Exhaust Line Research Articles

Ash Characteristic in the Exhaust Line of a Diesel Engine

Ash Characteristic in the Exhaust Line of a Diesel Engine

Development of an exhaust air turbine engine

The article discusses ways of utilizing exhaust gas heat to improve the power efficiency of heat engines. The concept of an air turbine engine is chosen to make a generator drive with the capacity of 150 kW intended to produce energy for a gas-pumping unit. In an air turbine engine atmospheric air heated by the exhaust gases of the gas turbine drive of a gas pumping unit serves as the working fluid. Three thermodynamic cycle schematics for an air turbine engine (ATE) are analyzed. The optimal design of an ATE comprising a two-stage axial compressor, a recuperative air heater (RAH), an ejector and a single-stage axial turbine is determined on the basis of thermodynamic calculations. Compressed air from the ATE compressor unit is used in the ejector as the active flow, while the combustion products of the NK-16ST engine are used as the passive flow. The recuperative air heater and ejector are located in the exhaust line of the gas pumping unit. The chosen design concept of the air turbine engine corresponds to the technical requirements of gas transmission enterprises.

The Wetting Behavior of Fresh and Aged Soot Studied through Contact Angle Measurements

In this work, contact angle measurements for soot samples collected from a kerosene lantern, wood-burning fireplace, and municipal bus engine exhaust lines are reported. Contact angles for both freshly collected soot and samples treated with various doses of O3 (g), HNO3 (g), and H2SO4 (g) are considered. Use of a literature method has allowed estimation of the enthalpy of immersion (Himm) for the soot samples based on contact angle observed. Contact angles for freshly collected soot were 65 - 110 deg. indicating its hydrophobic nature. Chemical processing of soot usually resulted in smaller contact angles and large increases in immersion enthalpy. However, the dose of ozone, nitric or sulfuric acid vapor required to achieve alteration of the soot surface appeared to be considerably larger than that expected to be experienced by authentic atmospheric samples during the soot particles lifetime. The most significant variability of soot contact angle was observed for the municipal bus exhaust samples, suggesting that combustion chemistry may significantly affect wetting behavior.

Analysis of the backpressure effect of an Organic Rankine Cycle (ORC) evaporator on the exhaust line of a turbocharged heavy duty diesel power generator for marine applications

In marine and power generation sectors, waste heat recovery technologies are attracting growing attention in order to increase heavy duty diesel engines efficiency and decrease fuel consumption, with the purpose of respecting stringent emissions legislations.In this work, the backpressure effect of an Organic Rankine Cycle (ORC) evaporator on the exhaust line of a turbocharged, V12 heavy duty diesel engine, for typical marine and power generation applications has been investigated using the commercial software Ricardo WAVE. Three different state-of-the art turbocharging strategies are assessed in order to counterbalance the increased pumping losses of the engine due to the boiler installation: fixed turbine, Waste-Gate (WG) and Variable Geometry Turbine (VGT). At the same time, the steady-state thermodynamic performance of two different ORC configurations, simple tail-pipe evaporator and recuperated simple tail-pipe evaporator layouts, are assessed, with the scope of further increasing the engine power output, recovering unutilized exhaust gas heat. Several different working fluids, suitable for medium-high temperature waste heat recovery, are evaluated and screened, considering, as well, health and safety issues. Thermodynamic cycle parameters such as, for example, evaporation and condensing pressures, working fluid mass flow and cycle temperatures, are optimized in order to obtain the maximum improvement in Brake Specific Fuel Consumption (bsfc).From the engine side point of view, a VGT turbocharger is the most favorable solution to withstand increased backpressure, while, regarding the ORC side, between the considered fluids and layouts, acetone and a recuperated cycle show the most promising performance.

Modeling of a DOC SCR-F SCR Exhaust Line for Design Optimization Taking Into Account Performance Degradation Due to Hydrothermal Aging

Modeling of a DOC SCR-F SCR Exhaust Line for Design Optimization Taking Into Account Performance Degradation Due to Hydrothermal Aging

Robustness of the extended delayed-X harmonics synthesizer algorithm applied to engine exhaust noise control

Exhaust noise of a combustion engine contains several harmonic components of the fundamental frequency that depends on the engine speed. Active noise cancellation (ANC) in the exhaust line of a diesel-electric drive faces serious challenges such as high temperature, high sound pressure levels, standing waves phenomena, a time-varying environment, and slightly varying disturbance frequencies. In the case of a non-acoustic reference sensor, also an offset or a mismatch in the estimation of the disturbance frequencies negatively affects the performance. The extended delayed-X harmonics synthesizer (DXHS) is known from several researches to be appropriate for control of periodic noise with multiple harmonic components. The algorithm is robust against observation noise and fluctuation of the plant under control. In this paper, the extended DXHS is implemented in an ANC-system for a diesel-electric drive and experimentally investigated in laboratory experiments. A modified update rule, a convergence factor regu...

