Diesel Engine System Research Articles

Route-dependent optimal control of the after-treatment system of diesel engines

In this article, the optimal control problem for nitrogen oxide emission reduction is investigated for diesel engines with a lean nitrogen oxide trap. First, a control-oriented model is developed based on conservation laws. Then, the optimal control problem is formulated as a multistage decision problem and solved using a dynamic programming algorithm under dynamical model constraints. A trade-off between fuel economy and nitrogen oxide emission is considered in the cost function of optimization. To demonstrate the obtained optimal control scheme, the parameters of the lean nitrogen oxide trap model are identified with data obtained from a GT-power-based diesel engine simulator. The numerical simulation results for two standard driving cycles and a stochastically generated driving cycle in comparison to a conventional logic-based control scheme are provided using the identified model in the MATLAB/Simulink platform.

Results of simulation and experimental research of automobile gas diesel engine

The paper is dedicated to conversion of a truck diesel engine into a gas diesel engine. Different ways of diesel engine conversion for operation on natural gas were analyzed. The gas diesel working process with minimized portion of igniting diesel fuel supplied by the Common Rail system was selected as the most suitable for such an engine. Modular gas feed and electronic engine control systems were developed in MADI which may be mounted on high- and medium-speed gas diesel engines. The fuel supply system of the base diesel engine was preserved though a new algorithm of fuel injection for the gas diesel engine was developed. The systems were perfected using simulation by computer model developed in MADI and during engine tests. The gas diesel engine demonstrated good fuel efficiency and considerable decrease of NOx and CO2 emissions, though its power at low speed decreased compared to the base diesel engine. The ways to improve this drawback during the future work were proposed.

Waiting for Breakthrough in Conventional Submarine’s Prime Movers

Submarines, as a very expensive and sophisticated type of weaponry, are being intensively exploited by the armed forces of many countries. This means that submarines are sent ever longer patrols, sometimes to distant regions. To meet such requirements, submarine sub-systems and components must have high reliability and operational readiness indicators. Among the many machines and devices found on submarines, the ones that generate, store, and consume energy (mainly electricity) deserve special attention. The largest energy consumers on the submarine are the components of its propulsion system. One of the most complicated and loaded devices on board submarine is a power generator with a diesel engine driving it, on whose continuous and reliable work the safe performance of tasks depends. According to statistical research, despite its importance for the process of performing tasks by submarines, diesel engines are still the least reliable devices on submarines. Despite the constant technological development of piston engines, their work in very difficult conditions under heavy load and at high counter-pressure at the exhaust outlet promotes their malfunction and damage. From this point of view, the development of charge air systems for submarine diesel engines based on the construction experience of MTU Company is described in the paper. The classification of submarines, their propulsion systems, and the working conditions of engines on submarines are presented in the paper. Air-Independent Propulsion (AIP) systems with their applications on chosen submarines are also described. The most significant change in submarine propulsion system observed in 2018, transition from lead-acid to lithium-ion batteries, is also presented.

Automotive Waste Heat Recovery after Engine Shutoff in Parking Lots

<div class="section abstract"><span class="label">1</span><div class="htmlview paragraph">The efficiency of internal combustion engines remains a research challenge given the mechanical friction and thermodynamic losses. Although incremental engine design changes continue to emerge, the harvesting of waste heat represents an immediate opportunity to address improved energy utilization. An external mobile thermal recovery system for gasoline and diesel engines is proposed for use in parking lots based on phase change material cartridges. Heat is extracted via a retrofitted conduction plate beneath the engine block after engine shutoff. An autonomous robot attaches the cartridge to the plate and transfers the heat from the block to the Phase Change Material (PCM) and returns later to retrieve the packet. These reusable cartridges are then driven to a Heat Extraction and Recycling Tower (HEART) facility where a heat exchanger harvests the thermal energy stored in the cartridges. A series of mathematical models are created to estimate the recoverable heat from a standard parking lot configuration. A representative case study that considered 500 cars with periodic traffic flow over a period of 16 hours can heat approximately 25 kiloliters of potable water from 15°C to 50°C. Future development will involve the creation of strategies to extract heat during engine idling at traffic stops and drive through lanes.</div></div>

