scholarly journals Open Dual Cycle with Composition Change and Limited Pressure for Prediction of Miller Engines Performance and Its Turbine Temperature

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2870
Author(s):  
Antonio Lecuona ◽  
José I. Nogueira ◽  
Antonio Famiglietti
Keyword(s):  
Internal Combustion Engines ◽  
High Efficiency ◽  
Internal Combustion ◽  
Combustion Efficiency ◽  
Combustion Engines ◽  
Composition Change ◽  
Pressure Losses ◽  
Exhaust Temperature ◽  
Dual Cycle ◽  
Gas Recirculation

An improved thermodynamic open Dual cycle is proposed to simulate the working of internal combustion engines. It covers both spark ignition and Diesel types through a sequential heat release. This study proposes a procedure that includes (i) the composition change caused by internal combustion, (ii) the temperature excursions, (iii) the combustion efficiency, (iv) heat and pressure losses, and (v) the intake valve timing, following well-established methodologies. The result leads to simple analytical expressions, valid for portable models, optimization studies, engine transformations, and teaching. The proposed simplified model also provides the working gas properties and the amount of trapped mass in the cylinder resulting from the exhaust and intake processes. This allows us to yield explicit equations for cycle work and efficiency, as well as exhaust temperature for turbocharging. The model covers Atkinson and Miller cycles as particular cases and can include irreversibilities in compression, expansion, intake, and exhaust. Results are consistent with the real influence of the fuel-air ratio, overcoming limitations of standard air cycles without the complex calculation of fuel-air cycles. It includes Exhaust Gas Recirculation, EGR, external irreversibilities, and contemporary high-efficiency and low-polluting technologies. Correlations for heat ratio γ are given, including renewable fuels.

Maximum efficiencies for internal combustion engines: Thermodynamic limitations

2017 ◽  
Vol 19 (10) ◽  
pp. 1005-1023 ◽  
Author(s):  
Jerald A Caton
Keyword(s):  
Heat Transfer ◽  
Internal Combustion Engines ◽  
High Efficiency ◽  
Pressure Rise ◽  
Internal Combustion ◽  
Thermodynamic Evaluation ◽  
Combustion Engines ◽  
Automotive Engine ◽  
Specific Heats ◽  
Cycle Simulation

The thermodynamic limitation for the maximum efficiencies of internal combustion engines is an important consideration for the design and development of future engines. Knowing these limits helps direct resources to those areas with the most potential for improvements. Using an engine cycle simulation which includes the first and second laws of thermodynamics, this study has determined the fundamental thermodynamics that are responsible for these limits. This work has considered an automotive engine and has quantified the maximum efficiencies starting with the most ideal conditions. These ideal conditions included no heat losses, no mechanical friction, lean operation, and short burn durations. Then, each of these idealizations is removed in a step-by-step fashion until a configuration that represents current engines is obtained. During this process, a systematic thermodynamic evaluation was completed to determine the fundamental reasons for the limitations of the maximum efficiencies. For the most ideal assumptions, for compression ratios of 20 and 30, the thermal efficiencies were 62.5% and 66.9%, respectively. These limits are largely a result of the combustion irreversibilities. As each of the idealizations is relaxed, the thermal efficiencies continue to decrease. High compression ratios are identified as an important aspect for high-efficiency engines. Cylinder heat transfer was found to be one of the largest impediments to high efficiency. Reducing cylinder heat transfer, however, is difficult and may not result in much direct increases of piston work due to decreases of the ratio of specific heats. Throughout this work, the importance of high values of the ratio of specific heats was identified as important for achieving high thermal efficiencies. Depending on the selection of constraints, different values may be given for the maximum thermal efficiency. These constraints include the allowed values for compression ratio, heat transfer, friction, stoichiometry, cylinder pressure, and pressure rise rate.

Design and Operation of a Hybrid CCHP System Including PV-Wind Devices

2013 ◽  
Author(s):  
J. L. Wang ◽  
J. Y. Wu ◽  
C. Y. Zheng
Keyword(s):  
Fuel Consumption ◽  
Internal Combustion Engines ◽  
High Efficiency ◽  
Waste Heat ◽  
Internal Combustion ◽  
Energy System ◽  
Optimal Operation ◽  
Combustion Engines ◽  
Wind System ◽  
Fuel Price

CCHP systems based on internal combustion engines have been widely accepted as efficient distributed energy resources systems. CCHP systems can be efficient mainly because that the waste heat of engines can be recovered and used. If the waste heat is not used, CCHP systems may not be beneficial choices. PV-wind systems can generate electricity without fuel consumption, but the electric output depends on the weather, which is not reliable. A PV-wind system can be integrated into a CCHP system to form a higher efficient energy system. Actually, a hybrid energy system based on PV-wind devices and internal combustion engines has been studied by many researchers. But the waste heat of the engine is seldom considered in the previous work. Researches show that, 20∼30% energy can be converted into electricity by a small size engine while more than 70% is released. If the waste heat is not recovered, the system cannot reach a high efficiency. This work aims to analyze a hybrid CCHP system with PV-wind devices. Internal combustion engines are the prime movers whose waste heat is recovered for house heating or driving absorption chillers. PV-wind devices are added to reduce the fuel consumption and total cost. The optimal design method and optimal operation strategy are proposed basing on hourly analyses. Influences of the device cost and fuel price on the optimal dispatch strategies are discussed. Results show that all of the excess energy from the PV-wind system is not worth being stored by the battery. The hybrid CCHP system can be more economical and higher efficient in the studied case.

