Applying Thermodynamics in Search of Superior Engine Efficiency

2002 ◽  
Author(s):  
Charles A. Amann
Keyword(s):  
Thermal Efficiency ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Heat Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Closed Cycle ◽  
Engine Efficiency ◽  
Operating Cycles ◽  
Thermodynamic Processes

Historically, a succession of thermodynamic processes has been used to idealize the operating cycles of internal combustion engines. In this study, the 256 possible combinations of four reversible processes – isentropic, isothermal, isochoric, and isobaric – are surveyed in search of cycles promising superior thermal efficiency. Regenerative cycles are excluded. The established concept of the air-standard cycle, which mimics the internal combustion engine as a closed-cycle heat engine, is used to narrow the field systematically. The approach relies primarily on graphical interpretation of approximate temperature-entropy diagrams and is qualitative only. In addition to identifying the cycles offering the greatest efficiency potential, the compromise between thermal efficiency and mean effective pressure is addressed.

Applying Thermodynamics in Search of Superior Engine Efficiency

2005 ◽  
Vol 127 (3) ◽  
pp. 670-675 ◽  
Author(s):  
Charles A. Amann
Keyword(s):  
Thermal Efficiency ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Heat Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Closed Cycle ◽  
Engine Efficiency ◽  
Operating Cycles ◽  
Thermodynamic Processes

Historically, a succession of thermodynamic processes has been used to idealize the operating cycles of internal combustion engines. In this study, the 256 possible combinations of four reversible processes—isentropic, isothermal, isochoric, and isobaric—are surveyed in search of cycles promising superior thermal efficiency. Regenerative cycles are excluded. The established concept of the air-standard cycle, which mimics the internal combustion engine as a closed-cycle heat engine, is used to narrow the field systematically. The approach relies primarily on graphical interpretation of approximate temperature-entropy diagrams and is qualitative only. In addition to identifying the cycles offering the greatest efficiency potential, the compromise between thermal efficiency and mean effective pressure is addressed.

Performance study of the hypocycloid gear mechanism for internal combustion engine applications

2019 ◽  
pp. 146808741989358 ◽  
Author(s):  
Mostafa A ElBahloul ◽  
ELsayed S Aziz ◽  
Constantin Chassapis
Keyword(s):  
Internal Combustion Engine ◽  
Thermodynamic Model ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Otto Cycle ◽  
Engine Efficiency ◽  
Gear Mechanism ◽  
Crank Mechanism

Fuel conversion efficiency is one of the main concerns in the field of internal combustion engine systems. Although the Otto cycle delivers the maximum efficiency possible in theory, the kinematics of the slider–crank mechanism of the conventional internal combustion engines makes it difficult to reach this level of efficiency in practice. This study proposes using the unique hypocycloid gear mechanism instead of the conventional slider–crank mechanism for the internal combustion engines to increase engine efficiency and minimize frictional power losses. The hypocycloid gear mechanism engine’s kinematics provides the means for the piston-rod assembly to reciprocate in a straight-line motion along the cylinder axis besides achieving a nonlinear rate of piston movement. As a result, this characteristic allows for a true constant-volume combustion, which in turn would lead to higher work output. An in-cylinder gas volume change model of the hypocycloid gear mechanism engine was developed and incorporated into the thermodynamic model for the internal combustion engine cycle. The thermodynamic model of the hypocycloid gear mechanism engine was developed and simulated using MATLAB/Simulink software. A comparison between the conventional engine and the hypocycloid gear mechanism engine in terms of engine performance characteristics showed the enhancements achieved using hypocycloid gear mechanism for internal combustion engine applications. The hypocycloid gear mechanism engine analysis results indicated higher engine efficiency approaching that of the Otto cycle.