An electrochemical model of an amperometric NOx sensor

To help design future amperometric NOx sensors, a physics-based sensor model that includes diffusion and electrochemical submodels is developed. It is shown that NO is partly reduced in the O2 sensing chamber which affects NO concentration in the O2 sensing and in the NOx sensing chamber. Therefore, the electrochemical model is developed to simulate partial reduction of NOx on the O2 sensing electrode and reduction of NOx on the NOx sensing electrode. A transport model that simulates diffusion of the gas species through the sensor diffusion barriers and sensor chambers is coupled to the electrochemical submodels. A fully controlled sensor test-rig that provides controlled gas mixtures is employed to carry out experiments to estimate model parameters. Then, the sensor is installed on the exhaust system of a medium duty Diesel engine and then on a port injection spark ignition engine. Experiments at different engine operating conditions with different NOx concentrations from 0 to 2820 ppm have been performed to validate the model accuracy at different operating conditions. Through the validation process, the NOx sensing cell voltage is changed experimentally at different NOx concentrations to evaluate the model accuracy at different cell voltages. The model results closely match the experiments with the maximum 12% error for the NOx sensing pumping current.

A Convergence Study on the Effects of NH 3 /NOx Ratio and Catalyst Type on the NOx Reduction by Urea-SCR System of Diesel Engine

Diesel engines have important advantages over its gasoline counterpart including high thermal efficiency, high fuel economy and low emissions of CO, HC and CO2. However, NOx reducing is more difficult on diesel engines because of the high O2 concentration in the exhaust, marking general three way catalytic converter ineffective. Two method available technologies for continuous NOx reduction onboard diesel engines are Urea-SCR and LNT. The implementation of the Urea-SCR systems in design engines have made it possible for 2.5l and over engines to meet the tightened NOx emission standard of Euro-6. In this study, we investigate the characteristics of NOx reduction with respect to engine speed, load, types of catalyst and the NH3/NOx ratio and present the conditions which maximize NOx reduction. Also we provide detailed experimental data on Urea-SCR which can be used for the preparation for standards beyond Euro-6.

Formation and Study of Static and Dynamic Characteristics of Electronically Controlled Diesel Engine

Abstract Manufacturing companies of electronic control systems of diesel engines protect access to a program operation algorithm of the regulator that makes impossible adjustments and settings of its work, for example, at re-equipment or operational development of a new diesel engine. Therefore, it is important to acknowledge the solution of the scientific and technical problem of an effective and reliable system creation of electronic control of diesel fuel supply with an open program algorithm of its work. During the current research, settlement and experimental studies of a diesel engine supplied with a system of electronic control of a crankshaft rotation frequency developed by the authors show rather high adequacy in results. The dynamic mathematical model of the single-cylinder diesel engine supplied with the electronic regulator of rotation frequency has been developed and verified.

Model-based multi-critical optimisation of combustion engine fuel consumption and emissions

The combustion engine is a typical nonlinear multi-input multi-output (MIMO) system with strong couplings, actuator constraints, and fast dynamics. This paper addresses a model-based multi-critical optimisation approach in diesel engines, which allows to improve emission performance and to provide a reference for the design and optimisation of the diesel engine system. The first part of this paper introduces a data-based modelling method that appears particularly suitable for emission modelling. The Design of Experiments (DoE) method helps to generate and collect the required measurement for data-based modelling in a short time, despite the increasing number of manipulated variables. The second part establishes a new model-based multi-critical optimisation approach that supports the optimisation of fuel consumption and emissions based on engine models. This proposed model-based framework consists of system identification and multi-critical optimisation. This framework has the ability to achieve the fast and precise solving of multi-critical optimisation problem and is suitable for implementation in the engine control unit. The experiment results illustrate that the model-based multi-critical optimisation significantly improves the engine exhaust emissions and fuel consumption against the original ECU.

