High-pressure Equipment Research Articles

The Strength and Minimum Wall Thickness of Wellhead Equipment for Ultrahigh-Pressure Oil and Gas Wells

Summary As oil and gas wells are drilled to greater depths, wellhead pressure is expected to exceed the 20 ksi (138 MPa) limit specified by API SPEC 6A and other industrial standards, necessitating the development of 25 ksi (172.4 MPa) equipment. This paper focuses on the strength design and analysis of ultrahigh-pressure wellhead equipment, reviewing various wall-thickness calculation formulas and design criteria based on basic mechanical theory. It traces the flange wall thickness calculations in API SPEC 6A, discusses issues with 25-ksi equipment, and analyzes safety factors, methods, and allowable stresses in different standards. The findings of the research indicate that for high-pressure equipment with a pressure of 25 ksi (172.4 MPa), the optimal ratio of outer diameter to inner diameter is 2, and the structure can meet the requisite strength requirements. The wall thickness design method for structures such as flanges in traditional American Petroleum Institute (API) specifications uses the maximum principal stress criterion for calculation, which is not applicable to high-pressure equipment. For high-strength steel with high yield ratio used in high-pressure equipment, yield strength and tensile strength should be combined in design and use, fully utilizing the material’s properties. It is recommended to use finite element analysis for high- and ultrahigh-pressure complex structures, following the latest design concepts such as elastic-plastic ASME standards. The research provides a theoretical basis for designing ultrahigh-pressure wellhead equipment.

Investigation on the morphology and temperature distribution of hydrogen jet flames impinging on barrier walls

Hydrogen is often stored and transported in a high-pressure state, posing a risk of jet flames in the event of accidental leakage. Firewalls are commonly installed around high-pressure hydrogen storage and transportation equipment to protect surrounding facilities and personnel from the fire hazards caused by hydrogen leaks. By combining experimental and numerical simulation methods, this study investigated the effects of varying hydrogen release pressure, nozzle shape, nozzle-wall distance, and barrier height on the behavior of high-pressure hydrogen jet flames. A predictive model for the flame extension length after contact with the wall was proposed. The study found that when the wall height is sufficient to cause complete flame deflection, the temperature distribution near the wall exhibits a strong regularity. The temperature of the barrier wall below the nozzle height is higher than that above the nozzle height, indicating that enhanced thermal protection is needed in this region for practical applications.

Pressure-Compensated Fiber-Optic Photoacoustic Sensors for Trace SO2 Analysis in Gas Insulation Equipment.

A high-sensitivity fiber-optic photoacoustic sensor with pressure compensation is proposed to analyze the decomposition component SO2 in high-pressure gas insulation equipment. The multiple influence mechanism of pressure on photoacoustic excitation and cantilever detection has been theoretically analyzed and verified. In the high-pressure environment, the excited photoacoustic signal is enhanced, which compensates for the loss of sensitivity of the cantilever. A fiber-optic F-P cantilever is utilized to simultaneously measure static pressure and dynamic photoacoustic wave, and a spectral demodulation method based on white light interference is applied to calculate the optical path difference of the F-P interferometer (FPI). The real-time pressure is judged through the linear relationship between the average optical path difference of FPI and the pressure, which gives the proposed fiber-optic photoacoustic sensor the inherent advantages of being uncharged and resistant to electromagnetic interference. The average optical path difference of FPI is positively related to pressure, with a responsivity of 0.6 μm/atm, which is based on changes in the refractive index of gas. In the range of 1-4 atm, the SO2 sensor has a higher detection sensitivity at high-pressure, which benefits from the pressure compensation effect. With the pressure environment of gas insulation equipment at 4 atm as the application background, the SO2 gas is tested. The detection limit is 20 ppb with an averaging time of 400 s.

