High Pressure Temperature Research Articles

A new strategy to prepare ammonium aluminum carbonate hydroxide using plasma electrolytic oxidation in electrolyte containing carbon nanotubes

In this work, a plasma electrolytic oxidation (PEO) technique was used to prepare ammonium aluminum carbonate hydroxide (AACH) in an electrolyte containing carbon nanotubes (CNTs). CNTs were also involved in the composite coating on the surface of 6063 aluminum alloy. The formation mechanism of AACH and effects of CNTs on the microstructure and corrosion behavior of the PEO coatings were investigated. The surface morphology, pore distribution, phase composition, functional groups and electrochemical characteristics of the PEO composite coatings were examined using scanning electron microscopy (SEM), Image Pro software, X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR) and electrochemical workstations, respectively. Results showed that the rod-like AACH was generated around the discharge channel by reacting between ammonia, carbon dioxide and AlOOH under transient high temperature and high pressure environment with the presence of CNTs. The surface micropores of the composite coatings were enlarged due to the excellent electrical conductivity of CNTs. With the by addition of CNTs of 1.5 g/L, the self-corrosion current of the coating was the smallest, and the polarization resistance Rp was larger than that of 1.0 g/L and 2.0 g/L CNTs.

Experimental and numerical studies on the performance of a precooled supersonic ejector

Precooling the secondary flow enhances the performance of the supersonic ejector. However, reducing the temperature of the secondary flow without experiencing significant pressure loss presents a challenge, particularly when the secondary flow is at high temperature and negative pressure. In response to this challenge, an original design for a two-strut supersonic ejector incorporating a plate-fin precooler is developed. Experimental and numerical calculation methods are employed to analyze the system’s performance under various secondary flow conditions, including ambient air, precooled gas, and non-precooled gas. Moreover, the impact of the secondary flow, including total temperature and mass flow rate on the flow structure and mixing process of the supersonic ejector is analyzed. The results show that the shock waves, reflected shock waves and shock trains exist in the flow channel of supersonic ejector simultaneously. The shock waves intensity decreases with the rise of the total temperature and mass flow rate of the secondary flow. Moreover, this leads to the static pressure behind the nozzle changing from a ω−shape to a U-shape along the flow direction. Meanwhile, the precooler has minimal impact on the pressure loss of the secondary flow while achieving a remarkable pressure recovery coefficient of over 97% and a temperature drops of above 40%. Thus, precooling the secondary flow helps decrease the static pressure in the suction chamber, which results in a minimum 29% increase in compression ratio, enhancing the pumping capacity of supersonic ejector. The study also observed that the drop of secondary flow temperature leads to a lower velocity ratio between the secondary and primary flows, which is beneficial for their mixing process.

A novel compact supercritical CO2 solar receiver based on impinging jet: Heat transfer performance and thermal stress analysis

The compact solar receiver can withstand high temperature and high pressure, which provides promising solutions for direct supercritical CO2 (S-CO2) solar receiver applications. However, it still suffers from local high temperature and large thermal stress due to the non-uniform heating boundary condition. The impinging jet method can significantly enhance the local heat transfer coefficient, holding significant potential in reducing the local high temperature of the compact S-CO2 receiver. Inspired by this, a novel design for a compact S-CO2 receiver using the impinging jet was proposed in this work. The heat transfer performance and stress behavior of the jet channel within the receiver were numerically investigated. The results showed that the jet channel has a significantly higher heat transfer performance than the rectangular channel, and the shorter flow path of the jet channel also effectively reduces the pressure loss. Meanwhile, the jet pattern significantly enhances the temperature uniformity, thereby reducing the thermal stress. In addition, increasing the channel aspect ratio improves the thermo-hydraulic performance, but increase the stress at the same time. The increase in the number of jet holes and the jet hole diameters not only enhance the thermo-hydraulic performance, but also reduce the stress of the jet channel.

