Effects of intake valve opening duration on performance optimization of an Atkinson cycle engine under part load

2021 ◽  
pp. 095440702110105
Author(s):  
Qingyu Niu ◽  
Baigang Sun ◽  
Yue Wu ◽  
Lingzhi Bao ◽  
Qinghe Luo
Keyword(s):  
Fuel Economy ◽  
Performance Optimization ◽  
Operating Conditions ◽  
Intake Valve ◽  
Compression Pressure ◽  
Part Load ◽  
Atkinson Cycle ◽  
Lower Load ◽  
Valve Opening ◽  
Dimensional Simulation

A comprehensive analysis of the intake valve opening duration (IVOD) effects on the performance of an Atkinson cycle engine is conducted in this work using numerical simulation and experimental validation. Through one-dimensional simulation, the relationship between the range of IVOD and the compression ratios is firstly investigated under the constraint of compression pressure. Two representative IVOD, 295 and 314°CA, are then respectively applied to the performance simulation and experiment of a practical Atkinson cycle engine. The simulation shows the combination of a late intake valve opening timing (IVO) angle and a late exhaust valve opening timing (EVO) angle is profitable for improving the fuel economy under part load operating conditions (i.e. 2000 rpm@2 bar and 3000 rpm@3 bar). The experimental results present the Atkinson cycle engine under both IVOD scenarios considerably improves the brake specific fuel consumption (BSFC) and reduces the pumping mean effective pressure (PMEP) compared to those of the original Otto cycle engine. Meanwhile, the comparison between two IVOD scenarios show that the shorter IVOD leads to an improvement of indicated thermal efficiency, especially at lower load. Considering fuel economy, a shorter IVOD is more favorable at part load for the Atkinson cycle engine. Two main contributions of this work are to numerically quantify the IVOD range for the Atkinson cycle engine under part load, and to experimentally validate the effectiveness of simulation. The findings of this work are expected to support the design of Atkinson cycle engines and provide a guideline of IVOD optimization under part load.

Design, Development, and Evaluation of a Control Framework for an Atkinson Cycle Engine

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
G. Murtaza ◽  
A. I. Bhatti ◽  
Q. Ahmed
Keyword(s):  
Fuel Economy ◽  
Gasoline Engine ◽  
Thermodynamic Cycle ◽  
Mean Value ◽  
Operating Conditions ◽  
Intake Valve ◽  
Design Development ◽  
Engine Model ◽  
Atkinson Cycle ◽  
Control Framework

The efficiency of the spark ignition (SI) engine degrades while working at part loads. It can be optimally dealt with a slightly different thermodynamic cycle termed as an Atkinson cycle. It can be implemented in the conventional SI engines by incorporating advanced mechanisms as variable valve timing (VVT) and variable compression ratio (VCR). In this research, a control framework for the Atkinson cycle engine with flexible intake valve load control strategy is designed and developed. The control framework based on the extended mean value engine model (EMVEM) of the Atkinson cycle engine is evaluated in the view of fuel economy at the medium and higher load operating conditions for the standard new European driving cycle (NEDC), federal urban driving schedule (FUDS), and federal highway driving schedule (FHDS) cycles. In this context, the authors have already proposed a control-oriented EMVEM model of the Atkinson cycle engine with variable intake valve actuation. To demonstrate the potential benefits of the VCR Atkinson cycle VVT engine, for the various driving cycles, in the presence of auxiliary loads and uncertain road loads, its EMVEM model is simulated by using a controller having similar specifications as that of the conventional gasoline engine. The simulation results point toward the significant reduction in engine part load losses and improvement in the thermal efficiency. Consequently, considerable enhancement in the fuel economy of the VCR Atkinson cycle VVT engine is achieved over conventional Otto cycle engine during the NEDC, FUDS, and FHDS cycles.

Effects of passive pre-chamber jet ignition on combustion and emission at gasoline engine

2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110671
Author(s):  
Wei Duan ◽  
Zhaoming Huang ◽  
Hong Chen ◽  
Ping Tang ◽  
Li Wang ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Gasoline Engine ◽  
Combustion Process ◽  
Pressure Rise ◽  
Spark Ignition ◽  
Combustion Stability ◽  
Intake Valve ◽  
Part Load ◽  
Significant Difference ◽  
Valve Opening

Pre-chamber jet ignition is a promising way to improve fuel consumption of gasoline engine. A small volume passive pre-chamber was tested at a 1.5L turbocharged GDI engine. Combustion and emission characteristics of passive pre-chamber at low-speed WOT and part load were studied. Besides, the combustion stability of the passive pre-chamber at idle operation has also been studied. The results show that at 1500 r/min WOT, compared with the traditional spark ignition, the combustion phase of pre-chamber is advanced by 7.1°CA, the effective fuel consumption is reduced by 24 g/kW h, and the maximum pressure rise rate is increased by 0.09 MPa/°CA. The knock tendency can be relieved by pre-chamber ignition. At part load of 2000 r/min, pre-chamber ignition can enhance the combustion process and improve the combustion stability. The fuel consumption of pre-chamber ignition increases slightly at low load, but decreases significantly at high load. Compared with the traditional spark ignition, the NOx emissions of pre-chamber increase significantly, with a maximum increase of about 15%; the HC emissions decrease, and the highest decrease is about 36%. But there is no significant difference in CO emissions between pre-chamber ignition and spark plug ignition. The intake valve opening timing has a significant influence on the pre-chamber combustion stability at idle operation. With the delay of the pre-chamber intake valve opening timing, the CoV is reduced and can be kept within the CoV limit.

