Binary Fuels Research Articles

Effective use of biohydrocarbon fuel compositions in the energy complex of the agroindustrial complex

The problem of searching for alternative ways of power supply for the transport and technological complex of the agroindustrial complex is discussed. The ecological and economic expediency of the transfer of agricultural machinery (mainly diesel) to supply by fuel produced from biomass is substantiated. It is noted that the large-scale use of biological energy as the main motor fuel for diesel engines is hampered by a significant difference in their physicochemical properties from the properties of traditional hydrocarbon fuels. One of the alternative solutions to the problem is the use of energy biological products as an additive to the base hydrocarbon fuel. At the same time, the most acceptable physicochemical properties of a two-component fuel, meeting the requirements of efficient organization of the working process of a diesel engine are provided by appropriate choice of the value of this additive. The paper suggests a technique for optimizing the component composition of binary fuel, which provides the utmost possible improvement of the economic and environmental performance of an engine running on this fuel. A method for improving the combustion performance of biohydrocarbon fuels based on the use of chemical activation agents is methodologically substantiated. Results of experimental approbation of a set of proposed measures for improving binary fuel parameters in conditions of full-scale tests on the engine are presented. Based on the results of the conducted study, it is concluded that the proposed concept of the method aimed at improving the indicators of binary biohydrocarbon fuels can be attributed to one of the promising directions in the field of actively developing bioener-gy. The use of such fuels makes it possible to convert almost any serial engine into a competitive power plant with higher environmental and economic performance compared to engines running on traditional petroleum fuels. In its key basis, the method is aimed at an efficient and cost-effective solution of urgent problems of energy conservation and raising the level of environmental and fuel and energy security in the environment of agricultural production.

5-2-3 BDF/アルコール混合燃料燃焼時のミクロ爆発

5-2-3 BDF/アルコール混合燃料燃焼時のミクロ爆発

A new design method for fluidized bed conversion of largely heterogeneous binary fuels

Binary fuels of a fluidized bed combustor or gasifier are solids composed of two groups of particles. Their optimal handling in the same bed becomes rather difficult if their hydrodynamic properties differ by two orders of magnitude or more. Both of these fuel classes are directly fed into the reactor in most cases but the rather homogeneous fuel originally fed switches into a binary character inside the reactor in some others. A typical example of the latter case is the thermal utilization of rubber wastes. A novel design is proposed in the present paper by setting up a non-mixing, non-elutriated binary bed. Design criteria and procedure are formulated as well. One of the known calculation methods is proposed to be applied for assuring a segregated bed by means of choosing the bed components, geometry, and gas velocity conveniently. Cold model experiments are proposed to be applied for assuring no elutriation of the fine fuel particles and no sinking of the coarse fuel particles in the same time. A simple experiment is proposed for determining the common minimum fluidization velocity of the binary bed because known calculation methods can not be applied here.

Experimental and modeling study on ignition delay times of dimethoxy methane/n-heptane blends

Ignition delay times of dimethoxy methane (DMM), n-heptane and DMM/n-heptane mixtures were measured behind reflected shock waves. The experiments were performed at the temperature ranges of 1100–1600K, at pressures of 2 and 10atm and equivalence ratios of 0.5, 1.0 and 2.0. A chemical kinetic model for DMM/n-heptane blends was built and validated with the experimental data. The calculations well agreed with the measurements for pure fuel and binary fuels. Based on the experimental and calculated results, effects of pressure, equivalence ratio and DMM blending ratio on ignition delay times were analyzed. Through sensitivity analysis, the most important reactions were found and then the effect of equivalence ratio on ignition delay times was interpreted. The ignition delay times of DMM/n-heptane blends decreased with the addition of DMM. Kinetic analysis revealed that the concentration of radical pool increased with the increase of DMM addition, resulting in an enhancement effect on the chemical reactivity.

Ignition of a Binary Component Fuel Droplet in a Rapid Compression Machine: Comparative Analysis

