O2 Mixture Research Articles

Deposition of Ti-Zr-O-N films by reactive magnetron sputtering of Zr target with Ti ribbons

In this work, we explore the addition of Ti ribbons on the racetrack of a Zr target to prepare Zr-O-N films including Ti, by reactive magnetron sputtering with a mixture of N2 and O2 as reactive gases. This approach is simple and not invasive, it avoids the modification of the target and minimizes its contamination. These films were compared in terms of chemical composition, density, film growth and crystallographic structure with others prepared in identical conditions without Ti ribbons. In addition, the composition and density of the films were correlated with crystallographic references from literature. The color and electrical properties of the films were evaluated as well.It was observed that poisoning of the Zr target is promoted by the increase of the N2 + O2 flow and the reduction of magnetron current, but it is retarded by the introduction of the Ti ribbons. This effect was particularly remarkable at lower target current, since the sputtering is confined in areas nearer to the racetrack, where the Ti ribbons are located. To account for the poisoning of the target and compare it among the different samples, a ‘poisoning parameter’ was defined, using a combination of the chemical composition of the films and the deposition rates. The color and electrical properties of the films correlate surprisingly well with their oxygen-to-metal ratio, while the concentration of N does not seem to play any significant role.

Comparison of the Interrupting Capability of Gas Circuit Breaker According to SF6, g3, and CO2/O2 Mixture

In the study, an interrupting performance test on the 145 kV gas circuit breaker is performed according to three different gases: SF6, g3 (5% NovecTM4710 with 95% CO2), and CO2(70%)/O2(30%) gases. Thanks to research advancements, it is confirmed that CO2 and g3 (5% NovecTM 4710) gases, respectively, have 40% and 75% dielectric strength, compared to that of SF6 gas. The filling pressure and transient recovery voltage criteria of each gas were determined differently in order to compare the maximum interrupting performance of each gas. The pressure of SF6 gas was determined to be 5.5 bar, which is typically used in circuit breakers. The pressure of the other two gases was determined to be 8.0 bar (the maximum available pressure of the test circuit breaker) to find the maximum interrupting performance. Moreover, the rate-of-rise of transient recovery voltage of SF6 was determined as 10 kV/μs, which is the value at the state of maximum interrupting performance of the test circuit breaker with SF6. On the other hand, the rate-of-rise of transient recovery voltages of g3 (5% NovecTM4710 with 95% CO2) and CO2(70%)/O2(30%) gases were, respectively, determined as 4∼5 kV/μs to find the interruption available point. The characteristics of arc conductance, arc current, and arc voltage near the current zero, and post-arc current are analyzed to compare the interrupting performance, according to different arc-quenching gases. The arc current is measured using a current transformer (Rogowski coil), and a signal processing method of the arc current and arc voltage is introduced to increase the reliability of the interrupting performance results. As a result of the test, it is confirmed that the critical arc conductance for all test conditions converged within a certain range and the value is around 0.7 mS. In addition, the critical current slope just before the current zero-crossing during the interrupting process is shown to be 1.8 A/μs between interruption success and failure. Consequently, it is verified that the CO2(70%)/O2(30%) mixture and g3 (5% NovecTM4710 with 95% CO2) have a similar arc extinguishing performance and SF6 has a relatively higher extinguishing performance than that of CO2(70%)/O2(30%) mixture and g3 (5% NovecTM4710 with 95% CO2) under the aforementioned filling pressure and TRV conditions.

