Performance Of Catalytic Converter Research Articles

Enhancing catalytic converter performance: effects of noble metals and rare earth washcoating on CO and NOx conversion

Enhancing catalytic converter performance: effects of noble metals and rare earth washcoating on CO and NOx conversion

Catalytic converter performance prediction and engine optimization when powered by diisopropyl ether/gasoline blends: Combined application of response surface methodology and artificial neural network

The main objective of this study is to develop a neural network model to predict high-accuracy responses and optimize the input parameters using response surface methodology to improve catalytic converter performance when powered by diisopropyl ether/gasoline blends. The engine exhaust gas was treated by a commercial catalytic converter by varying the brake power, engine speed, and compression ratio, and the pollutant levels were measured. Again, the experiment was repeated, and the exhaust gas was treated by a sucrose/alumina catalyst-coated converter and the results were compared. Experimentally obtained data were employed to develop a neural network and response surface methodology model. The developed artificial neural network yielded higher R2 values of over 0.9977 for commercial catalytic converter and over 0.99633 for sucrose/alumina catalyst-coated converter. Furthermore, mean square error values were less than 3 % for all the responses which indicates higher prediction accuracy. Similarly, the developed response surface methodology model exhibited a higher F-value and lower p-value which indicates the model is accurate. Moreover, the desirability factor of over 0.99 for both cases shows the model's high stability. The predicted optimum brake power of 8.01 kW at 2500 rpm and 9.5 compression ratio produced lesser emissions and the validation test error was found to be less than 4 %. Thus, the authors conclude that the combined application of artificial neural network and response surface methodology will be efficient in exhaust gas pollution level prediction and optimization.

Study on Influence of Core Structure on Catalytic Converter Performance Using CFD

In recent years, as the automotive industry is growing, one of the major hope for future vehicles is to meet emissions regulations. Automobiles pollute the air, and clean-air laws have made Catalytic Converters a legal requirement because they convert harmful pollutants from an engine's exhaust into cleaner emissions. The device works with the principle of a catalyst, something that causes or speeds up a chemical reaction without itself being changed. But the presence of a catalytic converter increases the exhaust back pressure which has an indirect effect on the engine efficiency ie engine efficiency decreases, thus increasing fuel consumption. The performance of a catalytic converter is substantially affected by the flow distribution inside the substrate, a uniform flow distribution can increase its efficiency, lower the pressure drop and optimize engine performance. The flow distribution in a catalytic converter assembly 15 is governed by the geometry configurations of the inlet and outlet cone section, the substrate, and exhaust gas compositions, and therefore a better design of the catalytic converter is very important. This Project deals with the fundamental understanding and study of complex processes taking place involving fluid flow, pressure, and velocity profiles in the catalytic converter using ANSYS WORKBENCH 2022 R1. The main objective of our analysis is to determine the most effective and optimum design of a Catalytic Converter

Key design and layout factors influencing performance of three-way catalytic converters: Experimental and semidecoupled numerical study under real-life driving conditions

The optimization of three-way catalyst (TWC) design and layout is important for reducing mobile source emissions and requires numerical modeling. To date, the high computational cost of accurate models has inspired the development of numerous tradeoff approaches; however, none of them is fully satisfactory. To address this gap, we herein theoretically and experimentally explore the key design and layout factors influencing TWC performance under transient driving conditions, starting with the optimization and verification of a simplified reaction mechanism. This mechanism is used to construct a semidecoupled posttreatment GT-Power model featuring boundary conditions derived from experimental and upstream engine modeling results, and experiments on a real engine are carried out to evaluate the model accuracy. The performance of three posttreatment systems is analyzed to identify the key performance-affecting parameters, and the following conclusions are drawn. (1) For a single reactor, cell density is the most important factor influencing pressure loss.(2) The exhaust temperature rapidly decreases in the longitudinal direction of the reactor in the initial start stage, although the reaction rate always decreases in this direction during the whole cycle.(3) One-dimensional plug-flow reactor simulations do not account for inhomogeneity and local turbulence, thus overestimating the performance of large reactors.(4) Under the employed conditions, the exhaust temperature is sufficiently high for pollutant conversion, although the efficiency of this conversion often decreases in the high-speed stage. Moreover, we show that high-speed adaptation can be enhanced by increasing the crosswise size of the reactor and propose a new reactor structure. Compared with our model, this structure is characterized by a lower catalyst loading and NOx conversion efficiency but achieves higher hydrocarbon and CO conversion efficiencies. Thus, our study provides a useful and effective method for evaluating the design/layout of posttreatment devices and facilitates the development of more efficient TWCs, contributing to the establishment of a more ecofriendly society.

