Research on H_2 speed governor for diesel engine of marine power station

The frequency stability of a marine power system is determined by the dynamic characteristic of the diesel engine speed regulation system in a marine power station. In order to reduce the effect of load disturbances and improve the dynamic precision of a diesel engine speed governor, a controller was designed for a diesel engine speed regulation system using H2 control theory. This transforms the specifications of the system into a standard H2 control problem. Firstly, the mathematical model of a diesel engine speed regulation system using an H2 speed governor is presented. To counter external disturbances and model uncertainty, the design of an H, speed governor rests on the problem of mixed sensitivity. Computer simulation verified that the H2 speed governor improves the dynamic precision of a system and the ability to adapt to load disturbances, thus enhancing the frequency stability of marine power systems.

Engineering Geological Study of Regional Tectonic Stability in the Area of the Longyang Gorge Power Station on the Huanghe (Yellow) River

In the stability study of the regional structures in the area of the Longyang Gorge Hydroelectrical Power Station, a model of the current stress-deformation field of the area was constructed based on analyses of available data of regional surveys and historical earthquakes and field investigations of active faults and ancient earthquakes. This model was examined and verified by physical and mathematical simulation experiments, and quantitative relations and data were obtained.

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.

Effects of Hydrogen Addition on Power and Emissions Outputs from Diesel Engines

Energy efficiency and environmental impact have become dominant topics in internal combustion engines development. Among many strategies to improve power and emissions outputs from diesel engines is the partial mix of hydrogen and air as fresh charge components to form extremely lean and homogenous mixture, which resist the spontaneous combustion, while diesel fuel is injected directly inside combustion chamber using the conventional fuel injection systems. This contribution presents an analytical and experimental investigation for the effects of adding hydrogen on diesel engines power output and the reduction of emissions. Parametric analysis is used based on lamped parameters modeling of intake manifold to estimate in cylinder trapped charge. The fuel energy flow to engine cylinders is compared for a range of loads and concentrations to simulate relevant case studies. Diesel fuel reduction for significant range of part-load operation can be achieved by introducing hydrogen, along with power improvement emission reductions are affected positively as well. This is achievable without compromising the engine maximum efficiency, given that most engines are operated at small and part-load during normal driving conditions, which allow for introducing more hydrogen instead of large quantities of excess air during such operation conditions that also can be further improved by charge boosting.

Controlling of NO_x Emitted from a Diesel Engine Fueled on Biodiesel: Theoretical Modeling and Experimental Evaluation

The development of a diesel engine model using one-dimensional （1-D） fluid-dynamic engine simulation codes,and its validation using experimental measurements are described in this paper.The model was calibrated by running the engine on an electric dynamometer at eight steady-state operating conditions.The refined engine model was used to predict the oxides of nitrogen （NOx） less than those measured earlier in the experiments,and hence to recommend changes in the engine for the verification of the results.The refined engine model is greatly influenced by the start of injection angle （ψ）,ignition delay （φ）,premix duration （DP）,and main duration （DM） for the prediction of reduced NOx emissions.It is found that optimum ψ is 6.5° before top dead center （BTDC）.At this angle,the predicted and experimental results are in good agreement,showing only a difference of up to 4%,6.2%,and 7.5% for engine performance,maximum combustion pressure （Pmax）,and NOx,respectively.

Study on Effects of Diesel Engine Cooling System Parameters on Water Temperature

A simulation model for a certain diesel engine cooling system is set up by using GT-COOL. The backwater temperature response in different operating conditions is simulated numerically. The effects of single or multiple system parameters on the water temperature are analyzed. The results show that, changing different single parameters, the time taken for the steady backwater temperature is different, but relatively short;and if multiple parameters are changed, the time will be longer. Referred to the thermal balance test, the simulation results are validated and provide a basis for the intelligent control of the cooling system.

Experimental investigation of power output and soot emission for micro-emulsification diesel oil using for vehicle

The micro-emulsification diesel oil with water dopant of 5%, 10% and 15% was prepared using the NAA micro-emulsification compound developed by the authors. The engine bench testing was carried out on the 485QB diesel engine. From the testing results of velocity, loading and exhaust gas, it can be seen that the power decreases and the fuel consumption increases using the micro-emulsification diesel oil. But based on the actual fuel consumption, the use of emulsification diesel with water dopant of 10% can get the effect of oil saving; while with water donant of more than 15% , it doesnt work evidently. The investigation shows that using the micro - emulsification diesel oil, we can reduce the exhaust gas pollution and receive better environment benefit.

Evaluation of Diesel Engine Noise Reduction Measures Based on Hierarchy Diagnosis

Effect of different noise reduction measures for diesel engines was evaluated based on hierarchy diagnosis. The hierarchy diagnosis chart and hierarchy judgment matrix were given. Through evaluation of noise reduction measures, the main strategies of noise reduction were found. The result shows that the noise reduction level of different frequency belts varies from measure to measure. The reduction capacity of different measures could not add simply, which relates to the problem of parameter matching.