Impact of modified atmospheric packaging and edible coatings on quality of minimally processed prickly pear during cold storage

This study was performed to investigate the effect of different concentrations of modified atmospheric packaging (MAP) which consists of a mixture of gases CO2, N2 and O2, by some treatments such as (C): (60% Co2 /20% N2 /20% O2)and (D): (60% CO2 /20% N2 /20% O2) with edible coating and under vacuum packing where the treatment; (B) compared with control sample (A) on quality attributes and prolong shelf-life of minimally processed prickly pear during cold storage. All treatments were stored at (4±1°C) and relative humidity (90-95%) for 21 days and the quality parameters such as weight loss, firmness, total soluble solids (TSS), titratable acidity (TA), total caroteniods, total bacterial count, psychrophilic bacterial count, moulds and yeasts count, total colony count and sensory evaluation were done. The results observed the treatment (D) was the best for reduction of microbial load followed by treatment (C) then treatment (B) until 15 days of storage as compared to control (A) at 6 days of storage. The use of modified atmosphere packaging, either alone or in combination with the edible film, reduced the deterioration of the physiochemical characteristics of minimally processed prickly pear samples during cold storage. The obtained data indicated that the sensory evaluation, it became clear that packing in a modified atmosphere with edible coating (D) was the best, followed by packing in a modified atmosphere alone (C), which prolongs the shelf life, freshness and quality of the fruits when stored under the conditions of cooling and the relative humidity of the laboratory prickly pears which was more efficiency from storage under vacuum or without treatment as in the control sample (A). Also, these modified atmosphere packaging and edible coating showed a great influence on the quality and shelf life of the treated samples. Finally, it is evident from the results obtained that modified atmosphere packaging and edible film significantly affected the retention of the tested samples for quality characteristics in general.

Interplay between PEMFC Performance, Gas Diffusion Electrode Structure and Mass Transport Properties

Due to substantial research and development in the last two decades, energy conversion systems based on proton exchange membrane fuel cell (PEMFC) technology are emerging to the market. However, cost of the fuel cells is still high compared to the conventional energy generating systems like internal combustion engines. A decrease in Pt loading is a vital requirement for cost reduction and commercialization of the fuel cell technology. Operation of low-Pt PEMFCs showed that fuel cell performance is declining with a decrease in Pt loading and the voltage drop becomes very significant at high current density due to increasing mass transfer losses [1]. Thus, it is critical to understand this voltage loss phenomenon and mitigate it. Previously we developed a method for determining the oxygen mass transfer coefficient which is based on measurements of limiting current distributions using O2 mixtures with different diluents (from He to C3H8) [2]. In this work we studied effects of gas diffusion electrodes (GDEs) composition and structure such as cathode catalyst and microporous layer (MPL) loadings on oxygen mass transport and PEMFC performance.A segmented cell and data acquisition system were operated with commercially available 100 cm2 MEAs with cathode loadings of 0.1, 0.2 and 0.4 mgPt cm-2, while the anode Pt content was kept 0.1 mg cm-2. Cathode gas diffusion layer (GDL) was also varied to separate contributions from MPL and catalyst layer. 25BA (no MPL) and 25BC (with MPL) diffusion medias from Sigracet SGL were used for the cathode electrode. The experiments were performed at 80°C, fully humidified conditions and varied back pressures. Details of experimental procedures are presented in [2].A comparison of the IV curves showed that 25BA cannot provide good water and gas management at high current operation (Fig. 1 a). At the same time, an increase in Pt loading significantly improves the performance at low and high current regimes. The high performance of the sample MEA-0.4-25BC with Pt loading of 0.4 mgPt cm-2 and 25BC cathode GDL indicates on a possibility that part of catalyst layer acts as an MPL and actively participates in water removal from electrode structure to macro-porous layer of carbon paper.Using our previously described method we separated mass transport coefficients in gas phase (km, N2 ) and a combination of Knudsen diffusion and transport through ionomer/water films in overall GDE (kK+film ). Comparing results for MEA-25BA and MEA-25BC we extracted contribution from MPL (kK, MPL ) and cathode layer (CL) (kK+film, CL ). Further variation of back pressure allowed us to eliminate impact of Knudsen diffusion in CL and extract pressure independent contribution (kfilm,CL ) which represents a diffusion through the ionomer/water films in CL.The obtained values of pressure-independent oxygen mass transfer coefficients in CL (kfilm, CL ), Knudsen diffusion in MPL (kK, MPL ) and CL (kK, CL ) and molecular diffusion in N2 media (km, N2 ) are compared at Fig. 1 b. A reduction in Pt loading leads to a decrease in kfilm, CL as it was previously reported [3-6]. Interestingly, that MEA with the highest Pt content (MEA-0.4-25BC) is characterized by the greatest value of kK, MPL as well. All samples have nearly the same values of the O2 mass transfer coefficient in gas phase varying from 0.040 to 0.043 m s-1.Performances of the studied samples in terms of cell voltage at 1.5 A cm-2 and mass transport voltage losses (permeability and diffusion) are presented at Fig. 1 c. A direct comparison of the data shows that MEA-0.4-25BC has the best performance due to the greatest values of kfilm, CL and kK, MPL insuring a good gas transport within catalyst layer and MPL as well as water transport. Detailed analysis of the PEMFC performance, voltage losses and oxygen mass transfer coefficients at various operating conditions will be presented and discussed.ACKNOWLEDGEMENTSWe gratefully acknowledge funding from ONR (N00014-19-1-2159) and ARO (W911NF-15-1-0188). The authors are thankful G. Randolf and J. Huizingh for support of the operation as well as T. Carvalho for assisting with SEM.References A. Kongkanand, M. Mathias, J. Phys. Chem. Lett. 7 (2016) 1127.T. V. Reshetenko, J. St-Pierre, J. Electrochem. Soc., 161, F1089-F1100 (2014).Y. Ono, T. Mashio, S. Takaichi, A. Ohma, H. Kanesaka, K. Shinohara, ECS Trans. 28 (27) 69-78 (2010).N. Nonoyama, S. Okazaki, A.Z. Weber, Y. Ikogi, T. Yoshida, J. Electrochem. Soc. 158 (4) B416-B423 (2011).T. Greszler, D. Caulk P. Sinha, J. Electrochem. Soc. 159 (12) F831-F840 (2012).J.P. Owejan, J.E. Owejan, W. Gu, J. Electrochem. Soc. 160 (8) F824-F839 (2013). Figure 1

