Study on Miller Cycle Gas Engine for Co-Gernation Systems - Numerical Analysis for Improvement of Efficiency and Power

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

doi:10.4271/971709

Cited by 9 publications

(5 citation statements)

References 2 publications

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“…Miller cycle was first applied to a diesel engine by Miller 2 to decay NOx. The performance of a gas engine was improved by Shimogata et al 3 by Miller cycle. Okamoto et al 4 diminished the NOx more than 50% of a gas engine by combining EGR and Miller cycle.…”

Section: Introductionmentioning

confidence: 99%

Performance investigation and evaluation of an engine operating on a modified dual cycle

Gonca

Şahi̇n

2021

Intl J of Energy Research

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Summary In this study, a novel high‐performance engine cycle composed of 5 processes and including constant temperature process has been developed by using novel numerical methods and compared with the classical dual cycle. The results of the classical thermodynamic model demonstrated that the proposed cycle which has a constant temperature process is better in terms of thermal efficiency and dimensionless net work compared to the classical dual cycle. After the validation of superiority of the developed cycle over the classical dual cycle, performance investigations of the novel cycle engine have been carried out in terms of power, power density, destructed exergy, thermal efficiency, ecological coefficient of performance, effective ecological power density by developing a novel fuel‐air cycle model. The influences of design and operational parameters such as cut‐off ratio, compression ratio, cycle temperature ratio, equivalence ratio, engine speed, stroke length, cylinder bore, cylinder wall temperature, air intake temperature, pressure ratio, on the performance specifications have been numerically derived.

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Section: Introductionmentioning

confidence: 99%

Performance investigation and evaluation of an engine operating on a modified dual cycle

Gonca

Şahi̇n

2021

Intl J of Energy Research

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“…Miller and Lieberherr carried out the MC applications for a gas‐fueled engine. Shimogata et al claimed that thermal efficiency and power output of a cogeneration system including a gas engine could be augmented by the MC implementation. Okamoto et al combined exhaust gas recirculation (EGR) and MC methods to obtain maximum NO x reduction ratios for a gas engine.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of a novel eco‐friendly internal combustion engine cycle

Gonca

Şahi̇n

2019

Int J Energy Res

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Summary The Miller cycle applications have been performed to diminish NOx released from internal combustion engines (ICEs), in recent years. The Miller cycle provides decreased compression ratio and enhanced expansion ratio; hereby, maximum in‐cylinder combustion temperatures diminish, and NOx formations slow down remarkably. Another less‐known method is Takemura cycle application, which provides heat addition into engine cylinder at constant combustion temperatures. In this study, a novel cycle including the Miller cycle and the Takemura cycle has been developed by using novel numerical models and computing methods with seven processes and a novel way to decrease NOx emissions at higher levels compared with the single applications of known cycles. A comprehensive performance examination of the proposed cycle engine in terms of performance characteristics such as effective power (EFP), effective power density (EFPD), exergy destruction (X), exergy efficiency (ε), and ecological coefficient of performance (ECOP) has been conducted. The impacts of engine operating and design parameters on the performance characteristics have been computationally examined. Furthermore, irreversibilities depending on incomplete combustion loss (INCL), exhaust output loss (EXOL), heat transfer loss (HTRL), and friction loss (FRL) have been considered in the performance simulations. The minimum exergy destruction and maximum performance specifications have been observed with 30 of the compression ratio. Maximum effective power values have been obtained at range between 1 and 1.2 of equivalence ratio. The optimum range for exergy efficiency is between 0.8 and 1 of equivalence ratio. Increasing engine speed has provided enhancing effective power. However, an optimum range has been found for the exergy efficiency that is interval of 3000 to 4000 rpm. The results obtained can be assessed by researchers studying on modeling of the engine systems and designs.

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“…*For correspondence Miller Cycle [15] which is now widely applied on the hybrid vehicles is a low-cost solution for improving the thermal efficiency of gasoline engines. In Miller Cycle intake valves close before or after bottom dead center, which makes the expansion ratio larger than the compression ratio (CR) which decreases the compression work due to the advancement of intake valve closing, thereby improving the thermal efficiency [16][17][18][19][20][21][22][23]. Endo [24] described the design of a commercially available large scale gas engine working on the Miller cycle and claiming an advantage of more than 5% over conventional technologies in terms of fuel efficiency.…”

Section: Introductionmentioning

confidence: 99%

The thermodynamic analysis of an electrically supercharged Miller Cycle gasoline engine with early intake valve closing

et al. 2019

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Electric superchargers are able to improve the thermodynamic process of gasoline engines by selfadapting running state to dominate intake air in all operation conditions. This paper proposes a novel approach for electrically supercharged Miller Cycle with early intake valve closing based on thermodynamics to settle the fuel economy problem of gasoline engines at low load operations by taking advantages of the domination of electric superchargers to intake air. Electrically supercharged Miller Cycle with early intake valve closing was realized by matching an electric supercharger, redesigning the inlet cam, and setting the intake valves closing before bottom dead center while keeping intake valves opening constant. An over-expanded engine cycle is attempted to be used to promote thermal efficiency by increasing geometric compression ratio, in addition to maintaining the effective compression ratio. Here, it has been attempted to systematically analyze the law of the energy losses of the electrically supercharged Miller Cycle gasoline engine with early intake valve closing using a reliable thermodynamic model from the perspective of heat engine. The results indicate that electrically supercharged Miller Cycle with early intake valve closing could improve the thermal efficiency of gasoline engines by significantly decreasing the pumping and exhaust losses.

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Study on Miller Cycle Gas Engine for Co-Gernation Systems - Numerical Analysis for Improvement of Efficiency and Power

Cited by 9 publications

References 2 publications

Performance investigation and evaluation of an engine operating on a modified dual cycle

Performance investigation and evaluation of an engine operating on a modified dual cycle

Performance analysis of a novel eco‐friendly internal combustion engine cycle

The thermodynamic analysis of an electrically supercharged Miller Cycle gasoline engine with early intake valve closing

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