Diesel Engine System Research Articles

Adaptive feedforward control of exhaust recirculation in large diesel engines

Environmental concern has led the International Maritime Organization to restrict NOx emissions from marine diesel engines. Exhaust gas recirculation (EGR) systems have been introduced in order to comply to the new standards. Traditional fixed-gain feedback methods are not able to control the EGR system adequately in engine loading transients so alternative methods are needed. This paper presents the design, convergence proofs and experimental validation of an adaptive feedforward controller that significantly improves the performance in loading transients. First the control concept is generalized to a class of first order Hammerstein systems with sensor delay and exponentially converging bounds of the control error are proven analytically. It is then shown how to apply the method to the EGR system of a two-stroke crosshead diesel engine. The controller is validated by closed loop simulation with a mean-value engine model, on an engine test bed and on a vessel operating at sea. A significant reduction of smoke formation during loading transients is observed both visually and with an opacity sensor.

Simulation Modeling Method and Experimental Investigation on the Uniflow Scavenging System of an Opposed-Piston Folded-Cranktrain Diesel Engine

The scavenging process for opposed-piston folded-cranktrain (OPFC) diesel engines can be described by the time evolution of the in-cylinder and exhaust chamber residual gas rates. The relation curve of in-cylinder and exhaust chamber residual gas rate is called scavenging profile, which is calculated through the changes of in-cylinder and exhaust chamber gas compositions determined by computational fluid dynamics (CFD) simulation. The scavenging profile is used to calculate the scavenging process by mono-dimensional (1D) simulation. The tracer gas method (TGM) is employed to validate the accuracy of the scavenging profile. At the same time, the gas exchange performance under different intake and exhaust state parameters was examined based on the TGM. The results show that the scavenging process from 1D simulation and experiment match well, which means the scavenging model obtained by CFD simulation performs well and validation of its effectiveness by TGM is possible. The difference between intake and exhaust pressure has a significant positive effect on the gas exchange performance and trapped gas mass, but the pressure difference has little effect on the scavenging efficiency and the trapped air mass if the delivery ratio exceeds 1.4.

Mixing and combustion mechanisms within lateral swirl combustion system (LSCS) in a DI diesel engine

The fuel diffusion around the combustion chamber wall is the key to affecting the engine performance. The current enveloping combustion systems (e.g. ω combustion systems) mainly utilize the air in the radial direction of the combustion chamber along the spray track. In these systems, since the combustion chamber wall only envelops the spray without obvious guiding effect, it will cause difficulty in the fuel diffusion around the chamber wall and deteriorate the combustion. On the contrary, the LSCS, as a guiding combustion system, could effectively improve the diffusion around the chamber wall. Therefore, it is necessary to further understand the mixing and combustion mechanisms of the LSCS. In this study, the spray and combustion characteristics of the wall-impinging jet in the lateral swirl (LS) combustion chamber were investigated in a constant-volume combustion vessel through the high-speedphotography. These characteristics were compared between the ω and LS combustion systems through the image processing and the two-color method. The results show that the spray process in the ω combustion system contains free jet and wall jet, while the spray process in LS combustion system contains free jet, formation of LS, and LS & intervening wall jet after the separation of jet head from the convex edge. The LSCS forces the fuel spray to swirl along the circumference of the combustion chamber. As a result, it could strengthen the diffusing and mixing process, and avoid a large quantity of fuel burning near the wall to form a thermos constraint. The LSCS could improve the distribution of the air-fuel mixing and consequently accelerate the combustion and reduce the soot emission through the guiding effect of convex edge on the wall jet.

Diagnosing mechanical damages not detected by the OBD system of diesel engines

The paper presents the possibilities of diagnosing with the use of vibracoustic signal of mechanical damages of diesel engines, which are not detected by the OBD system. This system does not recognize such damages, but it masks them delaying information about the damage to the point where the regulatory values of controlling work of the engine will exceed the limit values. This is because the aim of the OBD system is to ensure the minimization of exhaust emissions. There were made measurements of vibroacoustic signal of the head of the car engine with fuel injection system Common Rail, where there were introduced mechanical failures typical and dangerous for the engine. It has been proved that the OBD system does not recognize these damages and the work of the engine is correct. Therefore, there is a need for an additional diagnostic system which supports the OBD system in detection of this type of damages. It seems that the use of vibroacoustic signal as an additional analyzed signal should improve the sensitivity of the on-board diagnostic system to damages of diesel engine. The author tested the sensitivity of vibroacoustic signal to damages introduced to the engine and he presented the proposition of the system based on simple measures of the vibroacoustic signal, which allows for both detecting mechanical damages and their identification.