A Simple Combustion Efficiency Indicator for Automobile Engines

1973 ◽  
Vol 6 (10) ◽  
pp. 399-400 ◽  
Author(s):  
M. S. Bolton ◽  
D. S. Taylor
Keyword(s):  
Carbon Monoxide ◽  
Internal Combustion Engines ◽  
Fuel Mixture ◽  
Internal Combustion ◽  
Combustion Efficiency ◽  
Exhaust Emission ◽  
Combustion Engines ◽  
Widespread Application ◽  
Mixture Ratio ◽  
Automobile Engines

A cheap device which can indicate carbon monoxide levels in exhaust emission of internal combustion engines, and hence could be used for adjusting the engine's operating air: fuel mixture ratio, would have widespread application in garages, etc. The instrument described here is sensitive to both unburnt hydrocarbons and carbon monoxide but measures the carbon monoxide to an accuracy well within the tuning capability of most carburation systems.

H2S and CO2 Filtration of Biogas Used in Internal Combustion Engines for Power Generation

2009 ◽  
Author(s):  
Jose Ignacio Huertas Cardozo ◽  
Sebastia´n Izquierdo Cifuentes
Keyword(s):  
Mass Transfer ◽  
Internal Combustion Engines ◽  
High Efficiency ◽  
Positive Impact ◽  
Low Cost ◽  
Renewable Energy Sources ◽  
Internal Combustion ◽  
Quasi Equilibrium ◽  
Combustion Engines ◽  
Fixed Amount

Currently, there is an increasing interest in connecting thousands of small electrical plants powered by renewable energy sources to national electrical grids. The use of biogas as fuel for internal combustion engines connected to an electric generator is emerging as one of the most attractive alternatives because of its very low cost benefit ratio and very high positive impact on the environment. However, the use of biogas to generate electricity has been limited by its high content of H2S (1800–3500 ppm) and CO2 (∼40%). CO2 presence reduces the energetic density of the fuel and therefore the power output of the system. The high content of H2S corrodes important components of the engine like the combustion chamber, bronze gears and the exhaust system. This work aims to design and manufacture a low-cost industrial filter for this application. Among the different available methodologies, CaO, NaOH and amines where selected as the most appropriate for a typical farm application of 100 kW electric generations. Since there is not reported data for the H2S absorbing capacity of these substances, it was proposed to measure it by means of a bubbler. It is an experimental set up where the gas stream passes through a fixed amount of the absorbing substance until it becomes saturated. The absorbing capacity is determined as the amount of substance being trapped divided by the mass of the absorbing substance being used. Results showed an absorbing capacity of 2.8, 41.4 and 124.8 g of H2S per Kg of NaOH, CaO and monoethanolamine respectively. A gas absorbing system of amines was designed and manufactured for H2S and CO2 biogas filtration. Three different types of amines were evaluated: Monoethanolamine, Diethanolamine, and methyldiethanolamine. Results show that all the amines require a ratio of amines to biogas flow of 0.7 to obtain a 95% of H2S filtering efficiency. This data represent only a 30% of H2S mass transfer efficiency of the filter when it is compared against the mass transfer expected under quasi equilibrium conditions. Work is under way to design a high efficiency amine column for biogas treatment.

Calculation of Exhaust Gas Heat Produce for Ron 95, Ron97 and Vpower Racing Base Fuels use in Internal Combustion Engines

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
I.B. Lias ◽  
H.B. Sharudin ◽  
M.H.B. Ismail ◽  
A.M.I.B. Mamat
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Exhaust System ◽  
Internal Combustion ◽  
Exhaust Gas ◽  
Combustion Engines ◽  
Exhaust Temperature ◽  
Different Types

The purpose of this study is to identify and analyse the calculation of exhaust gas heat produce (EGHP) in internal combustion engine (ICE) based on three types of fuel used specifically Petrol Ron 95, Petrol Ron 97 and Vpower racing base. The experimental test rig has used 1.6 CamPro Proton engine with 1561cc capacity and dynamometer. The calculation has used the basic formula of heat transfer equation and heat loss through the exhaust that included the mass flow rate of exhaust gas, specific heat of exhaust gas and temperature gradient. The exhaust temperature of ICE is generally in range from 400C to 600C and exhaust gas heat transfer affects the emissions burn-up in the exhaust system. This contributes significantly to the engine requirement. The experimental data was statistically analysed to identify the unknown parameter. High correlation of data variables can be determined based on the heat loss produced or EGHP. This also has significance by using different types of fuel in ICE.

A Cogging Torque Assisted Motor Driven Valve Actuation System for Internal Combustion Engines

2013 ◽  
Author(s):  
Bradley A. Reinholz ◽  
Rudolf J. Seethaler
Keyword(s):  
Internal Combustion Engines ◽  
High Efficiency ◽  
Acoustic Emissions ◽  
Internal Combustion ◽  
Performance Criteria ◽  
Combustion Engines ◽  
Cogging Torque ◽  
Actuation System ◽  
Stringent Performance ◽  
Valve Actuation

Electromechanical valve actuation (EVA) for internal combustion engines promises to significantly improve engine efficiency and lower emissions by reducing pumping losses and allowing for novel combustion strategies. However, current designs have not been able to meet the stringent performance criteria for reliability, efficiency, acoustic emissions, weight, and cost that are required by the automotive industry. This paper describes a novel cogging torque assisted motor driven (CTAMD) valve actuation system that promises to meet both the performance and robustness requirements. In contrary to existing EVA systems that recover the kinetic valve energy using a mechanical spring system, the CTAMD system recovers kinetic energy in a magnetic field. This allows for high efficiency while maintaining a simple and elegant electromechanical design. This paper describes the characteristics of CTAMD systems and outlines an electromechanical design for such a system. Then computer simulations of the proposed design are used to demonstrate the expected performance of the system. Finally, the simulated results are compared to other EVA systems to highlight the anticipated improvements.

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