Effect of injection strategies on a single-fuel RCCI combustion fueled with isobutanol/isobutanol + DTBP blends

© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence (http://creativecommons.org/licenses/by-nc-nd/4.0/).In recent years, improved combustion controllability through in-cylinder reactivity stratification by using two different fuels have led to introduction of dual-fuel reactivity controlled compression ignition (RCCI) strategy. In conventional RCCI, gasoline or natural gas can be used as the low-reactivity fuel, and diesel or biodiesel can be used as the high-reactivity fuel. This strategy has the potential to operate with a single low-reactivity fuel and direct injection (DI) of the same fuel blended with a small amount of cetane improver. In the present study, numerical simulations have been carried out to study injection strategy in a single-fuel RCCI engine fueled with isobutanol – isobutanol + 20% di-tert-butyl peroxide (DTBP). Firstly, the effects of start of injection (SOI) timing, injection pressure (pinj), spray cone angle (SCA), and DI fuel ratio were explored. Then, the effect of DI fuel ratio was discussed in each best case in order to decrease the high DI requirement. The results indicate that SOI = −88° ATDC, pinj = 1400 bar, and SCA = 45° can improve the single-fuel RCCI engine performance and emissions compared to the baseline case (SOI = −58° ATDC, pinj = 600 bar, SCA = 72.5°). Moreover, it is shown that by advancing the SOI timing to −88° ATDC, a 20% reduction in DI ratio, 3.3% increase in gross indicated efficiency (GIE) together with reductions in CO, and NOx emissions by 3.56 g/kW-h and 0.254 g/kW-h, could be achieved, respectively.Peer reviewedFinal Accepted Versio

Geometry optimization of double wishbone suspension system via genetic algorithm for handling improvement

Motion control, stability maintenance and ride comfort improvement are fundamental issues in design of suspension systems in off-road vehicles. In this paper, a double wishbone (DW) suspension system, mostly used in off-road vehicles, is modeled using ADAMS software. Geometric parameters of suspension system are optimized using genetic algorithm (GA) in a way that ride comfort, handling and stability of vehicle are improved. Simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in ADAMS and effects of optimization of suspension system during various driving maneuvers in both optimized and non-optimized conditions are compared. Simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance

THE INFLUENCE OF GEOMETRIC PARAMETERS AND MECHANICAL PROPERTIES OF ADHESIVE ON STRESS ANALYSIS IN ADHESIVELY BONDED ALUMINUM SINGLE LAP JOINT

The aim of this study was to investigate adhesively bonded joints, and the influence of geometric parameters and mechanical properties of the adhesive in single lap aluminum structures under tensile load. A finite element model has been constructed in the ANSYS FE package and the effects of adhesive thickness, rigidity, strength and geometry have been studied in order to adjust peel stress. Various paths have been defined and obtained along the length of the adhesive and aluminum joint overlap. The results indicate that by increasing the adhesive thickness, the stress concentration decreases in the areas prone to yielding if a flexible adhesive is used instead of a rigid one, and effective stresses along the overlap length are also reduced. In addition, for a given tensile force, three different adhesive area geometries are defined. Considering the variation of peel and shear stress along the corners, the amount of adhesive used according to the introduced geometries is saved without sacrificing joint strength

Analytical framework for analyzing brake squeal noise using assumed-modes approach

Sometimes a loud noise or high pitched squeal occurs when the brakes are applied. It is generated during the braking phase and is characterized by a harmonic spectrum. Brake squeal is induced by self-excited vibrations, consequences of local nonlinearities at the contact interface. Many researchers have examined the problem with experimental, analytical, and computational techniques, but there is still no method to fully annihilate brake squeal. This paper deals with presentation of a new model to analyze the brake squeal behavior. In this paper, a lumped-continuous vibration model is presented for the braking system and nonlinear equations are obtained using the Hamilton’s principle. Then, the linearization of nonlinear equations is done around the equilibrium point of system and linear stability analysis is discussed. Furthermore, the effects of different braking parameters such as friction coefficient, rotational speed, pad stiffness, calipers etc. on the brake squeal noise are investigated

Reactivity controlled compression ignition engine: Pathways towards commercial viability

© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence (http://creativecommons.org/licenses/by-nc-nd/4.0/).Reactivity-controlled compression ignition (RCCI) is a promising energy conversion strategy to increase fuel efficiency and reduce nitrogen oxide (NOx) and soot emissions through improved in-cylinder combustion process. Considering the significant amount of conducted research and development on RCCI concept, the majority of the work has been performed under steady-state conditions. However, most thermal propulsion systems in transportation applications require operation under transient conditions. In the RCCI concept, it is crucial to investigate transient behavior over entire load conditions in order to minimize the engine-out emissions and meet new real driving emissions (RDE) legislation. This would help further close the gap between steady-state and transient operation in order to implement the RCCI concept into mass production. This work provides a comprehensive review of the performance and emissions analyses of the RCCI engines with the consideration of transient effects and vehicular applications. For this purpose, various simulation and experimental studies have been reviewed implementing different control strategies like control-oriented models particularly in dual-mode operating conditions. In addition, the application of the RCCI strategy in hybrid electric vehicle platforms using renewable fuels is also discussed. The discussion of the present review paper provides important insights for future research on the RCCI concept as a commercially viable energy conversion strategy for automotive applications.Peer reviewe

