Decomposition Pressure Research Articles

Development of hydrogen peroxide based micro thruster utilizing biomass-based catalyst bed

Micro thrusters, also referred to as micro-newton thrusters, are thrusters having a wide range of force capabilities in the micro-newton range. Micro thrusters are used in CubeSats, tiny robots and drones, micro- and nanosatellites, spacecraft attitude control, etc. The aim of the present study is to develop a monopropellant thruster (MPT) for 90 % concentrated hydrogen peroxide (H2O2). A rotatory evaporator was used to obtain a 90 % H2O2 form the available concentration of 50 % H2O2. The next stage involved the designing of the monopropellant thruster utilizing the NASA CEA rocket performance algorithm and the derived mathematical model. The test facility was constructed which includes a thruster, a feed line system, a static test firing platform, a data collecting system and the measuring sensors. To measure the thrust of the thruster, a pendulum thrust mechanism was constructed and fabricated into an experimental test stand. Lastly, the MPT chamber, which uses stainless steel mesh, was prepared and packed with the biomass-based catalyst. The 14 bar injection pressure conditions were used for the fire tests. With a mass flow rate of 5 g/s and a decomposition pressure of 10 bar, the theoretical specific impulse (Isp) was calculated to be 1993.2 Ns/kg at an O/F ratio of 0.002. The test firing with 90 % concentrated hydrogen peroxide gave an experimental specific impulse of 794.5 Ns/kg, which gives efficiency of 39.9 %.

Deuterium retention in co-deposition with lithium in Magnum-PSI: experimental analysis and comparison with SOLPS-ITER

The vapor-box, a liquid metal design for the divertor, utilizes lithium recirculation through evaporation and condensation. Safety concerns arise from Li-D/T formation and co-deposition on vapor-box walls and the first wall, affecting tritium retention. Additively manufactured tungsten capillary porous structure (CPS) samples with Li were exposed to high heat flux D plasmas in the linear plasma device Magnum-PSI, to study D retention in Li–D co-deposition dependence on substrate temperature (200 ∘ C–428 ∘ C) and distance from the plasma beam center (25–85 mm). The D:Li ratio was determined via in-situ ion beam diagnostics with simultaneously analyzed Nuclear Reaction Analysis and Elastic Backscattering Spectroscopy spectra to maximize the precision. Experimental results approach close to the theoretical maximum at 40:60 D:Li ratio and deposited film thickness ranging from 0.02 to 3.2 µm. Witness plate temperatures above 400 ∘ C yielded Li films under 150 nm in thickness with lower D:Li ratios (5:95 D:Li ratio). At this temperature LiD decomposition pressure is comparable with vessel pressure during plasma. SOLPS-ITER simulations narrowed CPS surface temperature to 650 ∘ C–700 ∘ C, indicating Li+ plasma dominance near the target surface. Redeposition ratio of lithium on the CPS surface was determined to be around 80 % , matching quartz crystal microbalance results. However, SOLPS-ITER simulations lacked accuracy in recreating observed Li and D deposition layers on WPs, improvements are needed to model plasmas with significant Li quantities. Extension of SOLPS-ITER simulations to include LiD molecules and enhance heat flux accuracy is crucial for better alignment with experimental data.

Comparison of Mg-based liquid metal ion sources for scalable focused-ion-implantation doping of GaN

We compare the suitability of various magnesium-based liquid metal alloy ion sources (LMAISs) for scalable focused-ion-beam (FIB) implantation doping of GaN. We consider GaMg, MgSO4●7H2O, MgZn, AlMg, and AuMgSi alloys. Although issues of oxidation (GaMg), decomposition (MgSO4●7H2O), and excessive vapor pressure (MgZn and AlMg) were encountered, the AuMgSi alloy LMAIS operating in a Wien-filtered FIB column emits all Mg isotopes in singly and doubly charged ionization states. We discuss the operating conditions to achieve <20 nm spot size Mg FIB implantation and present Mg depth profile data from time-of-flight secondary ion mass spectrometry. We also provide insight into implantation damage and recovery based on cathodoluminescence spectroscopy before and after rapid thermal processing. Prospects for incorporating the Mg LMAIS into high-power electronic device fabrication are also discussed.

