[en] Highlights: • The fouling of JP10 in autoxidative and intermediate regime was studied. • The amount of the coke deposits of JP10 increases with the wall temperature. • The deposits of JP10 were mainly in the form of amorphous carbon. - Abstract: Exo-tetrahydrodicyclopentadien called JP-10 is an endothermic hydrocarbon fuel with high-energy density being used in aircrafts. We have investigated the fouling of JP-10 on the inner surface of SS316L tube at wall temperature from 260 °C to 350 °C and at 3.84 MPa with a flow rate of 0.5 ml/min for 24 h. The fouling of JP-10 was influenced by wall temperature, fuel temperature and the metal surface. The average values of coke deposits were measured to be between 7.52 μg/cm"2 and 10.67 μg/cm"2 by carbon burn-off method, and the maximum values of local coke deposits and average values of coke deposits increase with the wall temperature. At 350 °C and 300 °C, the locations of peak deposition shifted upstream as the wall temperature increased. The nature and morphology of deposits were characterized by field emission scanning electron microscopy (FESEM) and temperature programmed oxidation (TPO) profiles, and the deposits of JP-10 were mainly in the form of amorphous carbon. Structurally more ordered deposits were also found, and it should be caused by the catalysis of iron and nickel in metal surface.

[en] Graphical abstract: Experimental apparatus based on the synthetic-volumetric method for measuring solubilities of gases in liquids. Highlights: • We constructed an apparatus for measuring solubilities of sparingly-soluble gases. • We measured solubilities of five gases in four immidazolium-based ionic liquids. • We calculated Henry’s constants for gases in the ionic liquids studied in this work. -- Abstract: The synthetic-volumetric method is used for rapidly measuring solubilities of sparingly-soluble gases in monoethylene glycol and in four ionic liquids. Known molar quantities of solute and solvent are charged into an equilibrium vessel. Measured quantities at equilibrium include: temperature, pressure, quantities of fluids, and volumes of the gas and liquid phases in the equilibrium vessel. These measurements enable calculation of equilibrium compositions using material balances. No sampling or chemical analyses are required. Solubilities are reported for carbon dioxide, krypton, oxygen, and hydrogen in monoethylene glycol, l-n-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4], l-n-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM][Tf₂N], or 1-ethyl-3-methylimidazolium acetate [EMIM][AC]. Solubilities were measured over the temperature range (298 to 355) K and for pressures up to about 7 MPa using two different pieces of equipment, both based on the volumetric method: a low-pressure glass apparatus and a high-pressure stainless-steel apparatus. Special emphasis is given to experimental reliability to assure consistent data

[en] Highlights: • C_p of ethyl heptanoate and ethyl cinnamate were presented. • C_p of the two compounds rise with temperature and fall with pressure. • C_p of ethyl heptanoate is larger than that of ethyl cinnamate. • A correlation were presented for C_p of ethyl heptanoate and ethyl cinnamate. - Abstract: In this work, new experimental values for the isobaric molar heat capacities of ethyl heptanoate and ethyl cinnamate are presented at temperatures ranging from (305 to 387) K and under pressures up to 16.3 MPa. The relative expanded uncertainty of the isobaric molar heat capacity is estimated to be less than 1%. The isobaric molar heat capacities of ethyl heptanoate and ethyl cinnamate rise with the increasing temperature and fall with the increasing pressure. Based on the experimental findings in our work and from the literature, the isobaric molar heat capacities of saturated fatty acid methyl esters and fatty acid ethyl esters are found to rise with the carbon number, while the isobaric molar heat capacity of aromatic ester ethyl cinnamate is lower than that of the saturated fatty acid ethyl ester with the same or less carbon number due to the unsaturation. A correlation is proposed for the isobaric molar heat capacities of ethyl heptanoate and ethyl cinnamate with a maximum absolute relative deviation of 0.5%.

