Browse Topic: Exhaust systems
As hydrogen internal combustion engines (H2-ICE) gain traction, optimizing exhaust aftertreatment technologies for nitrogen oxide (NOx) control has become increasingly critical. While selective catalytic reduction (SCR) systems remain the primary approach for NOx mitigation, oxidation catalysts are also being explored to facilitate hydrogen oxidation and improve overall exhaust treatment efficiency. This work presents a multifunctional catalyst (MFC) concept that combines supported Pd and Cu-zeolite to enable simultaneous NOx reduction and hydrogen oxidation within a single catalytic unit. Preliminary results show that hydrogen oxidation on supported Pd occurs above 300 °C, while Cu-zeolite achieves nearly complete NOx conversion. Experiments on individual components indicate that supported Pd initiates ammonia oxidation only after hydrogen is depleted. In the presence of hydrogen, ammonia conversion remains below 20%, indicating that hydrogen availability suppresses ammonia oxidation
This study presents a fully integrated, vehicle-level thermal management model for gasoline fuel tanks, designed to predict transient fuel temperatures, tank wall heating, and vapor generation under real-world driving conditions. The model simulates coupled thermal contributions from exhaust radiation, transient underbody airflow, conductive heat transfer, in-tank pump heating, and dynamic changes in fuel composition and level. Validation against on-road measurements shows strong agreement for fuel temperature and vapor flow profiles. Results confirm that exhaust radiative heating is the dominant thermal load, particularly during the post-shutdown heat soak period. A well-designed heat shield reduced peak tank wall temperature by approximately 27 °C, significantly lowering fuel heating and evaporation. Parametric analysis indicates that while fuel Reid Vapor Pressure (RVP) and tank material influence evaporation, their effect is secondary to external heat mitigation. While this model
Fe/zeolite selective catalytic reduction (SCR) catalysts are commercially used for NOx emissions reduction from diesel engines. In comparison to Cu/zeolite, these catalysts are widely reported to form less N2O as a byproduct of the SCR reactions. However, Fe/zeolite SCR is less active than Cu/zeolite for low temperature NOx conversion under standard SCR conditions. In this study, a state-of-the-art Fe/zeolite SCR catalyst is probed with a combination of N2 physisorption, SEM/EDX, reactor-based performance and active site quantification. Measurements investigate the impact of degreening, mild and extreme hydrothermal aging. In a degreened condition, the impact of water vapor on standard and fast SCR and isothermal desorption of NH3 is assessed. The Fe/zeolite catalyst’s hydrothermal durability is studied following hydrothermal aging at temperatures from 550°C up to 950°C. NH3 adsorption and temperature programmed desorption (TPD) and NO2 adsorption and TPD experiments are used to
This paper presents the collaborative efforts of the USCAR GPF OBD Working Group to evaluate and recommend On-Board Diagnostic (OBD) monitoring requirements for Gasoline Particulate Filters (GPFs). The group, comprising representatives from major OEMs, aims to establish a unified understanding of GPF monitoring capabilities and propose regulatory recommendations to CARB. The paper outlines the physics of soot generation and oxidation, regulatory interpretations, and diagnostic strategies, culminating in a proposed framework for GPF OBD compliance. The material in this paper was previously presented at the 2024 SAE OBD Symposium [1].
In the pursuit of achieving stringent BS VI emission standards, maintaining the efficiency of Selective Catalytic Reduction (SCR) systems is paramount, especially in vehicles operating under low duty cycles. A significant concern in such scenarios is the accumulation of urea deposits within the SCR, which can lead to detrimental push-out effects and compromised catalyst performance. This issue is particularly prevalent during low-temperature operations, where the conditions are less favorable for the effective conversion of nitrogen oxides (NOx). To address this challenge, an innovative software control system has been developed to monitor operating conditions and detect potential urea deposit faults. The software continuously evaluates parameters such as temperature and vehicle duty cycle, identifying conditions that may lead to urea crystallization within the SCR system. When unfavorable conditions are detected, the software triggers a fault alert that activates a regeneration
Internal Combustion Engine (ICE) is the heart of an Automobile. The failure of any critical component of the ICE engine will directly affect the performance of the vehicle. The gaskets are among the many vital parts of an IC engine that are essential in ensuring appropriate sealing to prevent gas and liquid leakage and maintain optimal engine efficiency. Engines use a variety of gasket types to accommodate various sealing requirements. Among them the exhaust manifold gaskets are one of the critical gasket elements in ICE engines. Exhaust Gasket acts as a seal between cylinder head and extremely hot exhaust manifold, which prevents the leakage of hot exhaust gases produced during typical engine operating condition. The gaskets are crucial components because they endure extremely high mechanical loads from the exhaust manifold sliding and banana-shaped bending brought on by thermal expansion, as well as extremely high thermal loads from the high exhaust gas temperatures, which are more
This study addresses the challenge of ensuring the durability of closed couple exhaust manifolds in the compact engine bays of modern vehicles, focusing on a longitudinally mounted 1.2L 4-cylinder engine. The original sheet metal Exhaust manifold design failed the thermal fatigue bench durability test, requiring a complete redesign to improve strength without changing materials. Initial simulation predictions significantly deviated from physical test results, with repeated cracks observed during accelerated thermal fatigue bench testing, despite simulations predicting a higher number of cycles before failure. This difference highlighted the need for a deeper understanding of the manifold's failure modes, primarily thermal fatigue, and mechanical vibration during engine transients. The design of experiment (DOE) approach was used to find the effect of different parameters e.g., gas temperature, surface temperature, air flow, thermal gradient, on the durability result & also to
With the expansion of compressed natural gas (CNG) filling station in India, bi-fuel vehicles are gaining popularity in recent times. Bi-fuel engine runs on more than one fuel, say in both CNG and petrol. Hence, the engine must be optimized in both the fuel modes for performance and emissions. However, due to the inherent differences in combustion characteristics: ignition dynamics and fuel properties, they pose a significant challenge in case of detection of misfires. Misfires are caused because of faulty injection systems and ignition systems and incorrect fuel mixture. Accurate detection is essential as misfires deteriorate the catalysts performance and may impacts emission. Misfires (or engine roughness) is calculated from engine crankshaft speed signal. In this study, the effectiveness of crankshaft-based misfires detection method, comparison of misfire signals magnitude in bi-fuel modes and practices developed for accurate detection of misfires is presented.