Techno-economic and environmental assessment of hydrogen production through ammonia decomposition

Hydrogen is one of the potential candidates to replace fossil fuels to meet net zero emissions target. This study reports a detailed techno-economic and environmental assessment of hydrogen production through ammonia decomposition. The case study is based on a multiple catalytic packed bed reactor with intermediate heating system. Aspen plus® and MATLAB® were linked to evaluate economic and environmental impact of the process. The process parameter like furnace temperature, flue gas recirculation, ammonia decomposition temperature, market ammonia supply pressure, ammonia decomposition pressure, hydrogen purification unit's pressure and equivalence ratio, and economic parameters of capital expenditure (CAPEX) and operating expenditure (OPEX) were considered. The overall thermal efficiency of the developed process is found to be 79%. The levelized cost of hydrogen (LCOH) is estimated and found to be 6.05 USD/kg of H2 based on CAPEX and OPEX. A major contribution of up to 62.2% to LCOH comes from the price of feed Ammonia. Based on 25-year plant life with 10% discounted rate the plant is economically viable, with a return on investment of 23.7%, in a payback period of 3.58 years. Global warming potential of the process is also carried out.

Energy release behavior of Zr/B/KNO3 dual-fuel energetic composites: Powders and sticks

To enhance the reactivity of B/KNO3 (BPN) energetic composites and study the energy release behavior of energetic sticks, Zr/KNO3 (ZPN) was added to the BPN energetic system, and the energetic sticks with different ZPN/BPN ratios and different thicknesses were prepared by direct ink writing (DIW). In addition, the pore-size distribution, thermal decomposition characteristics, combustion characteristics, and pressure release characteristics of the different energetic sticks were studied. Considering this, the flame propagation behavior of the energetic powders and sticks was examined. The results demonstrate that energetic sticks with different ZPN/BPN ratios and thicknesses exhibit a consistent pore-size distribution. With increasing ZPN content, the peak temperature of the condensed phase reaction of the composite decreased from 479.9 °C to 362.1 °C, the reaction enthalpy increased from 879.5 to 3200.4 J·g−1, and the burning rate of the energetic sticks increased from 62.1 to 136.8 mm·s−1, indicating that the addition of ZPN improved the reaction characteristics of the composite. In addition, the reactivity of the energetic sticks can be regulated by adjusting their thickness With the increase of layers, the burning rate of energetic sticks increases from 58.6 mm·s−1 to 113 mm·s−1. The burning rate–time curves of all energetic sticks show different numbers and ranges of platforms. In comparison to energetic powder, energetic sticks exhibit lower pressure release and pressurization rates but a longer reaction time. This study provides valuable insights into the microscale reactivity regulation of BPN energetic composites and their application in microenergy devices.

Decomposition of light hydrocarbons on a Ni-containing glass fiber catalyst

The work is devoted to the study of the novel process of catalytic decomposition of light hydrocarbons on a catalyst at temperatures of 550 °С and 600 °C at various pressures. The CVD process is a new COx-free approach for hydrogen production. A glass fiber fabric was used as a catalyst, which was preliminarily modified by the application of additional outer layers of NiO and porous silica. A technical mixture of propane and butane was used as feedstock. The main purpose is to investigate the effects of pressure and temperature on the production of hydrogen and carbon nanofibers over a glass-based catalyst. As a result of the decomposition of the mixture, the yield of hydrogen was 266–848 L/gcat, and that of carbon nanofibers was 3–10 g/gcat. Increasing the pressure of propane-butane mixture decomposition led to an increase of the catalyst lifetime. The highest yield of hydrogen and carbon nanofibers was achieved at 1 bar and 600 °C.

Influence of the memory effect during CO2/CH4 mixed gas hydrate reformation process

