OBTAINING DIESEL FUEL WITH IMPROVED PROPERTIES

It is known that one of the ways to increase the level of operational properties of diesel fuels is the injection of special components – additives – into their composition. Today this way is a quite rational and economically feasible for Ukraine, especially in the absence of high-quality oil raw materials for the production of fuels, which in turn leads to a significant dependence on imports. The range of additives used in diesel fuels is very diverse, which makes it difficult to select a balanced package, especially considering their effectiveness and compatibility with each other. This procedure can be a bit simplified by adding poly-functional additives to diesel fuel, the use of which is devoted to a lot of periodical literature. Based on the relevance of the direction of scientific research related to improving the properties of diesel fuel, which is produced at the enterprises of the oil refining industry in Ukraine, we proposed to use a substance belonging to the class of aromatic diazocompounds and having polyfunctional properties in the composition of diesel fuels. Thus, this additive was added to a straight-run diesel fraction (240–350 °C) in an amount of up to 1.0%, followed by a study of the properties of the resulting mixture. Studies have shown that the additive significantly improves low-temperature properties (by -10 °C), contributes to an increase in fuel density and viscosity, and additionally gives diesel fuel a stable color (from yellow to orange). Consequently, it can be used in the composition of commercial diesel fuels with improved performance properties.

Modeling sub-boreal forest canopy bulk density in Minnesota, USA, using synthetic aperture radar and optical satellite sensor data

Background National estimates of canopy bulk density (CBD; kg m−3) for fire behavior modeling are generated and supported by the LANDFIRE program. However, locally derived estimates of CBD at finer scales are preferred over national estimates if they exist, as the absolute accuracy of the LANDFIRE CBD product is low and varies regionally. Active sensors (e.g., lidar or radar) are better suited for this task, as passive sensors are ill equipped to detect differences among key vertical fuel structures, such as coniferous surface fuels (≤2 m high) and canopy fuels above this threshold—a key categorical fuel distinction in fire behavior modeling. However, previous efforts to map CBD using lidar sensor data in the Superior National Forest (SNF) of Minnesota, USA, yielded substandard results. Therefore, we use a combination of dormant-season synthetic aperture radar (SAR) and optical satellite sensor data to (1) expand detectability of coniferous fuels among mixed forest canopies to improve the accuracy of CBD modeling and (2) better understand the influence of surface fuels in this regard. Response variables included FuelCalc output and indirect estimates of maximum burnable fuel based on canopy gap fraction (CGF) measured at ground level and 2 m above ground level. Results SAR variables were important predictors of CBD and total fuel density (TFD) in all independent model calibrations with ground data, in which we define TFD as the sum of CBD and primarily live coniferous surface fuel density (SFD) 0 to 2 m above ground. Exploratory estimates of TFD appeared biased to the presence of sapling-stage conifer fuel on measures of CGF at the ground level. Thus, modeling efforts to calibrate SFD with satellite sensor data failed. Both CGF-based and FuelCalc-based field estimates of CBD yielded close unity with satellite-calibrated estimates, although substantial differences in data distributions existed. Estimates of CBD from the widest CGF zenith angle range (0 to 38°) correlated best with FuelCalc-based CBD estimates, while both resulted in maximum biomass values that exceeded those considered typical for the SNF. Model results from the narrowest zenith angle range (0 to 7°) produced estimates of CBD that were more in line with values considered typical. LANDFIRE’s estimates of CBD were weakly, but significantly (P = 0.05), correlated to both narrow- and wide-angle CGF-based estimates of CBD, but not with FuelCalc-based estimates. Conclusions The combined use of field estimates of CBD, based on indirect measures of CGF according to Keane et al. (Canadian Journal of Forest Research 35:724–739, 2005), with SAR and optical satellite sensor data demonstrates the potential of this method for mapping CBD in the Upper Midwest, USA. Results suggested that the presence of live, coniferous surface fuels neither confounds remote detection nor precludes mapping of CBD in this region using SAR satellite sensor data, as C- and L-band idiosyncrasies likely limit the visibility of these smaller understory fuels from space. Nevertheless, research using direct measures of burnable SFD for calibrations with SAR satellite sensor data should be conducted to more definitively answer this remote detection question, as we suspect substantial bias among measures of CGF from ground level when estimating SFD as the difference between TFD and CBD.

