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The role of molecularly ordered structures in energy transport enhancement during combustion process : a new conception of a reaction mechanism of fuel components oxidation

Białecki T., Dzięgielewski W., Gawron B., Kaźmierczak U., Kulczycki A.

Journal of KONES

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2018

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Vol. 25, No. 4

17--24

EN

This article presents the results of investigations focused on the role of molecularly ordered structures (molecular clusters) on combustion process. The proposed new mechanism of the reactions initiation takes into account the role of molecular clusters in energy (heat and energy of electrons emitted by the surface of the walls of combustion chamber) conductivity regulation. Literature survey shows that molecular clusters created by aromatic hydrocarbons are responsible for particulate matter. The combustion process itself is not uniform in whole combustion chamber. Such diversity, caused mainly by heterogeneous thermal state of combustion chamber is recognized as significant reason to create various products of combustion including carbon oxides, carbon dioxides and nitrogen oxides. Jet fuel and its blends with n-butanol and biobutanol in concentration from 10 to 75 % (V/V) were subjected to laboratory tests. Such blends were also tested on the test rig with a miniature turbojet engine – MiniJETRig. Engine operating parameters and carbon oxide emission were measured. The relations between electrical conductivity and parameters of engine test (e.g. temperature in selected points in combustion chamber) were assessed. Engine tests were carried out according to specific profile of engine test, which models different engine operating modes. The results of experimental investigations, shown in the article, initially confirm the proposed mechanism of the oxidation reactions initiation during combustion process.

2

The influence of the chemical structure of synthetic hydrocarbons and alcohols on the lubricity of CI engine fuels and aviation fuels

Kulczycki A., Dzięgielewski W, Ozimina D.

Tribologia

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2017

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nr 3

91--100

EN

The paper covers the mechanism of lubrication layer formation by fuels containing synthetic hydrocarbons and alcohols. Development of alternative fuels containing FAME, alcohols, and synthetic hydrocarbons has increased the interest in the mechanism of lubrication of fuelling systems parts. Fuel lubricity tests have been conducted using the HFRR and BOCLE testing rigs. Fuels under testing, both for CI engines and for aviation turbine ones, contained synthetic components: saturated hydrocarbons both of even and odd number of carbon atoms, and butanol, isomers. These components have been added to conventional fuels, such as diesel fuel and Jet A-1 fuel at the concentration of 0–20% (V/V). All fuels under testing contained commercially available lubricity improvers (carboxylic acid). Test results were analysed using model αi described in [L. 6, 7]. As a result of the analysis, it has been found that the liquid phase, which is a lubricating film, should contain agglomerates or molecular clusters responsible for the transport of energy introduced into lubricating film by electrons emitted from metal surface. The mechanism enabling a description of the effect of base fuel without lubricity improvers on efficiency of such additives has been suggested.

PL

Przedmiotem artykułu jest mechanizm tworzenia warstwy smarującej przez paliwa zawierające syntetyczne węglowodory i alkohole. Rozwój paliw alternatywnych spowodował wzrost zainteresowania mechanizmem smarowania elementów układów zasilania silników. Badania smarności paliw prowadzono z użyciem aparatów HFRR i BOCLE. Badane paliwa do silników o ZS i paliwa do turbinowych silników lotniczych zawierały trzy serie syntetycznych komponentów: węglowodory parafinowe o parzystej liczbie atomów węgla, węglowodory parafinowe o nieparzystej liczbie atomów węgla oraz izomery butanolu. Powyższe syntetyczne komponenty były dodawane do mineralnych paliw: oleju napędowego i paliwa Jet A1 w ilości 0–20% (V/V). Wszystkie badane paliwa zawierały komercyjnie dostępne dodatki smarnościowe (kwas karboksylowy). Wyniki badań eksperymentalnych były analizowane z zastosowaniem modelu αi opisanego w publikacjach [L. 6, 7]. W rezultacie przeprowadzonej analizy stwierdzono, że faza ciekła – film smarny powinna zawierać aglomeraty lub klastry molekularne, które są odpowiedzialne za transport energii wprowadzanej do filmu smarnego przez elektrony emitowane z powierzchni metalu. Zaproponowano mechanizm, który może wyjaśnić wpływ paliwa bazowego (bez dodatków smarnościowych) na efektywność działania dodatków smarnościowych.

