Hydrocarbon Combustion Products Research Articles

Effect of Condensed Phase Particles on the Electromagnetic Field Characteristics of Combustion Products in a Flow Path of a Liquid-Propellant Engine. The Results of Experimental Studies

This paper describes the experimental study of amplitude (with a frequency of up to 50 kHz) and integral characteristics of the self-magnetic field of high-temperature combustion products of hydrocarbon fuel, which flow out of the nozzle of a standard liquid-propellant engine (LPE) with simulation of the heat of a combustion chamber with injection of aluminum-magnesium alloy particles (c-phase) into the combustion chamber. It is determined that the amplitude of the magnetic field intensity generated by high-temperature (up to 3500 K) combustion products depends on the LPE operation modes and the presence of k phase particles in the particle flow. The magnetic field amplitude increases by 20% during the LPE burnout ≈0.2 s earlier than the pressure drop in the combustion chamber. The total volumetric electric charge generated by the combustion product flow with the c-phase is estimated.

К расчету равновесных состояний продуктов сгорания углеводородов при недостатке кислорода

In this paper, we propose a unified approach to the computation of equilibrium states of hydrocarbon combustion products under the lack of oxygen when both gaseous and condensed carbon phases can appear simultaneously among the components of chemical reaction. One of the principles forming the basis of the approach is that the particles of a condensed substance are “large molecules” consisting of a great number of normal molecules. To illustrate the feasibility of the formulated approach, the problem of explosion of reacting gas mixture in a volume has been numerically solved. The computations have been performed for oxy-acetylene and air-acetylene mixtures.

Benzo[a]pyrene contamination in Rostov Region of Russian Federation: A 10-year retrospective of soil monitoring under the effect of long-term technogenic pollution

The aim of the current work was to study the main tendencies in the accumulation and distribution of benzo[a]pyrene in soils of the affected zone of the Novocherkassk regional power plant. Studies were conducted on the soils of monitoring plots subjected to Novocherkassk regional power plant emissions. Monitoring plots were established at different distances from the Novocherkassk regional power plant (1.0–20.0 km). Regularities in the accumulation and distribution of benzo[a]pyrene in chernozemic, meadow-chernozemic, and alluvial soils under the effect of aerotechnogenic emissions from the Novocherkassk regional power plant have been revealed on the basis of long-term monitoring studies (from 2002 to 2011). The tendencies in the distribution and accumulation of BaP in the studied soils coincided during the 10 years of monitoring studies. It has been found the 5-km zone to the northwest from the power station, which coincides with the predominant wind direction, is most subjected to contamination by benzo[a]pyrene, with the maximum accumulation at a distance of about 1.6 km from the source. Dynamics of pollutant accumulation in soils depends on number of Novocherkassk regional power plant emissions. The content of benzo[a]pyrene in the soil is an indicator of the technogenic load impact on the areas, for which the combustion products of hydrocarbon fuel are the major pollutants. A gradual decrease of the pollutant content in the soils was revealed during the period from 2002 to 2011. It explained by the significant decrease in the volume of pollutant emissions from the plant and the self-purification capacity of soils and mechanisms of benzo[a]pyrene degradation.

Monitoring of benzo[a]pyrene content in soils under the effect of long-term technogenic poluttion

The aim of the current work was to study the main tendencies in the accumulation and distribution of benzo[a]pyrene in soils of the affected zone of the Novocherkassk regional power plant. Studies were conducted on the soils of monitoring plots subjected to Novocherkassk regional power plant emissions. Monitoring plots were established at different distances from the Novocherkassk regional power plant (1.0–20.0km). Regularities in the accumulation and distribution of benzo[a]pyrene in chernozemic, meadow-chernozemic, and alluvial soils under the effect of aerotechnogenic emissions from the Novocherkassk regional power plant have been revealed on the basis of long-term monitoring studies (from 2002 to 2011). The tendencies in the distribution and accumulation of BaP in the studied soils coincided during the 10years of monitoring studies. It has been found the 5-km zone to the northwest from the power station, which coincides with the predominant wind direction, is most subjected to contamination by benzo[a]pyrene, with the maximum accumulation at a distance of about 1.6km from the source. Dynamics of pollutant accumulation in soils depends on number of Novocherkassk regional power plant emissions. The content of benzo[a]pyrene in the soil is an indicator of the technogenic load impact on the areas, for which the combustion products of hydrocarbon fuel are the major pollutants. A gradual decrease of the pollutant content in the soils was revealed during the period from 2002 to 2011. It explained by the significant decrease in the volume of pollutant emissions from the plant and the self-purification capacity of soils and mechanisms of benzo[a]pyrene degradation.