Normobaric hypoxia training in military aviation and subsequent hypoxia symptom recognition

Altitude hypoxia episodes are increasingly common in military aviation. Hypoxia training is mandatory for fighter pilots, but evidence-based data on the effects of training are scarce. The purpose of this study was to validate the normobaric hypoxia (NH) training effect. Data were collected from 89 pilots from the Finnish Air Force (FINAF). This survey was conducted in a tactical F/A-18C Hornet simulator in two sessions under normobaric conditions, in which the pilots performed flight missions and breathed 21% oxygen (O2) in nitrogen (N2), and blinded to the pilot, the breathing gas was changed to a hypoxic mixture containing either 8, 7 or 6% O2 in N2. The time taken to notice hypoxia symptoms and peripheral capillary O2 saturation was measured. A mean of 2.4 years after the initial training, pilots recognised their hypoxic symptoms 18 s quicker with 8% O2 mixture, 20 s quicker with 7% O2 and 10 s quicker with 6% O2. Our data indicate that NH training in a flight simulator helps pilots to recognise hypoxia symptoms earlier, and may, thus, enhance flight safety. Practitioner Summary: We show that hypoxia training enhances pilots’ ability to recognise symptoms of acute normobaric hypoxic exposure up to 2.4 years after an initial NH training session. Based on these data, refreshment NH training is nowadays mandatory every 3 years in the FINAF as opposed to the North Atlantic Treaty Organisation (NATO) Standardisation Agreement (STANAG) requirement of 5-year intervals between hypoxia trainings. Abbreviations: O2: oxygen; TUC; time of usefull consciousness; SpO2: peripheral capillary oxygen saturation; NATO: North Atlantic Treaty Organization; STANAG: stanrdization agreement; HH: hypobaric hypoxia; NH: normobaric hypoxia; FINAF: finnish air force; N2: nitrogen; ECG: electrocardiogram; CI: confidence interval; SD: standard deviation

Measurement of electronegativity during the E to H mode transition in a radio frequency inductively coupled Ar/O2 plasma* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11675039, 11875101, and 11935005) and the Fundamental Research Founds for the Central Universities, China (Grant Nos. DUT18TD06 and DUT20LAB201).