Quantitative evaluation of spheroidisation in 15CrMo steel based on deep learning

ABSTRACT 15CrMo steel has good mechanical properties and is widely used in high-temperature pressure components. After long term service, it is easy to cause material spheroidisation. The metallographic and mechanical property tests are used to evaluate the spheroidisation of specimens. Ultrasonic backscattering signal is sensitive to microstructure and contains more microstructure information, which can be used for the evaluation of spheroidisation. However, the ultrasonic backscattering signal is nonlinear, and feature extraction is difficult. In this study, ultrasonic testing is used to scan different spheroidisation specimens, and the ultrasonic backscattering signal is extracted as the input to the deep learning model, which is used to extract features from the backscattering signal. The models are evaluated using classification and regression evaluation metrics. The results show that the proposed CNN-LSTM model has good identification performance for the classification of spheroidisation and the prediction of mechanical properties. The classification accuracy, recall, precision, and F1-score are all 1. Additionally, the maximum predicted RMSE and MAE values are only 2.33 MPa and 1.70 MPa, and the minimum R 2 is only 0.97. The worst prediction is the tensile strength, with an average value of 442.2 MPa and a maximum value of 481.1 MPa.

The influence of sintering additives on densification and phase composition of ZrB2 – HfB2 composite

This work deals with the preparation of composites from the ZrB2-HfB2-MeX system (where: MeX = SiC, B4C, WC, MoSi2 and CrSi2). Three pressure-assisted sintering techniques were used to obtain the composites, i.e. hot-pressing (HP), spark-plasma sintering (SPS) and high pressure-high temperature (HPHT) sintering. Hot-pressing was selected as the most favourable sintering technique. The composites obtained via hot-pressing were characterized by high density and homogeneous microstructure. The work did not undermine or justify the need to reduce passivating oxide layers on boride grains. In the case of silicides, especially chromium silicide, there was a significant reduction in the sintering temperature of the ZrB2-HfB2 composites by about 500–600°C. In composites with the addition of silicides, there is a tendency to create complex solid solutions, which is visible as core-shell microstructures.

Is a Vitrimer with a High Glass Transition Temperature Available? A Case Study on Rigid Polyimides Cross-Linked with Dynamic Ester Bonds.

Vitrimers, possessing associative covalent adaptable networks, are cross-linked polymers exhibiting malleable (glass-like) feature and recyclable and reprocessable (thermoplastics-like) properties. The dynamic behaviors of vitrimer are dependent on both chain/molecular mobility (glass transition temperature, Tg) and dynamic bond-exchanging reaction rate (topology freezing transition temperature, Tv). This work aims on probing the effect of high Tg on the stress relaxation and physical recyclability of vitrimers, employing a polyimide cross-linked with dynamic ester bonds (Tg: 310°C) as the example. Due to its high Tg and chain rigidity, the cross-linked polyimide does not exhibit a high extent of stress relaxation behavior at 320°C (10°C above its Tg), even though the temperature is much higher than the hypothetical Tv. While raising the processing temperature to 345°C, the cross-linked polyimide exhibits a stress relaxation time of about 3300s and physical malleability. Nevertheless, side reactions may occur in the recycling and reprocessing process under the harsh condition (high temperature and high pressure) to alter the thermal properties of the recycled sample. The diffusion control plays a critical role on the topography transition of a vitrimer having a high Tg. The Tg ceiling is noticeable for developments of vitrimers.

Effect of Al‐Incorporation on the Sound Velocities of Superhydrous Phase B at High Pressure and High Temperature

AbstractSound velocities and densities of Al‐bearing superhydrous phase B (Al‐bearing SuB) were investigated up to 24 GPa and 1300 K by synchrotron X‐rays combined with ultrasonic interferometry techniques in a multi‐anvil apparatus. We found that Al + H incorporation decreases the adiabatic bulk modulus and shear modulus of SuB. Our results however suggest that this effect is less important than that of temperature. The presence of hydrous pyrolite with ∼10 wt.% Al‐bearing SuB in cold subducting slabs could explain up to ∼2% high velocity anomalies at the bottom of the mantle transition zone (500–660 km) while it turns into ∼7.7% low velocity anomalies below 660 km. Al‐bearing SuB is reportedly stable at mantle temperatures, where it could account for ∼12.2% low velocity anomalies beneath subduction zones in the uppermost lower mantle.