Flame Stabilisation Mechanism for Under-Expanded Hydrogen Jets

A hydrogen under-expanded jet released from a high-pressure vessel or equipment into the atmosphere through a 0.53 mm diameter orifice results in a sustained lifted flame for pressures above 4 MPa and flame blow-out at pressures below 3 MPa. Knowledge of whether the leaked hydrogen creates a sustained flame or is extinguished is an important issue for safety engineering. This study aims to clarify, in detail, a mechanism of flame stabilisation and blow-out depending on the spouting pressure. The model of flame stabilisation is derived using measurements and observations at the flame base location by means of high-speed schlieren images, laser diagnostics, and electrostatic probe techniques. The sustained stable flame originating from the 0.53 mm orifice is characterised by the existence of the spherical flame structures with a diameter of about 5 to 7 mm that appear one after another at the flame base and outside the streamlines of the hydrogen jet. As the spouting pressure reduces to 3.5 MPa, the sustained lifted flame becomes quasi-steady with higher fluctuations in amplitude of the flame base (lift-off height). In addition to that, flame structures are moving further from the hydrogen jet outlet, with a further decrease of spouting pressure leading to blow-out. The existence of spherical flame formations plays an important role in flame stabilisation. Based on the measurements of OH radicals using the PLIF method and ion currents, multiple flame surfaces were found to be folded in the flame structures. The hydrogen jet generates the vortex-like flow near its outer edge, creating flamelets upon ignition, ultimately forming the observed in the experiments spherical flame structures.

High-performance slow-curing polyurea compositions

Objectives. To improve the technology for obtaining polymer spray coatings based on polycarbodiimides (polyureas) by studying changes in the process and operational parameters due to the introduction of aspartic acid derivatives (AADs) into the composition.Methods. The process of the production of sprayed and contact polyureas involves a number of difficulties, not least in terms of the cost of the components and high-pressure equipment. For this reason, mathematical modeling was used to optimize experimental design. The curing time of the composition was measured under conditions simulated to be close to actual. After thermostating and mixing Components A and B in predetermined ratios, the gelation time was measured to represent the curing time of the composition. The hardness of the material was determined by the Shore method according to GOST 24621-91. Tensile strength and relative elongation were determined according to a standard method (GOST 30436-96).Results. The effect of three AADs on the properties of the finished polyurea was studied. It was found that the introduction of two of them (AAD-1 and AAD-2) into polyurea in an amount of up to 40 wt % produces slow-curing (>250 s) polyureas capable of manual application. The finished products have physical properties on par with machine-poured materials (breaking strength >73 MPa; tensile strength >23 MPa; elongation >500%). Compiled regression equations were used to construct graphs of equal levels showing the possible areas of directed modification of the studied compositions.Conclusions. AAD can be used as a modifying component for polyurea systems to obtain slow- curing polyureas with high performance properties, which can be purposefully controlled by mathematical modeling. The resulting products have commercial value due to their combination of valuable physical and mechanical properties.

О подходах к обеспечению герметичности оборудования высокого давления при его эксплуатации

The operation of high-pressure equipment requires special attention from the point of view of ensuring its safety. This problem is becoming increasingly relevant every year. According to various estimates, currently 60–80 % of high-pressure equipment at the industrial enterprises has already exhausted its standard service life. In this regard, there is a need to select and develop a promising method of operating production equipment that would consider the peculiarities of the state of modern domestic industry. The conducted analysis of the methods of operating high-pressure equipment showed that the strength criterion is used as the main criterion for assessing the technical condition of various devices and assemblies included in its composition. However, this approach contradicts the functional purpose of high-pressure equipment — its tightness. To increase the safety and tightness of such equipment when choosing a method of its operation, special schemes for sealing and monitoring of sealing units are proposed, allowing for conducting digitalization of their technical condition. Using this approach will allow to manage the process of ensuring the sealing of high-pressure equipment during its operation. Positive test results of the modernized sealing units in high-pressure equipment, subject to operating conditions, are a sufficient argument for its approval for use. The inclusion in the regulations on the system of maintenance and repair of enterprises operating hazardous production facilities, the requirements for ensuring the tightness of sealing units will allow: reduce the risk of depressurization of the sealing units; increase production profitability by reducing emissions; maintain the sustainability of the business using high pressure equipment. The feasibility of using this approach was repeatedly confirmed by the work of JSC IrkutskNIIkhimmash.

