scholarly journals Improving Fuel Economy and Engine Performance through Gasoline Fuel Octane Rating

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3499 ◽  
Author(s):  
José Rodríguez-Fernández ◽  
Ángel Ramos ◽  
Javier Barba ◽  
Dolores Cárdenas ◽  
Jesús Delgado
Keyword(s):  
Fuel Economy ◽  
Octane Number ◽  
High Performance ◽  
Engine Performance ◽  
Design Stage ◽  
Boost Pressure ◽  
Ambient Conditions ◽  
Auto Ignition ◽  
Spark Timing ◽  
Octane Rating

The octane number is a measure of the resistance of gasoline fuels to auto-ignition. Therefore, high octane numbers reduce the engine knocking risk, leading to higher compression threshold and, consequently, higher engine efficiencies. This allows higher compression ratios to be considered during the engine design stage. Current spark-ignited (SI) engines use knock sensors to protect the engine from knocking, usually adapting the operation parameters (boost pressure, spark timing, lambda). Moreover, some engines can move the settings towards optimized parameters if knock is not detected, leading to higher performance and fuel economy. In this work, three gasolines with different octane ratings (95, 98 and 100 RON (research octane number)) were fueled in a high-performance vehicle. Tests were performed in a chassis dyno at controlled ambient conditions, including a driving sequence composed of full-load accelerations and two steady-state modes. Vehicle power significantly increased with the octane rating of the fuel, thus decreasing the time needed for acceleration. Moreover, the specific fuel consumption decreased as the octane rating increased, proving that the fuel can take an active part in reducing greenhouse gas emissions. The boost pressure, which increased with the octane number, was identified as the main factor, whereas the ignition advance was the second relevant factor.

Optical Investigation of the Effects of Ethanol/Gasoline Blends on Spark-Assisted HCCI

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Mohammad Fatouraie ◽  
Margaret Wooldridge
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Engine Performance ◽  
Optical Investigation ◽  
Release Rates ◽  
High Speed Imaging ◽  
Engine Operation ◽  
Auto Ignition ◽  
Spark Timing ◽  
Combustion Properties

Spark assist (SA) has been demonstrated to extend the operating limits of homogeneous charge compression ignition (HCCI) modes of engine operation. This experimental investigation focuses on the effects of 100% indolene and 70% indolene/30% ethanol blends on the ignition and combustion properties during SA HCCI operation. The spark assist effects are compared to baseline HCCI operation for each blend by varying spark timing at different fuel/air equivalence ratios ranging from Φ = 0.4–0.5. High speed imaging is used to understand connections between spark initiated flame propagation and heat release rates. Ethanol generally improves engine performance with higher net indicated mean effective pressure (IMEPn) and higher stability compared to 100% indolene. SA advances phasing within a range of ∼5 crank angle degrees (CAD) at lower engine speeds (700 rpm) and ∼11 CAD at higher engine speeds (1200 rpm). SA does not affect heat release rates until immediately (within ∼5 CAD) prior to auto-ignition. Unlike previous SA HCCI studies of indolene fuel in the same engine, flames were not observed for all SA conditions.

scholarly journals Numerical Study on the Performance and NOx Emission Characteristics of an 800cc MPI Turbocharged SI Engine

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7419
Author(s):  
Seungmin Kim ◽  
Jaesam Shim ◽  
Youngsoo Cho ◽  
Back-Sub Sung ◽  
Jungsoo Park
Keyword(s):  
Engine Performance ◽  
Boost Pressure ◽  
Exhaust Gas ◽  
Intake Valve ◽  
Si Engine ◽  
Spark Timing ◽  
Performance And Emissions ◽  
Valve Overlap ◽  
Engine Performance And Emissions ◽  
Exhaust Gas Emissions

