Determination of the Thermodynamic and Thermophysical Properties of Alternative Fuels
The procedure and results of calculation of the thermodynamic and thermophysical properties of alternative fuel are given.
09 BIOMASS FUELS↗
SEARCH · Engineering Papers
Results for “THERMODYNAMICS”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Thermodynamic Analysis of Prospects for Using Aluminum- and Boron-Containing Clusters in Combined High-Energy Fuels
The high enthalpies of combustion of atomic clusters Al{sub n}, B{sub n}, and C{sub n} (n = 1, 2, …, 7), Al{sub n}C{sub m} and B{sub n}C{sub m} (n = 1, …, 5 and m = 1, …, 5), Al{sub n}B{sub m} (n + m ≤ 7), and Al{sub n}H{sub m} and B{sub n}H{sub m} (n = 1, …, 4 and m ≤ 12) have been assessed. The specific energy release, the final adiabatic temperature, and the effectiveness of the combustion products of fuel mixtures based on kerosene, dimethyl ether, and ethyl alcohol with small additions of such clusters have been determined under the assumption of attaining a thermodynamic equilibrium in their combustion products. An analysis has been made of the potentials of small aluminum- and boron-containing clusters for use in improving thermochemical properties of the fuels. It has been shown that adding such clusters to traditional fuels in the amount of 10% of the fuel mass can increase the specific energy release of the fuel by 2 MJ/kg, the effectiveness of combustion products of the fuel by 10%, and their final temperature by 200 K.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Determination of the Thermodynamic Properties of the Cyclohexane + n-Octane + n-Hexadecane Liquid Mixture by the Acoustic Method
The propagation of sound in the ternary cyclohexane + n-octane + n-hexadecane mixture at temperatures of 298–433 K and pressures of 0.1–100.1 MPa was investigated experimentally. The maximum error in measuring the velocity of sound in this mixture was 0.1%. Experimental data on the velocity of sound in such a mixture were obtained for the first time. On the basis of these data, the density, the isobaric expansion coefficient, the isobaric and isochoric heat capacities, and the isothermal compressibility of the indicated ternary mixture of three compositions at a temperature of 298–348 K and a pressure of 0.1–100 MPa and the deviation of the velocity of sound in it from the ideal one were determined. With the use of a number of semiempirical equations, the deviation of the velocity of sound in this mixture from the ideal one was estimated on the basis of the data on the velocity of sound in its pure components and in their binary compounds. A good agreement between the calculation and experimental data has been obtained. A table of the thermodynamic properties of the cyclohexane + n-octane + n-hexadecane mixture is presented.
42 ENGINEERING↗
Equilibrium, Kinetic and Thermodynamic Studies Of Lead (II) Sorption on Hydrolyzed Starch Graft Copolymers
Hydrolyzed starch graft poly (acrylic acid) and starch graft poly(acrylonitrile) copolymers were used as a sorbents for the removal of Pb(II) from aqueous solution in batch process. The sorbents were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The effect of contact time, initial concentration and temperature were assessed to optimize the conditions for maximum sorption of the metal ions. The experimental data were analyzed by Langmuir, Freundlich, Temkin, Dubinin Radushkevich and Sips isotherm models. The Freundlich and the Sips isotherms confirmed the applicability of the models. The sorption capacity of the sorbent was found to be 118.61 mg/g for starch graft poly (acrylic) acid and 115.83 mg/g for starch graft poly (acrylonitrile). The Sorption kinetics was assessed by Lagergren pseudo first order, pseudo second order, Elovich equation, Intraparticle diffusion and the liquid film diffusion models. The experimental data fitted very well with the Elovich equation and the Intraparticle kinetic models. The thermodynamic analysis showed that the sorption was a spontaneous and endothermic process. The results indicated that starch graft copolymers can be used as an effective sorbents for Pb (II) removal from aqueous media.
36 MATERIALS SCIENCE↗
Kinetic, Isotherm and Thermodynamic Studies for Removal of Methylene Blue Using β-Cyclodextrin/Activated Carbon Aerogels
A novel aerogel (β-CD/AC) was prepared through polymerization reaction of β-cyclodextrin (β-CD) with activated carbon (AC) and vacuum freeze drying method. The structure and morphology of β-CD/AC were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) method and thermogravimetric analysis (TGA). β-CD/AC is used to deal with wastewater containing methylene blue (MB) dye. The effects of AC content in β-CD/AC, pH value, temperature, contact time and amount of adsorbent on the adsorption of MB were studied in detail. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. The Langmuir monolayer adsorption capacity of MB onto β-CD/AC was estimated as 166.67 mg/g. The kinetics of MB onto β-CD/AC was well described by the pseudo-second order model. The thermodynamic parameters indicated that the adsorption reaction of MB onto β-CD/AC was endothermic and spontaneous.