Fast estimation of diesel oxidation catalysts inlet gas temperature

With the tightening of on-board diagnostics requirements, accuracy of sensors is essential to monitor the efficiency and ensure a proper control of the after-treatment systems. Temperature sensors are commonly used in the exhaust line at the diesel oxidation catalyst-inlet of turbocharged diesel engines for control and diagnosis of the after-treatment system. In particular, negative temperature constant sensors are used for this purpose. However, due to the necessary robustness that on-board sensors must fulfil, thermal inertia causes significant differences during engine transient operating conditions in temperature measurements. A Kalman filter is proposed in this paper for the on-line dynamic estimation of the catalyst-inlet temperature, which combines a slow but accurate measurement of the on-board temperature sensor with a fast but drifted temperature model. A fast research-grade thermocouple is used as reference of the actual exhaust gas temperature as well as a frequency analysis is performed in order to calibrate the model and analyse results of the signal reconstruction. Results of the algorithm are then successfully proved in experimental transient tests and typical European approval test cycles.

A study on the indirect urea dosing method in the Selective Catalytic Reduction system

This article presents the results of studies on concept solution of dosing urea in a gas phase in a selective catalytic reduction system. The idea of the concept was to heat-up and evaporate the water urea solution before introducing it into the exhaust gas stream. The aim was to enhance the processes of urea converting into ammonia, what is the target reductant for nitrogen oxides treatment. The study was conducted on a medium-duty Euro 5 diesel engine with exhaust line consisting of DOC catalyst, DPF filter and an SCR system with a changeable setup allowing to dose the urea in liquid phase (regular solution) and to dose it in a gas phase (concept solution).The main criteria was to assess the effect of physical state of urea dosed on the NOx conversion ratio in the SCR catalyst. In order to compare both urea dosing methods a special test procedure was developed which consisted of six test steps covering a wide temperature range of exhaust gas generated at steady state engine operation condition. Tests were conducted for different urea dosing quantities defined by the a equivalence ratio.Based on the obtained results, a remarkable improvement in NOx reduction was found for gas urea application in comparison to the standard liquid urea dosing. Measured results indicate a high potential to increase an efficiency of the SCR catalyst by using a gas phase urea and provide the basis for further scientific research on this type of concept.

An assessment of the dual-mode reactivity controlled compression ignition/conventional diesel combustion capabilities in a EURO VI medium-duty diesel engine fueled with an intermediate ethanol-gasoline blend and biodiesel

This work investigates the capabilities of the dual-mode reactivity controlled compression ignition/conventional diesel combustion engine operation to cover the full operating range of a EURO VI medium-duty diesel engine with compression ratio of 17.5:1. This concept is based on covering all the engine map switching between the reactivity controlled compression ignition and the conventional diesel combustion operating modes. Specifically, the benefits of reactivity controlled compression ignition combustion are exploited whenever possible according to certain restrictions, while the conventional diesel combustion operation is used to cover the zones of the engine map in which the reactivity controlled compression ignition operation is limited.The experiments were conducted using a single-cylinder research diesel engine derived from the multi-cylinder production engine. In addition, considering the mandatory presence of biofuels in the future context of road transport and the ability of ethanol to be blended with gasoline, the low reactivity fuel used in the study is a blend of 20% ethanol by volume with 80% of 95 octane number gasoline. Moreover, a diesel containing 7% of biodiesel has been used as high reactivity fuel. Firstly, a reactivity controlled compression ignition mapping is performed to check the operational limits of the concept in this engine platform. Later, based on the results, the potential of the dual-mode concept is discussed.Results suggest that, under the constraints imposed, reactivity controlled compression ignition combustion can be utilized between 25% and 35% load. In this region of the map, reactivity controlled compression ignition can provide up to 2% increased gross indicated efficiency than conventional diesel combustion, but led to lower efficiency at low engine speeds. In addition, it was demonstrated that the regeneration periods of the diesel particulate filter during dual-mode operation can be reduced more than twice, which entails a great reduction of the diesel fuel amount injected in the exhaust line.