The main purpose of this study is to optimize engine performance and emission characteristics of off-road engines with retarded spark timing compared to MBT by repurposing the existing passenger engine. This study uses a one-dimensional (1D)-simulation to develop a non-road gasoline MPI turbo engine. The SI turbulent flame model of the GT-suite, an operational performance predictable program, presents turbocharger matching and optimal operation design points. To optimize the engine performance, the SI turbulent model uses three operation parameters: spark timing, intake valve overlap, and boost pressure. Spark timing determines the initial state of combustion and thermal efficiency, and is the main variable of the engine. The maximum brake torque (MBT) point can be identified for spark timing, and abnormal combustion phenomena, such as knocking, can be identified. Spark timing is related to engine performance, and emissions of exhaust pollutants are predictable. If the spark timing is set to variables, the engine performance and emissions can be confirmed and predicted. The intake valve overlap can predict the performance and exhaust gas by controlling the airflow and combustion chamber flow, and can control the performance of the engine by controlling the flow in the cylinder. In addition, a criterion can be set to consider the optimum operating point of the non-road vehicle while investigating the performance and exhaust gas emissions accompanying changes in boost pressure With these parameters, the design of experiment (DoE) of the 1D-simulation is performed, and the driving performance and knocking phenomenon for each RPM are predicted during the wide open throttle (WOT) of the gasoline MPI Turbo SI engine. The multi-objective Pareto technique is also used to optimize engine performance and exhaust gas emissions, and to present optimized design points for the target engine, the downsized gasoline MPI Turbo SI engine. The results of the Pareto optimal solution showed a maximum torque increase of 12.78% and a NOx decrease of 54.31%.

A CFD Investigation of Heat Transfer in a Diesel Fueled PPC Engine Applying Design of Experiments

2012 ◽  
Author(s):  
Helgi S. Fridriksson ◽  
Shahrokh Hajireza ◽  
Martin Tunér ◽  
Bengt Sunén
Keyword(s):  
Heat Transfer ◽  
Design Of Experiments ◽  
High Performance ◽  
Engine Performance ◽  
Boost Pressure ◽  
Low Temperature Combustion ◽  
Engine Design ◽  
Performance And Emissions ◽  
Temperature Combustion ◽  
Engine Performance And Emissions

Due to the nature of the engine cycle, heat transfer has a significant role in the estimation of engine efficiency. The effects are quite well known in the classic combustion concepts, compression ignition (CI) and spark ignition (SI) combustion. But for the newer, low temperature combustion (LTC) concepts, these effects are not that well known. In this paper, a commercial computational fluid dynamics (CFD) code, AVL FIRE, is used to evaluate engine performance and emissions for different thermal settings in the engine cylinder of a LTC engine. Design of experiments (DoE) methodology is applied to model the response variables and quantify the effects from different model variables on the response. The results show that, within the parameter space chosen for this work, the strongest effect on the in-cylinder heat transfer and engine performance comes from the temperature and pressure at inlet valve closing, as well as the piston wall temperature. The values giving the best combination of low heat loss and high performance are high temperature walls along with cold inflowing air and high boost pressure.

Development and Use of a Segregated-Solver for Detailed Modeling of End-Gas Detonation in a Lean-Burn Spark-Ignited Engine

2010 ◽  
Author(s):  
Scott B. Fiveland ◽  
Shriram Vijayaraghavan ◽  
Shaoping Shi ◽  
Steven W. Richardson ◽  
Michael H. McMillian ◽  
...  
Keyword(s):  
Flame Front ◽  
Engine Performance ◽  
Combustion Noise ◽  
Lean Burn ◽  
Modeling Tools ◽  
Gas Detonation ◽  
Detailed Chemistry ◽  
Auto Ignition ◽  
Spark Timing ◽  
Thermodynamic Conditions

End-gas detonation occurs in a spark-ignited engine when the advancing flame front compresses the end-gas mixture to its autoignition temperature. The rapid energy release results in shock waves which are undesirable due to resulting combustion noise and boundary layer breakdown leading to reduced engine performance and incipient engine damage. In a spark-ignited engine, end-gas knock can result from improper combinations of compression ratio, spark timing or inlet thermodynamic conditions (i.e. manifold temperature, pressure, and equivalence ratio). These variables exhibit very complex interactions, which require costly high dimensional experimental designs for proper evaluation. As a result, detailed modeling tools are needed to predict the onset of the end-gas detonation regime for engine design applications. Developing a solver to predict the end-gas detonation of gases ahead of the flame front in an operating engine is not trivial. In theory, the model would need to simultaneously resolve both the detailed fluid mechanics as well as describe the fuel decomposition using detailed chemistry. Calculations for this type can take weeks or months depending on the number of dimensions that are resolved. Since hundreds of computations may be necessary to optimize a given configuration, it is necessary to be able to not only compute the onset of auto-ignition and other parameters accurately, but efficiently. The objective of this work was to develop an efficient methodology that could be utilized to effectively predict detonation in an internal combustion spark-ignited engine. This paper presents the computational methodology, a review of the combustion tool capability, and a comparison to experiments. The work clearly demonstrates the existence of inhomogeneities in the temperature field and discusses their impact on the prediction of end-gas knock.