Endurance Test of Biodiesel Fueled Tractor Engine

A diesel engine for tractor was tested for 250 hours of durability with biodiesel fuel of 100%. An engine test cycle was designed based on the ISO test code of off-road vehicle. Eight test conditions, combination of three engine speeds and eight engine loads, were applied to the engine endurance test, and the engine was operated for eight hours in a day. Power output, fuel consumption rate, exhaust gas quality and particulate matter （PM） were measured and discussed. For the extensive 250 hours of the tractor diesel engine endurance test no significant changes of power output, fuel consumption rate, exhaust gas quality and PM were monitored and authors could not find any difference in the engine patterns of the two fuels of BDF100 and light oil. During all the engine endurance test conditions, no abrupt stopping was encountered but because of temperature down by the cold season the endurance test could not carried out for some periods. PMs were collected and the average F＇M was 0.027 g/kw which was far below than Tier 4 diesel engine PM of 0.3 g/kw h defined by US EPA PM of the diesel engine clas,;. Overall even 100% biodiesel can be an alternative fuel for light oil for diesel engine operation with some considerations for cold sea：son use.

Numerical Study on Application of CuO-Water Nanofluid in Automotive Diesel Engine Radiator

Application of CuO-water nanofluid with size of the nanoparticles of 20 nm and volume concentrations up 2% is numerically investigated in a radiator of Chevrolet Suburban diesel engine under turbulent flow conditions. The heat transfer relations between airflow and nanofluid coolant have been obtained to evaluate local convective and overall heat transfer coefficients and also pumping power for nanofluid flowing in the radiator with a given heat exchange capacity. In the present study, the effects of the automotive speed and Reynolds number of the nanofluid in the different volume concentrations on the radiator performance are also investigated. The results show that for CuO-water nanofluid at 2% volume concentration circulating through the flat tubes with Renf = 6000 while the automotive speed is 70 km/hr, the overall heat transfer coefficient and pumping power are approximately 10% and 23.8% more than that of base fluid for given conditions, respectively.

Study on Effects of Oxydal on Diesel Engine Combustion

Based on the analysis of the high temperature decomposition of oxydal(H2O2)and the combustion of diesel engine,the effects of H2O2 on the improvement of diesel combustion were studied.An oxydal spray system was designed to inject H2O2/water mixture into the manifold.The experiment was carried out on a 1135 diesel engine bench.The results show that H2O2 injection can make the curve of heat release rate move forward and decrease its peak value.The specific fuel consumption is decreased a little,while both NOx and PM emission are obviously reduced.

Application of Solid Oxide Fuel Cell-Auxiliary Power Unit on Different Trucks in Northeast China

A diesel engine of conventional trucks has a low efficiency under the idling condition,leading to a high cost for heating or cooling in the cab during night. The solution to this problem will have great significance on energy conservation and emission reduction. A new auxiliary power unit of solid oxide fuel cell( SOFCAPU) with high efficiency solves this problem perfectly. Heat pump air conditioner is considered as a promising device for the application of SOFC-APU with a high cooling and heating efficiency. To make a quantitative analysis for the application of SOFC-APU,a model is built in Matlab / Simulink. The diesel engine model and SOFC-APU model are fitted based on some experimental data of SOFC-APU and diesel engine during the idling operation. An analysis of the application of SOFC-APU on different trucks in Northeast China is comprehensively made,including efficiency and emission.

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.

Overview of Past, Present and Future Marine Power Plants

In efforts to overcome an foreseeable energy crisis predicated on limited oil and gas supplies, reserves; economic variations facing the world, and of course the environmental side effects of fossil fuels, an urgent need for energy sources that provide sustainable, safe and economic supplies for the world is imperative. The current fossil fuel energy system must be improved to ensure a better and cleaner transportation future for the world. Despite the fact that the marine transportation sector consumes only 5% of global petroleum production; it is responsible for 15% of the world NOx and SOx emissions. These figures must be the engine that powers the scientific research worldwide to develop new solutions for a very old energy problem. In this paper, the most effective types of marine power plants were discussed. The history of the development of each type was presented first and the technical aspects were discussed second. Also, the fuel ceils as a new type of power plants used in marine sector were briefed to give a complete overview of the past, present and future of the marine power plants development. Based on the increased worldwide concerns regarding harmful emissions, many researchers have introduced solutions to this problem, including the adoption of new cleaner fuels. This paper was guided using the same trend and by implementing the hydrogen as fuel for marine internal combustion engine, gas turbines, and fuel cells.

Test and Analysis for Spraying Ammonia in Diesel Engine

A certain amount of ammonia reducer were directly injected into the 4102BZLQ Diesel engine's combustion chamber when the combustion temperature decreases to 1573-1073K, NOx generated could be reduced to 1.11g/(kW·h). Based on PRF combustion mechanism, NO was tested by using the heavy-duty diesel engine test cycle of ESC thirteen conditions[1], the ammonia spray angle and amount were tested and optimized in different conditions. The test results show that the thermal efficiency of Diesel engine does not decrease while NO exhaust decreases.