[en] Graphical abstract: Henry’s constants for isobutane and cyclopropane in [HMIM][Tf_2N] and [P(14)666][TMPP]. - Highlights: • Solubilities of isobutane and cyclopropane in two ionic liquids were reported. • Solubilities were measured from T = (302 to 344) K and from (0.03 to 1.16) MPa. • The effects of temperature and pressure on the solubilities were investigated. • Solubilities of hydrocarbons in [HMIM][Tf_2N] and [P(14)666][TMPP] were compared. • A modified Krichevsky–Kasarnovsky equation was used to model experimental data. - Abstract: In this work, we presented the solubilities of isobutane and cyclopropane in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HMIM][Tf_2N]) and trihexyl tetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate ([P(14)666][TMPP]) from T = (302 to 344) K up to 1.16 MPa. Henry’s constants for isobutane and cyclopropane in [HMIM][Tf_2N] and [P(14)666][TMPP] were calculated from experimental results. Solubilities of isobutane and cyclopropane in [HMIM][Tf_2N] are apparently smaller than those in [P(14)666][TMPP]. The effects of temperature, pressure and the number of carbon atoms in the hydrocarbons on the solubility were investigated in detail. A modified Krichevsky–Kasarnovsky equation was successfully applied to correlate the experimental results. The mean absolute relative deviations and the maximum absolute relative deviations are less than (2.4 and 4.6)%, respectively

[en] Graphical abstract: Mutual diffusion coefficients of isopropanol + n-heptane as a function of mass fraction of isopropanol. - Highlights: • D_1_2 of isopropanol + n-heptane and isobutanol + n-heptane were measured. • Effect of T, w and M of the solute on D_1_2 were analyzed. • A new correlation is proposed for the experimental data. - Abstract: The mutual diffusion coefficients of isopropanol + n-heptane and isobutanol + n-heptane were measured at different concentrations and in the temperature range from (283.15 to 323.15) K. The measurements were carried out using a digital holographic interferometry system. For all the mixtures investigated, the mutual diffusion coefficient increases as the temperature increases. At the same concentration and temperature, the mutual diffusion coefficients of isobutanol + n-heptane were lower than those of isopropanol + n-heptane due to the fact that the molecular weight of isobutanol is larger than that of isopropanol. A new correlation is proposed for the mutual diffusion coefficients of isopropanol + n-heptane and isobutanol + n-heptane. The absolute average relative deviation between the correlation and experiment is less than 1.90%.

[en] Highlights: • Solubilities of CO_2, H_2, N_2 and O_2 in [HMIM][eFAP] were determined. • Ideal selectivities of CO_2/N_2, CO_2/H_2, and CO_2/O_2 in [HMIM][eFAP] were calculated. • Performance of ionic liquids in separating CO_2 from N_2, H_2 and O_2 was compared. - Abstract: Ionic liquids are promising solvents for extracting CO_2 from H_2, N_2 and O_2 using the absorption separation method. Solubilities of these gases in 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][eFAP]) were determined using an isochoric saturation method. Experimental result indicates that solubilities of H_2, N_2 and O_2 in [HMIM][eFAP] are much lower than that of CO_2. The performance of [HMIM][eFAP] in separating CO_2 from N_2, H_2 and O_2 can be improved by decreasing the temperature. Based on the solubility data, the ideal selectivities of CO_2/N_2, CO_2/H_2, and CO_2/O_2 in different ionic liquids were calculated and the effect of the ionic liquid structure on them were investigated.