Inactivation of microorganisms by high hydrostatic pressure: A literature review

The use of high hydrostatic pressure is intended to perform non-thermal inactivation of microorganisms in food products, to ensure their freshness and to prevent foodborne infections. These infections impact the healthcare system, the food industry, and consumers directly. This study aims to analyse the literature on the effectiveness of high hydrostatic pressure against pathogenic and opportunistic microorganisms transmitted through the consumption of contaminated food. Scientific publications for 2011-2023 were selected for the review. A total of 44 scientific publications were selected, the information from which was critically analysed, systematised and presented in the form of a literature review. The mechanisms of high hydrostatic pressure’s effect on microbial cells are described. To illustrate the effectiveness of high hydrostatic pressure against microorganisms, data from selected publications regarding efficiency and treatment parameters are presented in tables. The inactivation of such clinically important microorganisms as Bacillus cereus, Campylobacter jejuni, Clostridium perfringens, Escherichia coli, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and Toxoplasma gondii in liquids and food has been demonstrated. High-pressure treatment has been shown to be a non-thermal food processing method, which distinguishes this method from traditional thermal processing methods such as boiling or pasteurization. One of the notable advantages of using high hydrostatic pressure is the non-thermal inactivation of various microorganisms, which preserves the nutritional and flavour properties of the processed product. It is also noted that food products can be processed in the final packaging, which reduces the risk of microbial contamination at the post-processing stages. The main disadvantages are the impossibility of complete inactivation of bacterial spores and the high cost of high-pressure processing equipment. Combining high-pressure treatment with other methods, such as heat treatment, can overcome the limitations of spore inactivation

Characterization of Spray-Dried Microcapsules of Paprika Oleoresin Induced by Ultrasound and High-Pressure Homogenization: Physicochemical Properties and Storage Stability.

As an indispensable process in the microencapsulation of active substances, emulsion preparation has a significant impact on microencapsulated products. In this study, five primary emulsions of paprika oleoresin (PO, the natural colourant extracted from the fruit peel of Capsicum annuum L.) with different particle sizes (255-901.7 nm) were prepared using three industrialized pulverization-inducing techniques (stirring, ultrasound induction, and high-pressure homogenization). Subsequently, the PO emulsion was microencapsulated via spray drying. The effects of the different induction methods on the physicochemical properties, digestive behaviour, antioxidant activity, and storage stability of PO microencapsulated powder were investigated. The results showed that ultrasound and high-pressure homogenization induction could improve the encapsulation efficiency, solubility, and rehydration capacity of the microcapsules. In vitro digestion studies showed that ultrasound and high-pressure homogenization induction significantly increased the apparent solubility and dissolution of the microcapsules. High-pressure homogenization induction significantly improved the antioxidant capacity of the microcapsules, while high-intensity ultrasound (600 W) induction slowed down the degradation of the microcapsule fats and oils under short-term UV and long-term natural light exposure. Our study showed that ultrasound and high-pressure homogenization equipment could successfully be used to prepare emulsions containing nanoscale capsicum oil resin particles, improve their functional properties, and enhance the oral bioavailability of this bioactive product.

Study of blister phenomena on polymer liner of type IV hydrogen storage cylinders

Type IV hydrogen storage cylinder is a rising high-pressure hydrogen storage equipment, which is composed of a polymer liner and a fully wrapped carbon fiber composite. It is found that local blisters occur on polymer liners after rapid depressurization tests during the research and development process. Some manufacturers choose to add adhesives at the liner-composite interface to avoid blisters. In order to study the effect of adhesives to the local blisters, two type IV cylinders have been manufactured and tested, in which one has adhesives at the interface and the other does not. The depressurization tests were conducted from around 70 MPa–2 MPa under various mass flow rates. Digital radiography (DR) and videoscope have been used to conduct post-test inspections. Finite element analysis (FEA) was performed to verify the effect of adhesives, as well as estimating the pressure differential at the interface based on test results. According to the results of the test and FEA results, the use of adhesives at the interface does not effectively prevent the occurrence of local blisters. However, it does serve to slow down the blister propagation though. The results also indicate that the mass flow rate plays a crucial role in affecting the size of the local blister. Furthermore, based on the test and FEA results, an estimation of the local pressure differential at the interface that causes local blister was made. During the post-test inspection, it was observed that the size of several blisters initially increased but eventually decreased over time. Additionally, adjacent blisters were observed to merge as a single larger blister after the hydrostatic test. These results provide valuable insights into the formation and behavior of local blisters, which can inform future research and practical applications in relevant fields.