Modelling of water injection-induced shear stimulation and heat extraction in hot fractured reservoirs

Hydroshearing has been proposed as an effective technique for enhancing the permeability of fractured geothermal reservoirs. This approach involves complicated thermo-hydro-mechanical (THM) coupling, but the shear behaviour and its effect on flow and heat transfer are often simplified. In this study, Barton–Bandis (BB) joint behaviour is extended to include nonlinear rock joint deformation, shear dilation and post peak softening and healing behaviours. Two models of field-scale fractured geothermal reservoirs are considered. In addition, the widely used Mohr-Coulomb (MC) model is also incorporated into the THM coupled model for comparison. The results show that cold water injection-induced high-temperature rock contraction and fluid pressure increase, reducing the effective stress and promoting fracture shear deformation and irreversible slip. Moreover, shear dilation, shear softening, and nonlinear fracture opening notably alter reservoir permeability. The two models exhibit entirely different behaviours due to different pathway evolutions and consequent pressure build-up. The BB model displays a larger shear disturbance zone than the MC model, significantly enhancing the permeability and heat extraction within the fractured reservoirs. Accurate descriptions of the mechanical behaviour of rock fractures in hydroshearing models are crucial, suggesting the potential of these models to enhance fractured reservoirs and regulate fracturing for improved geothermal heat extraction.

Tribological behavior of PDC-cutter including cemented carbide and polycrystalline diamond composites produced by HPHT for drilling applications

In this study, the tribological behavior of PDC-cutter including WC particles/Ta-20Nb binder composite as substrate and polycrystalline diamond composite as PCD layer produced by high pressure-high temperature (HPHT) for drilling applications was investigated. To examine the metallurgical behavior, phase analysis, hardness of substrate and PCD layer, and tribological behavior, scanning electron microscopy, X-ray diffraction, Vickers microhardness, and wear tests were used, respectively. Due to the HPHT of the manufacturing process, the high hardness of the interfaces, especially for the WC/Ta-20Nb was achieved, which had ∼28% higher hardness than the diamond grits/Ta-20Nb binder. Therefore, no obvious porosity was observed in the interfaces and the composites were completely densified because the particles had good retention strength. The wear results showed that the tribological behavior of PCD layer/granite or marble pairs was directly influenced by the binder content, with samples having a lower binder content showing superior wear performance. Additionally, worn surface investigations demonstrated that adhesive and abrasive wear mechanisms were present in all pairs, with their intensities being strongly correlated with the binder concentration.

Amylose molecular weight affects the complexing state and digestibility of the resulting starch–lipid complexes

Previous RS5 (type 5 resistant starch) research has significantly broadened starch use and benefited society, yet the effects of the molecular weight of amylose on RS5 remain underexplored. In this study, amyloses with different molecular weights were complexed with caproic acid (C6), lauric acid (C12), and stearic acid (C18) to observe the effects of the molecular weight of amylose on the structure and in vitro digestive properties of RS5. Gel permeation chromatography revealed that the peak average molecular weight (Mp) values of high-amylose cornstarch NF-CGK (CGK), high-amylose cornstarch obtained via cornstarch via autoclave (high temperature and high pressure)-cooling combined pullulanase enzymatic hydrolysis (CTE), and high-amylose cornstarch NF-G370 (HCK) were 21,282, 171,537, and 188,084 before fatty acid complexation, respectively. Additionally, their weight average molecular weight (Mw) values of 32,429, 327,344, and 410,610 and hydrolysis rates of 58.12 %, 86.77 %, and 64.58 %, respectively. The hydrolysis rate of low-Mw amylose (GCK) complexes with fatty acids was lower than that of HCK and CTE starch–lipid complexes. However, HCK and CTE having similar molecular weights, there was no significant difference in the hydrolysis rate of starch–lipid complexes. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and complexing index analyses confirmed the formation of these complexes. This study proposed the mechanism of RS5 formation and provided guidance for its future development.