Modeling and Validation of a Diesel Engine with Turbocharger for Hardware-in-the-Loop Applications

This paper presents a simulator model of a diesel engine with a turbocharger for hardware-in-the-loop (HIL) applications, which is used to obtain engine performance data to study the engine performance under faulty conditions, to assist engineers in diagnosis and estimation, and to assist engineers in model-based calibration (MBC). The whole diesel engine system is divided into several functional blocks: air block, injection block, cylinder block, crankshaft block, cooling block, lubrication block, and accessory block. The diesel engine model is based on physical level, semi-physical level and mathematical level concepts, and developed by Matlab/Simulink. All the model parameters are estimated using weighted least-squares optimization and the tuning process details are presented. Since the sub-model coupling may cause errors, the validation process is then given to make the model more accurate. The results show that the tuning process is important for the functional blocks and the validation process is useful for the accuracy of the whole engine model. Subsequently, this program could be used as a plant model for MBC, to develop and test engine control units (ECUs) on HIL equipment for the purpose of improving ECU performance.

Investigation of an HD Engine Thermal Storage System

This paper presents a theoretical calculation and a preliminary design of a thermal storage system (TSS) for a heavy duty diesel engine, in order to re-utilise the wasted heat from the engine when in operation and reduce the warm-up time, thus reducing the engine emissions and improve the performance. The thermal storage mainly comprises of a heat exchanger filled with phase change material. A group of candidate materials were evaluated and NaOH H2O was selected for the particular application, as its phase change temperature is suitable and latent heat is relatively high. The storage was preliminarily designed considering the size of the engine and the quantity of heat requested, and the improvement of the engine was evaluated. The theoretical calculation suggested that nearly 40% improvement in warm-up time could be achieved with the TSS.

A Monitoring System for Diesel Engine Driven Generators Based on Electric Power Output Oscillation Assessment

Diagnosis is a main concern in power systems with generators driven by internal combustion engines, especially by low- and medium-speed diesel engines. The purpose of this paper is to develop a new diagnostic method that avoids generator operation in dangerous torque imbalance conditions. Torque in internal combustion engines has a periodic oscillation due to variations in the combustion process and pressure development between cylinders. A defective combustion in one or more cylinders produces an imbalance in torque oscillation. Analyzing the harmonic order of the generator power output makes it possible to detect and identify the cylinder that is producing the imbalance. This method has been tested with satisfactory results in a 11.6-MVA/600–r/min/10-kV diesel engine driven generator.

Experimental investigation on waste heat driven activated carbon-methanol adsorption cooling system

This paper presents design and fabrication of an adsorption refrigeration system working with activated carbon-methanol and coupled to the exhaust system of a multi-cylinder turbo-charged diesel engine. We have also carried out experiments to study the cycle time, refrigeration effect and COP of the cycle. This paper is reported of the original experimental data obtained from experimentation of a real adsorption refrigeration setup. We have studied and reported the effects of minimum bed temperature (T 1) and maximum bed temperature (T 3), the two most important parameters influencing the performance of an adsorption refrigeration system. From experimental result it is observed that the maximum temperature (T 3) of the cycle should be kept as high as possible to generate higher volume of methanol from the activated carbon and, hence, higher refrigeration effect and COP. Since, the temperature of hot water circulated through the desorption bed has been restricted to 90 °C, it takes long time duration to achieve T 3 above 80 °C and hence, during the experiment, the maximum temperature of the bed (T 3) has been limited to 80 °C. It is also observed that the minimum temperature of the bed (i.e., the temperature of the bed after end of adsorption) (T 1) should be kept as low as possible to optimize COP of the cycle. The experimental results show that, for T 1 of 30 °C and T 3 of 80 °C, the maximum refrigeration effect is 1519.41 kJ per cycle for the given configuration of the refrigeration system and the cycle COP is 0.21. Uncertainty analysis predicts that variation of experimental COP varies between ±6.59%. This paper also presents different practical problems that faced by the authors during fabrication of the setup, for the benefit of the future researchers. The study also aims to comment on the capability of meeting the air-conditioning requirement of a vehicle by the waste heat associated with exhaust gases only, without requiring any extra power from the engine, thereby reducing fuel consumption and environment pollution.