Improvement of flow field uniformity and temperature field in gasoline engine catalytic converter

The uneven temperature field, flow field, and internal low temperature of the catalytic converter can cause substrate thermal deformation and catalytic ability decrease, which is not conducive to the service life of catalytic converter and control of automotive pollutants emission. A novel substrate structure with uniformly changes cell density and a new heater of three layers diffuser with optimized flow field uniformity are proposed. Their application in catalytic converter can effectively improve the above problems. Firstly, physical and mathematical models of the new catalytic converter were established, and the accuracy was verified by experiments. Next, the flow characteristics and catalytic performance was analyzed. Finally, the effects of different parameters on catalytic performance and temperature were analyzed. The results show that: (1) Compared with traditional catalytic converter, gas uniformity and NO conversion efficiency of the new catalytic converter are increased by 0.0885% and 13.66%, respectively, improving flow field uniformity and NO conversion. (2) The NO conversion efficiency increases and then decreases with adding of electric power, exhaust inlet temperature and exhaust inlet velocity; substrate temperature increases with adding of electric power and exhaust inlet temperature, but decreases with increase of exhaust velocity. During heating time, the NO conversion efficiency and substrate temperature first increase and then tend to stabilize. After heating is stopped, the NO conversion efficiency and substrate temperature will decrease. (3) The field synergy theory shows that synergy angle cosβ tends to − 1 with increase of electric power, which means convective heat transfer effect inside substrate becomes worse. (4) The grey relational analysis shows that exhaust inlet temperature is a key factor affecting the new catalytic converter performance.

Enhancement of catalytic converter performance to reduce cold start emissions with thermal energy storage – An experimental study

A “Thermal Energy Storage” (TES) system can assist in solving the cold start emission problem associated with the catalytic converter. “Phase change materials” (PCMs) can be used in the TES system to absorb heat from the exhaust gases, liquefy it and store it as latent heat. This makes it possible to store the exhaust heat during the engine running conditions and to release it on the catalyst substrate during the off-engine and low temperature start. A catalytic converter is integrated with a TES unit with Mg70Zn24.9Al5.1 as PCM having melting point in range of 310 °C & 157 kJ/kg as heat of fusion. This paper presents Experimental investigation of Catalytic Converter for exhaust temperature, conversion efficiency with and without TES unit. The investigation includes the heat storage and retention time during engine operation. Test cycle of 150 min with each load were run including idle events in between at 2000 rpm for different load conditions. Results showcased maximum average conversion efficiency improvement for 60 %, 53 % and 30 % for HC, NOx and CO respectively at No load condition during cold start. Heat Retention time was found higher for high loads, 100 % & 75 % load temperature was observed to remain above 100 0C for nearly 350 min.

Analysis of Phase Change Material used as Thermal Energy Storage Unit in Catalytic Converter.