Safety Management and Accident-Control Strategy for a Commercial-Scale Plant for Supercritical Water Oxidation of Sludge

Supercritical water oxidation is a promising technology for decomposition of industrial wastewater and sludge. However, the system is operated under high temperature and pressure (usually higher than 500 °C and 25 MPa). Corrosion of component materials and salt deposition may lead to leakage or even the burst of the pressure vessel in the SCWO system, resulting in a high level of worry about the safe operation of the system. In this paper, the safety management and accident- control strategies are introduced according to a commercial-scale SCWO plant in China. The safety management strategy refers to the special design and operation strategies of some facilities. Different types of potential accidents are analyzed and the coping strategies for accidents of different levels of severity are described in detail. The strategies are valuable for the safe operation of commercial SCWO plants and other plants operated in high temperature and high pressure.

The operation strategy of river water source heat pump cold source system in a chemical industrial park in a region with hot summers and cold winters

At present, the energy consumption of the whole process of buildings in China accounts for 45 % of the total energy consumption of the country, and the carbon emissions account for 50.6 % of the total emissions of the country. Among the energy consumption of buildings, air conditioning energy consumption occupies a major proportion, about 2/3. Traditional air conditioning cooling mainly uses refrigerants such as Freon to circulate and cool under high temperature and high pressure, which not only has high energy consumption but also can cause the external environment temperature to be too high. River water source heat pump is a renewable energy technology that can use water bodies including groundwater, surface water such as rivers, lakes, reservoirs and oceans. This project mainly studies the operation strategy of related units using river water as the cold source in a chemical industrial park in Chongqing, from unit selection, establishment of energy consumption model to unit operation strategy analysis and research, to achieve the best state of energy utilization.

Micro-cracks evolution process and borehole stability analysis in deep pebbly sandstone based on THM coupling method

The heterogeneity of pebbly sandstone is strong due to the random distribution of gravel particles, resulting in unique mechanical behaviors and failure patterns under high temperature and high pressure. It poses significant challenges to exploring and developing oil and gas resources in deep pebbly sandstone reservoirs. Thus, to investigate the impact of high pressure, high temperature, and gravel distribution on the strength characteristics and failure patterns of pebbly sandstone, based on typical samples from the Tarim Basin, a numerical model that accurately represents the distribution of gravel particles in pebbly sandstone was built. Lastly, a Thermo-Hydro-Mechanical coupling model for pebbly sandstone boreholes was established to quantify the influence of the difference coefficient of in-situ stress and gravel volume fraction. The results show that during the rupturing process of pebbly sandstone, the micro-cracks initiation occurs and expands around the gravel, forming a shear-type fracture. At the same time, several secondary cracks are formed inside the rock. With increasing confining pressure, the number of secondary cracks decreases. The fracture morphology is complex in concentrated gravel distribution, whereas a single fracture dominates the failure pattern in uniform distribution. The micro-cracks are more likely to occur in the gravel areas around the borehole during drilling, resulting in the gravel accumulation areas prioritizing collapse rather than in the direction of minimum horizontal in-situ stress, significantly reducing the safe density window. The safety density window decreases with the increase of the gravel volume but increases when the gravel volume fraction is higher than 20%. The research results provide valuable guidance for efficient and safe drilling in pebbly sandstone formations.

