Research on Improving Thermal Efficiency through Variable Super-High Expansion Ratio Cycle

Akihisa, Daisuke; Sawada, Daisaku

doi:10.4271/2010-01-0174

Cited by 24 publications

(5 citation statements)

References 5 publications

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“…It is clear that the higher expansion ratio is very effective in improving the thermal efficiency of engines; advanced development and production implementations are rapidly increasing for both naturally aspirated SI engines and downsized boosted SI engines. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] It is necessary to explore and develop Miller cycle engine concepts with a high expansion ratio, variable valve actuation and an advanced boosting system.…”

Section: Introductionmentioning

confidence: 99%

Research on and development of a Miller cycle engine with multi-stage boosting

Liu

Zhu

Sun

2016

Proceedings of the Institution of Mechanical Engineers, Part D:

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In order to improve the thermal efficiency of engines, it is essential to increase their geometric compression ratio or the expansion ratio. This research explores the technology options to enable a higher expansion ratio in future boosted spark-ignition direct-injection engines, with the aim of significantly reducing the fuel consumption while achieving the same torque and combustion performances as those of baseline turbocharged engines. Variable-valve-actuation technologies such as the late-intake-valve-closing cam strategy and the early-intake-valve-closing cam strategy were considered, and their effectiveness in reducing the effective compression and preventing knock in high-compression-ratio engines was assessed. To compensate for the torque loss due to late intake valve closing or early intake valve closing, multi-stage boosting systems including the turbocharger–supercharger combination and the two-stage turbocharger were implemented and compared. In this study, a Miller cycle engine concept with a high expansion ratio of 12.0:1 was developed with variable valve actuation and multi-stage boosting. On the basis of this new concept, an engine was built and extensively tested on an engine dynamometer to assess its part-load fuel consumption and full-load performance. The experimental results indicated that this engine concept can improve the fuel economy of the vehicle by 3–4% at typical city and highway driving conditions while maintaining the same performance.

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Section: Introductionmentioning

confidence: 99%

Research on and development of a Miller cycle engine with multi-stage boosting

Liu

Zhu

Sun

2016

Proceedings of the Institution of Mechanical Engineers, Part D:

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show abstract

“…At high load, LIVC was also beneficial due to the enhanced knock resistance, but the improvement was limited by the heat transfer when the charge went back to the intake system. Akihisa and Sawada 79 also proved that the decoupling of the compression and expansion stroke yielded up to 20% fuel efficiency improvement by exceeding the expansion ratio to be 20:1.…”

Section: Strategies For Optimizing the Gas Exchange Processmentioning

confidence: 93%

Novel approaches to improve the gas exchange process of downsized turbocharged spark-ignition engines: A review

Akehurst

Brace

2015

International Journal of Engine Research

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Engine downsizing, which is the use of a smaller engine that provides the power of a larger engine, is now considered a mega-trend for the internal combustion engine market. It is usually achieved using one or more boosting devices including a supercharger or a turbocharger. Although supercharging is beneficial for engine's transient response, turbocharging technology is more widely adopted considering its advantages in fuel efficiency. Compared to turbocharged compression ignition engines, turbocharged spark-ignition engines tend to be more challenging with respect to the gas exchange process mainly due to their higher pumping loss, the need for throttling and the fact that spark-ignition engines demand more controllability due to the mitigation of knock, particularly with regard to minimizing trapped residuals. These challenges encourage the entire gas exchange process of turbocharged spark-ignition engines to be regarded as a complete air management system instead of just looking at the boosting system in isolation. In addition, more research emphasis should be focused on novel approaches to improve the gas exchange process of downsized turbocharged spark-ignition engines because the refinement of the conventional technologies cannot provide continuous gains indefinitely and only innovative concept may improve the engine performance to meet the fuel efficiency target and the more stringent emission regulation in the future. This article will first briefly review knowledge of the current state of the art technologies that are in production as opposed to approaches that are currently only being investigated at a research level. Next, more novel methods of the gas exchange process are introduced to identify the improved synergies between the engine and the boosting machine. The major findings to improve the gas exchange process that emerge from this review comprise four aspects (depending on the location where the novel technologies are implemented) which are as follows: charge air pressurization/de-pressurization improvement, combustion efficiency enhancement within the chamber, valve event-associated development and exhaust system optimization. Although the interaction between these technologies on different aspects of the gas exchange process was found to be highly complex, the optimization or the combination of these technologies is anticipated to further improve a downsized turbocharged spark-ignition engine's performance.

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“…Analyses were conducted with the statistical programming language R (R Foundation for Statistical Computing, Vienna, Austria) using the tidyverse, readxl, writexl, and MatchIt packages. 16…”

Section: Statistical Analysis and Propensity Score Analysismentioning

confidence: 99%

The relationship of ADHD and trauma mortality: An NTDB analysis

Zwemer

Mohseni

Forssten

et al. 2023

Trauma

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Objective Nearly 7% of the adult US population has symptomatic Attention Deficit Hyperactivity Disorder (ADHD), which is associated with an increased risk for traumatic injury. There is limited data on the outcome of hospitalized trauma patients with ADHD. This study aimed to use a large nationwide database to investigate the relationship between a diagnosis of ADHD and clinical outcomes in hospitalized patients after major trauma. Methods All patients 18 years or older in the National Trauma Database were retrospectively reviewed. Propensity score analysis was used to match patients with and without the diagnosis of ADHD at a 1:1 ratio based on age, sex, race, highest AIS in each region, comorbidities, and the presence of advanced directives limiting care. Outcomes of patients with ADHD admitted to the trauma service between the years 2015 and 2017 were compared to those without ADHD. The primary outcome of interest was in-hospital mortality, while the secondary outcomes included complications and hospital length of stay. Results There were 9399 patients included in the study with a diagnosis of ADHD. These patients were overall more likely to be younger, male, and Caucasian, compared to their matched counterparts without ADHD. ADHD was associated with a significantly lower in-hospital mortality than patients without ADHD. There was no difference in the ICU admission rate, ICU LOS, ventilator use, or complication rates between patients with and without ADHD. Conclusion A diagnosis of ADHD has a complex association with clinical outcomes after trauma. The current large national analysis found that patients with a diagnosis of ADHD had significantly lower overall in-hospital mortality.

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Research on Improving Thermal Efficiency through Variable Super-High Expansion Ratio Cycle

Cited by 24 publications

References 5 publications

Research on and development of a Miller cycle engine with multi-stage boosting

Research on and development of a Miller cycle engine with multi-stage boosting

Novel approaches to improve the gas exchange process of downsized turbocharged spark-ignition engines: A review

The relationship of ADHD and trauma mortality: An NTDB analysis

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