Discrete sliding mode variable structure control over the rotating speed of marine diesel engines

This article presents a discrete sliding mode variable structure control used for the speed governing system of marine diesel engines. It is widely accepted that the steady operation of marine diesel engines plays an important role in ensuring the power quality of marine electronic system and good engine performance. In other words, it means that a speed governor with excellent performance is crucial to ensuring the steady rotating speed of a diesel engine. However, due to the fact that diesel engine normally has a complex structure and is often influenced by multiple and nonlinear factors, a traditional proportional integral differential controller cannot optimize the sailing parameters of ships, making it difficult to satisfy the requirements of the speed control for diesel engines under various operation conditions. In view of this problem, this article developed a nonlinear mathematical model of the speed governing system for diesel engines based on experimental tests. Moreover, a discrete sliding mode controller was designed by applying the discrete sliding mode variable structure control, and a simulation model was then developed under the Simulink environment, illustrating that the performance of the designed sliding mode controller is much better than a traditional proportional integral differential controller. Finally, a bench test used for the nonlinear speed governing system based on the discrete sliding mode variable structure control approach was carried out using the bench of a diesel engine Model 2135. The experimental results further illustrated that the discrete sliding mode variable structure controller showed some super advantages, such as smaller overshoot and error, faster response and stronger anti-jamming capability, when comparing with the traditional proportional integral differential controller.

Fluid Flow Analysis of Jacket Cooling System for Marine Diesel Engine 93 Kw

The main function of cooling system is to control the temperature in the engine. To know the flow in the jacket cooling system for marine diesel engine 93 KW and the couple simulation between 1D modeling and 3D modeling, the methodology used. The analysis process was performed by using 3 diffrent softwares. The methodology to analysis fluid flow is CFD (computational fluid dynamic) with steps were problem identification, literature study, design the jacket cooling system based on the cummin diesel engine 93 KW, 1D modeling of cooling system, 3D modeling fluid flow in jacket cooling system, and conclusion. The input of 3D jacket cooling simulation are mass flow, fluid temperature, wall temperature, and heat transfer. The result from this bachelor thesis is fluid flow in jacket cooling system and another parameter output such as temperature flow and velocity if fluid in the jacket cooling system. The result of the flow in jacket cooling is much turbulance in various are of jacket cooling its mean the jacket cooling have a good enfficiency of heat transfer, and the fluid temperature show the increasing temperature from inlet to outlet because of heat transfer happen in the jacket cooling between wall of jacket cooling and fluid. The engine speed will affect the cooling system, if the engine speed is increasing, the speed of flow will increase because the cylinder block need more coolant and the temperature of cylinder block will increase

Diesel engine torsional vibration control coupling with speed control system

The coupling problems between shafting torsional vibration and speed control system of diesel engine are very common. Neglecting the coupling problems sometimes lead to serious oscillation and vibration during the operation of engines. For example, during the propulsion shafting operation of a diesel engine, the oscillation of engine speed and the severe vibration of gear box occur which cause the engine is unable to operate. To find the cause of the malfunctions, a simulation model coupling the speed control system with the torsional vibration of deformable shafting is proposed and investigated. In the coupling model, the shafting is simplified to be a deformable one which consists of several inertias and shaft sections and with characteristics of torsional vibration. The results of instantaneous rotation speed from this proposed model agree with the test results very well and are successful in reflecting the real oscillation state of the engine operation. Furthermore, using the proposed model, the speed control parameters can be tuned up to predict the diesel engine a stable and safe running. The results from the tests on the diesel engine with a set of tuned control parameters are consistent with the simulation results very well.