The autoignition characteristics of a binary component fuel droplet inside a rapid compression machine (RCM) were investigated. An RCM is an experimental setup for simulating a single compression stroke of an internal combustion engine. During the experimental time, the temperature and pressure inside the reaction chamber were temporally varied, and the ignition of a binary component droplet occurred when sufficient fuel vapor was generated around the droplet. n-Heptane was selected as the base fuel, and a specific volumetric ratio of iso-octane and n-decane was added as fuel additives. The droplet was placed at the center of the reaction chamber by suspending at the tip of a thermocouple, and its transient temperature was measured. The initial droplet diameter was in the range of 450−1000 μm, and the temporal variation of droplet diameter was measured by analyzing images from a high-speed charge-coupled device array camera. In the single component experiments, a monotonic increase of the ignition delay with droplet diameter was observed, and the gradient was different for n-heptane and n-decane. The iso-octane droplet did not ignite in the present experimental conditions. The addition of iso-octane in n-heptane increased the ignition delay by dissipation of n-heptane vapor and an autoignition temperature change. The ignition delay and maximum droplet diameter ignition limit rapidly changed when the volume fraction of iso-octane was approximately 0.5, and the effect of iso-octane on the ignition delay was diminished for lower volume fractions. The ignition delay also increased with n-decane addition by suppressing the evaporation process. Compared to iso-octane, the increase in the n-decane volume fraction resulted in a gradual change of the ignition delay and maximum droplet diameter ignition limit due to the different mechanism of the ignition suppression process.

Flame Spread over Binary Mixed Liquid Fuels—Super-Flash/Super-Flash Mixed Condition

In this study, we investigate the flame spread characteristics of binary mixed liquid fuels that are both in super-flash condition. We propose a method for estimating flashpoint and flame spread rate for binary mixed liquid fuels from binary vapor concentration distribution and compare these estimated values with experimental results. In addition, we measure the flame height and center of the flame leading edge for binary mixed liquid fuels. The results show that, when the flashpoint of each single fuel is known, the flashpoint of the binary mixed liquid fuel can be calculated. Moreover, the fuel that most influence combustion changes near the intersection of vapor concentration distribution in accordance with Raoult’s law. Photographs of the flame indicate discontinuity. We can calculate flame spread rate by using the ratio of each diffusion coefficient to judge equivalently. Finally, it is found that the flame height and center of flame leading edge are proportional to total vapor concentration of the binary mixed liquid fuels.

Effect of the initial pressure on the characteristics of the flame propagation in hydrogen-propane-air mixtures

This paper is aimed at an experimental investigation on effects of initial pressure on flame propagation characteristics of binary fuels hydrogen-propane-air mixtures at room temperature. The experiments are performed in a square channel equipped with perforated orifice obstacles. Four initial pressures are examined. Based on pressure transducers along the channel, the flame velocity, maximum pressure of the front peak and characteristic distances are measured. Successive stages are observed as flame propagates: (i) a velocity increase at the beginning, (ii) a velocity equal to the sound speed of combustion products and (iii) a decrease of the velocity. When the initial pressure is more important, the flame velocity and the maximal pressure of the front peak are higher, which yields a shorter characteristic distance of flame propagation. By means of a Schlieren photography technique, the physical mechanisms of flame propagation are identified in its initial stage. The physical mechanisms such as flame surface area increase and combustion product expansion as well as delayed combustion between two adjacent plates are responsible for flame acceleration upon its initial stage. The oscillations of the centerline flame velocity are due to the constrained-expanded structure of flow in reactants ahead of flame when it crosses the plates.

Frontispiece: Effect of Structural Characteristics of Binary Palladium-Cobalt Fuel Cell Catalysts on the Activity for Oxygen Reduction

Frontispiece: Effect of Structural Characteristics of Binary Palladium-Cobalt Fuel Cell Catalysts on the Activity for Oxygen Reduction

저온연소조건에서 n-heptane/alcohol 혼합연료의 냉염과 열염에 대한 착화지연 관찰

The ignition delay time is an important factor to understand the combustion characteristics of internal com- bustion engine. In this study, ignition delay times of cool and thermal flame were observed separately in homogeneous charge compression ignition(HCCI) engine. This study presents numerical investigation of ignition delay time of n-heptane and alcohol(ethanol and n-butanol) binary fuel. The O2 concentration in the mixture was set 9-10% to simulate high exhaust gas recirculation(EGR) rate condition. The numerical study on the ignition delay time was performed using CHEMKIN codes with various blending ratios and EGR rates. The results revealed that the ignition delay time increased with increasing the alcohol fraction in the mixture due to a decrease of oxidation of n-heptane at the low temperature. From the numerical analysis, ethanol needed more radical and higher temperature than n-butanol for oxidation. In addition, thermal ignition delay time is sharply increasing with decreasing O2 fraction, but cool flame ignition delay time changes negligibly for both binary fuels. Also, in high temperature regime, the ignition delay time showed similar tendency with both blends regardless of blending ratio and EGR rate.

Use of biofuel compositions as an alternative to improve environmental and energy safety in transport

The paper considers problems of energy supply and improving of environmental safety in transport, as well as one of the alternatives of their total solution based on the use of binary biohydrocarbon fuels. The authors considered basic physical and chemical properties of some fuel compositions and their impact on the performance of an engine. The results of testing of engines operating on two-component fuels are presented in the article.