The study of the memory effect can help to clarify the mechanisms of synthesis and decomposition of the CO2/CH4 mixed gas hydrate for mixed gas separation, CO2 sequestration, and CH4 recovery from unconventional natural gas reservoirs. To examine the impact of the memory effect on the CO2/CH4 mixed gas hydrate synthesis in terms of induction time, gas consumption rate, change of gas components, and separation factor, we conducted initial and second CO2/CH4 mixed gas hydrate synthesis experiments in a porous medium and deionized water system. The influence characteristics of the memory effect on CO2/CH4 hydrate synthesis under the predesigned decomposition temperatures (5 ∼ 25 °C) and pressures (0.5, 1.0, and 1.5 MPa) were investigated under decomposition times of 0.5 and 1.0 h. Compared to the induction time of the initial synthesis, the induction time of the second synthesis was greatly shortened, reaching a maximum of 87.42%. The induction time decreased with decreasing decomposition temperature and pressure in the same decomposition period. The decomposition time had a large effect on the peak value of the induction time during the second synthesis process. Besides, the memory effect was greatly affected by the decomposition time in depressurization cases, and the 0.5 h decomposition time was significantly better than that of 1.0 h. The memory effect had the strongest promotion effect on the second synthesis when the decomposition pressure and time were 1.0 MPa and 0.5 h, respectively. Furthermore, the memory effect improved the nucleation rate of the CO2/CH4 mixed gas hydrate and increased the amount of CO2 hydrate synthesis to 1.3 times that of the initial synthesis. Also, the memory effect influenced the hydrate to exhibit stronger CO2 selectivity, which provides a novel approach for the separation of mixed gases via the hydrate method.

Regulation of Ionic Bond in Group IIB Transition Metal Iodides

Using a swarm intelligence structure search method combining with first-principles calculations, three new structures of Zn–I and Hg–I compounds are discovered and pressure-composition phase diagrams are determined. An interesting phenomenon is found, that is, the compounds that are stable at 0 GPa in both systems will decompose into their constituent elements under certain pressure, which is contrary to the general intuition that pressure always makes materials more stability and density. A detailed analysis of the decomposition mechanism reveals the increase of formation enthalpy with the increase of pressure due to contributions from both ΔU and Δ[PV]. Pressure-dependent studies of the ΔV demonstrate that denser materials tend to be stabilized at higher pressures. Additionally, charge transfer calculations show that external pressure is more effective in regulating the ionic bond of Hg–I, resulting in a lower decomposition pressure for HgI2 than for ZnI2. These findings have important implications for designs and syntheses of new materials, as they challenge the conventional understanding on how pressure affects stability.

Experimental and numerical investigation of sulfuric acid decomposition for hydrogen production via iodine–sulfur cycle

In the context of global warming and the greenhouse effect, the iodine–sulfur cycle is an important method of producing hydrogen on a large scale with low carbon emissions using nuclear energy for future applications. The sulfuric acid decomposition reaction is a key step in this process. A sulfuric acid decomposer with good performance usually has the characteristics of high decomposition rate, small pressure drop loss and reasonable temperature distribution, which can ensure the efficient and stable process of sulfuric acid decomposition. Therefore, an accurate evaluation of the performance of the sulfuric acid decomposer unit and the reproducibility of the whole process is of utmost importance for designing and engineering an actual system for hydrogen generation. In this work, two sets of experimental systems were designed to measure the important kinetic parameters of sulfuric acid decomposition reaction and to determine the thermal hydraulics and chemical reaction performance indicators of the system. Then, a multi-field coupling model in which the phase change and chemical reactions were coupled by user-defined functions was developed based on the experimental kinetic parameters to account for the whole process. The thermal–hydraulic characteristics and the chemical reaction indexes predicted by the model are in good agreement with the experimental results. The maximum errors of the sulfuric acid decomposition fraction and pressure drop do not exceed 5% and 10%, respectively. Overall, this work provided a complete model for predicting the performance of the sulfuric acid decomposer.

Polyimide dynamically compressed to decomposition pressures: Two-wave structures captured by velocimetry and modeling

We performed a series of six plate impact experiments on polyimide and modeled them using new reactant and products equations of state combined with an Arrhenius rate model. The first experiment was diagnosed with embedded electromagnetic velocity gauges through which we directly observed attenuation of the lead shock to an approximately constant state over a propagation distance of roughly 4 mm. Simulated gauge profiles were in excellent qualitative agreement with experiment and suggested a sluggish chemical reaction that did not proceed to completion. The remaining five experiments were conducted in a transmission geometry and diagnosed velocimetrically at the sample/window interface. All five of these yielded profiles with a sharp shock followed by a more gradual approach to maximum interface velocity that was “rounded” to varying degree. These profiles proved difficult to interpret unambiguously due to the convolution of the reactive wave upon first shock with reflection of the lead wave and reshock or release by the window. Comparison with thermochemical calculations strongly suggests that the point of maximum interface velocity corresponds to the equilibrium reshock or release locus. We discuss the implications of this point for the practice of impedance matching based on the reflected Hugoniot of reactive materials such as polymers. The reactant and thermochemical products equations of state are developmental SESAME tables 97710 and 97720, respectively.