36 MATERIALS SCIENCE↗
Highly Efficient Removal of Lead Ions from Aqueous Solutions Using Chitosan/Rice Husk Ash/Nano Alumina with a Focus on Optimization by Response Surface Methodology: Isotherm, Kinetic, and Thermodynamic Studies
In the present study, an adsorbent named chitosan/rice husk ash/nano-γ alumina was prepared and used for the removal of lead ions from aqueous solutions. It was characterized by FESEM, FTIR, XRD, and BET. The important and interactive effects of some considered parameters, such as the initial lead ion concentration, pH, adsorbent mass and contact time, were estimated and optimized by using the central composite design (CCD). The Maximum adsorption efficiency of lead ions under optimum conditions, including the pH of 5, adsorbent mass of 0.01 g, the initial lead ion concentration of 30 ppm, and the contact time of 105 min, was achieved to be 90.98%. The adsorption kinetic was consistent with the pseudo-second-order model (R{sup 2} = 0.9967). The lead adsorption isotherms were well fitted to the Langmuir model, indicating the maximum adsorption capacity of 181.82 mg g{sup −1}. Thermodynamic parameters (R{sup 2}: 0.9200, ΔH°: − 22871.81 kJ mol{sup −1}, ΔG{sup °}: − 10.63 kJ mol{sup −1}, and ΔS{sup °}: 118.37 kJ mol{sup −1} K{sup −1}) were calculated and indicating adsorption process was exothermic and spontaneous in the temperature range of 283.15–313.15 k. The maintenance above 70% capacity of the adsorbent was observed by the regeneration study of chitosan/rice husk ash/nano-γ alumina after six cycles. Comparison of adsorption efficiency of the studied adsorbent and other adsorbents in the removal of lead ions was also done in this paper. Consequently, the excellent properties of the presented nanocomposite could make it an ideal adsorbent for the removal of lead ions from aqueous solutions. Graphical Abstract: .
77 NANOSCIENCE AND NANOTECHNOLOGY↗
High-Pressure and Temperature Dependence of Electronic, Magnetic, Elastic, Thermodynamic, and Transport Properties of Full-Heusler Alloys Co{sub 2}YIn (Y = Nb, Zr)
Structural, elastic, magnetic, and electronic properties of Co{sub 2}YIn (Y = Nb, Zr) have been investigated by means of the full-potential linearized augmented plane wave along with generalized gradient approximation + U/modified Becke-Johnson method in the stable Fm-3m phase. The optimized equilibrium lattice parameter in stable phase is 6.1744 Å for Co{sub 2}NbIn and 6.2824 Å for Co{sub 2}ZrIn. We have calculated the spin-resolved density of states for both the alloys to show that the ferromagnetic behavior of Co{sub 2}NbIn is due to the exchange splitting of Co and Nb atoms and due to Co and Zr in Co{sub 2}ZrIn. In spin-up configuration, there is absence of energy gap while an energy gap can be seen in spin-down state for both the alloys exhibiting a half-metallic character. Through the elastic constants and their discussions, we have predicted the elastic behavior of the materials. The quasi-harmonic approximations have been employed to study the pressure- and temperature-dependent thermodynamic properties. The Boltzmann theory is employed to investigate the electronic transport properties of these alloys. The defined material properties may pay as a prime stand for the application of material in spintronics and thermoelectrics.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Investigation of Electronic, Magnetic, Thermodynamic, and Thermoelectric Properties of Half-Metallic XLiSn (X = Ce, Nd) Alloys
We have investigated the electronic, magnetic, thermodynamic, and thermoelectric properties of half-Heusler CeLiSn and NdLiSn using density functional theory. The materials crystallize in F 4-bar 3mstructure with ferromagnetic state at optimized lattice parameter of 6.73 Å for CeLiSn and 6.74 Å for NdLiSn. The modified Becke-Johnson potential (mBJ) and generalized gradient approximation (GGA) have been used for computation of band structure, where mBJ shows a perfect half-metallic nature of the bands in both the alloys. The calculated magnetic moment of 1.0 μ{sub B} for CeLiSn and 3.0 μ{sub B} for NdLiSn follow Slater-Pauling rule, with ferromagnetic interactions. The temperature variation of the Seebeck coefficient shows the p-type behavior with room temperature values of 27 μV/K (43 μV/K) for CeLiSn (NdLiSn). Pressure-dependent variation of specific heat, Debye temperature, and Gruneisen parameter were calculated to infer the nature of lattice vibration and stability at high pressures.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Effect of High Pressure and Temperature on Magneto-Electronic, Thermodynamic, and Transport Properties of Antiferromagnetic HoPdX (X = As, Ge) Alloys
We present electronic, magnetic, thermoelectric, and thermodynamic properties of half-Heusler HoPdAs and HoPdGe materials in stable α-phase. They crystallize in cubic MgAgAs-type structure. The stable phase is found to be antiferromagnetic in comparison to the other magnetic and nonmagnetic states. The electronic structure calculations display the metallic behavior in both spin states. The effect of pressure and temperature on unit cell volume, thermal expansion coefficient, heat capacity, and Grüneisen parameter have also been analyzed using the quasi-harmonic Debye model. The alloys present a high absolute Seebeck coefficient with a value of 203.26 μV/K for HoPdAs and 53.19 μV/K for HoPdGe at room temperature.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Numerical Modeling of Gas-Liquid Compressible Pipe Flow Based on the Theory of Thermodynamically Compatible Systems
Based on the theory of thermodynamically compatible systems, we formulate the governing equations of a gas-liquid compressible pipe flow and develop the Runge–Kutta–TVD and Runge–Kutta–WENO high accuracy methods. The computational model is used to solve a series of test cases demonstrating its efficiency and capability to be applied to slug flows modeling.