Analysis of Benzo[a]Pyrene Contamination from an Long-Term Contaminated Soil

Analysis of benzo[a]pyrene contamination from an aged contaminated chernozemic, meadow-chernozemic and alluvial soils under the effect of aerotechnogenic emissions from the Novocherkassk regional power plant have been revealed on the basis of annual monitoring studies from 2008 to 2012. A new ecologically clean highly-effective express-method of subcritical water extraction has been developed for determination of benzo[a]pyrene from soils of the emissions zone. It has been found that the 5-km zone to the northwest and west from the power station, which coincides with the predominant wind directions, is most subjected to contamination by benzo[a]pyrene, with the maximum accumulation at a distance of about 1.6 km from the emissions source. The vertical distribution coefficients of benzo[a]pyrene between the 0-5 cm and 5-20 cm layers closely correlate with the contents of physical clay, clay, organic matter and cation exchange capacity. It has been shown that the content of benzo[a]pyrene in the soil is an indicator of the technogenic pressure impact on the areas, for which the combustion products of hydrocarbon fuel are the major pollutants.

Common properties of hydrocarbon combustion products and Brayton cycle

The energy released in the process of combustion of substances is the source of thermal energy in cycles of heat engines, while the combustion products are working media in the expansion processes. The composition of all combustibles is their common property - they are all hydrocarbons, i.e. their molecules consist of carbon and hydrogen atoms. This article will examine only the products of stoichiometric combustion the oxidation of fuel components in the environment of atmospheric air. Products of combustion are mixtures of oxides of the constituent elements and the basic element of air - nitrogen. It is the combustion products that determine the expansion processes in the most common cycle of power plant operation- the Brayton cycle. The possibility of accurate calculation of combustion products properties in a fairly broad range of temperatures is required. One of the methods of calculating the properties of the major constituents of hydrocarbon stoichiometric combustion is presented in the paper.

Modeling of spontaneous condensation in high-speed expansion of gaseous mixture

Many efforts have been undertaken to model the condensation phenomena in high-speed steam flow in a steam turbine. Spontaneous vapor condensation takes place not only in high-speed flows involving pure steam such as in a steam turbine but also in other gaseous flows such as the flow of hydro-carbon combustion products through a supersonic nozzle. In the present paper, the condensation models for pure steam flow have been modified and extended to include spontaneous vapor condensation in flows of gaseous mixture containing that vapor. The modified condensation models are implemented into the Eulerian/Eulerian approach within CFD++, the commercial CFD software suite from Metacomp Technologies. It is shown that condensation would occur in a supersonic nozzle when hydro-carbon combustion products expand through the nozzle such that the water–vapor pressure at the nozzle exit is well above the saturation pressure at the local temperature. Another numerical investigation on the condensation taking place in transonic moist air flowing over a NACA 0012 airfoil with an angle of attack illustrates that there is a stationary double shock system in the flow over the upper surface of the airfoil.

Air consumption coefficients in a low-temperature heat engineering installation

Preparation of a working medium is considered from a mixture of combustion products of hydrocarbon fuel and air in the heat generator of a heat engineering installation. Calculation equations are obtained for consumption coefficients of primary and secondary air for this process.

Complex of Programs for Imitative Simulation of Acceleration, Heating, and Melting of Particles in Gas-Dynamic Channels of Technological Devices

This paper describes an interactive complex of programs designed for investigating the processes of acceleration, heating, and melting of particles in the gas‐dynamic channels of burners. To illustrate the efficiency of this method, we have investigated the possibility of melting of tungsten particles in the process of their acceleration and heating by combustion products of hydrocarbon fuel in the gas‐dynamic channel of the burner with the discharge method of acting on the flow.