Estimate of blow frequency range for an air drill hammer with a ring-shaped elastic valve in the backstroke exhaust line

The authors report and discuss the experimental results on an air drill hammer with an elastic valve installed in the backstroke exhaust line for mechanical closing. It is approved that such air hammer is capable to ensure the wanted blow capacity at the fixed blow energy by varying blow frequency through adjustment of cross section choke coupling the backstroke and front stoke chambers of the hammer. With the larger cross section of the choke coupling, the maximum blow frequency is achieved and remains the same later on.

Development and experimental verification of a robust active noise control system for a diesel engine in submarines

This paper presents the development and experimental validation of an ANC (active noise control)-system designed for a particular application in the exhaust line of a submarine. Thereby, tonal components of the exhaust noise in the frequency band from 75Hz to 120Hz are reduced by more than 30dB. The ANC-system is based on the feedforward leaky FxLMS-algorithm. The observability of the sound pressure in standing wave field is ensured by using two error microphones. The noninvasive online plant identification method is used to increase the robustness of the controller. Online plant identification is extended by a time-varying convergence gain to improve the performance in the presence of slight error in the frequency of the reference signal.

Development of a novel cooking stove based on catalytic hydrogen combustion

A hydrogen based cooking stove was developed and tested in respect to efficiency, functionality and hydrogen safety. Therefore the developed novel combustion unit technology is based on the catalytic oxidation of hydrogen on a platinum coated highly porous reticulated silicon carbide foam ceramics. Compared to other works [1], premixing of hydrogen and air is avoided, thus providing the basis for safe and reliable operation. With this catalytic combustion technology, no initial hydrogen ignition is required, implying a high application security. Separate air and hydrogen supplies make regulation of temperature and power efficient, simple and save.Catalytic hydrogen oxidation is performed already at room temperature; whereby at high hydrogen load, a small hydrogen slip is detected under cold start conditions, nevertheless in operation this becomes negligible. In order to overcome this issue, a hydrogen flow regulation, based on the hydrogen combustion temperature, was introduced.A heat exchanger is integrated into the exhaust line, in order to recover heat for the incoming air, required for the catalytic combustion. This leads to a stove efficiency of up to 80%, measured according to the DIN EN 30-2-1: 2005–08 test standard and greatly exceeds the postulated standard minimum efficiency of 35%. For comfortable and save use, the combustion unit is mounted under a glass ceramic coverage, as common for conventional electrical stoves.

Development of particle characteristics diagnosis system for nanoparticle analysis in vacuum.

A particle characteristics diagnosis system (PCDS) was developed to measure nano-sized particle properties by a combination of particle beam mass spectrometry, scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS). It allows us to measure the size distributions of nano-sized particles in real time, and the shape and composition can be determined by in situ SEM imaging and EDS scanning. PCDS was calibrated by measuring the size-classified nano-sized NaCl particles generated using an aqueous solution of NaCl by an atomizer. After the calibration, the characteristics of nano-sized particles sampled from the exhaust line of the plasma-enhanced chemical vapor deposition process were determined using PCDS.

303 相変化を伴う非定常壁面衝突噴霧に関する研究(OS2 エンジン技術の高度化に向けた先端研究,研究討論セッション)

Diesel particulate filter (DPF) is a very effective aftertreatment device to limit particulate emissions from diesel engines. When the DPF regeneration is performed, it is necessary the DOC works durably if the injected fuel is completely vaporized before entering the DOC, and uniform mixed with the exhaust gases. However, ensuring complete evaporation and an optimum mixture distribution in the exhaust line are challenging. Therefore, it is important that the fuel spray features are grasped to perform DPF regeneration effectively. This report focuses on impingement spray, to understand physical phenomenon.

