Exhaust Gas Composition Research Articles

High-Throughput Screening Approach to Identify New Catalysts for Total Oxidation of Methane from Gas Fueled Lean Burn Engines

In this contribution we present the results of a parallel high-throughput screening (HTS), which was carried out to identify new catalysts for the total oxidation of methane, a chemical compound that shows a significantly higher global warming potential compared to carbon dioxide. An interesting application for these materials is the abatement of unburned methane in exhaust gases from biogas fueled lean burn engines. After the synthesis of a high variety of different materials by a sol–gel procedure and their evaluation by infrared thermography under simplified reaction conditions, the activity of the most promising candidates was validated under a complex exhaust gas composition in a conventional plug flow reactor. The aging behavior of the best catalysts from the HTS was studied in a tenfold parallel reactor setup. Only a small number of the studied materials exhibited an interesting long term stability during the aging procedure. With this approach a high number of potential materials can be rapidly reduced to only a few catalysts which are promising for a possible industrial application.

Impact of Test Conditions on the Oxygen Storage Capacity of Pd Loaded Cerium Zirconium Oxide

An alternative method to determine the oxygen storage capacity (OSC) for powder materials is proposed in the current work. Dynamic and static OSC measurements were conducted at 510 °C using a thermally aged Pd loaded cerium zirconium oxide (30 wt% ceria, 1 wt% Pd). Particularly the influence of water and carbon dioxide in the gas feed on OSC determination was studied. The results demonstrate that the absence of H2O/CO2 and a static test procedure lead to overrated oxygen storage capacities. The method proposed here provides a simple, but not oversimplified method to determine the oxygen storage capacity under conditions closer to real applications by imitating the transient working mode of a gasoline engine and paying more attention to the exhaust gas composition.

The model of combustion process in the marine 4-stroke engine for exhaust gas composition assessment

The paper presents the model of combustion process in the marine, turbocharged, 4-stroke and Diesel engine. The main target of modeling is the assessment of the exhaust gas composition. Presented multi-zone, 3-D model of combustion process consists of the following sub-models of processes: the fuel injection, the brake-up and the evaporation of fuel and the turbulence flow and the heat transfer phenomena. Presented model basis on the 3Z-ECFM mechanism of combustion and the initial and boundary conditions collected during direct measurements. The positive validation of the calculation results are obtained for mean and maximum value of the combustion pressure and values of oxygen and nitric oxides fractions in the exhaust gas. Unfortunately, fractions of carbon compounds in the exhaust gas are not properly calculated.

Nonthermal Plasma System for Marine Diesel Engine Emission Control

A nonthermal plasma reactor (NTPR) using two 2.45-GHz microwave (MW) generators for the abatement of nitrogen oxides ( ${\text {NO}}_{\text {x}}$ ) and sulfur ( ${\text {SO}}_{\text {x}}$ ) contained in the exhaust gas of a 200-kW marine diesel engine was built and tested. Numerical analysis based on a nonthermal plasma kinetics model for the abatement of ${\text {NO}}_{\text{x}}$ and ${\text{SO}}_{\text{x}}$ from marine diesel engine exhaust gas was performed. A generic kinetic model that implements electron collisions and plasma chemistry has been developed for applications involving low-temperature (50–100 K) nonthermal plasma. Abatement efficiencies of ${\text {NO}}_{\text{x}}$ and ${\text {SO}}_{\text{x}}$ were investigated for a range of mean electron energies, which directly impact on the rate constants of electron collisions. The simulation was conducted using the expected composition of exhaust gas from a typical two-stroke, slow-speed marine diesel engine. The simulation results predict that mean electron energy of 0.25–3.2 eV gives abatement efficiency of 99% for ${\text {NO}}_{\text{x}}$ and ${\text {SO}}_{\text{x}}$ . The minimum residence time required was found to be 80 ns for the mean electron energy of 1 eV. Multimode cavity was designed using COMSOL multiphysics. The NTPR performance in terms of ${\text {NO}}_{\text{x}}$ and ${\text {SO}}_{\text{x}}$ removal was experimentally tested using the exhaust from a 2-kW lab scale, two-stroke diesel engine. The experimental results also show that the complete removal of NO is possible with the MW plasma (yellow color) generated. However, it was found that generating required MW plasma is a challenging task and requires further investigation.