42 ENGINEERING↗
2,6-Disubstituted 4-azidopyrimidines: synthesis, kinetic and thermodynamic studies of azide-tetrazole rearrangement by NMR spectroscopy
Thermodynamic and kinetic parameters of the tautomeric tetrazole-azide rearrangement for a series of 2,6-disubstituted 4-azidopyrimidines are determined by NOESY/EXSY and DNMR: ΔH = 15—28 kJ mol{sup –1}; ΔS = 47—65 J mol{sup –1} К–1; Е{sub a} = 93—117 kJ mol{sup –1}; lgA = 15.1—18.9. They are dependent on electronic properties of the substituents and the polarity of solvent.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Thermodynamic modeling of the deposition of Si—C—N films from the gas phase during the decomposition of organosilicon compounds
Thermodynamic modeling of the process of chemical vapor deposition (CVD) of SiC{sub x} and SiC{sub x}N{sub y} films from the gas phase was carried out using organosilicon compounds (EtN(SiMe{sub 3}){sub 2}, PhN(SiMe{sub 3}){sub 2}, and PhSiMe{sub 3}) at reactor pressures of 0.01 and 10 Torr in the temperature range of 500–1200 K. It was established that regions of existence of two phase complexes, namely, SiC + Si{sub 3}N{sub 4} + C and SiC + C, were present on the CVD diagrams calculated for the EtN(SiMe{sub 3}){sub 2}—He and PhN(SiMe{sub 3}){sub 2}—He systems. The CVD diagrams calculated for the EtN(SiMe{sub 3}){sub 2}—NH{sub 3}, PhN(SiMe{sub 3}){sub 2}—NH{sub 3}, and PhSiMe{sub 3}—NH{sub 3} systems have regions of existence of three phase complexes, namely, Si{sub 3}N{sub 4} + C, SiC + Si{sub 3}N{sub 4} + C, and SiC + C. The composition of the obtained silicon-containing films was calculated.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Influence of aging of poly[(trimethylsilyl)prop-1-yne] on the thermodynamics of sorption of light hydrocarbons
Changes in the properties of the poly[(trimethylsilyl)prop-1-yne] (PTMSP) film deposited on the walls of a quartz capillary under the action of high temperatures were studied by chromatographic methods. The change in the thermodynamic parameters of sorption of light hydrocarbons related to both physical aging of the PTMSP film and, possibly, its chemical destruction was examined.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
First-Principles and Thermodynamic Simulation of Elastiс Stress Effect on Energy of Hydrogen Dissolution in Alpha Iron
Mobile hydrogen, when dissolving in metals, redistributes due to the density gradients and elastic stresses, and enables destruction processes or phase transformations in local volumes of a solvent metal. It is rather important in solid state physics to investigate these interactions. The first-principle calculations performed in terms of the density functional theory, are used for thermodynamic simulation of the elastic stress effect on the energy of hydrogen dissolution in α-Fe crystal lattice. The paper presents investigations of the total energy of Fe–H system depending on the lattice parameter. As a result, the relation is obtained between the hydrogen dissolution energy and stress. A good agreement is shown between the existing data and simulation results. The extended equation is suggested for the chemical potential of hydrogen atom in iron within the local stress field. Two parameters affecting the hydrogen distribution are compared, namely local stress and phase transformations.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Thermodynamic Considerations of Direct Oxygen Removal from Titanium by Utilizing the Deoxidation Capability of Rare Earth Metals
Oxygen removal from metallic Ti is extremely difficult and, currently, there is no commercial process for effectively deoxidizing Ti or its alloys. The oxygen concentration in Ti scraps is normally higher than that in virgin metals such as in Ti sponges produced by the Kroll process. When scraps are remelted with virgin metals for producing primary ingots of Ti or its alloys, the amount of scrap that can be used is limited owing to the accumulation of oxygen impurities. Future demands of an increase in Ti production and of mitigating environmental impacts require that the amount of scrap recycled as a feed material of Ti ingots should also increase. Therefore, it is important to develop methods for removing oxygen directly from Ti scraps. In this study, we evaluated the deoxidation limit for β-Ti using Y or light rare earth metals (La, Ce, Pr, or Nd) as a deoxidant. Thermodynamic considerations suggest that extra-low-oxygen Ti, with an oxygen concentration of 100 mass ppm or less can be obtained using a molten salt equilibrating with rare earth metals. The results presented herein also indicate that methods based on molten salt electrolysis for producing rare earth metals can be utilized for effectively and directly deoxidizing Ti scraps.