Phase change Material(PCM) is widely used to heat storage applications. In this study PCM is used in the catalytic converter application to improve the performance of catalytic converter by maintaining the temperature above the light off temperature. Catalytic converter is inefficient at lower temperature or below the light off temperature the conversion efficiency is very low and practically it is zero. Using PCM conversion efficiency of catalytic converter is increased. PCM is placed above the substrate to absorb the heat from the exhaust gases which are leaving to the atmosphere in order to maintain the substrate temperature above the light off temperature. When the temperature is high at substrate then conversion of pollutants is better. PCM Store the heat by changing the phase from solid to liquid and return the heat to substrate by partial solidification. In this paper, performance of PCM (Mg70Zn24.9Al5.1) which is a eutectic alloy used for high temperature applications was investigated at various loading conditions by doing the simulation on catalytic converter for melting and solidification of PCM and validate the results with experimental work. The melting of PCM domain is simulated using ANSYS fluent 2019 R3 software. The assumptions used for the numerical study, methodology of the work and specification of software is also discussed in this paper. The contours of melting fraction of PCM at regular interval for different loading conditions (i.e. 0%, 50%, and 100% load) are represented for total melting period of the PCM.

Gain-scheduled output-feedback control of uncertain input-delay LPV systems with saturation via polytopic differential inclusion

This paper examines the control design for parameter-dependent input-delay linear parameter-varying (LPV) systems with saturation constraints. A linear differential inclusion approach is implemented to formulate the saturation nonlinearity. Subsequently, a gain-scheduled dynamic output-feedback controller is structured to conform to the saturation representation. By means of a Lyapunov–Krasovskii functional, sufficient delay-dependent conditions are derived for the analysis and feedback control synthesis of the closed-loop system in the presence of uncertainties and exogenous disturbances. Disturbance rejection objectives following an induced -norm and an norm formulation are examined. Estimation of the domain of attraction with the parametrisation of the admissible LPV controllers is presented. Three different optimisation objectives with respect to disturbance rejection, disturbance tolerance, and domain of attraction expansion are formulated. The proposed design methodology is examined in the context of the air-fuel ratio (AFR) regulation in a spark ignition (SI) engine with a speed-dependent delay and model parameters in the presence of canister purge disturbances and AFR dynamics uncertainty. The injector is restricted in the amount of fuel it can deliver to the cylinder. The three-way catalytic converter's performance in terms of oxygen storage and emission reduction is taken into consideration. Closed-loop simulation results are provided to validate the methodology.

Analysis and experimental research on the influence of VVT point selection on exhaust temperature in low speed operating conditions

During the development of a model equipped with dual VVT engines, a higher temperature of the catalyst was discovered. Therefore, the sweep point of VVT is optimized under low speed and high load conditions. The test results show that VVT has a significant effect on the temperature of the catalytic converter, and the temperature of the catalytic converter has decreased after optimization. At the same time, the VVT opening has little effect on the dynamics. In addition, VVT has an effect on the knocking tendency of the engine. When the knocking tendency increases, the temperature of catalytic converter and power performance of the engine are deteriorated. On the contrary, if the ignition angle can be advanced, the performance of the engine can be optimized.

Mathematical modeling of automotive catalytic converter for catalytic combustion of the volatile organic compound (voc) methane

Monolithic catalytic converters are used to minimize the emission of air pollutants to the environment. Volatile organic compounds (VOCs) are seen to be released in considerable amounts from these catalytic converters during the warm-up period. In this paper, the conversion of a slow oxidizing volatile organic compound (VOC) methane is analysed with numerical simulation using a noble metal catalyst (Pt/δ-Al2O3) and metal oxide catalyst CuO/δ-Al2O3. The transient, one-dimensional monolith model is developed using gas-phase energy balance, solid-phase energy balance, and gas-phase mass balance. The unsteady state analysis consists of a system of partial differential equations (PDEs). These equations are solved using an Implicit Scheme with the help of Matlab software. The conversion of methane is analysed with reaction temperature for both Pt/δ-Al2O3 catalyst and CuO/δ-Al2O3 catalyst. Also, the effect of the ageing of catalysts on catalytic converter performance was analysed.