In Situ Measurement Techniques Using Diamond Anvil Cell at High Pressure–Temperature Conditions: A Review

Diamond anvil cells have garnered significant attention in high‐pressure studies as a valuable tool for investigating material preparation, phase transition dynamics, and ultra‐high‐pressure physical chemistry. Its potential applications span fields such as materials science, condensed matter physics, chemistry, and geology. This study conducts a comprehensive review of the utilization of laser‐heated diamond anvil cell (LH‐DAC) devices in conjunction with in situ optical characterization techniques, such as X‐Ray and Raman scattering. Further, diverse in situ performance measurement methods encompassing electrical, thermal, magnetic, and acoustic analyses are examined. The development and role of the prevailing in situ measurement techniques have been described, along with the current progress in applied research for each technique. This study aims to facilitate the discovery of new structures and properties of materials under high pressure–temperature conditions.

Evaluating the Performance of Class F Fly Ash Compared to Class G Cement for Hydrocarbon Wells Cementing: An Experimental Investigation.

The following study presents the results of research in the field of the performance of geopolymers consisting of Class F fly ash with an alkaline activator solution consisting only of sodium metasilicate (Na2SiO3) and water. The performances of this geopolymer are compared to the those of American Petroleum Institute (API) Class G cement. This comparison is to evaluate the potential of the geopolymer as an alternative to cement in cementing hydrocarbon wells in the oil and gas industry. The gap in the research is determining the performance properties that restrict the use of fly ash in the oil and gas industry. Using only sodium metasilicate as an activator with water, the solution creates a strong binding gel for the geopolymer and activates the aluminosilicate properties of the fly ash. This geopolymer is compared with Class G cement without additives to determine their base performances in high pressure and high temperature conditions, as well as note any properties that are affected in the process. This commences by formulating recipes of these two materials from workable ratios and concentrations. The ratios are narrowed down to the best working models to proceed to comparative performance testing. The tests included exploring their vital performances in fluid loss and thickening time. The results produced suggest that Class G cement generally has less fluid loss at low temperature than the geopolymer but could not maintain its integrity and structure as temperatures increased. Class G cement exhibited stability, consistencies of 100 Bcs (Bearden Consistency Units), and a faster thickening time of 1 h and 48 min when placed under high temperature and high-pressure conditions, respectively. However, the geopolymer showed more consistency regarding fluid loss with respect to rising pressure and temperature, and smoother, less fractured samples emerging from both tests. Though the geopolymer showed stronger performances in thickening and water retention, the experiments showed that it is not a uniform and consistent material like Class G cement. Through the use of different additives and intricate design, the sample may show success, but may prove more difficult and complex to apply than the industry standard and uniform content of Class G cement.

Comparative analysis: CapEx in diamond mining versus diamond growing, based on open data sources and experimental results

The diamond industry has long been associated with environmental and social problems, ranging from mining practices to ethical concerns related to diamond sourcing. In recent years, there has been a growing interest in lab-grown diamonds as a sustainable alternative for diamond consumers. However, the production of lab-grown diamonds has own challenges. This article examines the capital expenditures per annualized carat of rough diamonds obtained through mining and two fabrication methods: high-pressure high-temperature (HPHT) and microwave plasma-assisted chemical vapour deposition (MP CVD). Lab-grown diamonds produced using HPHT and MP CVD methods require significantly higher capital expenditures per annualized carat compare to mined diamonds. HPHT diamonds require on-time CapEx of 500–833 US$ per carat annually, while MP CVD diamonds demand 549–1648 US$ per carat annually. Finding ways to reduce production cost and increase efficiency will be crucial in realizing the potential of lab-grown diamonds as a sustainable alternative to mined diamonds.

Performance Assessment of Bismuth Ferrite Nanoparticles in Enhancing Oilwell Cement Properties: Implications for Sustainable Construction