A Case Study on Application of DMAIC to Improve Delivery Efficiency

In this era of globalization, as competition intensifies, providing on timely delivered products and services has become a competitive advantage and a need to ensure survival. The Six Sigma’s problem solving methodology DMAIC has been one of the several techniques used by organizations to improve the deliveries of their products and services. This paper is based on an application of Six Sigma and DMAIC to improve on time deliveries within a MDF boards manufacturing organization in Sri Lanka. The paper follows the DMAIC methodology to systematically investigate the root causes of delivery failures and provide a solution to improve them. It begins with the past data analysis of the problem to find out major causes for delivery failures and after finding major causes further analysis is done to find out sub critical causes. Then reasons are analyzed for these sub causes and for these analyses Pareto charts, Brainstorming, Fish bone diagrams and verification sheets are used as tools and techniques. Finally to find out key root causes 5Y analysis is used and solutions have been proposed to overcome these issues. Product quality issues and Plant availability issues were the most problematic cause for delivery failures. Further analysis noted, Shives, Crack marks and Rough surface were the most problematic quality defects and to loss plant availability several mechanical and production related plant down time issues were caused. Metering belt broken, Doffing rolls drive chain broken and fibers leaking from gland packing at refiner 01 were the most significant causes identified as mechanical related plant down times and out feed board blockage, refiner 01 blow line blockage and forming line scalper exhaust line blockage were the most significant production related plant down time causes. This paper can be used as a guiding reference for managers and engineers to undertake specific product and process improvement projects, in their organizations, similar to the one presented in this paper. This study presents an industrial case which demonstrates how the application of Six Sigma and DMAIC can help manufacturing organizations to achieve product quality and plant availability improvements in their companies and thus contribute to their search for improvement of on time deliveries.

TiO x -Based Thermoelectric Modules: Manufacturing, Properties, and Operational Behavior

Substoichiometric titanium oxides are attractive thermoelectric materials for high-temperature modules. Their advantages are availability, economy, and safety. This paper gives results of thermoelectric data on scale-up titanium suboxides, manufacturing technologies of TiO x modules, glass coating as an option for oxidation protection, and test results of TiO x modules. The thermoelectric efficiency of TiO x is low compared with established thermoelectric materials. However, TiO x is very attractive for economic reasons, and there are still expectations for efficiency rise by modification of the material’s microstructure. TiO x can be produced in large quantities of several tens of kilograms. A manufacturing process for TiO x -based unileg n-type modules has been established, including all technological steps. The design of the TiO x -based modules was optimized for the thermoelectric conversion process and thermal robustness. A test device was used for experimental analysis with maximum temperature of 600°C at the hot side and 100°C at the cold side. This initial test revealed similar power output and internal resistance of all fabricated modules. Furthermore, thermal cycles with increasing and decreasing temperatures at the hot side were realized to characterize the reliability and stability of the modules. Additionally, modules were tested in a hot gas test rig to simulate the thermal stresses during power generation in the exhaust line of a passenger car.

진공공간 내 나노급 오염입자의 실시간 진단시스템 개발

Particle characteristics diagnosis system (PCDS) was developed to measure submicron particle characteristics by modulation of particle beam mass spectrometry (PBMS) with scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). It is possible to measure the particle size distribution in real-time, and the shape, composition can be measured in sequence keeping vacuum condition. Apparatus was calibrated by measuring the size classified NaCl particle which generated at atmospheric pressure. After the calibration, particles were sampled from the exhaust line of plasma enhanced chemical vapor deposition (PECVD) process and measured. Result confirms that PCDS is capable for analyzing particles in vacuum condition.

Thermoelectric Generators for the Integration into Automotive Exhaust Systems for Passenger Cars and Commercial Vehicles

A special thermoelectric generator system design and the setup of a thermoelectric generator for the integration into the exhaust line of combustion engine-driven vehicles are described. A prototype setup for passenger cars and the effects on the measured power output are shown. Measurement results using this setup show the potential and the limitations of a setup based on thermoelectric modules commercially available today. In a second step, a short outline of the detailed mathematical modeling of the thermoelectric generator and simulation studies based on this model are presented. By this means, it can be shown by which measures an improvement of the system power output can be achieved—even if today’s modules are used. Furthermore, simulation studies show how the exhaust gas conditions of diesel- and Otto-engines significantly affect the requirements on thermoelectric materials as well as the potential and the design of the thermoelectric generator. In a further step, the design and the setup of a thermoelectric generator for an application in a commercial vehicle are presented. This thermoelectric generator is designed to be integrated into the exhaust aftertreatment box of the vehicle. Experimental results with this setup are performed and presented. The results show that thermoelectric generators can become an interesting technology for exhaust waste heat recovery due to the fact that they comprise non-moving parts. However, the efficiency of the modules commercially available today is still far from what is required. Hence, modules made of new materials known from laboratory samples are urgently required. With regard to future CO2 regulations, a large market opportunity for modules with a high efficiency can be expected.