Thermodynamic analysis and economic assessment of a novel multi-generation liquid air energy storage system coupled with thermochemical energy storage and gas turbine combined cycle

Liquid air energy storage (LAES) is one of the most promising technologies to balance the demand and supply of electricity, which is attracting more and more researchers' attention, but the system's efficiency is still relatively low. To further improve the round trip efficiency (RTE) and energy utilization rate (EUR) of the LAES system, a novel LAES system coupled with thermochemical energy storage (TCES) and gas turbine combined cycle (GTCC) is proposed in this paper. In addition, based on the baseline liquid air energy storage (B-LAES) system, an improved liquid air energy storage (I-LAES) system is also proposed to utilize the excess air compression heat to produce cold energy or thermal energy under different operation modes. Thermodynamic analysis and economic assessment are performed to evaluate these three systems' performances. Compared with the B-LAES system and the I-LAES system, the LAES-TCES-GTCC system has the highest RTE of 123.07 % and the highest EUR of 88.74 %. The LAES-TCES-GTCC system also has the best economic feasibility, with a net present value of $24.08 million and a dynamic payback period of 7.29 years. For the novel LAES-TCES-GTCC system, enhancing the methanol decomposition pressure, direct normal irradiation, and mass flow of vapor all reduce the EUR. And the EUR reaches the maximum at an inlet air temperature of the throttle valve of −168 °C.

Evolution and mechanism of combustion microstructure of 600 ℃ high temperature titanium alloy

Oxides formed in the combustion process significantly affect the flame retardancy of titanium alloys, however, the evolution mechanism and formation mechanism of the combustion products of 600 ℃ high temperature titanium alloy remain uncertain. Frictional ignition method is employed in this paper to study the combustion behaviors of 600 ℃ high temperature titanium alloy, and the flame retardancy is evaluated according to the friction time, oxygen content and combustion state. <i>In-situ</i> observation of the burning phenomenon at the friction position and morphology after combustion is investigated, and the combustion states can be divided into oxidation stage, ignition stage and extended combustion stage. Further microstructure analysis is conducted subsequently by focus ion beam (FIB) and high resolution transmission electron microscope (HRTEM) to characterize the oxidation products with different valences in different zones of combustion microstructure. Al<sub>2</sub>O<sub>3</sub>, Ti<sub>2</sub>O<sub>3</sub> and TiO<sub>2</sub> are observed as the main combustion products in the heat-affected zone, melting zone and combustion zone, respectively. Notably, TiO<sub>2</sub> is found to be formed by Ti<sub>2</sub>O<sub>3</sub> under the combustion condition, which is different from the TiO<sub>2</sub> transformed from the TiO mesophase under oxidation condition. This results in a lax structure composed of spherical Ti<sub>2</sub>O<sub>3</sub> particles and porous Ti matrix in the melting zone. Thermodynamic calculations including Gibbs free energy and decomposition pressure are discussed to explain the evolution mechanisms and formation mechanisms of different oxides. It is revealed that an Al content of 6% is insufficient to form a continuous protective Al<sub>2</sub>O<sub>3</sub> layer at the interface of the melting zone and heat affected zone. The difference in reaction path between TiO<sub>2</sub> formed by TiO and by Ti<sub>2</sub>O<sub>3</sub> can be ascribed to the formation of gaseous TiO phase. The sharp increase of TiO vapor pressure at about 1800 K reduces the stability of titanium oxide, thus causing the as-formed TiO to evaporate rapidly and forcing titanium to transform into TiO<sub>2</sub> via a more stable phase, Ti<sub>2</sub>O<sub>3</sub>. The formation of the porous structure composed of Ti<sub>2</sub>O<sub>3</sub> and Ti at the melting zone provides a path for the rapid internal diffusion of oxygen, which severely deteriorates the oxygen prevention capability of as-formed oxide layers. Besides, the TiO<sub>2</sub> synthesized from Ti-O melt in the combustion zone can hardly protect the inner structure. Therefore, the flame retardancy of 600 ℃ high-temperature titanium alloy is far from satisfactory.

