scholarly journals Nissan gasoline engine strategy for higher thermal efficiency

2017 ◽  
Vol 169 (2) ◽  
pp. 141-145 ◽  
Author(s):  
Hideaki MIZUNO
Keyword(s):  
Heat Capacity ◽  
Energy Loss ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
Gasoline Engine ◽  
Loss Reduction ◽  
Miller Cycle ◽  
High Compression Ratio ◽  
Gasoline Engines ◽  
Evolution Trend

Rising highly concern about the environment has led to demands for the improvement of the efficiency of gasoline engines. Engine thermal efficiency will reach about 40% by technologies as boosted EGR, miller cycle and so on. This evolution trend will be continuously required to survive engines for the future. In this background, further improvement based on theoretical thermal efficiency of high compression ratio and specific heat capacity should be promoted. In addition, energy loss reduction such as represented by cooling loss and friction is also very important for the efficient and effective improvement. NISSAN’s challenges will be introduced to solve these propositions.

Application of Over-Expansion Cycle to a Larger Gasoline Engine With Late-Closing of Intake Valves

2002 ◽  
Author(s):  
Seiichi Shiga ◽  
Kenji Nishida ◽  
Shizuo Yagi ◽  
Youichi Miyashita ◽  
Yoshiharu Yuzawa ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Thermal Efficiency ◽  
Gasoline Engine ◽  
Engine Performance ◽  
Mechanical Efficiency ◽  
Expansion Ratio ◽  
Brake Thermal Efficiency ◽  
Gasoline Engines ◽  
Cylinder Test ◽  
Test Engine

This paper presents further investigation into the effect of over-expansion cycle with late-closing of intake valves on the engine performance in gasoline engines. A larger single-cylinder test engine with the stroke volume of 650 cc was used with four kinds of expansion ratio (geometrical compression ratio) from 10 to 25 and four sets of intake valve closure (I.V.C.) timings from 0 to 110 deg C.A. ABDC. Late-closing has an effect of decreasing the pumping work due to the reduction of intake vacuum, althogh higher expansion ratio increases the friction work due to the average cylinder pressure level. Combining the higher expansion ratio with the late-closing determines the mechanical efficiency on the basis of these two contrastive effects. The indicated thermal efficiency is mostly determined by the expansion ratio and little affected by the nominal compression ratio. The value of the indicated thermal efficiency reaches to 48% at most which is almost comparable with the value of diesel engines. The improvement of both indicated and brake thermal efficiency reaches to 16% which is much higher than ever reported by the authors. A simple thermodynamic calculation could successfully explain the behavior of the indicated thermal efficiency. The brake thermal efficiency could also be improved due to the increase in both mechanical and indicated efficiencies.

Study of Combustion and Emission Characteristics of Gasoline Engine with Miller Cycle

2014 ◽  
Vol 960-961 ◽  
pp. 1411-1415 ◽  
Author(s):  
Jian Wu ◽  
Wei Fan ◽  
Yang Hua ◽  
Yun Long Li ◽  
Shao Zhe Zhang ◽  
...  
Keyword(s):  
Heat Release ◽  
Compression Ratio ◽  
Gasoline Engine ◽  
Control Technology ◽  
Miller Cycle ◽  
High Compression Ratio ◽  
Combustion Heat ◽  
Geometry Compression ◽  
Cam Profile ◽  
Hc Emissions

On the basis of original engine, high compression ratio miller cycle can be realized, through perfecting the inlet cam profile, using higher geometry compression ratio, combining VVT control technology. The results indicate that the miller cycle achieved by VVT control technology can reduce pumping loss, and improve the effect utilization of energy. The combustion heat release rate is lower than the original engine, and combustion heat release are mainly concentrated on TDC later, lower the burning temperature. Compared with the original engine, NOX emissions decrease significantly, but CO and HC emissions increase somewhat.

scholarly journals A Theoretical Study on the Thermodynamic Cycle of Concept Engine with Miller Cycle

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1051
Author(s):  
Jungmo Oh ◽  
Kichol Noh ◽  
Changhee Lee
Keyword(s):  
Compression Ratio ◽  
Thermal Efficiency ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Expansion Ratio ◽  
Boost Pressure ◽  
Miller Cycle ◽  
Compression Pressure ◽  
Air Mass ◽  
Atkinson Cycle

The Atkinson cycle, where expansion ratio is higher than the compression ratio, is one of the methods used to improve thermal efficiency of engines. Miller improved the Atkinson cycle by controlling the intake- or exhaust-valve closing timing, a technique which is called the Miller cycle. The Otto–Miller cycle can improve thermal efficiency and reduce NOx emission by reducing compression work; however, it must compensate for the compression pressure and maintain the intake air mass through an effective compression ratio or turbocharge. Hence, we performed thermodynamic cycle analysis with changes in the intake-valve closing timing for the Otto–Miller cycle and evaluated the engine performance and Miller timing through the resulting problems and solutions. When only the compression ratio was compensated, the theoretical thermal efficiency of the Otto–Miller cycle improved by approximately 18.8% compared to that of the Otto cycle. In terms of thermal efficiency, it is more advantageous to compensate only the compression ratio; however, when considering the output of the engine, it is advantageous to also compensate the boost pressure to maintain the intake air mass flow rate.

THE OXIDATION, IGNITION, AND DETONATION OF FUEL VAPORS AND GASES: XII. THE HIGH COMPRESSION RATIO OTTO CYCLE GAS ENGINE AND THE ADVERSE EFFECT OF HIGH JACKET TEMPERATURES ON THERMAL EFFICIENCY

1949 ◽  
Vol 27f (11) ◽  
pp. 435-449 ◽  
Author(s):  
R. O. King ◽  
Edwin J. Durand ◽  
J. Alex. Morrison
Keyword(s):  
Adverse Effect ◽  
Quality Control ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
Diesel Oil ◽  
Surface Combustion ◽  
Compression Ignition ◽  
Otto Cycle ◽  
High Compression Ratio ◽  
Gas Engine

Town gas was used as the fuel for the C.F.R. engine during a series of engine trials run at a compression ratio of 10:1 and at jacket temperatures of 140°, 212°, 302°, and 351° F. The mixture strength at each jacket temperature was varied from the weakest to the richest on which the engine would run steadily. The object of the trials was (1) to determine the effect of jacket temperature on thermal efficiency and (2) to compare the performance of an Otto cycle engine run at 10:1 compression ratio with that of a compression ignition (Diesel) oil engine. The results of the trials show that thermal efficiency decreases as the jacket temperature is raised, that is, the decrease more than offsets the gain due to decrease of heat loss during combustion and expansion. It is indicated by the character of the results and by experiments described earlier that the observed loss of efficiency is due to flameless surface combustion of the fuel during compression. The performance of the C.F.R. engine running on town gas at 10:1 compression ratio as compared with that of a compression ignition oil engine running at 12:1 was superior in respect of maximum power (I.M.E.P.) developed and range of quality control and not greatly inferior in respect of thermal efficiency.

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