Effect of Drive Cycle and Gasoline Particulate Filter on the Size and Morphology of Soot Particles Emitted from a Gasoline-Direct-Injection Vehicle.

The size and morphology of particulate matter emitted from a light-duty gasoline-direct-injection (GDI) vehicle, over the FTP-75 and US06 transient drive cycles, have been characterized by transmission-electron-microscope (TEM) image analysis. To investigate the impact of gasoline particulate filters on particulate-matter emission, the results for the stock-GDI vehicle, that is, the vehicle in its original configuration, have been compared to the results for the same vehicle equipped with a catalyzed gasoline particulate filter (GPF). The stock-GDI vehicle emits graphitized fractal-like aggregates over all driving conditions. The mean projected area-equivalent diameter of these aggregates is in the 78.4-88.4 nm range and the mean diameter of primary particles varies between 24.6 and 26.6 nm. Post-GPF particles emitted over the US06 cycle appear to have an amorphous structure, and a large number of nucleation-mode particles, depicted as low-contrast ultrafine droplets, are observed in TEM images. This indicates the emission of a substantial amount of semivolatile material during the US06 cycle, most likely generated by the incomplete combustion of accumulated soot in the GPF during regeneration. The size of primary particles and soot aggregates does not vary significantly by implementing the GPF over the FTP-75 cycle; however, particles emitted by the GPF-equipped vehicle over the US06 cycle are about 20% larger than those emitted by the stock-GDI vehicle. This may be attributed to condensation of large amounts of organic material on soot aggregates. High-contrast spots, most likely solid nonvolatile cores, are observed within many of the nucleation-mode particles emitted over the US06 cycle by the GPF-equipped vehicle. These cores are either generated inside the engine or depict incipient soot particles which are partially carbonized in the exhaust line. The effect of drive cycle and the GPF on the fractal parameters of particles, such as fractal dimension and fractal prefactor, is insignificant.

Waste heat recovery of an ORC-based power unit in a turbocharged diesel engine propelling a light duty vehicle

The present technologies in internal combustion engines for transportation purposes clearly demonstrate the room for improvement still achievable. In a recent past, harmful emission reduction was the main goal: wonderful technologies were developed which strongly reoriented the interest and the use of such engines. Actually, CO2 is the most important driver: it calls for fuel consumption reduction (energy saving) and energy recovery from that usually wasted. Considering that about one third of the fuel energy is in the flue gases, the possibility to recover this energy and re-use it for engine and vehicle needs is one of the smartest ways to participate to reduce fuel consumption and, therefore, CO2 emissions. In particular, Organic Rankine Cycle (ORC)-based power units fed by the exhaust gases are promising and technologically ready, but they have a significant impact on the exhaust line and engine behavior. A trade-off between energy recovered in mechanical form and energy lost due to the engine back pressure, vehicle weight increase, discharge energy at the condenser, and the management of the strong off-design operating conditions is a key point which could definitively open the way to this technology or limit it to particular applications. The paper discusses the effects of the pressure losses produced by an ORC-based power unit mounted on the exhaust line of a turbocharged IVECO F1C engine, operated on a test bench. The interactions produced on the turbocharged engine have been experimentally investigated: the presence of an Inlet Guide Vane (IGV) system to manage the turbocharger makes the effect of the back pressure not straightforward to be predicted. The IGV opening and closure degree, in fact, can compensate the effect of the back pressure which intrinsically tends to increase specific fuel consumption. A wide experimental testing of the turbocharging group in order to understand its reaction and the net effect in terms of engine specific fuel consumption is presented. Finally, once the engine performances were verified, the contribution due to the heat recovery inside the ORC-based power unit fed by the exhaust gases in terms of mechanical power was evaluated and experimentally verified in some points, considering the strong off design conditions produced by the engine operating point variations. In fact, exhaust gas flow rate and temperature variations lead the evaporator, even though properly designed, to severe off-design conditions which modify the inlet working fluid conditions till to make the mechanical recovery impossible. Under the hypothesis that the engine propels a light duty vehicle, the effect of the extra weight is discussed re-evaluating the propulsion power increase in terms of fuel consumption.