Piston-Ring Oiling, Synthetic Fuels and Oils

1946 ◽  
Vol 175 (5) ◽  
pp. 219-219
Keyword(s):  
2021 ◽  
Author(s):  
Sebastian Blochum ◽  
Fabian H. Ruch ◽  
Thomas Bastuck ◽  
Martin Härtl ◽  
Richard Mittler ◽  
...  

Author(s):  
V.A. Munoz ◽  
R.J. Mikula ◽  
C. Payette ◽  
W.W. Lam

The transformation of high molecular weight components present in heavy oils into useable liquid fuels requires their decomposition by means of a variety of processes. The low molecular weight species produced recombine under controlled conditions to generate synthetic fuels. However, an important fraction undergo further recombination into higher molecular weight components, leading to the formation of coke. The optical texture of the coke can be related to its originating components. Those with high sulfur and oxygen content tend to produce cokes with small optical texture or fine mosaic, whereas compounds with relatively high hydrogen content are likely to produce large optical texture or domains. In addition, the structure of the parent chemical components, planar or nonplanar, determines the isotropic or anisotropic character of the coke. Planar molecules have a tendency to align in an approximately parallel arrangement to initiate the formation of the nematic mesophase leading to the formation of anisotropic coke. Nonplanar highly alkylated compounds and/or those rich in polar groups form isotropic coke. The aliphatic branches produce steric hindrance to alignment, whereas the polar groups participate in cross-linking reactions.


2019 ◽  
Vol 13 (3) ◽  
pp. 5513-5527
Author(s):  
J. W. Tee ◽  
S. H. Hamdan ◽  
W. W. F. Chong

Fundamental understanding of piston ring-pack lubrication is essential in reducing engine friction. This is because a substantial portion of engine frictional losses come from piston-ring assembly. Hence, this study investigates the tribological impact of different piston ring profiles towards engine in-cylinder friction. Mathematical models are derived from Reynolds equation by using Reynolds’ boundary conditions to generate the contact pressure distribution along the complete piston ring-pack/liner conjunction. The predicted minimum film thickness is then used to predict the friction generated between the piston ring-pack and the engine cylinder liner. The engine in-cylinder friction is predicted using Greenwood and Williamson’s rough surface contact model. The model considers both the boundary friction and the viscous friction components. These mathematical models are integrated to simulate the total engine in-cylinder friction originating from the studied piston ring-pack for a complete engine cycle. The predicted minimum film thickness and frictional properties from the current models are shown to correlate reasonably with the published data. Hence, the proposed mathematical approach prepares a simplistic platform in predicting frictional losses of piston ring-pack/liner conjunction, allowing for an improved fundamental understanding of the parasitic losses in an internal combustion engine.


1982 ◽  
Vol 32 ◽  
pp. 17-17
Author(s):  
Stephen R. Lefevre

Political scientists are increasingly interested in understanding policymaking in civilian, defense and space technologies. The answer to the question why this is, is found partly in the emergence of the policy field itself, and partly in the enormously expanded role that government stimulus of technological innovation is playing in the public and private sectors. A listing of some recent programs — breeder and fusion reactor R&D, the space shuttle, windmill farm demonstration programs, synthetic fuels programs, and dial-a-ride transportation systems — gives some indication of the scope of federal involvement, and points up some of the implications that this enlarged role has for the student of public policy. Why, for instance, has government elected to stimulate innovations in certain technologies and not others? Who are the key actors shaping the policymaking process in R&D? Are their gaps in federal efforts? Is the policy system responding effectively to needs for renewable energy sources, alternative home building materials, gasoline-efficient automobile engines, etc?


Author(s):  
Sonil Nanda ◽  
Falguni Pattnaik ◽  
Venu Babu Borugadda ◽  
Ajay K. Dalai ◽  
Janusz A. Kozinski ◽  
...  

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