Investigation of Performance and Fuel Economy for Cylinder Deactivation Engine at Part Load Operation

2016 ◽  
Vol 819 ◽  
pp. 443-448 ◽  
Author(s):  
S.F. Zainal Abidin ◽  
Mohd Farid Muhamad Said ◽  
Azhar Abdul Aziz ◽  
Mohd Azman Abas ◽  
N.I. Arishad
Keyword(s):  
Fuel Economy ◽  
Fuel Injection ◽  
Injection Timing ◽  
Original Performance ◽  
Part Load ◽  
Automotive Engine ◽  
Engine Efficiency ◽  
Efficiency Performance ◽  
Valve Opening ◽  
Load Conditions

In automotive engine applications, the spark ignition (SI) engines can operate at various engine speed and load conditions. However, most of the time was spend at part load operations, where they operate below their rated output especially during cruising or idling. The needs of improvement in term of engine efficiency at part load operation become more popular among the engine manufacturers. One of the main reasons for efficiency dropped at part load conditions is the flow restrictions at the throttle valve opening area due to nearly-close position to control amount of inducted air into the cylinder, which leads to increasing in pumping losses. Hence, there are a lot of studies and investigations have been carried out to tackle these problems without sacrificing the original performance. This paper will investigate further the engine efficiency, performance as well as fuel economy by using one-dimensional (1-D) simulation tool. A baseline simulation model of a 1.6 liters four cylinders, port fuel injection engine has been developed based on the actual engine geometries. This baseline model applied predictive combustion to predict the amount of cylinder pressure based on actual ignition and injection timing on bench. The simulated results show a very good agreement with the measured data. Additionally, this study also proved that the deactivation half of the cylinders can significantly reduce the pumping losses of fired cylinder while eliminated the pumping work of unfired cylinders.

Study on Intake Performance of Camless Engine

2014 ◽  
Vol 525 ◽  
pp. 198-202
Author(s):  
Ming Hai Xu ◽  
Liang Liu ◽  
Si Qin Chang
Keyword(s):  
Simulation Model ◽  
Mass Flow ◽  
Fuel Economy ◽  
Experimental Results ◽  
Load Control ◽  
Intake Valve ◽  
Camless Engines ◽  
Camless Engine ◽  
Valve Opening ◽  
Research Show

Electromagnetically-driven valve (EMVA) represents one of the most important developments in camless engines, which can realize unthrottled load control. An AVL-BOOST simulation model for a camless engine equipped with EMVA is built up and validated by the experimental results. The performance of the camless engine is simulated, and the intake performance and pumping loss are determined. The results of research show that the mass flow of the camless engine can be controlled by changing the intake valve opening duration, so that the load is controlled. They also show that the pumping loss can be reduced and the fuel economy can be improved during part load.

scholarly journals Simulation study on effect of late-intake-valve-closing Atkinson cycle on the performance of a direct injection engine based on fuel economy

2021 ◽  
Vol 260 ◽  
pp. 01017
Author(s):  
Yue Li ◽  
Zhi Ning ◽  
Ming Lü ◽  
Xin Zhi ◽  
Xian Luo
Keyword(s):  
Fuel Economy ◽  
Direct Injection ◽  
Simulation Software ◽  
Engine Fuel ◽  
Intake Valve ◽  
Direct Injection Engine ◽  
Atkinson Cycle ◽  
Partial Load ◽  
Hybrid Engines ◽  
The Impact

Given the wide application of hybrid engines, how to improve hybrid engine fuel economy is being more and more studied, and using the Atkinson cycle to improve fuel economy is considered effective. In this study, the in-cylinder direct injection engine model was established with the data obtained from a benchmarking test using the GT-POWER simulation software. The working process of this engine was simulated after using Atkinson cycle. This simulation primarily focused on the research of the impact on engine fuel economy with different late intake valve closing strategies. The simulation results were calculated under the partial load conditions which are typically used in hybrid engines. The results indicated that engine fuel economy improved and fuel consumption decreased by using the Atkinson cycle. However, the Atkinson cycle would cause a decrease in power.

