OS1-4 Low Cooling Heat Loss and High Efficiency Diesel Combustion using Restricted In-Cylinder Flow(OS1: Ultimate thermal efficiency,Organized Session Papers)

A new diffusion-based combustion concept (named it as Actively Controlled Rate of Diesel Combustion) for the confirmation of brake thermal efficiency optimum heat release rate profile based on multiple fuel injectors has been investigated. The outstanding results are; it is possible to achieve desired heat release rate profile only by the independent control of injection timing and duration of three injectors installed to a cylinder. The optimum brake thermal efficiency was not achieved with the Otto-like cycle but with the Sabathe-like cycle as predicted by a zero-dimensional thermodynamic model. Furthermore, smoke emissions were concurrently reduced with NOx emissions by increasing fuel amount from the side injectors without any deterioration in CO and total hydrocarbon emissions. On the other hand, brake thermal efficiency itself was not so improved than expected, because of lower heat release in the late part of combustion and unexpected less heat loss reduction. To solve these issues, combustion visualization and numerical simulation analysis were carried out. The results suggested that the adjacent sprays with narrower angle from each side injector deteriorated air entrainment and mixture formation, which might also result in the deterioration in wall heat loss in the expansion stroke. To solve both issues simultaneously, modified nozzle to inject against the swirl from the side injectors was utilized and achieved an improvement in both brake thermal efficiency and heat loss. That is the interdependent and reciprocal control of in-cylinder flow and fuel injection will be one of the breakthrough technologies for current trade-offs by the temporal and spatial spray flame optimization. Furthermore, the nozzle having higher flow rate with less number of orifice was utilized for the side injectors. Even though the smoke emissions were not optimized yet, brake thermal efficiency was much improved with higher heat release rate in the late part of combustion.

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Development of High Efficiency Gasoline Engine with Thermal Efficiency over 42%

10.4271/2017-01-2229 ◽

2017 ◽

Cited By ~ 11

Author(s):

Byeongsoek Lee ◽

Heechang Oh ◽

SeungKook Han ◽

SooHyung Woo ◽

JinWook Son

Keyword(s):

Thermal Efficiency ◽

High Efficiency ◽

Gasoline Engine

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Construction and Experimental Study of an Elevation Linear Fresnel Reflector

Journal of Solar Energy Engineering ◽

10.1115/1.4032682 ◽

2016 ◽

Vol 138 (3) ◽

Cited By ~ 5

Author(s):

J. D. Nixon ◽

P. A. Davies

Keyword(s):

Heat Loss ◽

Thermal Efficiency ◽

Theoretical Models ◽

Loss Coefficient ◽

Heat Transfer Fluid ◽

Stagnation Temperature ◽

Model Predictions ◽

The Difference ◽

Predicted Values ◽

Linear Fresnel Reflector

This paper outlines a novel elevation linear Fresnel reflector (ELFR) and presents and validates theoretical models defining its thermal performance. To validate the models, a series of experiments were carried out for receiver temperatures in the range of 30–100 °C to measure the heat loss coefficient, gain in heat transfer fluid (HTF) temperature, thermal efficiency, and stagnation temperature. The heat loss coefficient was underestimated due to the model exclusion of collector end heat losses. The measured HTF temperature gains were found to have a good correlation to the model predictions—less than a 5% difference. In comparison to model predictions for the thermal efficiency and stagnation temperature, measured values had a difference of −39% to +31% and 22–38%, respectively. The difference between the measured and predicted values was attributed to the low-temperature region for the experiments. It was concluded that the theoretical models are suitable for examining linear Fresnel reflector (LFR) systems and can be adopted by other researchers.