Environmental pollution is one of the growing concerns of our society. As vehicle emissions are a major contributor to air pollution, emission control is a primary goal of the Automotive industry. Vehicle emissions are higher due to improper combustion, which leads to toxic gases being generated from the exhaust system. Unburnt fuel is one of the leading causes of toxic pollutants such as Carbon Monoxide, Nitric Oxides (NOx) and Hydrocarbons. The catalytic converter converts these gases into less toxic substances such as Carbon Dioxide, Nitrogen, and water vapor. The catalytic converter performs efficiently after reaching its “Light Off” temperature, after which the catalyst becomes active. Hence, elevated temperature of the exhaust gases aids in efficient conversion. Presently, the gases from the exhaust system are approximately at a temperature of 300°C-600°C. This paper outlines the concept of a Peltier (Thermoelectric) Module - based system, which helps maintain the high
The study emphasizes on development of Diesel Exhaust Fluid (DEF) dosing system specifically used in Selective Catalytic Reduction (SCR) of diesel engine for emission control, where a low pressure pumpless DEF dosing system is developed, utilizing compressed air for pressurizing the DEF tank and discharging DEF through air assisted DEF injection nozzle. SCR systems utilize Diesel Exhaust Fluid (DEF) to convert harmful NOx emissions from diesel engines into harmless nitrogen and water vapor. Factors such as improper storage, handling, or refilling practices can lead to DEF contamination which pose significant operational challenges for SCR systems. Traditional piston-type, diaphragm-type, or gear-type pumps in DEF dosing systems are prone to mechanical failures leading to frequent maintenance, repairs, and costly downtimes for vehicles. To overcome the existing challenges and to create a more reliable and simple DEF delivery mechanism the pumpless DEF Dosing system is developed. The
This paper is to introduce a new catalyst family in gasoline aftertreatment. The very well-known three-way catalysts effectively reduce the main emission components resulting from the combustion process in the engine, namely THC, CO, and NOx. The reduction of these harmful emissions is the main goal of emission legislation such as Bharat VI to increase air quality significantly, especially in urban areas. Indeed, it has been shown that under certain operating conditions, three-way catalysts may produce toxic NH3 and the greenhouse gas N2O, which are both very unwanted emissions. In a self-committed approach, OEMs could want to minimize these noxious pollutants, especially if this can be done with no architecture change, namely without additional underfloor catalyst. In most Bharat VI gasoline aftertreatment system architectures, significant amounts of NH3 occur in two phases of vehicle driving: situations with the catalyst temperature below light-off, which appear after cold start or
In pursuit of a distinct sporty interior sound character, the present study explores an innovative strategy for designing intake systems in passenger vehicles. While most existing literature primarily emphasizes exhaust system tuning for enhancing vehicle sound quality, the current work shifts the focus toward the intake system’s critical role in shaping the perceived acoustic signature within the vehicle cabin. In this research work, target cascading and settings were derived through a combination of benchmark and structured subjective evaluation study and aligning with literature review. Quantitative targets for intake orifice noise was defined to achieve the desired sporty character inside cabin. Intake orifice targets were engineered based on signature and sound quality parameter required at cabin. Systems were designed by using advanced NVH techniques, Specific identified acoustic orders were enhanced in the intake system to reinforce the required signature in acceleration as well
The legislation of CEV Stage V emission norms has necessitated advanced Diesel Particulate Filter calibration strategies to ensure optimal performance across diverse construction equipment applications in the Indian market. Considering the various duty cycles of cranes, backhoe loaders, forklifts, compactors, graders, and other equipment, different load conditions and operational environments require a comprehensive strategy to enhance DPF efficiency, minimize regeneration frequency, and maintain compliance with emission standards. The DPF, as an after-treatment system in the exhaust layout, is essential for meeting emission standards, as it effectively traps particulate matter. Regeneration occurs periodically to burn the soot particles trapped inside the DPF through ECU management. Therefore, understanding soot loading and in-brick DPF temperature behavior across various applications is key. This paper explores the challenges in DPF calibration for CEV Stage V and provides a
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