Analysis of diesel engine isolation system with piston slap

An isolation system of diesel engine with cylinder gap was modeled to deeply study the effect of piston shock on the whole vibration system. With the diesel engine rotates at rated speed, the center of engine body mass moves in plane with an obvious ellipse, and the magnitude is enlarged high to 3.5 times of the origin. All the bottom three directional springs have the corresponding response with the fundamental frequency signal, and a characteristic frequency band, as the piston slap is considered.

Frictional behaviors in piston ring-cylinder liner system of diesel engine with solid particles considered

The abnormal wear of diesel engine cylinder often occurs due to the solid particles introduced along with the gas intake, as well as the product of fuel combustion. The main purpose of this research is to develop an unsteady-state liquid–solid model to predict the dynamic and lubrication behaviors of the piston ring-cylinder liner with the consideration of the surface roughness, operating load, material properties, and solid particles. Based on the Reynolds boundary condition, the unsteady-state liquid–solid lubrication model is solved with finite difference method. The accuracy of such model is verified upon the comparison with experimental results from a reciprocating friction test workbench at different working frequencies. The test uses actual piston ring specimens sliding on segments of cylinder liner to simplify the engine operation. Finally, the model is applied for a four-stroke diesel engine to reveal the effects of particle properties. It has found that particle diameter, concentration and yield strength have some significant influences on piston ring-cylinder liner system tribological property.

Simultaneous optimization of urea dosing and ammonia coverage ratio of selective catalytic reduction system in diesel engine by using physico-chemical model based NSGA-II algorithm

The selective catalytic reduction (SCR) technology shall achieve a high NOx conversion efficiency but a limited reductant slip to satisfy the increasingly stringent Euro VI regulations. The physico-chemical model based non-dominated sorting genetic algorithm (NSGA-II) was applied here to gain the desired urea dosage feed ratio and achieve the optimal trade-off between NOx reduction and NH3 slip so that some benefits such as fuel and urea efficiency gains may be materialized; moreover, the dependence of the optimized solution on dynamic model was illustrated based on a sensitivity study and a reduced order one-state model was utilized to capture essential behaviors of the system under low computational burdens. Two different steady operating conditions were selected to validate optimal results from the model based NSGA-II method and conclude that they shall be in good agreement with acceptable errors. The optimization results were demonstrated by means of several typical cases where effects of the temperature and the space velocity on ammonia coverage ratio and NOx conversion efficiency were analyzed. In addition, the full load optimal maps for the engine were obtained based on our method to provide a reference or benchmark on the control system.

A Study on Reasonable Ratios of Vegetable Oils and Diesel Oil in Mixed Fuel Used as an Alternative Fuel for Marine Diesel Engines in Vietnam

Vegetable oil is used directly as a fuel, in either modified or unmodified equipment, it is referred to as straight vegetable oil (SVO). SVOs have some advantages in comparison with fossil fuel oils such as: renewability, local availability, lower sulfur content, etc. avoiding the environmental effects caused by sulfuric acid, lower aromatic content and high biodegradability. However, SVOs are also attached to several disadvantages such as: high viscosity, low heating value, high fatty contents, influencing on injection process and causing engine coking if misused. In order to prevent such negative effects of diesel engine fuelled by SVO, one of potential solutions is using blends of SVO with diesel oil (DO). In such case, the reasonable ratio of SVO and diesel oil plays a very important role for normal running condition, but also seems to be challenge to identify. The article shows results of a study on defining the ratio for marine diesel application. It is firstly based on the assessment on the heat release processes inside the diesel engine cylinder upon a specific simulation with different blends of SVO and diesel oil. In comparison with the particular requirements for fuel of marine engines, the preferable percentage of vegetable oil in the fuel mixture is pointed out. And finally, the experiments with fuel system of a typical marine diesel engine, HANSHIN 6LU32, installed at the lab of Vietnam Maritime University in terms of checking real engine’s operation and reducing harmful emissions.

Ammonia Distribution Measurement on a Hot Gas Test Bench Applying Tomographical Optical Methods.