Materials for Hydrogen Storage and Transport: Implications for Risk-Based Inspection

The growing interest towards hydrogen technologies and their implementation in the hydrocarbon and chemical process industry makes maintenance planning of storage and transport equipment an emerging safety aspect. With respect to high-pressure working equipment, Risk-Based Inspection methodology (RBI) aims at minimizing the risk of loss of containment due to materials’ deterioration mechanisms. This set of procedures focuses on the mechanical integrity of equipment to achieve crucial risk mitigation by means of risk-informed inspection planning and maintenance activities. In addition, hydrogen-induced damages are often generalized or even neglected by the existing RBI standards and recommended practices. On this basis, high-pressure vessels, process piping and storage tanks working in gaseous or liquid hydrogen environments, which are exposed to hydrogen-induced deterioration mechanisms, might be subjected to an inaccurate evaluation of the associated risk and hazards when these RBI standards are applied. For this reason, this work proposes a review of the pipelines steels commonly used for gaseous hydrogen transport to investigate the possible limitations of the standard RBI planning methodologies, when applied to hydrogen technologies. More accurately, the pipeline steels’ susceptibility to hydrogen-induced degradations mechanisms will be discussed to underline assumptions and hypothesis limiting the conventional RBI applicability. Therefore, the overall suitability of standard RBI planning with respect to hydrogen equipment is discussed, highlighting possible relevant gaps as a general result.

The analysis of the effect of the pressurization block on diamond synthesis cavity by finite element method

The cubic press is a common high-pressure equipment, used in scientific research and industrial production of diamonds because of its large sample cavity, simple operation, low cost, and high production efficiency. However, the ultimate pressure of the cubic press is low, which can be increased by adding the pressurization block (PB) to the assembly. In this paper, the pressurization effect of differently-shaped PBs (circle pressurization block (CIPB), square pressurization block (SPB), square frustum pressurization block (SFPB), and concave pressurization block (COPB)) was compared by the finite element method (FEM) calculations. Although the bottom areas of these PBs were identical, the pressurization effect of COPBs was better than that of other PBs. The main reason was that the shape of the COPB better contained pyrophyllite and reduced its outward flow. FEM calculations were also used to investigate changes in the temperature and convection fields inside the assemblies using COPBs. The results showed that adding COPBs increased the temperature difference between the top and bottom of the catalyst, increased the catalyst's convection velocity, and ultimately accelerated the diamond growth rate.

Pressure Scanning Volumetry of Physically Aged Polymer Glasses, Fictive Pressure, and Memory Effect.

Physical aging of a glass decreases its volume, V, entropy, and enthalpy, H, toward the equilibrium state values. For glasses usually formed by cooling a melt, the effect is modeled in terms of non-exponential, nonlinear structural relaxation by using a plot of the heat capacity, Cp = (dH/dT)p, against T obtained from differential scanning calorimetry (DSC) cooling and heating scans. A melt becomes glass also on isothermal pressurizing and the glass formed becomes liquid on depressurizing, showing a hysteresis of the sigmoid-shape plot of -(dV/dp)T against p, which resembles the thermal hysteresis observed in the Cp against T plots. By analogy with DSC, it was named pressure scanning volumetry (PSV). Here, we use the known values of non-exponential and nonlinearity parameters β and x and volume of activation for structural relaxation time, ΔV*, of atactic poly(propylene) to investigate the effect of aging pressure, page, of aging time, tage, and of the pressurizing rate on aging features in PSV scans. The scans show a post- feature on depressurizing before the -(dV/dp)T overshoot peak appears. We provide quantitative plots (i) of the monotonic decrease of V and increase of fictive pressure, pf, with tage and (ii) of the memory (Kovacs) effect in V and pf of the polymer and (iii) provide generic plots of -(dV/dp)T against p for different combinations of β, x, and ΔV*. The study is of academic significance because PSV scans show a change in the density fluctuation response. It is of technological significance in polymer-extrusion processing and it may stimulate the commercial development of computer-controlled, high-pressure equipment.