Summary Oilwell cement ensures wellbore stability and isolates zones while bearing casing load and formation pressure. Its properties, crucial in extreme downhole conditions, include compressive strength, fluid loss resistance, and durability. In the present work, bismuth ferrite nanoparticles (BFO NPs) were synthesized using the sol-gel method and used as an additive in oilwell cement. The synthesized BFO NPs were characterized using Fourier transform infrared (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), and dynamic light scattering (DLS) techniques to analyze the functional groups, crystalline structure, morphological features, and hydrodynamic size distribution. Tests at 70°C and 2,000 psi revealed that 1% by weight of cement (BWOC) BFO NPs increased compressive strength by ~136% and reduced fluid loss to ~64% compared with base cement. It can be conjectured that the exposed facets of BFO NPs containing oxygen act as nucleating sites that promote the ordering of the silicate tetrahedra, thereby increasing the strength and crystallinity and reducing the water loss. The experimental results confirm that the BFO NPs can improve the properties of oilwell cement slurry at high-pressure, high-temperature (HPHT) conditions. This research underscores the potential of BFO NPs as sustainable additives for optimizing oilwell cement performance under challenging HPHT conditions, paving the way for advancements in sustainable construction practices.

Safety evaluation of offshore oil and gas well string based on corrosion rate prediction

The combined effects of corrosion, temperature, and pressure can cause safety issues such as shortened lifespan and failure of offshore high temperature and high pressure oil and gas well strings. This paper focuses on a certain sea area and conducts experiments on CO2 corrosion of different string materials under different temperature and partial pressure conditions. Combined with the two-phase flow wellbore temperature and pressure-coupling model, a corrosion rate prediction model based on Back Propagation Neural Network optimized by Genetic Algorithm (GA-BPNN) is established for predicting corrosion rate along the wellbore depth. At the same time, based on the API 5C3 standard, considering the degradation effect of thermally induced metal string strength and the influence of environmental pressure, a safety evaluation model of offshore oil and gas well string based on corrosion rate prediction was established, and analysis of the change law of residual strength of the string and prediction of remaining life under the influence of different factors were carried out.

Effect of finned configuration of circular tube based on fluid-structure coupling on hydrogen flow characteristics

Nuclear thermal propulsion has the characteristics of high specific impulse, large thrust, green and efficient, and is the primary choice of manned deep space exploration propulsion system. Because the circulating flow of propellant hydrogen in the internal pipeline of the engine is always affected by the harsh environment of high temperature and high pressure, it is very important to study the flow characteristics of hydrogen in the pipeline, the heat exchange characteristics of hydrogen and pipeline and the deformation characteristics of pipeline under heat stress. In this paper, the flow phenomena of hot hydrogen in round tubes in a laminar flow state were analyzed by numerical simulation with COMSOL Mulitiphisics6.0, and the fluid-structure coupling between hot hydrogen fluid and pipe was investigated by a multi-physics field. It is concluded that the smoother the inner wall of the pipeline is, the smaller the hydrogen flow velocity is, the smaller the surface pressure of the pipe wall is, and the smaller the fluid extrusion and impact deformation of the pipe in the typical pipe with the inner fin is. It inspires studying the application of hot hydrogen flow and pipeline configuration in nuclear thermal rocket engines, including improving heat transfer energy and uniformity.

Utilizing phased array ultrasound technique to examine seal surface contact status in premium connections

Premium connections are commonly employed in wells subjected to high temperature and high pressure (HTHP) conditions. The key parameter in evaluating the sealing capability of premium connections is the contact condition between the sealing surface. This paper presents a method based on phased array ultrasound testing (PAUT) technique to examine the metal-to-metal contact states of the seal surface in premium conditions, and presents experimental work on contact status of the seal surface in premium tubing connections using PAUT, testing impacts of torque, seal surface defects and thread compounds dosage. The experimental findings demonstrate an inverse relationship between the observed ultrasonic reflection amplitude and the applied torque on the premium. Additionally, there is a robust exponential correlation manifested between the ultrasonic reflection amplitude and the torque exerted on the premium. The ultrasonic reflection amplitude at the defect of the seal surface increases. Under equivalent make-up torque conditions, the ultrasonic reflection amplitude on the sealing surface of premium connections escalates as the dosage of thread compounds diminishes, and the importance of precise control of the amount of thread compound used was confirmed. These data demonstrate that PAUT provides a reliable detection technique for performance assessment on premium connections, both in quality control and field inspection.