Industrial scale 3D printed catalytic converter for emissions control in a dual-fuel heavy-duty engine

A full size ceramic substrate was successfully prepared using a robocasting 3D printer and tested as a methane oxidation catalyst in the after treatment system (ATS) of a heavy-duty diesel engine, converted to co-combust (dual fuel) with natural gas (NG). The 3D printed substrate performance exceeded that of a commercially sourced straight-channelled DOC over most working conditions, despite the 3D printed structure having a lower precious group metal (PGM) loading and channels per square inch (CPSI) density. At moderate and high inlet temperatures, where the reaction rate is limited by internal and external mass transfer, the enhanced catalytic activity of the 3D printed substrate is attributed to the generation of internal turbulence, which increases oxidation rates of methane (CH4) and non-methane hydrocarbons (NMHC). In contrast, there is relatively little difference between the catalytic activity of the 3D and straight-channelled substrates at low temperatures (e.g. cold start up), where the reaction is kinetically controlled and the additional turbulence/mass transfer of the 3D printed complex structure did not measurably alter the catalytic converter performance. Computational fluid dynamics (CFD) confirmed the increased turbulence within the channels of the 3D printed structure. We also report the effects of NG substitution on the fuel combustion efficiency under different engine load settings. The findings provide proof of concept evidence that 3D printing is a suitable means of designing a catalytic converter prototype with higher reaction activity than a conventionally extruded structure. This has significant implications for the design and potential mass production of new catalytic converters with enhanced efficiencies.

Effect of geometric parameters on the performance of motorcycle catalytic converters

The critical environmental issues of the Indonesian automotive market growth are the increase in air pollution. Vehicle exhaust emission can cause significant problems for the human health and the environment. Therefore, vehicle emission control is indispensable to mitigate the environmental problem. One of the most widely used methods to reduce automotive emission is utilization of catalytic converter in exhaust system. In fact, the catalyst performance in the reduction of noxious gases depends on its material and geometric design. This study aims to evaluate the effect of geometric parameter on the performance of motorcycle catalytic converters. In this experimental study, the catalytic converter made of brass foil plate is mounted on motorcycle muffler. The effectiveness of three catalyst geometry models namely flat perforated plate, folded perforated plate and rolled brass sheet, will be evaluated in relation to the reduction of hydrocarbon (HC) and carbon monoxide (CO) content. HC and CO emission levels are measured by four gas analyzers. The results show that the geometric parameter has a significant effect on HC and CO’s composition in the exhaust gas. For idle speed test, the second geometry model of catalyst presents the best performance in reduction of Hydrocarbon and CO2 concentration.

Potential fly ash waste as catalytic converter for reduction of HC and CO emissions

The huge amount of fly ash produced in the coal industry has caused environmental problems. This research presents the performance of catalytic converters manufactured from coal fly ash for the reduction of gas emissions of a motor vehicle. At idle engine speed and 0.1 MPa air pressure, the presence of activated fly ash as a catalytic converter could reduce the emissions of hydrocarbons (HC) and carbon monoxide (CO) up to 48 and 45%, respectively. The increase in the length of catalytic converter could further decrease the emissions of HC and CO. By increasing the engine speed, the emissions decreased with or without catalytic converter. The optimum air pressure was obtained at 0.1 MPa. The minimum emissions of HC and CO were observed at the engine speed of 2000 rpm, catalyst length of 9 cm and air pressure of 0.1 MPa with the value of 1260 and 8510 ppm, respectively. Therefore, the utilization of fly ash as catalytic converter in the exhaust system motor vehicles can minimize several environmental problems such as fly ash waste and gas emission.