Study on Interaction Characteristics of Injected Natural Gas and Crude Oil in a High Saturation Pressure and Low-Permeability Reservoir

Natural gas injection is considered for enhanced oil recovery (EOR) in a high saturation pressure reservoir in block B111 of the Dagang oilfield, China. To investigate the interaction characteristics of injected natural gas and crude oil, the ability for dissolution–diffusion and miscibility–extraction of natural gas in crude oil was tested using a piece of high-temperature and high-pressure PVT equipment. The physical properties and minimum miscible pressure (MMP) of the natural gas–crude oil system and their interaction during dynamic displacement were analyzed using the reservoir numerical simulation method. The results show the following: (1) Under static gas–oil contact conditions, natural gas has a significant dissolution–diffusion and miscibility–extraction effect on the crude oil in block B111, especially near the gas–oil interface. The content of condensate oil in gas phase is 10.14–18.53 wt%, while the content of dissolved gas in oil phase reaches 26.17–57.73 wt%; (2) Under the reservoir’s conditions, the saturated solubility of natural gas injected in crude oil is relatively small. The effect of swelling and viscosity reduction on crude oil is limited. As the pressure increases with more natural gas dissolved in crude oil, the phase state of crude oil can change from liquid to gas; accordingly, the density and viscosity of crude oil will be greatly reduced, presenting the characteristics of condensate gas; (3) The MMP of natural gas and crude oil is estimated to be larger than 40 MPa. It mainly forms a forward-contact evaporative gas drive in block B111. The miscible state depends on the maintenance level of formation pressure. The injected natural gas has a significant extraction effect on the medium and light components of crude oil. The content of C2–C15 in the gas phase at the gas drive front, as well as the content of CH4 and C16+ in the residual oil at the gas drive trailing edge, will increase markedly. Accordingly, the residual oil density and viscosity will also increase. These results have certain guiding significance for understanding gas flooding mechanisms and designing gas injection in block B111.

CNPC, Sinopec Drill Ultra Deep in Search of Energy Security

_ China has spudded the country’s first ultradeep scientific exploration well exceeding 10,000-m depth as drilling began 30 May on CNPC’s Take-1 borehole in the Fuman oil field which is situated in the Taklamakan Desert of the Xinjiang Uygur autonomous region. CNPC (China National Petroleum Corp.) operates Fuman, which produced a third of Xinjiang’s Tarim Basin oil output in 2022, and aims to drill to a design depth of 11,100 m in record time using its own automated drilling rig equipped to cope with the extreme temperatures and pressures found in Northwest China, China state media reported. In its current Five-Year Plan, China aims to develop Fuman into a field capable of producing 35.7 million BOE annually by 2025. Fuman is the country’s largest ultradeep field and Tarim’s main crude oil production block, with reserves believed to exceed 71.5 billion bbl, according to CNPC. Journey to the Center of the Earth It took the Soviet Union 20 years to drill what is so far the world’s deepest well—the Kola Superdeep Borehole—which Russia sealed off and abandoned in 1992 after having reached a depth of 12,262 m (7.5 miles). There, drillers encountered 180°C (356°F) which deformed drill bits and pipes and made rocks so malleable they resembled plastic. CNPC expects its new automated, 82-m-high, 2,000-ton rig to penetrate 11,100 m of over 10 layers of continental strata in a record 457 days, reaching rock from the Cretaceous period that formed 66 million to 145 million years ago. China may be right to call its new drilling machine “the world’s first” automated rig capable of reaching 12,000 m considering details of its functionality. NOV built the Doyon 26, nicknamed “The Beast,” for Doyon Drilling to deploy on Alaska’s North Slope (Alpine field) under a long-term contract with ConocoPhillips, according to Tony Crawford, who worked nearly 2 decades in drilling and business development for Nabors in Alaska, Russia, and Kazakhstan, and in rig manufacturing for NOV in Russia and the US. With the help of the “The Beast,” Alpine was the first North Slope field developed exclusively with horizontal well technology, accessing 50 square miles of subsurface from a single drilling pad, according to ConocoPhillips. “It looks like the Chinese have created their ‘beast,’ have automated it, and added high-pressure and high-heat equipment,” said Crawford, who now owns Inerfuel, a Houston company that promotes nanO2 combustion catalyst to reduce carbon emissions in drilling. NOV’s “The Beast” is designed for extended-reach drilling and can reach a depth of 12,192 m, but with a drilling crew on board, he said. “Nabors has a robotic rig that is fully automated, called PACE-R801, but its maximum drilling depth is about 6,500 m. Drillmec has automated control systems, but not automated pipe handling and (other) equipment. “All the wells (where Doyon 26) is drilling are low to medium pressure, 5,000 psi or less, low to medium heat (50–80°C); nothing like China,” Crawford said of the North Slope. “The formations there are super soft; imagine drilling in clay mixed with sand.”