scholarly journals Crystal Engineering Approach for Fabrication of Inverted Perovskite Solar Cell in Ambient Conditions

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1751
Author(s):  
Inga Ermanova ◽  
Narges Yaghoobi Nia ◽  
Enrico Lamanna ◽  
Elisabetta Di Bartolomeo ◽  
Evgeny Kolesnikov ◽  
...  
Keyword(s):  
Solar Cell ◽  
Crystal Engineering ◽  
High Performance ◽  
Perovskite Solar Cells ◽  
Perovskite Solar Cell ◽  
Layer By Layer ◽  
Ambient Conditions ◽  
Sequential Method ◽  
Engineering Approach ◽  
Hole Transporting

In this paper, we demonstrate the high potentialities of pristine single-cation and mixed cation/anion perovskite solar cells (PSC) fabricated by sequential method deposition in p-i-n planar architecture (ITO/NiOX/Perovskite/PCBM/BCP/Ag) in ambient conditions. We applied the crystal engineering approach for perovskite deposition to control the quality and crystallinity of the light-harvesting film. The formation of a full converted and uniform perovskite absorber layer from poriferous pre-film on a planar hole transporting layer (HTL) is one of the crucial factors for the fabrication of high-performance PSCs. We show that the in-air sequential deposited MAPbI3-based PSCs on planar nickel oxide (NiOX) permitted to obtain a Power Conversion Efficiency (PCE) exceeding 14% while the (FA,MA,Cs)Pb(I,Br)3-based PSC achieved 15.6%. In this paper we also compared the influence of transporting layers on the cell performance by testing material depositions quantity and thickness (for hole transporting layer), and conditions of deposition processes (for electron transporting layer). Moreover, we optimized second step of perovskite deposition by varying the dipping time of substrates into the MA(I,Br) solution. We have shown that the layer by layer deposition of the NiOx is the key point to improve the efficiency for inverted perovskite solar cell out of glove-box using sequential deposition method, increasing the relative efficiency of +26% with respect to reference cells.

scholarly journals Reliability-Oriented Design of Inverter-Fed Low-Voltage Electrical Machines: Potential Solutions

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4144
Author(s):  
Yatai Ji ◽  
Paolo Giangrande ◽  
Vincenzo Madonna ◽  
Weiduo Zhao ◽  
Michael Galea
Keyword(s):  
Power Density ◽  
High Speed ◽  
High Performance ◽  
Low Voltage ◽  
Electrical Machines ◽  
Design Stage ◽  
Switching Frequency ◽  
Special Focus ◽  
Electrical Machine ◽  
Engineering Approach

Transportation electrification has kept pushing low-voltage inverter-fed electrical machines to reach a higher power density while guaranteeing appropriate reliability levels. Methods commonly adopted to boost power density (i.e., higher current density, faster switching frequency for high speed, and higher DC link voltage) will unavoidably increase the stress to the insulation system which leads to a decrease in reliability. Thus, a trade-off is required between power density and reliability during the machine design. Currently, it is a challenging task to evaluate reliability during the design stage and the over-engineering approach is applied. To solve this problem, physics of failure (POF) is introduced and its feasibility for electrical machine (EM) design is discussed through reviewing past work on insulation investigation. Then the special focus is given to partial discharge (PD) whose occurrence means the end-of-life of low-voltage EMs. The PD-free design methodology based on understanding the physics of PD is presented to substitute the over-engineering approach. Finally, a comprehensive reliability-oriented design (ROD) approach adopting POF and PD-free design strategy is given as a potential solution for reliable and high-performance inverter-fed low-voltage EM design.

scholarly journals A Theoretical Study on the Thermodynamic Cycle of Concept Engine with Miller Cycle

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1051
Author(s):  
Jungmo Oh ◽  
Kichol Noh ◽  
Changhee Lee
Keyword(s):  
Compression Ratio ◽  
Thermal Efficiency ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Expansion Ratio ◽  
Boost Pressure ◽  
Miller Cycle ◽  
Compression Pressure ◽  
Air Mass ◽  
Atkinson Cycle