Design and Pinch Analysis of a GFT Process for Production of Biojet Fuel from Biomass and Plastics

Environmental problems are frequently related to energy use, estimated to grow at 1.6% per year until 2035. The transport sector accounts for 30% of energy demand and aviation is growing around 2.6% per year. Thus, low-emissions policies promote the use of sustainable aviation fuels. This work simulates a gasification and Fischer-Tropsch process to obtain biojet fuel from biomass and plastic waste. Syngas obtained through cogasification is purified by amine scrubbing and subjected to a Fischer-Tropsch process to produce hydrocarbons, which are upgraded for optimal fuel properties. Pinch analysis is applied to minimize energy usage, while Rankine cycles and a cooling tower are designed to cover the demand of electricity and cooling water. Results show that mass yields of the process towards biofuels are 13.06%, with an output of 1697.45 kg/h of biojet fuel. Density, kinematic viscosity, pour and flammability points and the lower calorific value of the biojet fuel comply with the ASTM D7566 standard. Pinch analysis allows to reduce 41.58% and 100% of cooling and heating demands, respectively, using biomass as renewable energy for heating. Moreover, steam generation covers 38.73% of the required electricity. The produced biojet fuel emits 20.14 gCO2eq/MJ and has a minimum selling price of 1.37 EUR/L.

Compensation of the error of automotive capacitive fuel level sensors when using them on special self-propelled rolling stock

Consumption of diesel fuel by the special rolling stock of Russian Railways per year amounts to tens of thousands of tons, and the issue of reliable accounting and control of its consumption is quite urgent. Currently, part of the special self-propelled rolling stock is equipped with on-board systems for measuring fuel consumption, however, in many units of this equipment, fuel control and accounting is carried out in manual mode. Massive introduction of on-board fuel consumption measurement systems on special self-propelled rolling stock is constrained, on the one hand, by the rather high cost of fuel sensors used on locomotives, on the other hand, by the increased error of relatively inexpensive automotive capacitive fuel level sensors. As part of the laboratory tests of such sensors, it was determined that when they operate on fuel of the same grade, the error corresponds to the passport and is at the level of 1 %, and when operating on fuel of different grades without additional recalibration, the error can reach 4 % or more. This is largely due to the simplified technology for measuring the amount of fuel in units of volume and insufficient compensation for changes in the density of diesel fuel. To solve this problem, an alternative to standard technology for determining the amount of fuel using automotive capacitive fuel level sensors is proposed, in which the dependence of the readings of these sensors on the fuel density at a standard temperature, once obtained in laboratory conditions, is used. Proposed technology of using automotive capacitive fuel level sensors on a special self-propelled rolling stock will allow keeping its relative reduced error at the level of 1 % and will provide measurement of the amount of fuel in units of mass.

Influence of physicochemical properties of gasoline on the formation of DISI engine fuel injector deposits

This paper describes the results of an engine study of the tendency for fuel injector deposits to form by gasolines of various compositions. Since the factors promoting the formation of fuel injector deposits in DISI engines have, in many cases, been insufficiently identified they require further research and investigation work, which was the greatest motivation for undertaking this project. The latest CEC F-113-KC test procedure for the most damaging deposits in DISI engine injectors was used for this purpose. The research results obtained in the framework of the conducted project indicated T90, aromatic and olefinic hydrocarbons, sulphur, ethanol, DVPE, IBP and fuel density as the most important factors causing the increase in the tendency for deposits to form on the injectors of SI type DISI engines.