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Właściwości i zastosowania wody pod- i nadkrytycznej

Światła-Wójcik D.

Wiadomości Chemiczne

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2010

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[Z] 64, 3-4

225-242

EN

In the last decades, sub- and supercritical water has received continuously increasing attention as a reaction medium. As safe, non-toxic, readily accessible it is used in chemical synthesis, waste destruction and biomass processing [1–4]. A broad area of technological and industrial applications of sub- and supercritical water arises from its physical and transport properties falling between those of a gas and a liquid. The solvent properties of water can rapidly change with increasing pressure and temperature [2, 5, 10]. Above the critical point (Tc = 647.1 K, Pc = 22.06 MPa) water becomes highly compressible and diffusive. The static dielectric constant approaches values characteristic for low-polar solvent (Fig. 5). Contrary to liquid water at ambient conditions, supercritical water is a poor solvent for ionic species but is well miscible with hydrocarbons and gases (Fig. 6). The ionic product of supercritical water can be a few orders of magnitude higher than in ambient water (Fig. 4) with consequent effect on the kinetics and mechanisms of chemical reactions. By adjustment of thermodynamic conditions one can tune density, viscosity, polarity or pH of water to the desired solvation properties without any change in the chemical composition. An alternation in the character of water solvent near and above the critical point is the consequence of the structural transformations in the hydrogen-bonded network. As evidenced by many experimental and simulation studies the average number of hydrogen bonds per molecule and the lifetime of H-bonds decrease with increasing temperature and decreasing density [2, 10, 19]. With respect to experiment computer simulation plays an equal, and sometimes pivotal role, in quantitative characterization and understanding of water under extreme conditions. Precise definition of an H-bond employed in computer simulation allows one to examine size and topology of clusters of hydrogen-bonded molecules for various thermodynamic states [17, 19]. Such knowledge is invaluable to link features of the hydrogen bonding with the macroscopic properties of water [10, 19]. This article provides an overview of three aspects concerning water from ambient to supercritical conditions. In Chapter 1 the physical and transport properties are reviewed. Features of hydrogen bonding and a relationship between the molecular engagement in hydrogen-bonded clusters and macroscopic properties of water are discussed in Chapter 2. Chapter 3 focuses on technological and industrial applications of sub- and supercritical water. The summary concludes on main research needs.

4

Molecular Clusters to Nanomaterials

Singh N., Lee H., Suh S., Kołaski M., Kim K.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 5-6

1021-1035

EN

Theoretical investigations of gas phase clusters enable the evaluation of intrinsic molecular properties and intermolecular interactions. Based on the microscopic determination of the properties of individual atoms, molecules, or clusters, one can predict the macroscopic properties of bulk matter. With the aid of theoretical insights into the interaction forces holding these clusters and subsequent properties of a large number of cluster systems (ranging from simple water clusters to large pi-systems), we have investigated the properties of various novel molecular systems including endo/exohedral fullerenes, nanotori, nonlinear optical materials, ionophores/receptors, polypeptides, enzymes, organic nanotubes, nanowires, and electronic and nano-mechanical molecular devices. This mini-review highlights some of the interesting results obtained in the course of our extensive theoretical investigations of clusters toward the molecular design approach of nanomaterials.

5

Nonadditive effects in small metal and polyatomic molecular clusters

Novaro O.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 7S

1432-1446

EN

A review of the role of multibody effects in the behavior of oligomer bound states, crystalline structures, adsorption properties of surfaces and dense states of matter is given. Special emphasis is placed on the work of W. Kołos and coworkers in the University of Warsaw and Mexico. New results including electron correlation are given here, confirming the enormous role played by the multibody corrections in the stability of metallic clusters as Lin and Ben, where nonadditive effects are very large, to the point of making the convergence of the multibody expabsion of the energy extremely doubtful. For polyatomic molecular clusters as (NH3)3 multibidy effects albeit small, still are quite relevant to determine the cluster stability and geometry.