An experimental,numerical,and analytical evaluation

The customarily discarded exhaust from the fossil fuel-based power plants of the off-grid mines holds the thermal potential to fulfill the heating requirement of the underground operation.This present research fills in an important research gap by investigating the coupling effect between a diesel exhaust heat recovery and an intake air heating system employed in a remote mine.An integrative approach comprising analytical,numerical,and experimental assessment has been adapted.The novel analytical model developed here establishes the reliability of the proposed mine heating system by providing comparative analysis between a coupled and a decoupled system.The effect of working fluid variation has been examined by the numerical analysis and the possible improvement has been identified.Experimental investigations present a demonstration of the successful lab-scale implementation of the concept and validate the numerical and analytical models developed.Successful deployment of the fully coupled mine heating system proposed here will assist the mining industry on its journey towards energy-efficient,and sustainable mining practices through nearly 70%reduction in fossil fuel consumption for heating intentions.

Experiment Study on the Exhaust-Gas Heat Exchanger for Small and Medium-Sized Marine Diesel Engine

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.

RE Catalyst for Exhaust Purification

With a rapid increase in volume of ve-hicles in the world,the polution causedby the automobile exhausted gas has be-come more and more serious.This problemhas brought to our government’s atten-tion.In Beijing,regulations regardingthe supervision of the exhaust have beenissued.At the Fifth National Meeting on RECatalytic purification of Automobile Ex-haust held in Beijing 1989,the partici-pants from institutes,universities,andfactories all over the country reportedand discussed the methods of purifica-

Design and Experiment for Exhaust Pipes of Pressure Wave Supercharged Diesel Engine

NOx and soot emissions from diesel engines can be greatly reduced by pressure wave supercharging(PWS).The diesel engine matched with PWS needs redesigning its exhaust pipes.Except for meeting the installation requirements,the exhaust gas must be stable in pressure before rushing into PWS.In this paper the lateral and center ported divergent exhaust pipes are designed,modeled geometrically and analyzed structurally based on a 3-D design software-CATIA to determine the structure of two exhaust pipes having the required inner volume.Then flow analysis for two exhaust pipes is done using a flow analysis software-ANASYS.Moreover,the optimal exhaust pipes are determined comprehensively and cast for engine test.Engine test results show that PWS is superior to turbocharging at low engine speeds and inferior to turbocharging in power and emissions at medium-to-high engine speeds.The performance of PWS engine under high speed operating conditions can be improved by contriving larger surge volume intake and exhaust pipes.