Thermodynamic Analysis of Evaporation of Levitated Binary and Ternary Liquid Fuel Droplets under Normal Gravity

The present study presents a thermodynamic model for predicting the vaporization characteristics of binary and ternary hydrocarbon fuel droplets under atmospheric pressure and normal gravity conditions. The model employs activity coefficients based on UNIFAC group contribution method and evaluates the vapor-liquid equilibrium of binary and ternary droplets. The gas-phase properties have been evaluated as a function of temperature and mixture molecular weight. The model has been validated against the experimental data available in literature. The validated model is used to predict the vaporization characteristics of binary and ternary fuel droplets at atmospheric pressure under normal gravity. Results show multiple slopes in the droplet surface regression indicating preferential vaporization of fuel components based on their boiling point and volatility. The average evaporation rate is dictated by the ambient temperature and also by composition of the mixture.

Investigation of Stochastic Radiation Transport Methods in Binary Random Heterogeneous Mixtures

This paper reviews existing Monte Carlo techniques for performing neutron transport simulations in binary random heterogeneous fissile fuels and presents a new approach offering superior efficiency at little cost in fidelity for problems involving densely packed, optically thick absorbers. The accuracy of the chord-length sampling technique is demonstrated to be a function of the total optical thicknesses and optical scattering thickness of the constituent materials as well as the packing density of the fissile kernels. The results of this parameter assessment provide a foundation for an original hybrid algorithm that combines homogeneous and explicit geometry models within a single Monte Carlo simulation. The geometry model utilized is selected according to the energy-dependent optical thickness. By partitioning the geometry representation within a single Monte Carlo simulation into homogenous and heterogeneous energy-dependent models, acceptable ensemble average results are obtained in a fraction of the run time of the detailed explicit geometry benchmark method.

Flame propagation of mixtures of air with binary liquid fuel mixtures

The laminar flame speeds of mixtures of air with 80% n-dodecane+20% methylcyclohexane and 80% n-dodecane+20% toluene, on a per volume basis, were determined in the counterflow configuration over a wide range of equivalence ratio, at atmospheric pressure and 403K unburned mixture temperature. The choice of the fuel blends was dictated by their anticipated compositions in jet fuels surrogates. Phenomenological analysis shows that the laminar flame speeds of binary fuels mixtures can be estimated using the laminar flame speeds and adiabatic flame temperatures of the neat components. The propagation rates of various binary fuels blends were computed using detailed descriptions of chemical kinetics and molecular transport and were found to be in good agreement with the estimations. Although the fuel initial consumption pathways and the resulting intermediates and radicals may be different for each neat component, the propagation of flames of binary fuels is mostly sensitive to the flame temperature through its influence on the main branching reaction H+O2→OH+O. Thus, kinetic couplings resulting from the presence of two different fuels, appear to have minor effect on flame propagation.

A liquid film or droplet of miscible binary fuel burning on a heated surface at elevated pressures

An experimental study has been made of the combustion and evaporation of miscible binary fuels on a heated surface at elevated pressures. Photographic observation was made for elucidating how the binary fuel droplets or films behaved on the heated surface and for obtaining the characteristic lifetime as a function of the surface temperature, the ambient pressure and the initial concentration of highly volatile component of the fuels. The binary fuels tested were mixtures of n-hexane and n-decane. The results showed that the lifetime curve both for the combustion and for the evaporation of n-hexane/ n-decane on the heated surface had two peaks at lower pressures, the first peak in the film-type evaporation region and the second peak in the spheroid-type evaporation region. The preferential evaporation of the highly volatile component was responsible for the appearance of the first peak in the film-type evaporation region. The second peak corresponded to Leidenfrost point. The increase in the ambient pressure caused a shift of the lifetime curve toward higher surface temperature and a decrease in the lifetime at two peaks. The lifetime curve decreased monotonically with increasing the surface temperature and the spheroid-type evaporation was not observed at higher pressures. The increase in the initial concentration of highly volatile component caused a shift of the first peak toward higher surface temperature, a decrease in its lifetime and a slight shift of the second peak toward lower surface temperature. The combustion caused a remarkable decrease in the lifetimes around the first peak and in the spheroid-type evaporation region and a slight increase in the surface temperature at the first peak, while the surface temperature at the second peak remained almost unchanged.

