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.

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.

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.

Influence of Diesel Engine Intake Throttle and Late Post Injection Process on the Rise of Temperature in the Diesel Oxidation Catalyst

In order to effectively implement DPF(Diesel Particulate Filters)regeneration control,thermal management of exhaust products before and inside Diesel Oxidation Catalyst(DOC)is necessary.In the present study,the Influence of the intake throttle valve and late post injection process on temperature rise inside DOC is analyzed through engine bench tests.The steady experiment results show that adjustment of the intake throttle valve can effectively increase exhaust temperature before DOC;in particular,with intake throttle valve opening at 20%,temperature before DOC can be increased by about 170℃ with respect to the full opening.An increase in the late post injection quantity can produce a significant rise of the temperature inside DOC,however its impact on the exhaust temperature before DOC is relatively limited.As the late post injection quantity increases,Hydrocarbon(HC)emissions also grow;in the present work it is shown that with a proper injection quantity,a considerable temperature increase inside the DOC can be obtained with relatively low HC emission.More specifically,with the intake throttle valve at 30%and DOC reaching ignition temperature as the late post injection quantity is increased,the exhaust temperature after DOC can be made larger than 550℃,adequate for DPF active regeneration.

Electronically Controlling the System of Preheating Intake Air by Flame for Diesel Engine Cold-Start

In order to improve the cold start performance of heavy duty diesel engine, electronically controlling the preheating of intake air by flame was researched. According to simulation and thermodynamic analysis about the partial working processes of the diesel engine, the amount of heat energy, enough to make the fuel self ignite at the end of compression process at different temperatures of coolant and intake air, was calculated. Several HY20 preheating plugs were used to heat up the intake air. Meanwhile, an electronic control system based on 8 bit micro controller unit (MCS 8031) was designed to automatically control the process of heating intake air. According to the various temperatures of coolant and ambient air, one plug or two plugs can automatically be selected to heat intake air. The demo experiment validated that the total system could operate successfully and achieve the scheduled function.

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.

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.

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.

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.

Miller Cycle with Early Intake Valve Closing in Marine Medium-Speed Diesel Engines

In this study,a one-dimensional simulation was performed to evaluate the performance of in-cylinder combustion to control NO_(x) emissions on a four-stroke,six-cylinder marine medium-speed diesel engine.Reducing the combustion temperature is an important in-cylinder measure to decrease NO_(x) emissions of marine diesel engines.The Miller cycle is an effective method used to reduce the maximum combustion temperature in a cylinder and accordingly decrease NO_(x) emissions.Therefore,the authors of this study designed seven different early intake valve closing(EIVC)Miller cycles for the original engine,and analyzed the cycle effects on combustions and emissions in high-load conditions.The results indicate that the temperature in the cylinder was significantly reduced,whereas fuel consumption was almost unchanged.When the IVC was properly advanced,the ignition delay period increased and the premixed combustion accelerated,but the in-cylinder average pressure,temperature and NO_(x) emissions in the cylinder were lower than the original engine.However,closing the intake valve too early led to high fuel consumption.In addition,the NO_(x) emissions,in-cylinder temperature,and heat release rate remarkably increased.Therefore,the optimal timing of the EIVC varied with different loads.The higher the load was,the earlier the best advance angle appeared.Therefore,the Miller cycle is an effective method for in-engine NO_(x) purification and does not entail significant cost.

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.

Fault Diagnosis for Manifold Absolute Pressure Sensor(MAP) of Diesel Engine Based on Elman Neural Network Observer

Intake system of diesel engine is a strong nonlinear system, and it is difficult to establish accurate model of intake system; and bias fault and precision degradation fault of MAP of diesel engine can＇t be diagnosed easily using model-based methods. Thus, a fault diagnosis method based on Elman neural network observer is proposed. By comparing simulation results of intake pressure based on BP network and Elman neural network, lower sampling error magnitude is gained using Elman neural network, and the error is less volatile. Forecast accuracy is between 0.015？0.017 5 and sample error is controlled within 0？0.07. Considering the output stability and complexity of solving comprehensively, Elman neural network with a single hidden layer and with 44 nodes is presented as intake system observer. By comparing the relations of confidence intervals of the residual value between the measured and predicted values, error variance and failures in various fault types. Then four typical MAP faults of diesel engine can be diagnosed： complete failure fault, bias fault, precision degradation fault and drift fault. The simulation results show： intake pressure is observable and selection of diagnostic strategy parameter reasonably can increase the accuracy of diagnosis;the proposed fault diagnosis method only depends on data and structural parameters of observer, not depends on the nonlinear model of air intake system. A fault diagnosis method is proposed not depending system model to observe intake pressure, and bias fault and precision degradation fault of MAP of diesel engine can be diagnosed based on residuals.

Validation of an Emission Model for a Marine Diesel Engine with Data from Sea Operations

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.

Performance of Tractor Diesel Engine with Animal-Fats Biodiesel

Animal fats biodiesel were manufactured and tested for its performance in the tractor engine and fuel adoptability in the field works. Four different fuels, three different content of biodiesel （BD20, BD50 and BD100） and light oil, were prepared and tested in the four strokes diesel engine. Power output, fuel consumption rate and exhaust gases of the four fuels in the diesel engine were compared and discussed. Power output of light oil engine was the greatest showing 5.3% difference between light oil and BDI00. But, almost no power difference between light oil engine and BD20 engine, light oil engine produced 0.37% more power than BD20 engine superior to better power than BD20 engine. Less exhaust gases of CO2, CO, NOx and total hydrocarbon （THC） were produced from animal fats biodiesel than light oil, which confirmed that biodiesel is environmental friendly fuel. For fuel adoptability in the tractor, biodiesel engine tractor showed its fuel competitiveness comparing with light oil for tractor works in the paddy field.

Application of Waste Biomass Pyrolysis Oil in a Direct Injection Diesel Engine： For a Small Scale Non-Grid Electrification

The population which could not access to electricity was around 1.2 billion in 2010 and is distributed in many low developing countries. With the increase in the population and the economic growth in those countries, waste generation is growing rapid especially for the organic and the plastic, and the uncontrolled waste disposal is becoming more serious issues to manage it. The interest on waste to energy is growing by the above drivers. This research was carried out for aiming to the real world adaption at the minimum cost of the pyrolysis oil from waste biomass in a diesel engine, mainly for electricity generation. The proposal of the appropriate adaptable blend ratio was the major scope rather than the optimization of the engine parameters. For the sake of it, the pyrolysis oil of the waste biomass was produced from a gasification pilot plant in Japan and blended with biodiesel at minimum effort. A small single cylinder diesel engine （direct injection） was used for the experiment with regard to full load power-output, exhaust emissions and fuel consumption.