This paper presents the evolution of the electronegativity with the applied power during the E to H mode transition in a radio frequency (rf) inductively coupled plasma (ICP) in a mixture of Ar and O2. The densities of the negative ion and the electron, as well as their ratio, i.e., the electronegativity, are measured as a function of the applied power by laser photo-detachment combined with a microwave resonance probe, under different pressures and O2 contents. Meanwhile, the optical emission intensities at Ar 750.4 nm and O 844.6 nm are monitored via a spectrograph. It was found that by increasing the applied power, the electron density and the optical emission intensity show a similar trench, i.e., they increase abruptly at a threshold power, suggesting that the E to H mode transition occurs. With the increase of the pressure, the negative ion density presents opposite trends in the E-mode and the H-mode, which is related to the difference of the electron density and energy for the two modes. The emission intensities of Ar 750.4 nm and O 844.6 nm monotonously decrease with increasing the pressure or the O2 content, indicating that the density of high-energy electrons, which can excite atoms, is monotonically decreased. This leads to an increase of the negative ion density in the H-mode with increasing the pressure. Besides, as the applied power is increased, the electronegativity shows an abrupt drop during the E- to H-mode transition.

Kinetics of Reaction of Oxygen with Uranium(IV) Chloride in Alkali Chloride Melts

Alkali chloride melts have numerous potential applications in nuclear fuel cycle including pyrochemical reprocessing of spent nuclear fuels, uranium electrowinning and electrorefining. Oxygen is a common technological impurity that can affect uranium speciation and behavior in fused salts. The present work was devoted to studying the reactions of oxygen with solutions of uranium tetrachloride in molten alkali chlorides. The experiments were performed in LiCl–KCl, NaCl–KCl–CsCl and NaCl–CsCl eutectic based melts at 450–750 oC. Pure oxygen and argon–oxygen mixtures (containing ca. 1 and 10 % O2) were used. Amount of oxygen passed through the melt varied from less than one to over 100 moles per mole of uranium present. Effect of moisture (0.4–2.5 % H2O) presence in oxygen or Ar–O2 mixtures was also investigated. The course of the reaction was followed by in situ electronic absorption spectroscopy measurements with the spectra recorded at the certain time intervals.Depending on temperature, cationic melt composition and oxygen-to-uranium molar ration the reaction resulted in oxidation of uranium(IV) to soluble uranyl chloride and/or precipitation of uranium dioxide. Analysis of the spectra provided the information on kinetics of U(IV) concentration change. Increasing temperature, O2 : U(IV) molar ratio or decreasing mean radius of alkali cations of the solvent melt resulted in faster decrease of U(IV) concentration in the melt.Under certain conditions U(IV) can be oxidized to UO2Cl4 2– without precipitation of UO2. Therefore sparging the melt with oxygen can be used as a way of separating uranium from certain fission products, for example rare earth elements. Rare earth chlorides react with oxygen yielding oxychlorides or oxides insoluble in alkali chloride melts. Interaction of oxygen with melts containing a mixture of uranium and rare earth chlorides was therefore also investigated and an example of the spectra recorded in LiCl–KCl–UCl4–NdCl3 melt is shown in Fig.Fig. Spectra recorded in the course of reaction of O2 with LiCl–KCl–UCl4–NdCl3 melt at 550 oC. Arrows show the direction spectra changed. Figure 1

Resistance Change Behavior Under Voltage Pulses at Reset Process of Ti/HfO2/Au-Reram with Various HfO2 Layer Conditions