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Experimental Comparison of GCI and Diesel Combustion in a Medium-Duty Opposed-Piston Engine

Volume 1: Large Bore Engines; Fuels; Advanced Combustion ◽

10.1115/icef2018-9701 ◽

2018 ◽

Cited By ~ 2

Author(s):

Reed Hanson ◽

Ashwin Salvi ◽

Fabien Redon ◽

Gerhard Regner

Keyword(s):

Thermal Efficiency ◽

Combustion Efficiency ◽

Experimental Comparison ◽

Diesel Combustion ◽

Compression Ignition ◽

Piston Engine ◽

Load Range ◽

Combustion Performance ◽

Poppet Valve

The Achates Power Inc. (API) Opposed Piston (OP) Engine architecture provides fundamental advantages that increase thermal efficiency over current poppet valve 4 stroke engines. In this paper, combustion performance of diesel and gasoline compression ignition (GCI) combustion in a medium duty, OP engine are shown. By using GCI, NOx and/or soot reductions can be seen compared to diesel combustion at similar or increased thermal efficiencies. The results also show that high combustion efficiency can be achieved with GCI combustion with acceptable noise and stability over the same load range as diesel combustion in an OP engine.

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Optimization of piston bowl and valve system in compression ignition engine fueled with gasoline/diesel/polyoxymethylene dimethyl ethers for high efficiency

International Journal of Engine Research ◽

10.1177/1468087419865384 ◽

2019 ◽

pp. 146808741986538

Author(s):

Bowen Li ◽

Haoye Liu ◽

Linjun Yu ◽

Zhi Wang ◽

Jianxin Wang

Keyword(s):

Heat Transfer ◽

Thermal Efficiency ◽

High Efficiency ◽

Compression Ignition ◽

Combustion Mode ◽

Compression Ignition Engine ◽

Valve System ◽

Percentage Points ◽

Polyoxymethylene Dimethyl Ethers ◽

Variable Valve

Polyoxymethylene dimethyl ethers, with excellent volatility and oxygen content of up to 49%, have great potential to improve engine performance and emission characteristics. In this study, experiments were carried out in a single-cylinder engine fueled with gasoline/diesel/polyoxymethylene dimethyl ethers blend fuel using multiple premixed compression ignition combustion mode along with engine optimization to exploit the high-efficiency potential. The thermal efficiency was increased by 9.4 percentage points after transforming the combustion mode from conventional diesel mode to gasoline/diesel/polyoxymethylene dimethyl ethers multiple premixed compression ignition mode. A fully variable valve system and a redesigned low-heat-transfer piston were used to further improve the thermal efficiency. The low-heat-transfer piston had a 15% lower area–volume ratio compared with the original ω-type piston. By replacing the original ω-type piston with the low-heat-transfer piston, the heat transfer loss was reduced by 2.29 percentage points and thus indicated thermal efficiency could be increased by 2.37 percentage points, which was up to 50.03%. On the basis of the low-heat-transfer piston, indicated thermal efficiency could be further increased to 51.09% with the application of fully variable valve system due to the longer ignition delay and more premixed combustion. At the same time, NOX emissions could be controlled below 0.4 g/kW·h using high exhaust gas recirculation ratio, which equaled the NOX emission limit of Euro VI standard. Although soot emissions could be increased due to weak turbulence and insufficient intake charge using the low-heat-transfer piston and fully variable valve system, it was still lower than those of the original diesel engines.

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Development of a 6 MW-Class High-Efficiency Gas Turbine M7A-01

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/94-gt-066 ◽

1994 ◽

Author(s):

T. Sugimoto ◽

K. Ikesawa ◽

S. Kajita ◽

W. Karasawa ◽

T. Kojima ◽

...

Keyword(s):

Gas Turbine ◽

Thermal Efficiency ◽

High Efficiency ◽

Axial Flow ◽

Inlet Temperature ◽

Gas Temperature ◽

Flow Compressor ◽

Exhaust Gas Temperature ◽

Cycle Efficiency

The M7A-01 gas turbine is a newly developed 6 MW class single-shaft machine. With its high simple-cycle efficiency and high exhaust gas temperature. it is particularly suited for use in electric power generation and co-generation applications. An advanced high efficiency axial-flow compressor, six can-type combustors, and a high inlet temperature turbine has been adopted. This results in a high thermal efficiency of 31.5% at the gas turbine output shaft and a high overall thermal efficiency of co-generation system. In addition, low NOx emissions from the combustors and a long service life permit long-term continuous operation under various environmental limitations. The results of the full load shop test, accelerated cyclic endurance test and extra severity tests verified that the performance, the mechanical characteristics and the emission have satisfied the initial design goals.