Measuring the distribution of gas concentration is a very common problem in a variety of technological fields. Depending on the detectability of the gas, as well as the technological progress of the sector, different methods are used. In this paper, we present a device and methods to detect the ammonia concentration distribution in the exhaust system of diesel engines in order to increase the performance of the exhaust aftertreatment system. The device has been designed for usage on a hot gas test bench simulating exhaust gas conditions. It consists of multiple optical beams measuring ammonia line concentrations by applying nondispersive absorption spectroscopy in the deep ultraviolet region. The detectors consist of photodiodes allowing high sampling rates up to 3 kHz while providing a high signal-to-noise ratio. A detection limit of only 1 ppm has been achieved despite the short path length of only eight centimeters. The obtained line concentrations form an inverse problem. The methodology of the tomographic techniques is described in detail in order to best solve the inverse problem and obtain the ammonia concentration distribution images for each time step.

Life cycle and economic assessment of a solar panel array applied to a short route ferry

This paper was to investigate the potential benefits of solar panel systems if applied for obtaining propulsion power of a short route ferry operating in the Marmara Sea. The life cycle assessment was applied to evaluate the long-term environmental impact of the solar power systems on-board in replace of conventional diesel engine systems. The cost and benefit of such systems were evaluated through the economic assessment where the life cycle cost relative to installation, operation and recycling of the solar panels, fuel savings and payback time were considered. Research findings revealed the payback time would be around three years, whereas the accumulative fuel cost saving would be over $300,000 by the end of vessel life. The sensitivity analysis using two varying parameters - energy efficiency and investment cost - implied, that the longer payback time would be positively associated with lower energy efficiencies and higher investment costs. It was also suggested that the marginal cost of the carbon credit should be $ 190 per tonne or higher to make the shipping business successful.

Optimisation of torsional vibration system for a heavy-duty inline six-cylinder diesel engine

Torsional vibration is one of the major issues and very important calculation for the safe running of heavy-duty diesel engines, specifically crankshaft. Because of different applications of a heavy-duty diesel engine, different driven machine and different attaching systems are inevitable that affect the torsional system. The cranktrain contains the flywheel and torsional damper. The properties of these parts have significant effect on torsional vibration of the system as well as the crankshaft strength. Initial selection of these properties is usually specified based on engine designer experience and also the torsional vibration calculation of the cranktrain. In this paper, the focus is to find the optimum and reliable operating points for the elements in cranktrain using computer-aided engineering (CAE) tools. These are parameters like tuned mass inertia, flywheel inertia, damper stiffness, damper inertia, damper damping, coupling damping and coupling stiffness. The effect of these parameters on system design criteria, especially crankshaft life, was investigated. The results show high sensitivity of crankshaft safety factor to parameters like tuned mass inertia, damper damping coefficient and damper stiffness. Therefore, damper selection is the most important factor to increase the crankshaft life. The new contribution is that the parameters related to the whole cranktrain system that have the greatest effect were obtained and an optimisation was executed on these parameters to fulfil the vibration targets as well crankshaft life.

O-Rings Material Deterioration due to Contact with Biodiesel Blends in a Dynamic Fuel Flow

O-rings are a primary component made from polymeric materials in most diesel engine systems. For oil-fuelled operations, O-rings tend to degrade after exposure to fuel in certain operating condition and periods. Degradation of O-rings can cause engine leakage. This study is intended to test the O-rings material which contacted with biodiesel in dynamic flow by considering the potential deterioration caused. The use of biodiesel may contribute to accelerating deterioration of O-rings. The boiler fuel system was duplicated in this test, where the biodiesel used was palm oil based. The O-rings tested are made of materials of Fluorocarbon elastomer (FKM), Nitrile Rubber (NR) and Silicone Rubber (SR). The effects on O-rings were observed on changes in mass, volume, and thickness. The material compatibility is indicated by elongation, swelling and chemical resistance of elastomers with various fuel flow rates. The fuel flow with high volumetric rate tends to damage the O-rings faster as effected on the immersion test. FKM-Viton performed as materials with the best physical and chemical resistance. Dynamic fuel flow in the engine system showed that SR is deteriorated faster than NBR and FKM. The resistance of O-ring material to fuel in the system is not linearly influenced by the amount of biodiesel in the fuel.