HC, CO and NOx emissions reduction efficiency of a prototype catalyst in gasoline bi-mode SI/HCCI engine

Lean and highly diluted homogeneous charge compression ignition (HCCI) engines offer great potential in improving vehicle fuel economy and contribute in reducing CO2 emissions. Hydrocarbons and CO emissions from HCCI engines can be higher than those from spark ignition (SI) engines, especially at low engine load when the residual gas required to control NOx emission are elevated. Although, NOx emissions are significantly low, a bi-functional after treatment device will be required to control HC, CO and NOx emissions under lean and stoichiometric (oxygen free) engine operating conditions. This paper describes studies on the NOx, HC and CO emissions reduction efficiency of a prototype catalyst, under lean and stoichiometric engine conditions at different loads, speeds, and A/F. A comparative study of catalyst performance will be analysed under HCCI stoichiometric and SI operation under three engine speeds and load of 4bar (Net Mean Effective Pressure, NMEP). Experimental results indicate that the HC and CO emissions reduction over the prototype catalyst was in the range of 90–95% while the maximum NOx emissions reduction under lean engine operating conditions was in the range of 35–55%. The catalyst efficiency in reducing the three pollutant emissions is closely related to the exhaust gas conditions (e.g. temperature and space velocity), oxygen and composition i.e. NOx, CO and HC concentrations.

Temperature Distribution of Biodiesel Blends Combustion in Boiler using CFD-Fluent

The use of biodiesel have been tested on some combustion devices extensively, including on the boiler. Biodiesel blends use in boiler is possibly affect ed the behaviour of combustion. It can be evaluated by analysing the exhaust gas composition and temperature. This study is conducted to show the distribution of temperature in the combustion chamber and boiler stack’s using Computational Fluid Dynamic (CFD) software Fluent. Experimentally, the tests carried out on the fire tube boiler vertical type cylinder with pressure of 3 bar. Temperature measurement is performed at three points in the combustion chamber and boilers’ stack using optional thermocouple and gas analyzer IMR 1400. The biodiesel used in the tests is palm oil based with blending portion varies from 5-25%. The results show that in the higher blend of biodiesel, the temperature of combustion chamber tend to be lower but the exhaust gas temperature at the end of the chimney was likely to increase. On the other hand, the simulation using FLUENT showed the pattern of temperature distribution was relatively equal between the use of biodiesel in the blends under 25% compared to the use of diesel (B0).

Operational malfunctions of turbochargers – reasons and consequences

The paper discusses the most frequently occurring types of damage in turbochargers fitted in modern combustion engines and their influence on the engine basic operational indexes. The following causes of turbocharger malfunctions have been discussed: no lubrication, low lubricant pressure, reduced lubricant quality, foreign objects in the charged air and in the exhaust gas. Example malfunctions resulting from the said causes have been shown. The experimental part discusses the influence of a reduction of the charging pressure resulting from a leakage in the intake system on the effective parameters of a diesel engine fitted in light-duty and heavy-duty vehicles. The leakage in the intake system has been simulated by boring holes of the diameter of 3 and 12 mm in the intake manifold downstream of the turbocharger. The influence has been determined of the leakage of the turbocharging system on the value of the charging pressure, maximum effective power, engine torque, unit and hourly fuel consumption and the concentration of the exhaust components. A significant impact has been observed of the leakage of the turbocharging system on the effective parameters of the tested diesel engine and exhaust gas composition.