The effect of decomposition of natural gas hydrate on deep-water drilling

One of the significant challenges in deep-water drilling is calculating BHP during kickoff caused by natural gas hydrate decomposition. In this paper, the heat transport theory, seepage mechanics, and hydrate decomposition kinetics serve as the foundation for the hydrate decomposition and bottom hole pressure model. Research shows 42.8 m3 of gas have entered Well X cumulatively, resulting in a 1.66 MPa pressure decrease and a 6.9-hour-recovery period. The monitoring of high saturation and porosity formations needs to be strengthened, and drilling parameters need to be modified to protect the stability of the wellbore, according to the analysis of formation parameters and drilling parameters.

Raman spectroscopy and X‐ray diffraction of diphenylphosphoryl azide under high pressures

AbstractDiphenylphosphoryl azide ((C6H5O)2P(O)N3, DPPA) was studied by in situ Raman scattering spectroscopy and synchrotron angle‐dispersive X‐ray diffraction (ADXRD) technologies up to 11.6 GPa at room temperature. The analyses of Raman spectra revealed that the liquid DPPA transformed from Phase I to Phase II at 0.4 GPa and went to Phase III at 1.3 GPa. The first phase transition was attributed to the change of molecular conformation, and the second phase transition was induced by the deformation of benzene rings. The XRD results suggested that DPPA remained in a liquid state during the two phase transitions. The azide group became increasingly asymmetric under pressure and decomposed at 11.6 GPa. The low decomposition pressure of the azide group is conducive to the formation of polymeric nitrogen. Exploring the behaviors of the azide group under pressure might be helpful for understanding the potential application of DPPA in the synthesis of high energy density materials (HEDMs).

Quantum-Chemical Kinetic Study of the Unimolecular Decomposition Reactions of 1-Bromo-3-Chloropropane

The pressure and temperature dependence of the thermal decomposition of 1-bromo-3-chloropropane has been theoretically investigated. The reaction takes place majorly through the elimination of HBr. Molecular properties of 1-bromo-3-chloropropane and transition states were derived from MN15/6-311++G(3df,3pd) and G4 quantum-chemical calculations. The resulting rate constants obtained from the unimolecular reaction rate theory for the high- and low-pressure limits of reaction BrCH2CH2CH2Cl → CH2CHCH2Cl + HBr at 400-1000 K were k∞ = 6.1 × 1013 exp(-57.2 kcal mol-1/RT) s-1 and k0 = [BrCH2CH2CH2Cl] 1.45 × 10-1 (T/1000 K)-7.9 exp(-55.9 kcal mol-1/RT) cm3 molecule-1 s-1. A value of -26.3 ± 1.0 kcal mol-1 for the standard enthalpy of formation of 1-bromo-3-chloropropane at 298 K was derived.

Research on Dynamic Movement of Temperature and Pressure During Hydrate Depressurization Mining

Abstract It is of great significance to study the dynamic movement of temperature and pressure during depressurization mining process of hydrate reservoir. This paper first obtains the formula for calculating the temperature and pressure of hydrate decomposition based on the law of conservation of mass, conservation of energy, and phase equilibrium, Hydrateressim (HRS) is used to carry out the numerical simulation of the front edge of the one-dimensional model. The results show the pressure and the hydrate saturation front are correlated with the temperature front edge and compared with the Computer Modelling Group Ltd. (CMG) simulation results. It is found that the pressure front edge is an area in the balance model and an interface in the dynamic model. Then the movement of the front edge of the three-dimensional model was simulated. By simulating the movement regulation of pressure, temperature, and hydrate saturation front of each layer at different times, the longitudinal decrease of each layer is compared and analyzed. The conclusion drawn is that the bottom-hole pressure of the production well is an important factor for production, and the endothermic reaction of hydrate will cause the dynamic movement of temperature to lag slightly behind the pressure and hydrate saturation. By determining the relationship between the pressure and the temperature front, the position of the front edge of the hydrate saturation can be inferred that it is the position of the decomposition front and it overcomes the limitation of the experimental method that the hydrate saturation cannot be measured.