Research status and development trend of available exhaust energy management for diesel engine at different altitudes

In order to improve the boosting pressure, intake flow rate and matching characteristics of a diesel engine and turbocharging system at varying altitudes, it is very important to utilize and manage available exhaust flow energy. The advanced air management system can effectively utilize exhaust flow energy and improve the intake pressure of the diesel engine at high altitudes. In this paper, the key thermodynamic parameters of air management systems, management of exhaust flow energy and control of air path at different altitudes are reviewed. At last, two aspects containing control strategy, control algorithm of the air management system were put forward.

System Modelling of Organic Rankine Cycle for Waste Energy Recovery System in Marine Applications

Recent regulatory developments in the maritime industry will hasten the shift in usage of conventional marine fuels like HFO and MDO to a cleaner fuel like Liquefied Natural Gas (LNG) to meet its ambitious target of lowering carbon dioxide and other noxious gases emissions. Efficient use of energy and waste heat recovery and onboard a ship will help the industry meet this target in the meantime. This paper presents the findings from the modelling of a dual fuel marine diesel engine and ORC system cooled by vaporising LNG and simulation using a system engineering software, Siemens Simcenter Amesim 16. Engine manufacturer’s design data is used as inputs to run the ORC systems running on two working fluids, n-heptane and n-octane to derive the net work and thermal efficiency when installed on a LNG-fuelled Platform Supply Vessel. The ORC system running on n-heptane is found to provide an annual fuel savings of 7% with an estimated payback period of 2.7 years, making it an attractive option for shipowners.

Experimental investigation on a 3000 bar fuel injection system for a SCR-free non-road diesel engine

The upcoming Stage V emissions regulation for Non-Road Heavy Duty Diesel Engines will force OEMs to adopt Diesel Particulate Filters, adding a further degree of complexity to the aftertreatment system, which in several cases already includes specific devices for NOx reduction. Since complex aftertreatment systems can rise packaging problems as well as reliability issues, the authors evaluated the performance of a Stage V compliant engine layout which can avoid dedicated aftertreatment devices for NOx. This engine features a low pressure exhaust gas recirculation system, a two-stage turbocharger and a 3000 bar injection pressure-capable fuel injection system. This paper focus on the experimental assessment of the performance of the fuel injection system, demonstrating how increasing the rail pressure from 2000 to 3000 bar can dramatically improve the NOx-Soot and NOx-Particulate Number trade-off, together with the engine efficiency, without adversely affecting the emission of nanoparticles. In particular, extremely high injection pressures in conjunction with the use of after injection as a soot reduction technique, was found to be capable of achieving a 50% smoke reduction with a more than acceptable engine efficiency degradation.

A BRIEF REVIEW OF TECHNOLOGY SOLUTIONS ON FUEL INJECTION SYSTEM OF DIESEL ENGINE TO INCREASE THE POWER AND REDUCE ENVIRONMENTAL POLLUTION

The regulations on emissions of internal combustion engines are becoming more stringent, while fossil fuel sources are at risk of depleting after 100 years. That motivates researchers and engine manufacturers to constantly improve new technologies on the engine to reduce emissions that pollute the environment and increase the number of engines using fuel. Replace from environmentally friendly sources. Improvements and application of modern technologies have a profound impact on engines, increasing capacity, efficiency and environmental friendliness but also making it more complex and difficult to access. The fact shows that the fuel system has a direct impact on the engine's working processes, determining the engine's output power and exhaust gas quality. Therefore, the application of new technology solutions on fuel supply system for diesel engines will create breakthroughs to affirm the great role and competitiveness of modern diesel engines. This paper evaluates structural improvements in the fuel system to increase engine capacity and reduce environmental pollution.