Improving catalytic converter performance by controlling the structural and redox properties of Zr-doped CeO2 nanorods supported Pd catalysts

The work herein introduces a facile and novel synthesis procedure for producing Zr-doped CeO2 nanorod catalysts applicable for upgrading the car catalytic converter system. Four different concentrations of Zr-doped CeO2 nanorods (5, 10, 15, and 20 mol%) were synthesized. Some characterization techniques were utilized to describe their structure. Pd metal was impregnated on the CexZr1−xO2–Al2O3. The activity and selective oxidation of the major pollutants from motor vehicles such as CO, NOx, and CH were studied in a down-flow microreactor. The Zr ions were successfully doped into the ceria lattice, positively influencing the specific surface area, which had a major impact on the efficiency of the catalyst. The optimum Zr-doped catalyst was found to be Pd/Ce0.8Zr0.2O2–Al2O3 with the highest surface area (SBET = 111) and higher activity at lowest oxidation temperature (T90%) of 205 and 360 for CO and CH and T70% of 460 for NOx. Pd/Ce0.8Zr0.2O2–Al2O3 showed potential to be used in the car catalytic converter system, resulting in the production of a cost-effective catalyst for a more efficient automotive industry.

Modeling of three-way catalytic converter performance with exhaust mixtures from dithering natural gas-fueled engines

The behavior of a three-way catalytic converter (TWC) to treat the exhaust from a natural-gas fueled engine in fuel dithering conditions was evaluated by numerical simulation. A validated comprehensive and thermodynamically consistent surface reaction mechanism was utilized to model the natural gas engine exhaust conversion in the TWC at dithering conditions. The mechanism was implemented in a tank-in-series model to study the TWC behavior while air to fuel ratio was cyclically varied (dithering conditions). The simulation results were evaluated by comparison with data collected from a TWC operated at dithering conditions. The microkinetic reaction model predicted the post catalyst total hydrocarbon (THC), NO and CO concentrations well when 5 reaction steps out of 115 elementary steps were modified. Both simulations and experiments showed that TWC window widened in the dithering conditions, particularly dithering yielded improved NO conversion as compared to steady state operation at higher air to fuel ratios. Simulations showed that this was due to a higher number of surface vacancies with dithering that improved NO adsorption and surface reaction. Both dithering parameter including amplitude and frequency was modeled and the results indicated there is an optimal dithering amplitude to achieve lower exhaust emission, larger dithering amplitude decreased the THC conversion because the air fuel ratio shifted to the fuel rich side. Simulations indicated that the dithering frequency did not noticeably impact the exhaust conversion simply because the transition time is relative short.

Emission Treatment towards Cold Start and Back Pressure in Internal Combustion Engine against Performance of Catalytic Converter: A Review

Nowadays, regulation for the vehicles emissions has becoming more stringent in order to reduce the effect of pollutant gases that was being released by the vehicles exhaust. The development of catalytic converter is to resolve the pollution emission aspect. There are lots of improvements done by the researchers towards improving catalytic converter, yet there are still key issues which give negative impact to the environment. One of the problems that are being concern by among of researchers is the cold-start and back pressure problems that usually occur in the composition of catalytic converter. Presented here is a review of cold-starts and back pressure problems together with several alternatives taken by not affecting the performance of vehicles engine and fuel consumption. The review also includes alternative system development and selection of materials to resolve these problems.

Modeling of three-way catalytic converter performance with exhaust mixture from natural gas-fueled engines

The ability of a three-way catalytic converter (TWC) to treat the exhaust from a natural-gas fueled engine was evaluated by numerical simulation. A comprehensive and thermodynamically consistent surface reaction mechanism describing the surface reactions in the TWC was built by compiling elementary-step reaction kinetics involving CH4, CO, formaldehyde, NO, NH3 and N2O from literature sources. The reaction parameters are taken from literatures and fitting calculations. The mechanism was implemented in a one-dimensional PFR model describing a single channel of the catalyst. The simulation results were evaluated by comparison with field data collected from a TWC operated isothermally at steady-state. The model predicted the major trends in conversion/formation of all species in the TWC over a wide range of air to fuel ratios. Sensitivity analysis was utilized to study the key reaction steps that impact the exhaust emission mole fraction. It was found that methane, NO, CO and formaldehyde are most sensitive to the corresponding adsorption steps, while NH3 and N2O are sensitive to the reactions that relate to their formations, such as reactions involving surface hydrogen atoms for NH3 and NO for N2O.