Experimental study and recognition of natural gas hydrate chemical reagent - CO2 exploitation

Abstract In order to solve the problems of slow replacement rate and low degree of substitution in the process of CO2 displacement by natural gas hydrate, a method of chemical reagent-CO2 displacement combined mining experiment was proposed. Taking the thermodynamic methanol inhibitor as an example, three groups of experiments were carried out: critical temperature pressure condition for CH4 decomposition at different methanol concentrations, CH4 hydrate decomposition under the condition of methanol reagent at 30% concentration, and methanol reagent-CO2 combined mining. Experiments show that: (1) The concentration of methanol plays a decisive role in hydrate recovery. Methanol reagent has the property of highly reducing the formation temperature of hydrate. Methanol solution concentration is positively correlated with the critical temperature drop of hydrate decomposition and formation pressure. (2) The methanol solution decomposition of hydrate can be roughly divided into three stages: the initial stage of rapid decomposition, the competitive stage of hydrate decomposition and stable transformation, and the stable stage of decomposition. Through experimental simulation, it is concluded that formation pressure is a direct factor affecting the decomposition ability of methanol reagent to hydrate. By changing formation pressure, the rate of CH4 hydrate recovery can be improved. (3) A higher hydrate decomposition rate can be obtained based on the methanol reagent-CO2 displacement mining method. In the action of the methanol reagent, the subsequent injection of CO2 still promotes the decomposition of CH4, that is, the displacement of CO2 hydrate after the decomposition of the hydrate based on the methanol reagent is feasible. The research results are of great significance especially for large-scale mine test mining of permafrost natural gas hydrate chemical reagent method.

Subsolidus phase diagram for the Y2O3–Fe2O3–CoOx system and stability boundary of YFe1-xCoxO3

The phase diagram for the ½Y2O3–½Fe2O3–CoOx system is experimentally studied and constructed at 1373 ​K in air. It is also assessed for various temperatures inside 1173–1573 ​K interval based on the homogeneity ranges of YFe1-xCoxO3 and mixed cobalt/iron oxide phases. The stability boundary of YFe1-xCoxO3 oxides in respect to Po2 is estimated. It is shown that the limiting composition of YFe1-xCoxO3 solid solution at 1373 ​K is linearly decreasing from x=0.45 in air down to x=0 corresponding to the decomposition pressure of YFeO3 equal to lg(Po2/atm)= −13.3.

The Na–H system: from first-principles calculations to thermodynamic modeling

Abstract The Na–H system thermodynamic properties were assessed using Gibbs free energy model parameters obtained from best fit optimizations to combined experimental and first-principles predicted data. The first-principles finite temperature thermodynamic property predictions, based upon density functional theory ground state minimizations and direct method lattice dynamics, were used to supplement the Na–H dataset wherever experimental information was unavailable or unattainable. The predictions proved to be important for extending the evaluation of the heat capacity of the stable NaH phase to cover the complete 0 – 2000 K temperature range. The predicted thermodynamic properties of the hypothetical NaH3 end-member representing complete interstitial H substitution in solid body-centered cubic Na, provided a physical basis for modeling H dissolution in the Na lattice. The modeling also showed satisfactory agreement with experimental measurements of NaH enthalpies of formation, NaH decomposition pressures, and H solubility in liquid Na.

Liquid state properties and solidification features of the pseudo binary BaS-La2S3

The high temperature thermodynamic properties of chalcogenides materials based on BaS remain elusive. Herein the pseudo binary BaS-La2S3 is investigated above 1573 K. The liquid properties of BaS-La2S3 are measured by means of high resolution in-situ visualization coupled with thermal arrest measurements in a thermal imaging furnace. This enables to report the first observation of such melts in a container-less setting. The melting points of BaS and La2S3 are revisited at 2454 K and 2004 K respectively. La2S3 demonstrates a high stability in its liquid state, in strike difference with the sublimation observed for BaS. BaS is however partially stabilized with the addition of few percents of La2S3. The remarkable chemical and thermal stability of La2S3-rich samples contrasts with the partial decomposition and high vapor pressure observed for BaS-rich samples. Observations and analysis of the solidified samples suggest three different solid solutions. Solid and liquid densities are investigated along the different compositions, supporting a first estimate of the volumetric thermal expansion coefficient for La2S3.