Efficiency enhancement of spark-ignition engines using a Continuous Variable Valve Timing system for load control

Energy ◽  
2018 ◽  
Vol 161 ◽  
pp. 649-662 ◽  
Author(s):  
Julian D. Osorio ◽  
Alejandro Rivera-Alvarez
Keyword(s):  
Spark Ignition ◽  
Continuous Variable ◽  
Load Control ◽  
Variable Valve Timing ◽  
Spark Ignition Engines ◽  
Efficiency Enhancement ◽  
Valve Timing ◽  
Timing System ◽  
Variable Valve

Controlling Backfire Using Changes of the Valve Overlap Period for a Hydrogen-Fueled Engine Using an External Mixture

2007 ◽  
Author(s):  
T. C. Huynh ◽  
J. K. Kang ◽  
K. C. Noh ◽  
Jong T. Lee ◽  
J. A. Caton
Keyword(s):  
High Efficiency ◽  
Engine Performance ◽  
Continuous Variable ◽  
Operating Conditions ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Wide Range ◽  
Timing System ◽  
Variable Valve ◽  
Valve Overlap

The development of a hydrogen-fueled engine using an external mixture (e.g., using port or manifold fuel injection) with high efficiency and high power is dependent on the control of backfire. This work has developed a method to control backfire by reducing the valve overlap period while maintaining or improving engine performance. For this goal, a single-cylinder hydrogen-fueled research engine with a mechanical continuous variable valve timing system was developed. This facility provides a wide range of valve overlap periods that can be continuously and independently varied during firing operation. By using this research engine, the behavior of backfire occurrence and engine performance are determined as functions of the valve overlap period for fuel-air equivalence ratios between 0.3 and 1.2. The results showed that the developed hydrogen-fueled research engine with the mechanical continuous variable valve timing system has similar performance to a conventional engine with fixed valve timings, and is especially effective in controlling the valve overlap period. Backfire occurrence is reduced with a decrease of the valve overlap period, and is also significantly decreased even under operating conditions with the same volumetric efficiency. These results demonstrate that decreasing the valve overlap period may be one of the methods for controlling backfire in a hydrogen-fueled engine while maintaining or improving performance.

Controlling Backfire for a Hydrogen-Fueled Engine Using External Mixture Injection

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
T. C. Huynh ◽  
J. K. Kang ◽  
K. C. Noh ◽  
Jong T. Lee ◽  
J. A. Caton
Keyword(s):  
High Efficiency ◽  
Engine Performance ◽  
Continuous Variable ◽  
Operating Conditions ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Wide Range ◽  
Timing System ◽  
Variable Valve ◽  
Valve Overlap

The development of a hydrogen-fueled engine using external mixture injection (e.g., using port or manifold fuel injection) with high efficiency and high power is dependent on the control of backfire. This work has developed a method to control backfire by reducing the valve overlap period while maintaining or improving engine performance. For this goal, a single-cylinder hydrogen-fueled research engine with a mechanical continuous variable valve timing system was developed. This facility provides a wide range of valve overlap periods that can be continuously and independently varied during firing operation. By using this research engine, the behavior of backfire occurrence and engine performance are determined as functions of the valve overlap period for fuel-air equivalence ratios between 0.3 and 1.2. The results showed that the developed hydrogen-fueled research engine with the mechanical continuous variable valve timing system has similar performance to a conventional engine with fixed valve timings, and is especially effective in controlling the valve overlap period. Backfire occurrence is reduced with a decrease in the valve overlap period, and is also significantly decreased even under operating conditions with the same volumetric efficiency. These results demonstrate that decreasing the valve overlap period may be one of the methods for controlling backfire in a hydrogen-fueled engine while maintaining or improving performance.

scholarly journals Impact of Exhaust Gas Recirculation on Gaseous Emissions of Turbocharged Spark-Ignition Engines

2020 ◽  
Vol 10 (21) ◽  
pp. 7634
Author(s):  
Pedro Piqueras ◽  
Joaquín De la Morena ◽  
Enrique José Sanchis ◽  
Rafael Pitarch
Keyword(s):  
Nitrogen Oxides ◽  
Exhaust Gas Recirculation ◽  
Spark Ignition ◽  
Exhaust Gas ◽  
Variable Valve Timing ◽  
Spark Ignition Engines ◽  
Gaseous Emissions ◽  
Valve Timing ◽  
Variable Valve ◽  
Gas Recirculation