Structural-parametrical synthesis of electronic control unit of fuel feeding system of vehicle diesel engine

We draw a conclusion that in the fuel feed system of the transport diesel engine, it is expedient to use a two-channel electronic control unit. The selection of appropriate channel of the electronic control unit is done by the driver depending on road conditions. This scheme of electronic unit makes it possible to minimize both dynamic errors, which appear during motion of vehicle in the rough terrain, when there is a significant change in load within a short time interval, and the static errors, which appear when moving along the routes with high-quality road surface, but with lengthy ascends and descents. The proposed fuel feed system is in a certain sense universal. The channel, providing high dynamic accuracy of fuel feed control, contains ae sensor of angular velocity of crankshaft rotation of the diesel engine, and the sensors of position of fuel pump lath and the pedal of fuel feed control, the outputs of which are connected to inputs of the electronic unit, which implements a linear combination of the input signals of sensors. The channel that provides for invariance of the fuel feed system to the action of external disturbances realizes a control algorithm, which uses, in addition to the output signals of the above-indicated sensors, information about the displacement velocity of the fuel pump lath of the diesel engine. High accuracy and interference protection of the closed fuel feed system may be achieved by using a digital electronic control unit with the implementation of digital Butterworth and Lanczos low-frequency filters.

Model of exhaust system of a traction diesel engine with pulse supercharging on transient modes

A mathematical model of joint operation of a piston engine with pulse turbine drive, compressor as well as air supply of a diesel locomotive is presented in the article. This model in an integral part of the complex engine-generator power unit of a diesel locomotive in steady states and transient conditions, developed by the authors. The periodic process in the exhaust manifold is represented as two specific characteristic ranges which encompass the process of forced exhaust and the scavenging process. The scavenging calculation is carried out jointly with the processes taking place in the inlet manifold of the engine, including inlet devices of the locomotive. The process of forced exhaust is calculated separately from the inlet processes and doesn`t require usage of empirical coefficients of impulsiveness. Both processes are represented as systems of nonlinear algebraic equations describe in the quasi-steady flow of working fluid in the elements of the inlet and exhaust tracts. The gas-dynamic calculation of the turbine in the transition process is conducted while taking into account changes in flow angles on the rotor blades. As a result of numerical calculation of the a8S22W diesel operational indices in transient modes, a satisfactory compliance of the calculated and the experimental results was obtained.

Reliability Analysis of Transit Fuel System in Diesel Engine

Reliability Analysis of Transit Fuel System in Diesel Engine

Evaluation of the biodiesel fuels lubricity using vibration signals and multiresolution analysis

The vibration is an important feature associated with metallic contact during operation of the injection system of diesel engines, also its analysis constitutes a tool to evaluate the lubricity indirectly. In this sense, this work uses multiresolution analysis to characterize vibration signals, improving lubricity evaluation. The experimental setup consisted of the lubricity analysis of different fuels using HFRR equipment where friction coefficient was monitored during the test as well as vibration signals. After that, Discrete Wavelet Transform generated time-scale representation of the vibration signals. This analysis provides complementary information about lubrication, in real time, and it can be associated with wear scar diameter (WSD). The results demonstrated the feasibility of this approach to evaluate fuels lubricity in a dynamic way.

Overall efficiency optimization of controllable mechanical turbo-compounding system for heavy duty diesel engines

A controllable mechanical turbo-compounding (CMTC) system including continuously variable transmission (CVT) and power turbine bypass valve is proposed to recover waste heat from engine exhaust. The combined matching principle considering swallowing capacity of both charging turbine and power turbine, main gear ratio is investigated at first based on the analysis of individual influence. Then the effects and strategies of CVT and power turbine bypass valve are studied for better performance under off-design conditions. At last, the transient response of intake pressure of engine with CMTC system is researched and the fuel saving potential is tested under driving cycle conditions. The results indicate that the overall fuel efficiency elevates at the off-design conditions if CVT is adopted due to the improvement of power turbine operating efficiency by speed modulation. The diversion of exhaust through power turbine bypass valve under the low load condition is necessary. The back pressure of the charging turbine infuences the transient response of intake pressure for a fixed CMTC configuration. A method featured by the assistance of power turbine bypass valve is tested to improve the transient response of the intake pressure. The fuel consumption reduces by 2% and 3.4% under highway fuel economy test (HWFET) and Tianjin 503 (TJ503) driving cycles respectively.