An Experimental Study of Emission and Combustion Characteristics of Marine Diesel Engine with Fuel Injector Malfunctions

Abstract The presented paper shows the results of the laboratory study on the relation between chosen malfunctions of a fuel injector and composition of exhaust gas from the marine engine. The object of research is a marine 3-cylinder, four-stroke, direct injection diesel engine with an intercooler system. The engine was loaded with a generator and supercharged. The generator was electrically connected to the water resistance. The engine operated with a load between 50 kW and 250 kW at a constant speed. The engine load and speed, parameters of the turbocharger, systems of cooling, fuelling, lubricating and air exchange, were measured. Fuel injection and combustion pressures in all cylinders of the engine were also recorded. Exhaust gas composition was recorded by using a electrochemical gas analyzer. Air pressure, temperature and humidity were also recorded. Emission characteristics of the engine were calculated according to ISO 8178 standard regulations. During the study the engine operated at the technical condition recognized as „working properly” and with simulated fuel injector malfunctions. Simulation of malfunctions consisted in the increasing and decreasing of fuel injector static opening pressure, decalibration of fuel injector holes and clogging 2 neighboring of 9 fuel injector holes on one of 3 engine cylinders.

Characteristics of charcoal combustion and its effects on iron-ore sintering performance

Using biomass for partial or complete replacement of coke breeze in iron ore sintering process is an attractive technique for reducing emissions of greenhouse gas and gaseous pollutants. But one drawback of this technique is that low or medium grade charcoal may lead to the failure in achieving proper sintering performance. In this paper, the behaviors of coke combustion versus charcoal combustion in sintering bed were compared. The results of thermal profile and exhaust gas composition indicated that the sinters quality was deteriorated at high charcoal proportion. Lacking heat release in melting zone and the excessively high combustion rate were the reasons to weak sinters. In order to ensure the sintering performance when using medium grade charcoal in sintering bed, the effects of three improving measures (proposing the equivalent fixed carbon substitution approach, increasing charcoal particle size and adopting coated charcoal combustion) were experimentally tested. The results showed that equivalent fixed carbon substitution approach was more effective to produce sufficient heat in melting zone at medium grade charcoal combustion. Additionally, it was also found that increasing charcoal particles size and applying coated charcoal combustion method could reduce combustion rate to achieve a proper matching condition between flame front speed and heat transfer front speed. Consequently, with the help of equivalent fixed carbon substitution approach, coarse charcoal and coated charcoal particles, the peak temperature, holding time above 1100°C, melting quantity index and combustion efficiency were increased in the charcoal sintering process.

Study on a Fixed Bed Gasification of Polyurethane SRF from Electronic Waste

With expanding economic growth, the consumption and changing period of electronics products have increased rapidly last a couple of decades in Korea. A refrigerator generally contains 10% of polyurethane. Since the amount of used refrigerators collected at recycling facilities of E-wastes has increased since 2007, the generation of polyurethane waste has also increased. Polyurethane recycling technologies have been investigated such as polyol production and sound-absorbing materials, which are not commercialized yet due to high cost of the technology. However many kinds of plastic wastes are being used as solid refuse fuel (SRF) like RDF, so polyurethane in E-waste could be utilized as valuable fuels, since it has higher heating values and contains low sulfur, low chlorine, and less hazardous substances. In this study an attempt to fabricate pellet type of SRF from polyurethane waste was conducted to use them as fuels even though it was not easy to make pellet, because characteristics of polyurethane were high volume and low density. Recently, Korean Association of Electronics Environment (KAEE) is producing pelletized SRF. The basic characteristics of polyurethane such as elemental composition, thermal properties and proximate analysis were carried out to assess whether they could be used as fuels or not. Using a fixed bed test reactor, gasification experiments were also conducted at the temperature of 1,000 ℃ by measuring exhaust gas compositions and gas pollutants.