Onset Criteria for Bulk-Mode Thermoacoustic Instabilities in Supercritical Hydrocarbon Fuels

We have investigated supercritical-p (p > 1192 psi (8.22 MPa)) methanol at pressures up to 1645 psi (11.3 MPa) flowing through a heated tube at flow rates of 4-7 lb/hr (1.8-3.2 kg/hr). Tube heated lengths have been varied from 4 to 6 in (10 to 15 cm), internal diameters from 0.027 to 0.069 in (0.069 to 0.175 cm), and heat inputs between zero and 800 Watts. Fluid temperature at the tube inlet remained subcritical (T < 464°F (513K)); outlet temperatures were transcritical or supercritical. Two phenomena were observed: system-wide bulk-mode oscillations and localized acoustic modes. In the present study, modeling and predictive efforts are undertaken to characterize system-wide bulk-mode oscillations. The parameter space has been nondimensionalized, yielding four dimensionless variables. Stability criteria based on these dimensionless groups have been established for two separate test articles and fluids; both criteria suggest that the heat required for the onset of oscillations is proportional to the mass flow rate times the mean pressure and inversely proportional to the fuel density.

Study oil density in flow, system of automated measurement and inaccuracies

The paper reviews the issues of specification of fluid fuel amount with high measuring accuracy transported through oil pipelines. The operation algorithm of vibration-frequency densitometer for automatic measurement of fluid fuel density with high measuring accuracy in technological process in the exploitation conditions is based on the hybrid test method. For this purpose test equations on measuring links using simple additive and multiplicative tests, as well as their combinations have been developed, test equations composed, and as a result of their solution the main test equation obtained. The mathematic-statistic estimation of the results of densitometer measurements correcting test algorithms for the definition of measurement errors and composing inaccuracies, the method of automated calibration are presented as well.

Comparison Between a Center-Mounted and a Side-Mounted Injector for Gasoline Applications: A Computational Study

The differences between a center-mounted and a side-mounted injector for gasoline direct injection (GDI) applications are analyzed through computational fluid dynamics (CFD). The Engine Combustion Network’s (ECN) axisymmetric 8-hole Spray G injector is compared to a 6-hole injector designed to be side-mounted in an engine. Nozzle-flow simulations are carried out with the commercial CFD software CONVERGE, injecting Euro 5 certification gasoline into a constant volume chamber. Low-load operating conditions are targeted, setting the injection pressure at 50 bar and the ambient pressure to be representative of very early pilot injections. The phase change is handled with the Homogeneous Relaxation Model (HRM), which is assessed and adapted to gasoline flash-boiling conditions. The simulation domains are generated leveraging real injector internal geometries obtained by micron-resolution X-ray tomographic measurements, which introduce manufacturing tolerances and surface roughness in the computational study. Steady needle lift conditions are analyzed. The near-field fuel density distributions and plume morphologies are evaluated, validated and compared to X-ray radiography measurements. A computational best practice is defined and single plume characteristics and variability trends are highlighted as functions of the geometry of the orifices. The plume-plume interaction dynamics are identified and assessed, underlining differences from center- to side-mounted injectors at strong flashing conditions. The obtained numerical framework allows the identification of near-nozzle injection characteristics such as single plume direction, cone angle, spray initial velocity and spatial fuel density distribution. The presented results represent a unique dataset for the initialization of more-affordable Lagrangian spray models, which differentiate the behavior of side-mounted and center-mounted injectors.

Implicit-Explicit Methods for a Convection-Diffusion-Reaction Model of the Propagation of Forest Fires

Numerical techniques for approximate solution of a system of reaction-diffusion-convection partial differential equations modeling the evolution of temperature and fuel density in a wildfire are proposed. These schemes combine linearly implicit-explicit Runge–Kutta (IMEX-RK) methods and Strang-type splitting technique to adequately handle the non-linear parabolic term and the stiffness in the reactive part. Weighted essentially non-oscillatory (WENO) reconstructions are applied to the discretization of the nonlinear convection term. Examples are focused on the applicative problem of determining the width of a firebreak to prevent the propagation of forest fires. Results illustrate that the model and numerical scheme provide an effective tool for defining that width and the parameters for control strategies of wildland fires.