Volkswagen e a variação do valor de suas ações: o impacto da galezia de seus motores à diesel

As empresas que possuem ações negociáveis em bolsa de valores e que como a Volkswagen se posicionam em algum nível diferenciado de governança, sendo inclusive que afirma em seu Anuário de Responsabilidade Corporativa que adotam estratégias com base nos preceitos GRC – Governança, Risco, Conformidade, não deveriam praticar ações conflituosas com esta abordagem. No entanto, pode-se apontar, ao menos um caso em que a Volkswagen executou ações inadequadas que feriram os princípio das boas práticas de governança. O presente estudo tem, então, como objetivo identificar a influência da prática inadequada de governança no desempenho das ações da Volkswagen na bolsa alemã. A citada pratica executada pela Volkswagen envolveu a alteração de software de emissão de poluentes dos motores de pequeno porte a Diesel quando submetidos a teste, o que veio a ser conceituado pelo mercado como galezia (ou fraude) do sistema de avaliação de emissão de poluentes dos motores à Diesel da marca. A análise dos valores das ações diante das notícias divulgadas, confirma a literatura sobre o tema, já que constata-se uma acentuada redução no preço das mesmas.

Modernization of the fuel system of diesel engine of agricultural tractor

The decrease in fuel systems reliability depends mostly on the fuel contamination. To solve the problem, an improved scheme of fuel system is proposed, it includes a fuel preheater and a rough filter of new design. A new design of rough filter is developed, it has a coiled filter element with the improved purification efficiency and good replacement life due to the effective spreading of porosity of filter material by means of its aimed crimping. This allows to reduce evenly the porosity in the direction of fuel stream and to increase the replacement life. The operational tests of improved fuel systems were performed on the basis of agricultural enterprises of the Tomsk region. The MTZ-82 agricultural tractor was chosen as subject of research. The working capacity of fuel system elements in regular and improved versions was evaluated by determining the numeral characteristics of random distribution of mean lifetime and parameters of reliability. Based on test results, the functions of distribution of probability of failure-free operation of the fuel injection pump plungers, the couple of injection jets, the injector spray nozzles of regular and improved diesel fuel systems are constructed. The study reveals that the improved version of fuel system decreases the failure rate of parts by 1.7-2.2 times in comparison with the regular one. It proves that the reliability is improved by means of reducing of contamination through the heated rough filter. The obtained results show the substantial improvement of fuel system reliability with the use of new rough filter.

The combustion and emission characteristics of a multi-swirl combustion system in a DI diesel engine

In this study, the authors developed a new multi-swirl combustion system (MSCS) and investigated its combustion and emission characteristics. The MSCS combines the structural features of a double swirl combustion system (DSCS) and a lateral swirl combustion system (LSCS) and utilizes the arc structure of the MSCS to lead fuel to (1) form multi-swirls in both a longitudinal and lateral direction, (2) accelerate the fuel/air mixture and (3) improve the combustion process in a diesel engine. An experimental study and simulation analysis was used to verify the MSCS combustion and emission characteristics. In the experimental study, tests at various speeds were conducted using a single-cylinder diesel engine. The experimental results, including the brake specific fuel consumption (BSFC), soot emission, NOx emission and in-cylinder pressure were recorded and compared with results from a DSCS that was operated under the same condition. In the simulation, the fuel spray process was studied using AVL-Fire. The fuel velocity profile and the fuel/air equivalent ratio distribution were studied to verify the formation of multi-swirling fuel in the combustion chamber. The experimental results show that the BSFC of the MSCS was lower by 4–5g/(kWh), and the soot emission was lower by about 60% in comparison to the results from the DSCS. The simulation results show that the fuel formed two longitudinal swirls in opposite directions after touching the circular ridge, and the fuel in the outer chamber formed two swirls in lateral space after touching the convex edge. This multi-swirl enlarged the diffusion space of the fuel in both the inner and outer combustion chamber and accelerated the formation of the fuel/air mixture, which led to a decrease in soot emission and fuel consumption from the MSCS.

Reliability analysis of multi-state repairable system with dynamic transition probabilities

Inadequate maintenance decisions lead to incremental overall costs. In order to minimize costs in maintenance of the multi-state repairable system, we model a preventive maintenance (PM) scheme of the multistate repairable system using non-Markov process. The periodically decreasing reliability model of the non-Markov dynamic system with dynamic transition probabilities is established to satisfy the probability change. The diesel engine system is taken as an example to illustrate the model. The reliability of the diesel engine is analyzed and its PM scheme is worked out. RENO software is used to simulate the diesel engine system. The maintenance cost of components and the optimal PM interval data of the system are obtained by using the minimal average cost as the objective function. The adaptability of PM is judged, and the optimal PM scheme is presented.