1. Introduction Recently the application of ReRAM to artificial synapse has been paid much attention in the field of neuromorphic computing([1],[2]). For the implementation of neuromorphic synaptic devices, gradual resistance change response by applying voltage pulse trains is required. We investigated the condition of Ti/HfOx/Au-ReRAM to possess gradual resistance change by changing sputtering conditions of HfOx layer. 2. Sample preparation and experiments Figure 1 shows the structure of Ti/HfOx/Au device. For deposition of HfOx film, we used reactive sputtering with Ar and O2 mixture gases. At this time, we adopted two types of Ar/O2 flow ratios, which is (1)7.8 : 15.6 sccm and (2)7.8 : 2.0 sccm. These devices have a bipolar memory characteristic. SET occurs when a positive voltage is applied, and RESET occurs when a negative voltage is applied. We measured resistance change of RESET process of the ReRAM device with applying DC voltage pulses. 3. Results and discussion Figure 2 shows resistance change behavior with applying voltage pulses at RESET process. Pulse width is 1.0 uA and pulse period is 2.0 uA. Figure 2(a) is the resistance change behavior of device (1) with constant amplitude voltage pulses. Resistance change was rarely observed when pulse amplitude is -1.5 V, however, gradual resistance change more than 1 digit was observed when pulse amplitude is -1.6 V. Moreover, when we applied -1.7 V, gradual resistance change more than 2 digits within 40 pulses was observed. In the case of this device, resistance change was ideal for the use of neuromorphic synaptic device. Figure 2(b) is the results of device (2). Gradual resistance change was observed after 60 pulses when pulse width is -1.5 V. However resistance increased more than 3 digits after a few pulses were applied when pulse amplitudes were -1.6 V and -1.7 V. In the case of device (2), resistance change is almost binary and it is not suitable for use of artificial synapse device. The difference of resistance change behavior may come from spatial variation of oxygen vacancies. For further understanding of the mechanisms, we will evaluate the difference of atomic composition of HfOx layer by XPS and XRD.

Selective etching of SiN against SiO2 and poly-Si films in hydrofluoroethane chemistry with a mixture of CH2FCHF2, O2, and Ar

Gas chemistry has a significant impact on etch selectivity in semiconductor device fabrication, which is important for realization of atomic-scale removal and formation of high-aspect ratio features. To widen the controllable changes in the etchant composition in etching processes, our previous calculation showed the possibility of the controllable generation of CH2F and CHF2 related ions and radicals from a 1,1,2-trifluoroethane (CH2FCHF2) parent gas. The etch selectivity among silicon nitride (SiN), silicon dioxide (SiO2) and poly-Si films using CH2FCHF2 plasma mixed with O2 and Ar was investigated. The effects of the CH2FCHF2 and O2 partial pressures on the composition of CHF2+ and CH2F+ ions, which were measured with a quadrupole mass spectrometer, and on the possible reactions with respect to the CH2FCHF2 and O2 mixed gas phase were investigated using quantum chemical calculations. The etch selectivity was investigated through surface etching reactions for SiN, SiO2, and poly-Si films.

Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties

Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N2, Ar, and O2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5–30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of ~0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from ~2.22 to ~2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.

Phase equilibrium modeling for confined fluids in nanopores using an association equation of state

The conventional cubic‒plus‒association equation of state (CPA EoS) is extended to describe the phase behavior of non‒associating and associating fluids in nanopores. To consider the effects of molecule‒wall interaction, a new pressure term was introduced into the CPA EoS. The modified Laplace equation was used to describe the capillary condensation in confined space. A thermodynamic model, i.e., mCPA/Laplace, based on modified CPA EoS and Laplace equation was presented. Furthermore, while correlations among the tensile strength, fluid critical point, and liquid spinodal point were discussed, the negative pressure for the mCPA/Laplace and mSRK models was studied. The calculations of the mCPA/Laplace model for pure O2, Ar, N2, Kr, CO2, C2H6, C3H8, n‒C4H10, n‒C5H12, n‒C6H14, n‒C7H16 and certain binary mixtures agreed with experimental data. Using the parameter database from the experimental data, this promising study can be extended to both shale oil and shale gas.