313 高圧雰囲気中における二成分溶解性燃料液滴の壁面蒸発(OS-2 液滴の着火・燃焼)

313 高圧雰囲気中における二成分溶解性燃料液滴の壁面蒸発(OS-2 液滴の着火・燃焼)

313 高温壁面での二成分混合燃料の蒸発に及ぼす燃料組成の影響

313 高温壁面での二成分混合燃料の蒸発に及ぼす燃料組成の影響

Determination of laminar flame speeds using digital particle image velocimetry: Binary Fuel blends of ethylene, n-Butane, and toluene

The atmospheric laminar flame speeds of mixtures of air with ethylene, n-butane, toluene, ethylene-n-butane, ethylene-toluene, and n-butane-toluene were experimentally and computationally investigated over an extended range of equivalence ratios. Binary fuel blends with 1:1, 1:2, and 2:1 molar ratios were examined. Experimentally, the laminar flame speeds were determined using digital particle image velocimetry (DPIV). Since the use of DPIV enables the mapping of the two-dimensional flow field adhead of the flame, the reference speed based on the minimum axial velocity point as well as the imposed strain rate can be identified simultaneously. The latter can now be unambiguously determined by the radial velocity gradient at the minimum velocity point. By systematically varying the imposed strain rate, the corresponding laminar flame speed was obtained through nonlinear extrapolation to zero strain rate. The associated experimental accuracy of the DPIV measurements was also assessed and discussed. Computationally, the laminar flame speeds were simulated for all single-component fuel/air and binary fuel blend/air mixtures with a detailed kinetic model. Comparison of experimental and computed flame speeds shows generally good agreement. A semiempirical mixing rule was developed. The mixing rule which requires only the knowledge of the flame speeds and flame temperatures of the individual fuel constituents, is shown to provide acurate estimates for the laminar flame speeds of binary fuel blends under the conditions tested.

Ignition of binary mixture droplets by a propagating laminar flame

An experimental study was made of the ignition process of single droplets of binary mixtures subjected to a laminar flat flame propagating through a lean homogeneous propane/air mixture at constant pressure. Binary fuels consisting of n -hexane and n -hexadecane or n -dodecane, and benzene and n -hexadecane were tested. Water-emulsified liquids consisting of n -dodecane, and pure fuels like n -hexane, n -octane, n -dodecane, and n -hexadecane, were used as well. A combustion chamber made of a transparent duct was installed with spark electrodes, fine quartz fibers to suspend fuel droplets, and a shutter to allow the burned gas to escape at the top end. A high-speed video camera was provided for photographic observation of each droplet ignited by the propagating flame. The ignition delay of pure fuel droplets increased monotonically with increase of the initial droplet diameter and decrease of fuel volatility. The influence of the initial droplet diameter on the ignition delay decreased with increasing fuel volatility. Ignition delay of the binary fuel droplets decreased with an increase of the volume concentration of the higher-volatility fuel. Ignition delay of the binary fuels showed a minimum and a maximum as a function of the initial droplet diameter. The diameters at the minimum and the maximum of ignition delay decreased with increasing higher-volatility fuel concentration. For the emulsified fuel, on the other hand, ignition delay increased with increasing initial droplet diameter and increasing water content. Part of the propagating flame behind the droplet became convex toward the unburned gas as it passed a droplet of higher-volatility fuels, while the flame remained flat for the lower-volatility fuels. The deformation length of the propagating flame behind the droplet increased with increasing higher-volatility fuel concentration.

Ignition of a Binary Fuel Droplet by a Propagating Laminar Flame.

An experimental study has been made of the ignition process of a binary fuel droplet subjected to a laminar flat flame propagating through a lean homogeneous propane-air mixture at constant pressure. A combustion chamber made of a transparent duct was installed with spark electrodes, a fine quartz fiber to suspend a fuel droplet and a shutter to allow the burned gas to flow out. A high speed video camera was provided for the photographic observation of the droplet ignited by the propagating flame and for the determination of the ignition delay. The ignition delay showed a peak as a function of initial droplet diameter and the diameter at the peak ignition delay decreased with an increase in the n-hexane or the benzene volume concentration. Also evident was that the ignition delay decrased largely with an increase in the n-hexane or the benzene volume concentration.

Homogenizing Effect of Addition of Ethers to Immiscible Binary Fuels of Ethanol and Oil.

Immiscible binary liquid fuels of ethanol and oil could be homogenized by addition of a small amount of methyl tert-butyl ether, ethyl tert-butyl ether, tert-amyl methyl ether, tetrahydrofuran, tetrahydropyran, or 1, 4-dioxane. As oils, diesel fuel, soybean oil, and rape oil were used. Liquid-liquid solubility curves for the ternary systems of ether, ethanol, and oil (referred to as ether + ethanol + oil) were measured at 298.15K.