Development of Catalytic Converter Using Non-Precious Metals

This paper shows the uses of low cost metal for the development of catalytic converters. While bringing down the cost, attention must be paid on the performance capability of the catalytic converter. The objective of this work is to develop and design a low cost catalytic converter using copper as the main catalyst in the catalyst system. Copper powder was chosen as the alternative catalyst to reduce the use of precious group metals (PGMs) platinum, palladium, and rhodium. A spark ignition engine’s catalytic converter has to perform the oxidation of CO, oxidation of HC and reduction of NOxsimultaneously in order to satisfy its performance requirement. These three chemical reactions are taking place simultaneously in a three way catalytic converter. To investigate the chemical kinetics and fluid flow characteristics of a catalytic converter, simulations have been carried out using COMSOL. From COMSOL MULTIPHYSICS, catalytic converter’s velocity field and pressure distribution have been simulated. From COMSOL REACTION ENGINEERING LAB, NO and CO concentration from a catalytic converter kinetics model have been plotted. NO and CO conversion for different air to fuel ratio had shown that for rich mixture, NO reduction reaches its maximum but CO oxidation is at its minimum. In lean mixture, CO oxidation is at its maximum but NO reduction is at its minimum. Simulations have shown the actual characteristics of the catalytic converter performance. The flow throughout catalytic converter and the backpressure have successfully determined and the catalyst conversion efficiency also shown clearly.

On the primary emission of formic acid from light duty gasoline vehicles and ocean-going vessels

We present determinations of fuel-based emission factors for formic acid (EFHCOOH) from light duty gasoline vehicles (LDGVs) and in-use ocean-going vessels. Emission ratios, from which the emission factors were derived, were determined from LDGVs through measurement of HCOOH and carbon dioxide (CO2) in the exhaust of a fleet of eight LDGVs driven under the California Unified Cycle at the California Air Resources Board's Haagen-Smit Laboratory. Emission ratios from in-use ocean-going vessels were determined through direct measurement of HCOOH and CO2 in ship plumes intercepted by the R/V Atlantis during the 2010 California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign within 24 nautical miles of the California coast. The eight car fleet average EFHCOOH was 0.94 ± 0.32 (1σ) and 0.57 ± 0.18 mg (kg fuel)−1 for the cold start and hot running phases of the drive cycle, respectively. This difference suggests that catalytic converter performance and the air/fuel equivalence ratio are important metrics contributing to EFHCOOH. EFHCOOH was determined to be 1.94 ± 1.06 mg (kg fuel)−1 for a single diesel vehicle driven under highway driving conditions, higher on average than any individual LDGV tested. In comparison, HCOOH primary emissions from in-use ocean-going vessels were substantially larger, averaging 20.89 ± 8.50 mg (kg fuel)−1. On a global scale, HCOOH primary emissions from fossil fuel combustion are likely to be insignificant relative to secondary production mechanisms, however primary emissions may contribute more significantly on a finer, regional scale in urban locations.

A case study in multi‐scale model reduction: The effect of cell density on catalytic converter performance

One of the challenges of full‐scale computer simulation of a catalytic reactor is to consider the different scales involved in the problem in a practical fashion. In a monolith catalytic converter, these scales range from the molecular scale for the reactions, through the pore scale, washcoat scale, channel scale, and finally the full converter scale. This paper describes the implementation of a model reduction methodology using look‐up tables to perform a consistent comparison of six different catalytic converters used for the catalytic combustion of methane. A detailed mechanistic model for methane combustion is used. Diffusion in the non‐uniform washcoat is considered. The converters have different cell densities and wall thicknesses. Steady state and transient light‐off simulations are performed. Efficient computational speed is achieved by successive model reduction, which allows the preservation of detailed small‐scale information. The results obtained show that there is a non‐intuitive relationship between the various operating parameters, which can only be deduced from a comprehensive model.