대형 경유트럭의 NOx저감장치에 따른 배출가스 특성비교

With increasing of GDP, the registration number of passenger cars has exceeded 20 million last year in Korea. Especially, the registration number of the diesel engine vehicles has been increasing. However, the WHO(World Health Organization) IARC (International Agency for Research on Cancer) has reported that diesel engine exhaust gas is an one of HAPs, which has carcinogenic for human, and they have designated it to Group 1. To solve this problem, exhaust gas from diesel engines has to be controlled. Thus, it has been controlling by European regulatory standard in Korea. On the other hand, in order to meet the enhanced emission regulations, all manufacturing company applied NOx control device to vehicles such as EGR (Exhaust Gas Recirculation), SCR (Selective Catalytic Reduction) and so on. However, these devices (EGR, SCR) were operated by difference reaction mechanism respectively, and the composition of exhaust gas would be differenced from that of them. In this study, it was conducted to evaluate variety characteristics on changing of exhaust gas composition by each NOx control device, and the heavy duty diesel trucks were chosen as experimental vehicles. From the result, it revealed that vehicles (with EGR) were discharged higher THC as 52.5% than that of others (with SCR). However, it did not followed that trend, in the case of CO; it was discharged as 57.2% lower than that of others (with SCR). In the future, these data would be used to apply to efficient NOx control device for meeting to EURO 6.

Effects of temperature and rich-phase composition on the performance of a commercial NOx-Storage-Reduction material

A thin self-supported wafer of a commercial NOx-Storage-Reduction (NSR) material was investigated by operando transmission FT-IR to assess the effects of the operating temperature and the composition of the rich period (in particular with respect to H2, CH4, CO, CO2 and C3H6 reactants) on the deNOx activity. The DeNOx activity was high at 300°C under the simulated exhaust gas composition, but dropped sharply at 200°C and 100°C, primarily due to a loss of the NOx storage ability. The origin of the trapping loss depended on the temperature. Pt-bound CO(ads) were observed at 200°C, pointing to a significant poisoning of metallic Pt sites by strongly bound carbon monoxide, hindering NOx decomposition and reduction. Surprisingly, no Pt-CO was observed at 100°C, revealing the absence of accessible metallic Pt at this temperature, most likely due to the presence of a fully oxidized (or nitrated) Pt surface. In contrast, an important NSR activity could be obtained at 200°C and even at 100°C when H2 was used as the only reducing agent in a C-free feed. Propene had a similar detrimental effect as that of CO, while methane only induced a minor loss of trapping efficiency. The presence of a large concentration of CO2 also induced a trapping loss, albeit significantly less marked than those due to propene and CO. The combination of all the C-containing compounds (i.e. CO, CO2, C3H6, CH4) led to an almost complete inhibition of the NSR activity at temperatures equal to or lower than 200°C. The operando analysis also revealed that the nature of the NOx species trapped varied with the temperature; nitrates were the dominant species at 300°C, while nitrites were more prominent at 200°C and 100°C.

Experimental and numerical studies on a trapped vortex combustor with different struts width

To investigate the effect of strut width on combustion efficiency and pollutant emissions, a trapped vortex combustor with interchangeable aerodynamic multi-point fueling (AMF) setups is designed. Exhaust gas composition is measured at the exit of the combustor. Results show that lacking of protection of slenderer struts leads that the flame coming from cavity is prone to be quenched; thus combustion efficiency for cavity-only fueling conditions is relative lower. Thus, CO and HC emissions are relative higher. However, as main fueling is available, the corresponding overall combustion efficiencies become higher especially for Ma = 0.3. This can be attributed to larger number of struts and thus larger wet perimeter of mainstream passages. Additionally, activating of main fueling is helpful for decreasing CO and HC and thus elevating combustion efficiency. Numerical simulations of non-reacting and reacting flow are also accomplished. Although the numerical simulation results exhibit flow structure discrepancy between non-reacting and reacting simulations, the conclusion about protection of wider struts and mixing enhancement of slenderer struts are accordant.

Performance Evaluation of Mixed-Potential HC, NOx and NH3 Sensors in Diesel and Lean Gasoline Engine Exhaust