Piston ring–liner lubrication and tribological performance evaluation: A review

2017 ◽  
Vol 232 (2) ◽  
pp. 193-209 ◽  
Author(s):  
Cristiana Delprete ◽  
Abbas Razavykia
Keyword(s):  
Internal Combustion Engines ◽  
Piston Ring ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Power Losses ◽  
Oil Consumption ◽  
Major Power ◽  
Power Sources ◽  
Engine Efficiency

Internal combustion engines are at present used as the major power sources for transportation and power generator. Improvement of the internal combustion engine efficiency is expected due to strict environmental standards and energy costs. Any reduction in oil consumption, friction power losses and emissions results in improving engines’ performance and durability. Automotive industries have intense passion to increase engines’ efficiency to meet the fuel economy and emission standards. Many studies have been conducted to develop reliable approaches and models to understand the lubrication mechanisms and calculate power losses. This review paper summarizes the synthesis of the main technical aspects considered during modeling of piston ring–liner lubrication and friction losses investigations. The literature review highlights the effects of piston ring dynamics, components geometry, lubricant rheology, surface topography and adopted approaches, on frictional losses contributed by the piston ring-pack.

scholarly journals Theoretical Performance Comparison between Inline, Offset and Twin Crankshaft Internal Combustion Engines

2008 ◽  
Vol 3 (1) ◽  
pp. 17
Author(s):  
Taj Elssir Hassan ◽  
Abdelfattah Bilal ◽  
Maisara Mohy Eldin Gasim
Keyword(s):  
Internal Combustion Engines ◽  
Thrust Force ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Performance Comparison ◽  
Combustion Engines ◽  
Engine Efficiency ◽  
Output Torque ◽  
Computational Work ◽  
Cylinder Bore

The twin crankshaft engine is anew configuration of internal combustion engine that introduced to solve the engine liner wear problems, increase the engine efficiency and it has other advantages over conventional engines. In this research, a computational work was carried out to compare the performance of three l engine configurations, namely, the conventional (inline) engine, the offset crankshaft engine and the twin crankshaft engine, of the same cylinder bore, speed, crank arm, piston mass and heat addition. The performance measured was the side thrust force that causes liner wear and the output torque. Results showed that the twin crankshaft engine is superior in terms of torque which means it has larger efficiency than the other configurations.

scholarly journals A review of split-cycle engines

2018 ◽  
Vol 21 (6) ◽  
pp. 897-914 ◽  
Author(s):  
Joshua Finneran ◽  
Colin P Garner ◽  
Michael Bassett ◽  
Jonathan Hall
Keyword(s):  
Thermal Management ◽  
Thermal Efficiency ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Engine Design ◽  
Work Assessment ◽  
In Series ◽  
Management Issues

This article reviews split-cycle internal combustion engine designs. The review includes historical work, assessment of prototypes and discussion of the most recent designs. There has been an abundance of split-cycle engine designs proposed since the first in 1872. Despite this, very few prototypes exist, and no split-cycle engines are reported to be in series production. The few split-cycle prototypes that have been developed have faced practical challenges contributing to limited performance. These challenges include air flow restrictions into the expansion cylinder, late combustion, thermal management issues, and mechanical challenges with the crossover valve actuation mechanism. The main promoted advantage of split-cycle engines is the increased thermal efficiency compared to conventional internal combustion engines. However, an efficiency improvement has not thus far been demonstrated in published test data. The thermodynamic studies reviewed suggest that split-cycle engines should be more efficient than conventional four-stroke engines. Reasons why increased thermal efficiency is not realised in practice could be due to practical compromises, or due to inherent architectural split-cycle engine design limitations. It was found that the number of split-cycle engine patents has increased significantly over recent years, suggesting an increased commercial interest in the concept since the possibility of increased efficiency becomes more desirable and might outweigh the drawbacks of practical challenges.

Methods for rapid estimation of indicator and efficient efficiency of internal combustion engines

2021 ◽  
pp. 216-221
Author(s):  
Keyword(s):  
Internal Combustion Engine ◽  
Thermal Cycle ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Heat Content ◽  
Internal Combustion ◽  
Working Fluid ◽  
Combustion Engines ◽  
Working Process ◽  
Thermodynamic Processes

The article discusses the issue of a quantitative computational assessment of the efficiency of the thermal cycle of a piston internal combustion engine based on the values of the effective and indicator efficiency. A simplified technique for the operational assessment of the efficiency of the thermal cycle of a piston internal combustion engine is proposed. The technique is based on a mathematical description of thermodynamic processes occurring during the development of the thermal cycle of an engine with ignition of the working mixture from compression (diesel engine), which allows it to be expanded to new engines, including those operating under electronic control. Keywords heat cycle; the working process; diesel; heat content of the working fluid; expansion