Dependence of CO emissions on the rate of product cooling

Detailed chemical kinetics simulations of the cooling of hydrocarbon combustion products show that the mole fraction of CO freezes well above equilibrium levels at a value that depends on the cooling rate. The frozen mole fraction of CO can be expressed as a function of the system pressure and the mole fractions of CO 2, O 2, and H 2O X CO, f = 2.0 × 10 −9[ X CO 2 /( X O 2 X H 2O )]( Pτ) −1.6where τ is the temperature relaxation time, inversely proportional to the cooling rate. The ratio of mole fractions in this result can also be derived by partial equilibrium analysis. However, this derivation yields X CO, f proportional to X OH 2 rather than ( Pτ) −1.6. The dependence on cooling rate is shown to be a kinetic effect due to the relatively slow forward rate of the principal CO oxidation reaction. This rate is proportional to PX OH, and X CO freezes when X OH is too small to maintain the consumption rate for CO that is needed to keep X CO near equilibrium at a given cooling rate. Partial equilibrium analysis shows that X OH, f , the value of X OH when X CO freezes, is proportional to ( Pτ) −1. The temperature, T f where X OH equals X OH, f is found by setting X OH, f = X OH,0 exp(−γ OH/ T f ), where γ OH is a fitting parameter related to equilibrium constants. Using T f and the equilibrium value of γ OH with the temperature-dependent result of the partial equilibrium analysis gives X CO proportional to ( Pτ) −1.56. This gives values of frozen X CO in reasonable agreement with the detailed chemical kinetics results. At high cooling rates, γ OH is a function of τ that can be found by a curve fit to X OH vs. T data from detailed kinetics calculations. Using this function to calculate T f improves the agreement with the detailed chemical kinetics results.

Approximate model for analysis of equilibrium flows of chemically reacting gases

Approximate equations describing with high accuracy the change in molar mass and specific internal energy, including its thermodynamic and chemical parts, due to a shift of the chemical equilibrium of gaseous hydrocarbon combustion products are obtained. The approximate model allows one to calculate the detonation parameters at the Chapman-Jouguet point with an accuracy of1%.

Environmental and dietary estrogens and human health: is there a problem?

It has been hypothesized that organochlorine pesticides and other environmental and dietary estrogens may be associated with the increased incidence of breast cancer in women and decreased sperm concentrations and reproductive problems in men. However, elevation of organochlorine compounds such as dichlorodipehenyldichloroethylene (DDE) and polychlorinated biphenyls (PCBs) in breast cancer patients is not consistently observed. Reanalysis of the data showing that male sperm counts decreased by over 40% during 1940 to 1990 indicated that inadequate statistical methods were used and that the data did not support a significant decline in sperm count. Humans are exposed to both natural and industrial chemicals which exhibit estrogenic and antiestrogenic activities. For example, bioflavonoids, which are widely distributed in foods, and several industrial compounds, including organochlorine pesticides and various phenolic chemicals, exhibit estrogenic activity. Humans are also exposed to chemicals which inhibit estrogen-induced responses such as the aryl hydrocarbon receptor (AhR) agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin and related chlorinated aromatics, polynuclear aromatic hydrocarbon combustion products, and indole-3-carbinol, which is found in cruciferous vegetables. Many of the weak estrogenic compounds, including bioflavonoids, are also antiestrogenic at some concentrations. A mass balance of dietary levels of industrial and natural estrogens, coupled with their estimated estrogenic potencies, indicates that the dietary contribution of estrogenic industrial compounds is 0.0000025% of the daily intake of estrogenic flavonoids in the diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Electric arc metallising with dispersion of metal by combustion products of hydrocarbon fuel

Electric arc metallising with dispersion of metal by combustion products of hydrocarbon fuel

Hydrocarbon and Metal Contents in a Sediment Core from Halifax Harbour: A Chronology of Contamination

In a dated core from the Northwest Arm of Halifax Harbour, pollutant hydrocarbon concentrations have increase 100-fold since about 1900 (15–20 cm depth). Aliphatic contaminants characteristic of sewage and urban runoff have had a steady, exponential growth overtime, while aromatic hydrocarbon combustion products are currently declining slightly from a subsurface maximum around 1950 (5–10 cm depth). Present levels of these compounds are among the highest reported in the literature. Similarly, contamination of sediments by the metals Cu, Zn, Pb, and Hg has also increased from 1890 to 1970, with maximum levels among the highest reported from other urban and industrialized coastal marine areas in the world. In contrast, the concentrations of natural product hydrocarbons such as squalene and perylene have not changed significantly in this century.