Liquid Level Measurement and Control in High Temperature and High-pressure Environments of Nuclear Power Plant

There are many pieces of high-temperature and high-pressure system equipment in nuclear power plants, such as deaerators, high-pressure feedwater heaters, steam-water separation reheaters, etc. The media parameters in these systems and equipment are high and the working conditions are complex. It is necessary to solve the above problems by adopting multi-channel averaging, increasing the slope of the condensing line, and separating the sampling ports of multiple channels. After practical verification, the above solution can effectively solve or reduce the above problems, which can provide a reference for the liquid level measurement and control in subsequent similar high-pressure and high-temperature environments in nuclear power plants.

Thermo-economic analysis of a novel partial cascade organic-steam Rankine cycle

Conventional heat batteries and concentrated solar power systems adopt subcritical steam Rankine cycles (SRCs) to avoid the technical challenges of supercritical cycles. The water evaporation temperature of 310–337 °C and live steam pressure of 10–14 MPa limit the cycle efficiency (around 42%). This paper proposes a novel partial cascade organic-steam Rankine cycle (ORC-SRC) system to increase the fluid evaporation temperature and thermal efficiency. The ORC-SRC uses a mixture of biphenyl and diphenyl oxide as the top cycle fluid. The mixture absorbs heat from the molten salts and evaporates at about 400 °C to drive a turbine, and then the exhaust vapor releases heat to the bottom SRC. The ORC contributes to saturated steam generation, and molten salts supply the rest heat to the SRC through the steam superheater and reheater. The fundamentals of the system are illustrated, and mathematical models are built. Thermo-economic performance of the system is investigated. The results show that the proposed system significantly increases the average temperature of the power fluid in the heating process, leading to a maximum cycle efficiency of 45.3%. Meanwhile, the moderate live steam pressure of 7.44 MPa in the SRC reduces the leakage loss of the high-pressure turbine and equipment costs. Despite a smaller temperature drop of molten salts during discharge, the equivalent payback period of the ORC-SRC is within 4 years.

Dual-Effect Salt-Tolerant Slope-Suspended Solar Evaporators: High Evaporation Efficiency and Industrialized Implementation

Construction of Janus-wetting interfaces in solar thermal evaporation is one of the most widely applied strategies to overcome salt accumulation to prolong a system’s lifetime. Nevertheless, hydrophobicity and steam escape in traditional Janus floating evaporators are negatively correlated, resulting in the trade-off between salt resistance and the evaporation rate. Herein, a scalable suspended-slope evaporator (SSE) based on the inverse wettability polypyrrole (PPy) fabric is designed to surmount the long-term trade-off for achieving continuous and stable high-rate water desalination. Experiments and numerical simulations indicate that the suspended structure opens the “shackles” brought by the upper hydrophobic PPy fabric to steam escape, and the Marangoni convection induced by the inclined structure further enhances salt resistance performance. With this structure employed, SSEs present good salt tolerance (no obvious salt accumulation in 21 wt % brine for 5 h) and excellent solar evaporation performance (evaporation rate of 2.46 kg m–2 h–1 in 3.5 wt % brine, and the energy efficiency is 85.48%). Additionally, there is no need for special customized high-pressure equipment in the whole synthesis process, which has great significance for the widespread practical application. This work elucidates the intrinsic effects of the device structure on solar evaporators while providing insights for designing high-efficiency and salt-tolerant solar evaporators.