Numerical Study of SI Engine Part Load Operating Conditions Using Different VVA Strategies

2011 ◽  
Author(s):  
Michele Battistoni ◽  
Carlo N. Grimaldi ◽  
Francesco Mariani
Keyword(s):  
Numerical Study ◽  
Control Strategies ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Load Control ◽  
Valve Closure ◽  
Intake Valve ◽  
Flamelet Model ◽  
Part Load ◽  
Engine Model

In SI engines, VVA (Variable Valve Actuation) technology is mainly used for the reduction of pumping losses at part load. This paper presents the results of fluid dynamic analyses on a 4V engine about the effects of different VVA strategies, by comparing and discussing the results in terms of organized charge motions, turbulence levels, flame developments, NO and CO emissions. CFD simulations cover five load control cases: comparison is among conventional throttling, EIVC (Early Intake Valve Closure) with symmetric and asymmetric intake lifts, LIVC (Late Intake Valve Closure) and symmetrical Multi-Lift strategies. 3D U-RANS simulations are performed, adopting the Extended Coherent Flamelet Model (ECFM) for the description of premixed SI combustion. The 3D model is also coupled to a 1D engine model which provides inlet/outlet boundary conditions. Simulation results highlight the potential of asymmetric Early Intake Valve Closure (EIVC) strategy which allows reducing pumping losses and, at the same time, achieving good turbulence intensity and combustion speed, if compared to other load control strategies. Multi-Lift strategy resulted excellent in terms of burn duration, but pumping losses are practically the same as in the throttled engine.

scholarly journals Effect of Valve Timing and Excess Air Ratio on Torque in Hydrogen-Fueled Internal Combustion Engine for UAV

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 771 ◽  
Author(s):  
Cheolwoong Park ◽  
Wonah Park ◽  
Yongrae Kim ◽  
Young Choi ◽  
Byeungjun Lim
Keyword(s):  
Gasoline Engine ◽  
Combustion Engine ◽  
Control Unit ◽  
Operating Conditions ◽  
Exhaust Valve ◽  
Airflow Rate ◽  
Intake Valve ◽  
Hydrogen Fuel ◽  
Excess Air ◽  
Valve Opening

In this study, in order to convert a 2.4 L reciprocating gasoline engine into a hydrogen engine an experimental device for supplying hydrogen fuel was installed. Additionally, an injector that is capable of supplying the hydrogen fuel was installed. The basic combustion characteristics, including torque, were investigated by driving the engine with a universal engine control unit. To achieve stable combustion and maximize output, the intake and exhaust valve opening times were changed and the excess air ratio of the mixture was controlled. The changes in the torque, excess air ratio, hydrogen fuel, and intake airflow rate, were compared under low engine speed and high load (wide open throttle) operating conditions without throttling. As the intake valve opening time advanced at a certain excess air ratio, the intake air amount and torque increased. When the opening time of the exhaust valve was retarded, the intake airflow rate and torque decreased. The torque and thermal efficiency decreased when the opening time of the intake and exhaust valve advanced excessively. The change of the mixture condition’s excess air ratio did not influence the tendency of the torque variation when the exhaust valve opening time and torque increased, and when the mixture became richer and the intake valve opening time was fixed. Under a condition that was more retarded than the 332 CAD condition, the torque decreased by about 2 Nm with the 5 CAD of intake valve opening time retards. The maximum torque of 138.1 Nm was obtained at an optimized intake and the exhaust valve opening time was 327 crank angle degree (CAD) and 161 CAD, respectively, when the excess air ratio was 1.14 and the backfire was suppressed. Backfire occurred because of the temperature increase in the combustion chamber rather than because of the change in the fuel distribution under the rich mixture condition, where the other combustion control factors were constantly fixed from a three-dimensional (3D) computational fluid dynamics (CFD) code simulation.

Control-Oriented Model of Atkinson Cycle Engine With Variable Intake Valve Actuation

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
G. Murtaza ◽  
A. I. Bhatti ◽  
Q. Ahmed
Keyword(s):  
Engine Performance ◽  
Mean Value ◽  
Vital Role ◽  
Intake Valve ◽  
Valve Timing ◽  
Part Load ◽  
Engine Model ◽  
Atkinson Cycle ◽  
Engine Part ◽  
Proposed Model

With the advancement in the innovated technologies, optimum efficiency of spark ignition (SI) engine can be accomplished during the entire engine operating range, particularly at part load. In this research, a novel control-oriented extended mean value engine model (EMVEM) of the Atkinson cycle engine is proposed, wherein the Atkinson cycle, variable valve timing (VVT), overexpansion, and variable compression ratio (VCR) characteristics are incorporated. For this purpose, an intake valve timing (IVT) parameter is introduced, which has a vital role in modeling the inclusive dynamics of the system and to deal with engine performance degrading aspects. The proposed model is validated with the experimental data of a VVT engine, obtained from literature, to ensure that the proposed model has the capability to capture the dynamics of the Atkinson cycle engine, and engine load can be controlled by IVT parameter, instead of the conventional throttle. The potential benefits of late intake valve closing (LIVC) tactic and copious integrated characteristics are appreciated as well. Furthermore, simulation results of the developed model primarily indicate the reduction in the engine part load losses and enhancement in thermal efficiency due to overexpansion, which has a great significance in the enhancement of the performance, fuel economy, and emissions reduction. Besides, the constraints on LIVC and overexpansion become evident.

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