Theory of surface deposition from a binary dilute vapor-containing stream, allowing for equilibrium condensation within the laminar boundary layer

Deposition rates on solid targets cooled far below the dew point of undersaturated, dilute binary vapor and hot gas mainstreams have recently been found to be reduced and sharply surface temperature dependent compared to their pure vapor deposition counterparts. A rational yet tractable theory to account for such observations is formulated and exploited in particular cases of current practical interest; e.g. the deposition of trace multiple alkali sulfate vapors present in flowing combustion products. Our physicochemical model is based on the formation of a binary solution condensate aerosol near the deposition surface, with the resulting droplets collected by the mechanism of thermophoresis. The binary vapors, assumed here to be in local equilibrium with the solution aerosol phase, are collected by the familiar mechanism of Fick (concentration) diffusion across the prevailing laminar boundary layer (LBL) but we do not make the restrictive assumption that the Fick diffusivities are equal to the energy diffusivity of the carrier gas. As by-products of our calculation of the total (aerosol + vapor) deposition rate we obtain the BL position of condensation onset, as well as the structure of the LBL on either side of this binary “fog-locus”. Illustrative predictions are shown for the effects of Na 2SO 4(g) addition on salt deposition rates from combustion product streams containing a fixed amount of K 2SO 4(g), on the assumption that the resulting Na 2SO 4 + K 2SO 4 droplets form nearly ideal solutions, having droplet thermophoretic diffusivities within two decades of the host gas momentum diffusivity, v. With systematic corrections for the effects of (a) alkali salt vapor dissociation/equilibrium chemical reaction with the hydrocarbon combustion products and (b) slight solution non-ideality, the present theoretical formalism should be useful in accounting for binary nucleation onset effects observed in recent deposition rate experiments using alkali-seeded atmospheric pressure flat flames.

A nonequilibrium theory of surface deposition from particle-laden, dilute condensible vapor-containing laminar boundary layers

The deposition rate of a condensible substance from, say, flowing combustion products to “cold” solid surfaces can be strongly influenced by the simultaneous presence of a particulate aerosol since the particles can: (a) “scavenge” vapor, thereby influencing the vapor deposition rate; and (b) thermophoretically drift to the cold surface, carrying their inventory of scavenged condensate. A rational, yet quite tractable thermophysical model of these nonequilibrium processes is developed here for high Reynolds number laminar stagnation region boundary layer flow, and implemented to the point of calculating and displaying the effects of mainstream particle loading, vapor loading and particle size on the deposition rate of condensible material at surface temperatures well below the vapor dew point. Despite the complexity of this multiphase flow situation, our theoretical model is quite general and is cast in terms of dimensionless parameters which dictate the importance of vapor-phase scavenging and particle thermophoresis, as well as the Kelvin (surface tension) effect in modifying the submicron particle (free-molecule) growth law. Illustrative numerical results are displayed for the deposition of alkali sulfate-like vapor from the combustion products of hydrocarbon fuel (or coal) with air, including the interesting “structurerd of such nonequilibrium multiphase boundary layers. As a useful by-product, our results reveal which combinations of particle-phase parameters cause (a) previous “uncoupled” vapor/particle deposition rates to be approximately valid as well as (b) recent local vapor/condensate equilibrium limit results to be sufficiently accurate. We conclude with an outline of straightforward extensions of the present theory to include such factors as: (i) a nonuniform (polydispersed) particle size mainstream aerosol; and (ii) size-dependent particle thermophoretic diffusivity; which are likely to be important in current or future engineering applications.

Rapid computation of chemical equilibrium composition: An application to hydrocarbon combustion

AbstractA scheme for rapidly computing the chemical equilibrium composition of hydrocarbon combustion products is derived. A set of ten governing equations is reduced to a single equation that is solved by the Newton iteration method. Computation speeds are approximately 80 times faster than the often used free‐energy minimization method. The general approach also has application to many other chemical systems.

Emission of polycyclic aromatic hydrocarbons with the combustion products of hydrocarbon fuel mixtures

The use of small quantities of hydrogen as an additional fuel and spraying component is discussed in solving the problem of reducing emissions of toxic and carcinogenic materials with the combustion products of hydrocarbon fuels. The spent gases of thermal motors based on hydrocarbon fuels include, as well as other harmful metals, polycyclic aromatic hydrocarbons. Problems of the carcinogenic action of these hydrocarbons are considered in detail. The results of investigations show that significant reduction in hydrocarbon emission with the spent gases of motors may be achieved with realization of progressive methods.