MgF2 as an effective additive for improving ionic conductivity of ceramic solid electrolytes

As typical solid-state electrolytes (SSEs), Na1+xZr2SixP3−xO12 NASICONs provide an ideal platform for solid-state batteries (SSBs) that display higher safety and accommodate higher energy densities. The critical points for achieving SSBs with higher efficiencies are to improve essentially the ionic conductivity and to reduce largely the interfacial resistance between SSEs and cathode materials, which would necessitate extremely high level of craftsmanship and high-pressure equipment. An alternative to higher-performance and lower-cost SSBs is additive manufacturing. Here, we report on an effective additive, MgF2, which was used in synthesizing NASICONs, resulting in SSEs with fewer defects and higher performance. With an addition of mere 1 wt% MgF2 additive, the total room-temperature ionic conductivity of the NASICON electrolyte reaches up to 2.03 mS cm−1, improved up to ∼ 181.3%, with an activation energy of 0.277 eV. Meanwhile, the stability of the Na plating/stripping behavior in symmetric cells increases from 236 to 654 h. We tried to reveal the microscopic origins of the higher ionic conductivity of MgF2-doped NASICONs by comprehensive in-house characterizations. Our study discovers a novel MgF2 additive and provides an efficient way to prepare higher-performance SSEs, making it possible to fabricate lower-cost SSBs in industries.

Accessing Diverse Azole Carboxylic Acid Building Blocks via Mild C-H Carboxylation: Parallel, One-Pot Amide Couplings and Machine-Learning-Guided Substrate Scope Design.

This manuscript describes a mild, functional group tolerant, and metal-free C-H carboxylation that enables direct access to azole-2-carboxylic acids, followed by amide coupling in one pot. This demonstrates a significant expansion of the accessible chemical space of azole-2-amides, compared to previously known methodologies. Key to the described reactivity is the use of silyl triflate reagents, which serve as reaction mediators in C-H deprotonation and stabilizers of (otherwise unstable) azole carboxylic acid intermediates. A diverse azole substrate scope designed via machine-learning-guided analysis demonstrates the broad utility of the sequence. Density functional theory calculations provide detailed insights into the role of silyl triflates in the reaction mechanism. Transferrable applications of the protocol are successfully established: (i) A low pressure (CO2 balloon) option for synthesizing azole-2-carboxylic acids without the need for high-pressure equipment; (ii) the use of 13CO2 for the synthesis of labeled compounds; (iii) isocyanates as alternative electrophiles for direct C-H amidation; (iv) and the use of the developed chemistry in a 24 × 12 parallel synthesis workflow with a 90% library success rate. Fundamentally, the reported protocol expands the use of heterocycle C-H functionalization from late-stage functionalization applications toward its use in library synthesis. It provides general access to densely functionalized azole-2-carboxylic acid building blocks and demonstrates their one-pot diversification.

Blast Wave Generated by Delayed Ignition of Under-Expanded Hydrogen Free Jet at Ambient and Cryogenic Temperatures

An under-expanded hydrogen jet from high-pressure equipment or storage tank is a potential incident scenario. Experiments demonstrated that the delayed ignition of a highly turbulent under-expanded hydrogen jet generates a blast wave able to harm people and damage property. There is a need for engineering tools to predict the pressure effects during such incidents to define hazard distances. The similitude analysis is applied to build a correlation using available experimental data. The dimensionless blast wave overpressure generated by delayed ignition and the follow-up deflagration or detonation of hydrogen jets at an any location from the jet, ∆Pexp/P0, is correlated to the original dimensionless parameter composed of the product of the dimensionless ratio of storage pressure to atmospheric pressure, Ps/P0, and the ratio of the jet release nozzle diameter to the distance from the centre of location of the fast-burning near-stoichiometric mixture on the jet axis (30% of hydrogen in the air by volume) to the location of a target (personnel or property), d/Rw. The correlation is built using the analysis of 78 experiments regarding this phenomenon in the wide range of hydrogen storage pressure of 0.5–65.0 MPa and release diameter of 0.5–52.5 mm. The correlation is applicable to hydrogen free jets at ambient and cryogenic temperatures. It is found that the generated blast wave decays inversely proportional to the square of the distance from the fast-burning portion of the jet. The correlation is used to calculate the hazard distances by harm thresholds for five typical hydrogen applications. It is observed that in the case of a vehicle with onboard storage tank at pressure 70 MPa, the “no-harm” distance for humans reduces from 10.5 m to 2.6 m when a thermally activated pressure relief device (TPRD) diameter decreases from 2 mm to a diameter of 0.5 mm.