Exhaust gas recirculation is one of the technologies that can be used to improve the efficiency of spark-ignition engines. However, apart from fuel consumption reduction, this technology has a significant impact on exhaust gaseous emissions, inducing a significant reduction in nitrogen oxides and an increase in unburned hydrocarbons and carbon monoxide, which can affect operation of the aftertreatment system. In order to evaluate these effects, data extracted from design of experiments done on a multi-cylinder 1.3 L turbocharged spark-ignition engine with variable valve timing and low-pressure exhaust gas recirculation (EGR) are used. The test campaign covers the area of interest for the engine to be used in new-generation hybrid electric platforms. In general, external EGR provides an approximately linear decrease of nitrogen oxides and deterioration of unburned hydrocarbon emissions due to thermal and flame quenching effects. At low load, the impact on emissions is directly linked to actuation of the variable valve timing system due to the interaction of EGR with internal residuals. For the same external EGR rate, running with high valve overlap increases the amount of internal residuals trapped inside the cylinder, slowing down combustion and increasing Unburnt hydrocarbon (HC) emissions. However, low valve overlap (i.e., low internal residuals) operation implies a decrease in oxygen concentration in the exhaust line for the same air–fuel ratio inside the cylinders. At high load, interaction with the variable valve timing system is reduced, and general trends of HC increase and of oxygen and carbon monoxide decrease appear as EGR is introduced. Finally, a simple stoichiometric model evaluates the potential performance of a catalyst targeted for EGR operation. The results highlight that the decrease of nitrogen oxides and oxygen availability together with the increase of unburned hydrocarbons results in a huge reduction of the margin in oxygen availability to achieve a complete oxidation from a theoretical perspective. This implies the need to rely on the oxygen storage capability of the catalyst or the possibility to control at slightly lean conditions, taking advantage of the nitrogen oxide reduction at engine-out with EGR.

A novel volumetric efficiency model for spark ignition engines equipped with variable valve timing and variable valve lift Part 1: model development

2016 ◽  
Vol 231 (2) ◽  
pp. 175-191 ◽  
Author(s):  
Amir Hasan Kakaee ◽  
Behrooz Mashadi ◽  
Mostafa Ghajar
Keyword(s):  
Experimental Data ◽  
Spark Ignition ◽  
Volumetric Efficiency ◽  
Valve Lift ◽  
Variable Valve Timing ◽  
Spark Ignition Engines ◽  
Valve Timing ◽  
Real Time Applications ◽  
Variable Valve Lift ◽  
Variable Valve

Estimation of the air charge and the volumetric efficiency is one of the most challenging tasks in the control of internal-combustion engines owing to the intrinsic complexity and the non-linearity of the gas flow phenomena. In particular, with emerging new technologies such as systems with variable valve timing and variable valve lift, the number of effective parameters increases greatly, making the estimation task more complicated. On the other hand, using a three-way catalyst converter needs strict control of the air-to-fuel ratio to around the stoichiometric ratio, and hence more accurate models are required for estimation of the air charge. Therefore, various models have been proposed in the literature for estimation of the volumetric efficiency and the air charge. However, they are either strictly based on physical first principles, making them impractical for conventional applications, or nearly fully empirical and need many experimental data for calibration. In this paper, using a novel approach, a new semiempirical model is proposed for estimation of the volumetric efficiency, which is calibrated with very few experimental data and can be used easily for real-time applications. In addition to the valve timings, the engine speed and the intake manifold pressure, the inlet valve lift is also considered as the model input. The generalizability of the model is proved by applying it to estimate the volumetric efficiency of six different engines. Furthermore, a systematic approach is taken to simplify the proposed model and to strengthen its prediction capability. The result is a simple, practical and generalizable model which can be used for various spark ignition engines, can be trained with very few data and can be utilized for estimating accurately the volumetric efficiency in real-time applications.

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