Experimental Investigation on Space-dispersed Double-wall Jet Combustion System for DI Diesel Engine

A space-dispersed double-wall jet combustion system was developed by adopting the wall-guiding spray method and the stratification theory.The experimental test was carried out to optimize the structural parameters of the diesel-engine combustion system,including chamber structure,swirl ratio of cylinder head,included angle of jet orifice,number and diameter of jet orifice,fuel injection pressure and timing.The effect of double-wall jet combustion system on combustion and engine performance was tested to obtain the best performance indexes,and the double-wall jet combustion system was compared to the prototype.The results show that NOx is reduced from 712 PPm to 487 PPm at 2 100 r/min,and from 593 PPm to 369 PPm at 3 000 r/min,which are reduced by 31.6% and 37.7%,respectively.The smoke intensity was reduced form 3.67 BSU to 2.1 BSU,and the oil consumption was reduced from 240.5 g/(kW·h) to 225.4 g/(kW·h),which was decreased by 6.3% at low speed.The pressure in the cylinder was obviously reduced from 115 bar to 108 bar,which was reduced by 6%.

Overall optimization of Rankine cycle system for waste heat recovery of heavy-duty vehicle diesel engines considering the cooling power consumption

The Rankine cycle system for waste heat recovery of heavy-duty vehicle diesel engines has been regarded as a promising tech- nique to reduce fuel consumption. Its heat dissipation in the condensation process, however, should be take：l away in time, which is an energy-consuming process. A fan-assisted auxiliary water-cooling system is employed in this paper. Results at 1300 r/min and 50% load indicate that the cooling pump and cooling fan together consume 7.66% of the recovered power. What＇s worse for the heavy load, cooling accessories may deplete of all the recovered power of the Rankine cycle system. Af- terwards, effects of the condensing pressure and water feeding temperature are investigated, based on which a cooling power consumption model is established. Finally, an overall efficiency optimization is conducted to balance the electric power gener- ation and cooling power consumption, taking condensing pressure, pressure ratio and exhaust bypass valve as major variables. The research suggests that the priority is to increase condensing pressure and open exhaust bypass valve appropriately at high speed and heavy load to reduce the cooling power consumption, while at low speed and light load, a lower condensing pressure is favored and the exhaust bypass valve should be closed making the waste heat recovered as much as possible. Within the sub-critical region, a larger pressure ratio yields higher overall efficiency improvement at medium-low speed and load. But the effects taper off at high speed and heavy load. For a given vehicular heavy-duty diesel engine, the overall e：＇ficiency can be improved by 3.37% at 1300 r/min and 25% load using a Rankine cycle system to recover exhaust energy. The improvement becomes smaller as engine speed and load become higher.

Effects of injection timing,before and after top dead center on the propulsion and power in a diesel engine

It is well known that injection strategies including the injection timing and pressure play the most important role in determining engine performance,especially in pollutant emissions.However,the injection timing and pressure quantitatively affect the performance of diesel engine with a turbo charger are not well understood.In this paper,the fire computational fluid dynamics(CFD)code with an improved spray model has been used to simulate the spray and combustion processes of diesel with early and late injection timings and six different injection pressure(from 275 bar to 1000 bar).It has been concluded that the use of early injection provides lower soot and higher NOx emissions than the late injection.In this study,it has been tried using the change of fuel injection time at these two next steps:before top dead center(BTDC)and after top dead center(ATDC)in order to achieving optimum emission and power in a specific point.

基于GT-power和Simulink的相继增压切出过程仿真研究

相继增压的动态切换特性对发动机性能有着重要的影响。为了研究相继增压系统空气阀相对燃气阀延迟关闭时间对切出过程柴油机性能的影响,建立了基于GT-power和MATLAB/Simulink的联合仿真平台。采用GT-power软件建立了TBD234V12柴油机仿真模型,MATLAB/Simulink软件建立了调速器、相继增压控制器和增压器喘振指数监测器仿真模型。对不同的阀门响应时间和空气阀延迟时间进行了相继增压柴油机切出过程瞬态仿真计算,结果表明切出过程中适当的空气阀延迟时间可以明显改善切出过程柴油机稳定性和排放,阀门响应时间增加会使柴油机性能和排放恶化。通过仿真计算确定了最佳的阀门控制策略。

基于GT-Power的柴油机进排气系统多目标优化

针对所研究的全柴490柴油机,建立进排气系统的三维模型并进行离散化,确定所需优化的结构参数,包括进气总管长度、谐振腔容积、进气歧管长度和直径以及排气歧管长度和直径。在GT-Power中建立柴油机的数值仿真模型,并通过台架试验把各个稳态工况下的仿真数据与试验数据作对比,验证模型的有效性。以进排气系统的各个结构参数为试验因子,采用试验设计(DOE)方法,得出一系列性能参数作为试验响应,拟合2阶模型响应面,并以扭矩最大、油耗率最少为优化目标,利用遗传算法进行多目标优化。通过把原始参数与取整后的优化参数作对比,发现扭矩最大提升达2.238%,同时油耗有所降低,最多下降2.189%。