Kinetics and Mechanisms of Reactive-Ion Etching of Si and SiO2 in a Plasma of a Mixture of HBr + O2

In this paper, we investigate the kinetics and mechanisms of reactive-ion etching of Si and SiO2 in the plasma of an HBr + O2 mixture with a variable initial composition under conditions of the high-frequency (13.56 MHz) inductive discharge. In the experimental and theoretical (model) analysis of the plasma parameters, the key plasma-chemical processes that form the stationary composition of the gas phase are identified and the densities of active particle fluxes onto the surface under processing are determined. It is found that the increase in the O2 concentration in the plasma-forming mixture is accompanied by a decrease in the kinetic coefficients (probability of effective interaction and etching yield) that characterize the heterogeneous stages of the etching process. It is assumed that the main mechanism of this effect is the oxidation of SiBrx etching products to low volatile compounds of the SiBrxOy type.

Effect of concentration inhomogeneity on the pulsating instability of hydrogen–oxygen detonations

One-dimensional, unsteady gaseous detonation propagation in a non-homogeneous medium is investigated numerically using the reactive, compressible Navier–Stokes equations with detailed chemistry. The effect of concentration inhomogeneity on the pulsating mode is modeled by a sinusoidal distribution of H2 mole fraction in a H2–O2 mixture. The mixture inhomogeneity, varied by changing the disturbance frequency and amplitude, has significant effects on the pulsating behavior of the detonation due to the interaction of the leading shock with the local gradient. Initially exhibiting a four-period pulsation, the detonation wave entering a non-homogeneous medium can adapt and re-establish into a new propagation mode. For a fixed, large-amplitude sinusoidal disturbance, the period-doubling limit cycle is prone to be destroyed, resulting in a chaotic mode for the propagating detonation front in the non-homogeneous mixture; lowering the disturbance frequency also favors a transition from a periodic pulsation to a chaotic one. When the disturbance amplitude decreases, the propagating detonation can transit quickly to a new pulsating behavior, which tends to be more regular. For a very small amplitude of inhomogeneous variation, it is found that the frequency corresponding to the wavelength close to that of the intrinsic pulsation in the uniform mixture makes the original four-period mode become a double-period mode; for a frequency less than this value, the double-period mode is prone to become more unstable. Consequently, this demonstrates that inhomogeneity could have a positive effect on stabilizing a pulsating detonation.

Dynamics of detonation transmission and propagation in a curved chamber: a numerical and experimental analysis

The dynamics of detonation transmission from a straight channel into a curved chamber was investigated numerically and experimentally as a function of initial pressure (10 kPa ≤ p0 ≤ 26 kPa) in an argon diluted stoichiometric H2–O2 mixture. Numerical simulations considered the two-dimensional reactive Euler equations with detailed chemistry; hi-speed schlieren and OH* chemiluminescense were used for flow visualization. Results show a rotating Mach detonation along the outer wall of the chamber and the highly transient sequence of events (i.e. detonation diffraction, re-initiation attempts and wave reflections) that precedes its formation. An increase in pressure, from 15 kPa to 26 kPa, expectedly resulted in detonations that are less sensitive to diffraction. The decoupling location of the reaction zone and the leading shock along the inner wall determined where transition from regular reflection to a rather complex wave structure occurred along the outer wall. This complex wave structure includes a rotating Mach detonation (stem), an incident decoupled shock-reaction zone region, and a transverse detonation that propagates in pre-shocked mixture. For lower pressures, i.e. ≤ 10 kPa, the detonation fails shortly after ignition. However, the interaction of the decoupled leading shock with the curved section of the chamber results in detonation initiation behind the inert Mach stem. Thereafter, the evolution was similar to the 15 kPa case. Simulations and experiments qualitatively and quantitatively agree indicating that the global dynamics in this configuration is mostly driven by the geometry and initial pressure, and not by the cellular structure in highly compressed regions.