The Atkinson cycle, where expansion ratio is higher than the compression ratio, is one of the methods used to improve thermal efficiency of engines. Miller improved the Atkinson cycle by controlling the intake- or exhaust-valve closing timing, a technique which is called the Miller cycle. The Otto–Miller cycle can improve thermal efficiency and reduce NOx emission by reducing compression work; however, it must compensate for the compression pressure and maintain the intake air mass through an effective compression ratio or turbocharge. Hence, we performed thermodynamic cycle analysis with changes in the intake-valve closing timing for the Otto–Miller cycle and evaluated the engine performance and Miller timing through the resulting problems and solutions. When only the compression ratio was compensated, the theoretical thermal efficiency of the Otto–Miller cycle improved by approximately 18.8% compared to that of the Otto cycle. In terms of thermal efficiency, it is more advantageous to compensate only the compression ratio; however, when considering the output of the engine, it is advantageous to also compensate the boost pressure to maintain the intake air mass flow rate.

Polyimide-Silica Hybrid Aerogels with High Mechanical Strength for Thermal Insulation Applications

2011 ◽  
Vol 1306 ◽  
Author(s):  
Wenting Dong ◽  
Wendell Rhine ◽  
Shannon White
Keyword(s):  
Thermal Conductivity ◽  
High Performance ◽  
Ambient Conditions ◽  
Separation Membranes ◽  
Low Dielectric ◽  
Aging Conditions ◽  
Hybrid Aerogels ◽  
Mechanical Strengths ◽  
The Relationship ◽  
Silica Hybrid

ABSTRACTHigh performance polyimides have been widely investigated as materials with excellent thermal, mechanical, and electronic properties due to their highly rigid structures. Aspen has developed an approach to prepare polyimide aerogels which have applications as low dielectric constant materials, separation membranes, catalyst supports and insulation materials. In this paper, we will discuss the preparation of polyimide-silica hybrid aerogel materials with good mechanical strengths and low thermal conductivities. The polyimide-silica hybrid aerogels were made by a two-step process and the materials were characterized to determine thermal conductivity and compressive strength. Results show that compressive moduli of the polyimide-silica hybrid aerogels increase dramatically with density (power law relationship). Thermal conductivity of the aerogels is dependent on the aging conditions and density, with the lowest value achieved so far being ~12 mW/m-K at ambient conditions. The relationship between aerogel density and surface area, thermal stability, porosity and morphology of the nanostructure of the polyimide-silica hybrid aerogels are also described in this paper.

High-performance inverted planar perovskite solar cells without a hole transport layer via a solution process under ambient conditions

2015 ◽  
Vol 3 (38) ◽  
pp. 19294-19298 ◽  
Author(s):  
Xichang Bao ◽  
Qianqian Zhu ◽  
Meng Qiu ◽  
Ailing Yang ◽  
Yujin Wang ◽  
...  
Keyword(s):  
Relative Humidity ◽  
High Performance ◽  
Perovskite Solar Cells ◽  
Solution Process ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Ambient Conditions ◽  
High Quality ◽  
Ito Glass

High-quality CH3NH3PbI3 perovskite films were directly prepared on simple treated ITO glass in air under a relative humidity of lower than 30%.

scholarly journals Improved Morphology of Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) Thin Films for All-Electrospray-Coated Organic Photovoltaic Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yingjie Liao ◽  
Takeshi Fukuda ◽  
Norihiko Kamata
Keyword(s):  
Thin Films ◽  
High Performance ◽  
Photovoltaic Cells ◽  
Spray Coating ◽  
Organic Photovoltaic ◽  
Organic Photovoltaic Cells ◽  
Ambient Conditions ◽  
Deposition Parameters ◽  
Coating Methods ◽  
Organic Devices

Spray coating technique has been established as a promising substitute for the traditional coating methods in the fabrication of organic devices in many reports recently. Control of film morphology at the microscopic scale is critical if spray-coated devices are to achieve high performance. Here we investigate electrospray deposition protocols for the fabrication of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films with a single additive system under ambient conditions at room temperature. Critical deposition parameters including solution composition, applied voltage, and relative humidity are discussed systematically. Optimized process for preparing homogenous PEDOT:PSS thin films is applied to all-electrospray-coated organic photovoltaic cells and contributes to a power conversion efficiency comparable to that of the corresponding all-spin-coated device.

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