Mixed-potential sensors fabricated via well-established commercial manufacturing methods present a promising avenue to enable the widespread utilization of NOx, hydrocarbon, and ammonia sensing technology. These devices are fundamentally simple, inexpensive, and robust devices owing to their close relationship to the well-established and ubiquitous automotive Lambda sensor. Our first dynamometer experiments (2014) focused on testing a single device in lean-burn, diesel exhaust from a 1.9L GM turbo-diesel engine in both NOx and HC modes with gas sampling occurring both before and after the DOC. In general, there was excellent qualitative agreement between actual exhaust gas composition (determined by FTIR and FID) however the inability to reproduce engine exhaust gas conditions exactly made precisely correlating sensor data to specific engine events while testing in the respective sensor operating modes difficult. Recently, multiple mixed potential sensors were tested simultaneously in the exhaust of a lean-burn, 4 cylinder 2.0-liter naturally aspirated, direct injection gasoline engine (model year 2008, E87 European model BMW 1-series 120i.) A mixed potential NOx sensor and a new NH3 sensor were tested downstream of the three way catalyst while a dedicated HC sensor was simultaneously tested upstream of the TWC. The sensor response and heater power applied to the sensors (e.g. sensor temperature) were continuously monitored while the high frequency impedance of a dedicated fourth sensor was tested for the purpose of independently monitoring sensor electrolyte temperature stability during dynamometer operation. Data from the sensors were collected under rich, stoichiometric, lean homogeneous, and lean stratified conditions (0.98<λ<1.8) and at various engine loads. To simulate the occurrence of ammonia slip in a selective catalytic reduction (SCR) emissions system, ammonia was injected upstream of the NH3 sensor to evaluate the ammonia sensitivity in the presence other exhaust gas constituents. The sensor response in the exhaust gas environment was compared with laboratory calibrations to assess the relative importance of the varying interferents species on the sensor response to the target species and to develop quantitative calibration curves relevant to the exhaust gas environment.

Catalytic Total Oxidation of SOFC Exhaust Gas on Cu-Mn Catalysts

SOFC exhaust gas oxidation technology will contribute to reducing the pollutants and providing economically feasible SOFC systems. The Cu-Mn based materials, known as CO and H2 oxidation catalysts, were tested as novel metal-free SOFC exhaust gas oxidation catalysts. Catalysts are prepared with incipient wetness impregnation method using metal nitrate precursors on γ-Al2O3. Various Cu-Mn catalysts are also prepared to study the effect of CuO-MnO ratio on catalytic activity. The feed gas was synthesized as similar composition of SOFC exhaust gas. The optimized conversion was obtained when CuO and MnO had the same weight ratio(CuO/MnO wt. ratio = 1). The conversion of CO, H2 and CH4 is 43.4, 36.1 and 58.0, repectively.

Development and Investigation of Diesel Fuel Reformer for LNT Regeneration

In the present work, an exhaust after treatment system combining Lean NOX Trap (LNT) plus exhaust bypass, passive catalyst for selective catalytic reduction (SCR), and engine independent LNT reductant supply by on-board exhaust fuel reforming was developed. To demonstrate the mobile production of synthesis gas with focus on automotive application, an outline fuel reformer has been developed which is predominantly operated using engine exhaust gas. The reformer concept and design are described in detail. The reaction process is a variable superposition of exothermic catalyzed partial oxidation (CPOx) and endothermic steam (steam reforming (SR)) and CO2 (dry reforming (DR)) reformation. This strong dependence of the reformer operation on the engine’s exhaust gas composition was intensively studied by steady-state experiments on an engine test bench. Besides operating the reformer within thermal limits, the control strategy is designed in terms of low hydrocarbon emissions and high energetic efficiency. In comparison to pure CPOx, exhaust gas reforming showed favorable thermal behavior as well as efficiency benefits of up to 20 % due to the endothermic part of the reaction. The reformer could achieve a reductant yield of above 50 %, whereas only 10–25 % for medium engine load and up to 45 % for high engine load could be realized by engine-rich operation. For the investigated diesel engine-rich calibrations, the undesired HC emission reached a percentage share of the reductants of 15–55 %, whereas the reformer showed only up to 12 %.

Concept of the multidimensional diagnostic tool based on exhaust gas composition for marine engines

Abstract This paper presents the concept of a multi-dimensional marine engine diagnostic tool. The dimensions of the tool are diagnostic signals, which form a vector in affine space. The distance of the resulting vector from reference vectors for considered technical states of the engine is the result of diagnosis. Moreover, diagnostic signals, derived from the composition of the exhaust gas, are also considered. The chosen diagnostic signals are the nitric oxide, carbon oxide, carbon dioxide and oxygen contents in the exhaust gas and the temperatures behind all engine cylinders of the marine engine. Analyses were based on laboratory tests of a 4-stroke marine engine. The operation of the proposed diagnostic tool has been partly verified by a passive experiment under sea operation conditions of a main propulsion marine engine.