Experimental Density Data of Three Carbon Dioxide and Oxygen Binary Mixtures at Temperatures from 276 to 416 K and at Pressures up to 20 MPa

In the context of power-to-gas systems, including power-to-gas–oxyfuel, possible storage of a mixture of CO2 and O2 requires density data information and evaluation of equations of state. Densities of three CO2–O2 binary systems were measured using a vibrating tube densitometer, and the forced path mechanical calibration method in the gas, liquid, and supercritical regions between 276 and 416 K and at pressures up to 20 MPa (maximum expanded uncertainties U(p) = 0.0005 MPa, U(T) = 0.3 K, and U(ρ) = 15 kg·m–3). The mole fractions of the prepared CO2–O2 mixtures are 0.726:0.274, 0.517:0.483, and 0.872:0.128. The Peng–Robinson cubic equation of state (PR EoS) and the EoS-CG, based on GERG-2008 (and implemented in Refprop v10.0), were considered for the analysis of the data. Comparisons were carried out with literature data. It appears that the data are overall better predicted by the EoS-CG than the PR EoS

Emission Characteristic of a Dual fuel Compression Ignition Engine Operating on Diesel + Hydrogen & Diesel + HHO gas with same Energy Share at Idling Condition

Clean burning nature and renewability of hydrogen makes it viable and alternative / supplementary fuel for utilization in IC engine. In the past two decades, researchers have gained interest in using hydrogen in Internal combustion (IC) engines. Electrolysis is the widely used technique for production of hydrogen. The effect on emission parameters of using hydrogen and HHO gas in a dual fuel engine at idling condition was focused in this research work. HHO gas was synthesized from stored cylinders of hydrogen & oxygen in 2:1 ratio. The mixture of H2 and O2 are produced in stoichiometric ratio similar to electrolysis of water. Effect of introduction of hydrogen gas and stimulated HHO gas on emission characters such as unburnt hydrocarbon (UHC), carbon dioxide (CO2), oxides of nitrogen (NOx) and smoke of the engine were noted at idling condition (1700 rpm). Engine was supplied with 6, 12, 18, 24, 30, 36 LPM of hydrogen and 9, 18, 27, 36, 45, 54 LPM of HHO gas where the composition of mixture was maintained in the ratio of 2:1 and energy supplied by Hydrogen and HHO gas remains same. Introduction of hydrogen and HHO gas has reduced the total diesel fuel consumption and formation of CO2 at all operating condition than neat diesel operation. There was slight increase in UHC emission with hydrogen and by substituting HHO gas the UHC emission was reduced.

Oxidation of pentan-2-ol – part II: Experimental and modeling study

The oxidation of pentan-2-ol was investigated at high-pressure in a jet-stirred reactor and in a shock tube. Experiments in the JSR were carried out at 10 atm, between 500 and 1180 K, for five different equivalence ratios of φ = 0.35, 0.5, 1, 2, 4 and 1000 ppm of fuel, at a constant residence time of 0.7 s. Reactant, product and intermediate species mole fractions were quantified using Fourier transform infrared spectrometry (FTIR) and gas chromatography (GC). Ignition delay times were measured for pentan-2-ol/O2 mixtures in argon in a shock tube at 20 and 40 bar, in a temperature range of 1070–1460 K and for equivalence ratios of φ = 0.5, 1 and 2. Ignition delay times of a stoichiometric mixture were also measured in air at 20 bar. Under these conditions, this alcohol exhibited no low-temperature reactivity in either experimental set-ups. Based on ab initio calculations presented in the companion paper, a detailed kinetic mechanism was developed in order to reproduce the present data and analyze the reaction pathways.