Avaliação da eficiência na geração de energia elétrica de um motor híbrido (combustão + ar comprimido) a partir de testes em protótipo real

2020 ◽  
Vol 7 (1) ◽  
pp. 34-45
Author(s):  
Rodrigo Gasparini Croce ◽  
Antônio Dariva ◽  
Emerson Pereira Trarbach ◽  
Filipe Arthur Firmino Monhol
Keyword(s):  
Internal Combustion Engines ◽  
High Efficiency ◽  
Combustion Engine ◽  
Hybrid Approach ◽  
Internal Combustion ◽  
Compressed Air ◽  
Combustion Engines ◽  
Test Procedures ◽  
Engine Efficiency ◽  
Low Efficiency

The continuous research for high efficiency and low emission engines are the technological challenges nowadays. Internal combustion engines are widely used due to low-cost if compared to the electrical vehicles' propulsion systems. Unfortunately, internal combustion engines have low efficiency; about 20%-25% are converted to mechanical power. A new hybrid approach engine running on ethanol and compressed air is presented in this paper. As a result, the global engine efficiency is improved once a part of energy comes from compressed air stored in an external reservoir. By measuring the ethanol consumption and the compressed air flux is possible to calculate the global engine efficiency when it runs a stationary electric generator connected to a known load. This paper presents a conceptual working flow of an Internal Combustion Engine and a Hybrid Engine but focused to the prototype developed. The test procedures and results are shown and the potential to apply this new concept in a vehicle.

scholarly journals Assessment of thermodynamic cycle of internal combustion engine in terms of rightsizing

2019 ◽  
Vol 178 (3) ◽  
pp. 182-186
Author(s):  
Zbigniew SROKA ◽  
Maciej DWORACZYŃSKI
Keyword(s):  
Internal Combustion Engine ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Combustion Process ◽  
Thermodynamic Cycle ◽  
Internal Combustion ◽  
Research Problem ◽  
Combustion Engines ◽  
Operating Characteristics ◽  
Swept Volume

The modification of the downsizing trend of internal combustion engines towards rightsizing is a new challenge for constructors. The change in the displacement volume of internal combustion engines accompanying the rightsizing idea may in fact mean a reduction or increase of the defining swept volume change factors and thus may affect the change in the operating characteristics as a result of changes in combustion process parameters - a research problem described in this publication. Incidents of changes in the displacement volume were considered along with the change of the compression space and at the change of the geometric degree of compression. The new form of the mathematical dependence describing the efficiency of the thermodynamic cycle makes it possible to evaluate the opera-tion indicators of the internal combustion engine along with the implementation of the rightsizing idea. The work demonstrated the in-variance of cycle efficiency with different forms of rightsizing.

Improving the tribological behavior of internal combustion engines via the addition of nanoparticles to engine oils

2015 ◽  
Vol 4 (4) ◽  
Author(s):  
Mohamed Kamal Ahmed Ali ◽  
Hou Xianjun
Keyword(s):  
Internal Combustion Engines ◽  
Tribological Behavior ◽  
Internal Combustion ◽  
Valve Train ◽  
Combustion Engines ◽  
Power Losses ◽  
Oil Consumption ◽  
Engine Oils ◽  
Engine Efficiency ◽  
Sliding Surfaces

AbstractThe friction between two sliding surfaces is probably one of the oldest problems in mechanics. Frictional losses in any I.C. engine vary between 17% and 19% of the total indicated horse power. The performance of internal combustion engines in terms of frictional power loss, fuel consumption, oil consumption, and harmful exhaust emissions is closely related to the friction force and wear between moving parts of the engine such as piston assembly, valve train, and bearings. To solve this problem, most modern research in the area of Nanotribology (Nanolubricants) aims to improve surface properties, reduce frictional power losses, increase engine efficiency, and reduce consumed fuel and cost of maintenance. Nanolubricants contain different nanoparticles such as Cu, CuO, TiO

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