[en] Graphical abstract: Experimental critical pressures of 2-butanol + hexane + heptane system. - Highlights: • Critical properties of six binary systems and two ternary systems were measured. • Six binary systems containing 2-butanol show non-ideal behavior in their T_c–x_1 curves. • Non-ideal behavior of mixtures with 2-butanol relies on azeotropy. • Experimental data for binary systems were fitted well with Redlich–Kister equation. • Critical surfaces of ternary systems were plotted using the Cibulka’s expressions. - Abstract: In this work, we used a flow method for measurement of critical properties of six binary mixtures (2-butanol + cyclohexane, 2-butanol + hexane, 2-butanol + heptane, 2-butanol + octane, 2-butanol + nonane and 2-butanol + decane) and two ternary mixtures (2-butanol + hexane + heptane and 2-butanol + octane + decane). The critical properties were determined by observing the disappearance and reappearance of the gas–liquid phase meniscus in a quartz glass tube. The standard uncertainties of temperatures and pressures for both binary and ternary mixtures were estimated to be less than 0.2 K and 5.2 kPa, respectively. These critical data provide the boundaries of the two-phase regions of the related mixture systems. Six binary systems show non-ideal behaviors in the loci of critical temperatures. We used the Redlich–Kister equations to correlate the critical temperatures and pressures of these systems and listed the binary interaction parameters. The maximum average absolute deviation (AAD) of each binary system between experimental data and calculated results from Redlich–Kister equations is 0.038% for critical temperatures, and 0.244% for critical pressures. Moreover, the two ternary systems were newly reported and correlated by Cibulka’s and Singh’s expressions. The maximum AAD of critical temperatures and critical pressures are 0.103% and 0.433%, respectively.

[en] Improvement in hydrophilicity of polypropylene (PP) separator and its stability is essential for enhancing the comprehensive performance of battery. In this study, the PP separators were surface modified by direct fluorination with F₂/N₂ and F₂/O₂/N₂ gas atmosphere. The alkali absorption ratios (AARs) of these two kinds of fluorinated separators are 302.7% and 418.4%, respectively, which is about nine and twelve times than that of the virgin PP separator. At the same time, the AARs of the fluorinated separators stored for 90 days at ambient temperature in air environment still remain. The surface energy of PP separators is increased from 37.8 mN/m to 47.7 mN/m and 48.9 mN/m determined by contact angle measurement after direct fluorination. X-ray photoelectron spectroscopy (XPS) and attenuated total reflection infrared spectroscopy (ATR-FTIR) results indicate that polar groups, such as -C=O(OH) and -C-F_x, are introduced into the polymeric structures of the two fluorinated separator surfaces. Larger quantity of polar groups, especially -C=O(OH), are introduced on separator surface by the F₂/O₂/N₂ modified route, which results in the difference of the AARs and behavior of alkali absorption. Scanning electron microscope (SEM) demonstrates that the size and shape of micropores of PP separators remain almost unchanged after direct fluorination.

[en] In order to close the nuclear fuel cycle, advanced concepts for separating out fission products are necessary. One approach is to use a dispersion fuel form in which a fissile core is surrounded by an inert matrix that captures and immobilizes the fission products from the core. If this inert matrix can be easily separated from the fuel, via e.g. solution chemistry, the fission products can be separated from the fissile material. We examine a surrogate dispersion fuel composition, in which hafnia (HfO₂) is a surrogate for the fissile core and alkaline earth metal oxides are used as the inert matrix. The questions of fission product incorporation in these oxides and possible segregation behavior at interfaces are considered. Density functional theory based calculations for fission product elements (Xe, Sr, and Cs) in these oxides are carried out. We find smaller incorporation energy in hafnia than in MgO for Cs and Sr, and Xe if variation of charge state is allowed. We also find that this trend is reversed or reduced for alkaline earth metal oxides with large cation sizes. Model interfacial calculations show a strong tendency of segregation from bulk MgO to MgO-HfO₂ interfaces.

[en] Breakdown in ablative pulsed plasma thrusters (APPTs) must be studied in order to design new types of APPTs and measure particular parameters. In this paper, we studied a parallel-plate ablative pulsed plasma thruster that used a coaxial semiconductor spark plug. By operating the APPT about 500 times with various capacitor voltages and electrode gaps, we measured and analyzed the voltage of the spark plug, the voltage between the electrodes, and the discharge current. These experiments revealed a time delay (∼1–10 μs) between spark plug ignition and capacitor discharge, which may affect the performance of high-pulsing-rate (>10 kHz) and double-discharge APPTs, and the measurements of some of the APPT parameters. The delay time decreased as the capacitor voltage increased, and it increased with an increasing electrode gap and increasing number of ignitions. We explain our results through a simple theoretical analysis