Deactivation of Pd Catalysts by Water during Low Temperature Methane Oxidation Relevant to Natural Gas Vehicle Converters

Effects of H2O on the activity and deactivation of Pd catalysts used for the oxidation of unburned CH4 present in the exhaust gas of natural-gas vehicles (NGVs) are reviewed. CH4 oxidation in a catalytic converter is limited by low exhaust gas temperatures (500–550 °C) and low concentrations of CH4 (400–1500 ppmv) that must be reacted in the presence of large quantities of H2O (10–15%) and CO2 (15%), under transient exhaust gas flows, temperatures, and compositions. Although Pd catalysts have the highest known activity for CH4 oxidation, water-induced sintering and reaction inhibition by H2O deactivate these catalysts. Recent studies have shown the reversible inhibition by H2O adsorption causes a significant drop in catalyst activity at lower reaction temperatures (below 450 °C), but its effect decreases (water adsorption becomes more reversible) with increasing reaction temperature. Thus above 500 °C H2O inhibition is negligible, while Pd sintering and occlusion by support species become more important. H2O inhibition is postulated to occur by either formation of relatively stable Pd(OH)2 and/or partial blocking by OH groups of the O exchange between the support and Pd active sites thereby suppressing catalytic activity. Evidence from FTIR and isotopic labeling favors the latter route. Pd catalyst design, including incorporation of a second noble metal (Rh or Pt) and supports high O mobility (e.g., CeO2) are known to improve catalyst activity and stability. Kinetic studies of CH4 oxidation at conditions relevant to natural gas vehicles have quantified the thermodynamics and kinetics of competitive H2O adsorption and Pd(OH)2 formation, but none have addressed effects of H2O on O mobility.

A study of the effect of post injection on combustion and emissions with premixing enhanced fueling strategies

An empirical investigation was carried out in a compression ignition engine to characterize the effect of the post injection timing on the post injection power production, the exhaust temperature, and the exhaust gas composition. Due to the potential emission reduction benefits of alternative fuels, numerous fuel injection strategies were investigated, including direct injection diesel, dual fuel diesel and ethanol, dual fuel diesel and butanol, and direct injection butanol. For all of the tested fuel injection strategies, the results indicated that the engine power output, the exhaust gas temperature, and the exhaust gas composition were very sensitive to the post injection timing. For producing additional power output, a relatively early post injection timing was the most suitable and the power output gradually declined when the post injection timing was delayed. A relatively early post injection timing was also preferable for raising the exhaust gas temperature. For generating highly reactive species, such as hydrogen and reactive light hydrocarbons, the results suggested that an intermediate post injection timing was the most suitable. Furthermore, a late post injection timing was the least desirable due to a very low contribution to power output, a minimal increase in the exhaust gas temperature, and a very low amount of reactive species in the exhaust gas. In general, the alternative and dual fuel injection strategies resulted in reduced nitrogen oxide emissions, reduced smoke emissions, and reduced exhaust gas temperatures compared to the traditional diesel fuel injection. For the alternative and dual fuel tests, it was found that an early post injection was able to reduce the hydrocarbon and carbon monoxide emissions relative to the quantity without a post injection.

Current status and prospects for the use of low-carbon gaseous fuels in transport

The paper presents a detailed analysis of the issues related to an improvement of the efficiency of energy conversion in SI engines, fueled by low-carbon gaseous fuels. The research was conducted on an engine fueled with natural gas (CNG) and methane/hydrogen blends. The applied gaseous fuels are characterized by a reduced share of carbon, which enables a reduction of the emission of CO2. The object of the research was a 1.6 dm3, 4-cylinder engine originally fitted in Opel Astra F. The engine was equipped with a CNG injection system. The final analysis includes the influence of the ignition advance angle and fuel composition on the engine performance and exhaust gas composition.