36 MATERIALS SCIENCE↗
Thermodynamic Study on MgO Solubility in High-Alumina-Content Slag System
In the current study, the MgO solubility in molten slag was measured to clarify the effect of basicity and Al{sub 2}O{sub 3} content on the MgO solubility equilibrating with the spinel solid phase in the CaO-SiO{sub 2}-Al{sub 2}O{sub 3} system. The MgO solubility decreased with the increasing basicity of the slag. However, the MgO solubility in the spinel equilibrium region exhibited different dependence when compared with the basicity dependence in the MgO equilibrium region. The aforementioned experimental results were quantitatively analyzed using magic-angle spinning (MAS) {sup 27}Al nuclear magnetic resonance (NMR) spectroscopy, in which the fraction of Al ions in the slag of spinel equilibrium region was changed to 4, 5, and 6. In addition, the analysis of the degree of Al avoidance modeling indicated that the change in bridging oxygen (BO) linkage species (distinguished into Al-O-Al, Si-O-Si, and Al-O-Si) was based on the Al/Si ratio change. The aforementioned change in BO linkage species led to a change in the MgO solubility with the stability of the alumina. Thus, the spinel equilibrium dissolution mechanism is discussed in detail in terms of the thermodynamic and structural influence in molten slag.
36 MATERIALS SCIENCE↗
Passivation Threshold for the Oxidation of Liquid Silicon and Thermodynamic Non-equilibrium in the Gas Phase
The present study focuses on a specific step of the metallurgical path of purification to provide solar-grade silicon: the removal of boron through the injection of H{sub 2}O(g)-H{sub 2}(g)-Ar(g) (cold gas process). A progressive increase of the oxidant H{sub 2}O(g) concentration at injection increases the speed of the process until a silica layer appears at the surface of the liquid silicon to be purified. It then stops the purification. During the process, silica aerosols may form in the gas boundary layer. This modifies the flows of oxidants and the gas concentrations at the liquid silicon surface. Using a monodimensional model, this article shows that a hypothesis of thermodynamic equilibrium of silica aerosols with the gas phase in the boundary layer has to be dropped in order to explain the appearance of a silica passivating layer. The passivation threshold is defined as the limit concentration of the oxidant at the injection below which there is no silica on the liquid silicon surface and beyond which silica particles appear on the liquid silicon surface. Three experiments of estimation of the passivation threshold with the injection of water vapor are used to confirm an empirical criterion for the prediction of the appearance of the silica layer. Two other sets of experiments with the injection of Ar-O{sub 2} are also being studied where the kinetics of the formation of silica aerosols seems to be slower than when water vapor is used. An optimization of the speed of boron removal under the assumption of a maximal concentration of water vapor before the appearance of a passivating silica layer would require an increase of the liquid silicon surface temperature from the fusion temperature of silicon.
36 MATERIALS SCIENCE↗
Thermodynamic Analysis of Deoxidation of Titanium Through the Formation of Rare-Earth Oxyfluorides
In this work, the possibility of the direct removal of oxygen species from metallic Ti through the formation of rare-earth oxyfluorides has been investigated from a thermodynamic viewpoint. The deoxidation limit of β-Ti using rare-earth metals (M: Y, La, Ce, and Nd) as deoxidants was evaluated. It was found that Ti metal with an oxygen concentration of 200 mass ppm or less could be theoretically obtained under the M/MOF/MF{sub 3} equilibrium at 1300 K (1027 °C), which suggested a possibility of reducing the oxygen content in Ti below 500 mass ppm utilizing a fluoride-based molten salt. Furthermore, a new deoxidation process, in which oxygen was removed in the form of MOF compounds using Mg deoxidant, was discussed as well. The obtained results revealed that the oxygen content in β-Ti could be theoretically reduced to a level below 1000 mass ppm using a MF{sub 3}-containing molten salt equilibrated with Mg. Rare-earth metals and their alloys are usually produced by the electrolysis in a fluoride-based molten salt; hence, the modern industrial electrolysis techniques can be potentially utilized for deoxidizing Ti scrap.
36 MATERIALS SCIENCE↗