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Development of an 8MW-Class High-Efficiency Gas Turbine, M7A-03

Volume 4: Turbo Expo 2007, Parts A and B ◽

10.1115/gt2007-28361 ◽

2007 ◽

Author(s):

Kazuhiko Tanimura ◽

Naoki Murakami ◽

Akinori Matsuoka ◽

Katsuhiko Ishida ◽

Hiroshi Kato ◽

...

Keyword(s):

Gas Turbine ◽

Thermal Efficiency ◽

High Performance ◽

High Efficiency ◽

High Reliability ◽

Pressure Ratio ◽

Combined Cycle ◽

Gas Temperature ◽

Turbine Cooling ◽

Distributed Power Generation

The M7A-03 gas turbine, an 8 MW class, single shaft gas turbine, is the latest model of the Kawasaki M7A series. Because of the high thermal efficiency and the high exhaust gas temperature, it is particularly suitable for distributed power generation, cogeneration and combined-cycle applications. About the development of M7A-03 gas turbine, Kawasaki has taken the experience of the existing M7A-01 and M7A-02 series into consideration, as a baseline. Furthermore, the latest technology of aerodynamics and cooling design, already applied to the 18 MW class Kawasaki L20A, released in 2000, has been applied to the M7A-03. Kawasaki has adopted the design concept for achieving reliability within the shortest possible development period by selecting the same fundamental engine specifications of the existing M7A-02 – mass air flow rate, pressure ratio, TIT, etc. However, the M7A-03 has been attaining a thermal efficiency of greater than 2.5 points higher and an output increment of over 660 kW than the M7A-02, by the improvement in aerodynamic performance of the compressor, turbine and exhaust diffuser, improved turbine cooling, and newer seal technology. In addition, the NOx emission of the combustor is low and the M7A-03 has a long service life. These functions make long-term continuous operation possible under various environmental restraints. Lower life cycle costs are achieved by the engine high performance, and the high-reliability resulting from simple structure. The prototype M7A-03 gas-turbine development test started in the spring of 2006 and it has been confirmed that performance, mechanical characteristics, and emissions have achieved the initial design goals.

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Effects of Absorber Emissivity on Thermal Performance of a Solar Cavity Receiver

Advances in Condensed Matter Physics ◽

10.1155/2014/564639 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10 ◽

Cited By ~ 7

Author(s):

Jiabin Fang ◽

Nan Tu ◽

Jinjia Wei

Keyword(s):

Heat Loss ◽

Thermal Performance ◽

Thermal Efficiency ◽

Radiative Heat ◽

Slight Effect ◽

Radiative Heat Loss ◽

Total Heat Loss ◽

Convective Heat Loss ◽

Performance Curves ◽

Variation Tendency

Solar cavity receiver is a key component to realize the light-heat conversion in tower-type solar power system. It usually has an aperture for concentrated sunlight coming in, and the heat loss is unavoidable because of this aperture. Generally, in order to improve the thermal efficiency, a layer of coating having high absorptivity for sunlight would be covered on the surface of the absorber tubes inside the cavity receiver. As a result, it is necessary to investigate the effects of the emissivity of absorber tubes on the thermal performance of the receiver. In the present work, the thermal performances of the receiver with different absorber emissivity were numerically simulated. The results showed that the thermal efficiency increases and the total heat loss decreases with increasing emissivity of absorber tubes. However, the thermal efficiency increases by only 1.6% when the emissivity of tubes varies from 0.2 to 0.8. Therefore, the change of absorber emissivity has slight effect on the thermal performance of the receiver. The reason for variation tendency of performance curves was also carefully analyzed. It was found that the temperature reduction of the cavity walls causes the decrease of the radiative heat loss and the convective heat loss.

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