Synthesis gas as a fuel for internal combustion engines in transportation

© 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).The adverse environmental impact of fossil fuel combustion in engines has motivated research towards using alternative low-carbon fuels. In recent years, there has been an increased interest in studying the combustion of fuel mixtures consisting mainly of hydrogen and carbon monoxide, referred to as syngas, which can be considered as a promising fuel toward cleaner combustion technologies for power generation. This paper provides an extensive review of syngas production and application in internal combustion (IC) engines as the primary or secondary fuel. First, a brief overview of syngas as a fuel is presented, introducing the various methods for its production, focusing on its historical use and summarizing the merits and drawbacks of using syngas as a fuel. Then its physicochemical properties relevant to IC engines are reviewed, highlighting studies on the fundamental combustion characteristics, such as ignition delay time and laminar and turbulent flame speeds. The main body of the paper is devoted to reviewing the effect of syngas utilization on performance and emissions characteristics of spark ignition (SI), compression ignition (CI), homogeneous charge compression ignition (HCCI), and advanced dual-fuel engines such as reactivity-controlled compression ignition (RCCI) engines. Finally, various on-board fuel reforming techniques for syngas production and use in vehicles are reviewed as a potential route towards further increases in efficiency and decreases in emissions of IC engines. These are then related to the research reported on the behavior of syngas and its blends in IC engines. It was found that the selection of the syngas production method, choice of the base fuel for reforming, its physicochemical properties, combustion strategy, and engine combustion system and operating conditions play critical roles in dictating the potential advantages of syngas use in IC engines. The discussion of the present review paper provides valuable insights for future research on syngas as a possible fuel for IC engines for transport.Peer reviewe

Mathematical optimization of variable valve timing for reducing fuel consumption of A SI engine

In this study, the sensitivity analysis and Quasi-Newton algorithms are used to optimize valve timing XU7/L3 engine in order to reduce fuel consumption and increase engine performance. At first, all components of engine are modeled in GT-POWER and a comparison with experimental results is performed to confirm the accuracy of the model. Then, GT-POWER model is coupled with MATLAB-SIMULINK to control inputs and outputs with sensitivity analysis and Quasi-Newton algorithms. The results obtained indicate that optimal valve timing significantly reduces brake specific fuel consumption (BSFC). Moreover, the convergence rate of Quasi-Newton algorithm for reaching the optimal point is higher than the one of sensitivity analysis algorithm

Analytical framework for analyzing brake squeal noise using assumed-modes approach

Sometimes a loud noise or high pitched squeal occurs when the brakes are applied. It is generated during the braking phase and is characterized by a harmonic spectrum. Brake squeal is induced by self-excited vibrations, consequences of local nonlinearities at the contact interface. Many researchers have examined the problem with experimental, analytical, and computational techniques, but there is still no method to fully annihilate brake squeal. This paper deals with presentation of a new model to analyze the brake squeal behavior. In this paper, a lumped-continuous vibration model is presented for the braking system and nonlinear equations are obtained using the Hamilton’s principle. Then, the linearization of nonlinear equations is done around the equilibrium point of system and linear stability analysis is discussed. Furthermore, the effects of different braking parameters such as friction coefficient, rotational speed, pad stiffness, calipers etc. on the brake squeal noise are investigated

Comparative Study on Chemical Kinetics Mechanisms for Methane-Based Fuel Mixtures under Engine-Relevant Conditions

© 2021 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/)The use of natural gas in pure or in a blended form with hydrogen and syngas in spark ignition (SI) engines has received much attention in recent years. They have higher diffusion coefficient and laminar flame speed, a small quenching distance and wider flammability limit which compensate the demerits of the lean-burn natural gas combustion. Therefore, a careful examination of the chemical kinetics of combustion of gaseous fuel blends is of great importance. In this paper, performance of the various chemical kinetics mechanisms is compared against experimental data, accumulated for methane-based fuel blends under engine-relevant conditions to find the most appropriate mechanism in engine simulations. Pure methane, methane/syngas, and methane/propane blends are mainly studied at various temperatures, pressures, and equivalence ratios. The ignition delay time and laminar flame speed are used as quantitative metrics to compare the simulation results with the data from experiments. The mechanisms were shown to be mainly consistent with the experimental data of lean and stoichiometric mixtures at high pressures. It was also shown that the GRI-3.0 and 290Rxn mechanisms have high compatibility with the ignition delay times and laminar flame speed at high pressures and lean conditions, and they can be utilized for simulations of SI engine combustion due to their lower computational cost. The results of present research provide an important contribution to the methane-based fuel blends combustion simulation under SI engine-relevant conditions.Peer reviewe