Development of a Late Intake-Valve Closing (LIVC) Miller Cycle for Stationary Natural Gas Engines - Effect of EGR Utilization

Okamoto, Kazuhisa; Zhang, Furong; Shimogata, Satoshi; Shoji, Fujio

doi:10.4271/972948

Cited by 11 publications

(6 citation statements)

References 5 publications

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“…Many modern large -bore ICEs adopt Miller/Akinson cycle to limit maximum in -cylinder pressure and/or NO x level while preserving high expansion ratio to obtain low BSFC (c.f. [9,12,23,24,27,28]), however, such approach requires high efficiency boost group.…”

Section: Engine Modelmentioning

confidence: 99%

“…Such cycles allow to decrease effective compression ratio while preserving high expansion ratiothis has a positive effect on both BSFC and NO x level of an SI engine (c.f. [9,12,23,24,26,27]). When dealing with requirement to lower NO x level, there are different technologies available -lowering engine compression ratio, increasing air excess, application of cooled external EGR, advancing combustion towards BDC (late combustion), application of exhaust SCR system, etc.…”

mentioning

confidence: 99%

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Optimization of 2‑Stage Turbocharged Gas SI Engine Under Steady State Operation

Vítek¹,

Máček²,

Klima³

et al. 2017

Journal of Middle European Construction and Design of Cars

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The proposed paper deals with an optimization of a highly-turbocharged large-bore gas SI engine. Only steady state operation (constant engine speed and load) is considered. The paper is mainly focused on theoretical potential of 2-stage turbocharging concept in terms of performance and limitation. The results are obtained by means of simulation using complex 0-D/ 1-D engine model including the control algorithm. Different mixture composition concepts are considered to satisfy different levels of NOx limit - fresh air mixed with external cooled EGR is supposed to be the right approach while optimal EGR level is to be found. Considering EGR circuit, 5 different layouts are tested to select the best design. As the engine control is relatively complex (2-sage turbocharger group, external EGR, compressor blow-by, controlled air excess), 5 different control means of boost pressure were considered. Each variant based on above mentioned options is optimized in terms of compressor/turbine size (swallowing capacity) to obtain the best possible BSFC. The optimal variants are compared and general conclusions are drawn.

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Section: Engine Modelmentioning

confidence: 99%

mentioning

confidence: 99%

Optimization of 2‑Stage Turbocharged Gas SI Engine Under Steady State Operation

Vítek¹,

Máček²,

Klima³

et al. 2017

Journal of Middle European Construction and Design of Cars

View full text Add to dashboard Cite

show abstract

“…Increasing the Geometric Compression Ratio (GCR) with VVT extends the expansion stroke. Thus, it was reported that some improvement in the power density decreased due to VVT [20][21][22]. This VVT+GCR method is most preferred in today's modern Atkinson cycle engines.…”

Section: Introductionmentioning

confidence: 99%

Quasi-Realistic Performance Analysis of Modern Atkinson Cycle

Özdemir

UYSAL>

MENKÜÇ>

et al. 2022

International Journal of Automotive Science and Technology

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In this study, a quasi-realistic thermodynamic analysis was performed to investigate the effects of design and operating parameters on the performance of a single-cylinder modern Atkinson cycle engine. Fortran was used for all calculations. It was assumed that the fuel-air mixture was used as the working fluid, and iso-octane was used as the fuel. The Wiebe function was used for the combustion process and it was assumed that the specific heat of the working fluid varies with temperature. In the calculations, heat transfer loss, combustion efficiency, mechanical friction, and pumping losses were taken into account. In the analysis, the closing of the intake valve, equivalence ratio, geometric compression ratio, and the initial conditions of the intake proses were used as independent variables. The effects of these variables on brake mean effective pressure, effective power, specific fuel consumption, and thermal efficiency were investigated. Increasing the inlet pressure, increasing the geometric compression ratio, and delaying the closing of the intake valve increased the mean effective pressure, thermal efficiency, engine output power, and torque. The increase in the inlet temperature adversely affected the engine performance and the specific fuel consumption increased. Engine performance parameters worsened when the equivalence ratio fell below 0.8 and rose above 0.9.

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“…The minimum fuel consumption was obtained by LIVC timing. Okamoto et al [13] investigated the effects of intake valve closing timing and EGR rate on engine performance and NOx emissions in a Miller cycle supercharged engine. They found that thermal efficiency is 38 % with LIVC timing and EGR.…”

Section: Introductionmentioning

confidence: 99%

Performance and Emission Characteristics of a Miller Cycle Engine

Demirci¹,

Uyumaz²,

Sarıdemir³

et al. 2018

International Journal of Automotive Engineering and Technologies

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In this study, intake and exhaust cams were designed to perform the late intake valve closing (LIVC) Miller cycle operation (MA and MB cycles) using spline functions in a single-cylinder, four-stroke, spark-ignition (SI) engine. A special camshaft was manufactured and adapted to the engine to adjust valve opening and closing timings. The experiments were conducted at two different Miller cycle operation and the results were compared with Otto cycle. The tests were conducted between 1700-3200 rpm engine speed range at wide open throttle (WOT). In the experiments, the variation of brake torque, power output, specific fuel consumption (SFC), thermal efficiency, HC, CO, NOx emissions and exhaust gas temperature versus engine speed were investigated. More power output was obtained with Otto cycle than Miller cycles for all engine speeds. Brake torque and engine power decreased by 5.24%, and 1.17% respectively with MA cycle compared to Otto cycle at 2600 rpm engine speed. Thermal efficiency increased by 1.29%, while the SFC decreased 2.08 % with Otto cycle in comparison with MA cycle at maximum brake torque speed. HC and CO emissions increased by 6.48% and 11.66%, respectively with MA cycle compared to Otto cycle at the same operation condition. NOx emissions decreased up to 7.79% with MA cycle compared to Otto cycle due to the lower exhaust gas temperature at maximum brake torque engine speed of 2600 rpm.

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Development of a Late Intake-Valve Closing (LIVC) Miller Cycle for Stationary Natural Gas Engines - Effect of EGR Utilization

Cited by 11 publications

References 5 publications

Optimization of 2‑Stage Turbocharged Gas SI Engine Under Steady State Operation

Optimization of 2‑Stage Turbocharged Gas SI Engine Under Steady State Operation

Quasi-Realistic Performance Analysis of Modern Atkinson Cycle

Performance and Emission Characteristics of a Miller Cycle Engine

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