Langmuir probe and optical emission spectroscopy studies for RF magnetron sputtering during TiON thin film deposition

Low-pressure plasma of gas mixture of Ar, O2 and N2 generated by RF magnetron sputtering was characterized by Langmuir probe and optical emission spectroscopy (OES). The electron temperature (Te), ion density (ni) and electron energy distribution function (EEDF) in Ar-O2-N2 plasma atmosphere were calculated from I-V characteristic of Langmuir probe. Boltzmann plot method was applied for calculating the vibrational temperature (Tvib) of the second positive system of N2 (N2SPS) in Ar-O2-N2 plasma. The Te, ni, EEDF and Tvib in Ar-O2-N2 plasma were studied as a function of O2 percentages. It was found, the Tvib increased from 0.47 eV to 0.55 eV as the oxygen percentage in Ar-N2-O2 plasma increased from 10% to 40%. Further, the Te increased from 1.6 eV to 3 eV as the O2 concentration increased from 10% to 40%.

Effects of the Different Solid Deposits on the Corrosion Behavior of Pure Fe in Water Vapor at 500°C.

A comprehensive corrosion investigation of pure Fe in an environment of solid sodium salt deposit (i.e., NaCl or Na2SO4) with mixtures of H2O and O2 at 500°C was conducted by mass gain measurement, X-ray diffraction (XRD), scanning electron microscope (SEM), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results showed that corrosion rates were accelerated with solid NaCl or Na2SO4 deposit due to their reaction with the formed protective scale of Fe2O3 and subsequently resulted in its breakdown. The corrosion rate of pure Fe with solid NaCl is higher than that with solid Na2SO4 because of the lower activation energy (Ea) for chemical reaction of Fe in solid NaCl+H2O+O2 (i.e., 140.5 kJ/mol) than that in solid Na2SO4+H2O+O2 (i.e., 200.9 kJ/mol). Notably, the electrochemical corrosion rate of pure Fe with solid NaCl deposit, 1.16 × 10−4 A/cm2, was a little lower than that with solid Na2SO4 deposit.

In Situ Electrochemical Study of Na-O2/CO2 Batteries in an Environmental Transmission Electron Microscope.

Metal-air batteries are potential candidates for post-lithium energy storage devices due to their high theoretical energy densities. However, our understanding of the electrochemistry of metal-air batteries is still in its infancy. Herein we report in situ studies of Na-O2/CO2 (O2 and CO2 mixture) and Na-O2 batteries with either carbon nanotubes (CNTs) or Ag nanowires as the air cathode medium in an advanced aberration corrected environmental transmission electron microscope. In the Na-O2/CO2-CNT nanobattery, the discharge reactions occurred in two steps: (1) 2Na+ + 2e- + O2 → Na2O2; (2) Na2O2+ CO2 → Na2CO3 + O2; concurrently a parasitic Na plating reaction took place. The charge reaction proceeded via (3) 2Na2CO3 + C → 4Na+ + 3CO2 + 4e-. In the Na-O2/CO2-Ag nanobattery, the discharge reactions were essentially the same as those for the Na-O2/CO2-CNT nanobattery; however, the charge reaction in the former was very sluggish, suggesting that direct decomposition of Na2CO3 is difficult. In the Na-O2 battery, the discharge reaction occurred via reaction 1, but the reverse reaction was very difficult, indicating the sluggish decomposition of Na2O2. Overall the Na-O2/CO2-CNT nanobattery exhibited much better cyclability and performance than the Na-O2/CO2-Ag and the Na-O2-CNT nanobatteries, underscoring the importance of carbon and CO2 in facilitating the Na-O2 nanobatteries. Our study provides important understanding of the electrochemistry of the Na-O2/CO2 and Na-O2 nanobatteries, which may aid the development of high performance Na-O2/CO2 and Na-O2 batteries for energy storage applications.