High-pressure Environment Research Articles

Combined Effects of the Thermal-Acoustic Environment on Subjective Evaluations in Urban Park Based on Sensory-Walking

Studying the impact of various factors on environmental perception is crucial because humans live in an environment where these factors interact and blend. The thermal-acoustic environment is the major factor that affects the overall perception of urban parks. This study focuses on urban parks in the subtropical region, with Xihu Park in Fuzhou, China, as the research area. Through measurements and questionnaires, this study explores the effects of the thermal-acoustic environment in urban parks on subjective evaluation (thermal assessment, acoustic assessment, and overall environmental assessment). The results reveal that: (1) a higher temperature significantly increases the sensation of heat and lowers thermal comfort, heat acceptance, and overall thermal environment evaluation scores. The type of sound source has a significant positive impact on thermal assessment, and the higher the ranking of the sound source type, the greater its positive impact on thermal assessment. (2) Regarding acoustic evaluation, higher sound pressure level is associated with more negative subjective ratings of loudness, harshness, intensity, and excitement. In contrast, positive sound sources can enhance comfort, preference, disorder, coordination, and overall soundscape evaluation. Additionally, temperature increases tend to result in more negative harshness, intensity, and coordination ratings. The interaction between temperature and sound pressure level also significantly affects subjective loudness, harshness, and intensity. (3) Overall environmental evaluation is also affected by temperature, with increasing temperatures leading to decreased comfort and satisfaction while increasing irritation. High sound pressure environments result in worse overall irritation ratings, while positive sound sources can significantly enhance overall comfort, irritation, and satisfaction ratings. Furthermore, the interaction between temperature and sound pressure level significantly impacts overall irritation and satisfaction ratings. These findings are significant for managing and improving the park’s thermal environment and soundscape, providing a practical framework for landscape architects.

Analysis of containment pressure control strategy in HPR1000 NPP under severe accidents

Containment is the last barrier of preventing the release of radioactive fission products in a nuclear power plant (NPP). It has the top priority of its strategy in a severe accident (SA) to ensure the integrity of containment. Generally, there are two ways for the containment heat removal. One is to set exchangers or sprays to cool the atmosphere in the containment like CPR1000. The other is to set sprays out of the steel containment to remove heat like AP1000. After Fukushima Daiichi nuclear accident, mitigation strategies after severe accidents are focused and specific systems of dealing with containment failure threat are required to design in new built NPPs. HPR1000 is a generation-Ⅲ PWR in China, which deployed the dedicated severe accident (SA) system of containment spray to address the above conditions. Containment spray in HPR1000 has two identical trains isolated physically, and each train is capable to reduce containment pressure after severe accidents. The containment spray system cannot start automatically, but only be started by operator during severe accidents. According to the lessons from Fukushima accident, it is hard for the operator to make the right choice in such a high-pressure environment during severe accidents, so the proper start-up time is better given in advance as possible. This paper assesses the effectiveness of the containment spray, conducts sensitive calculations of different start-up time, and discuss the negative effects of containment spray. Based on the calculation results, insights of containment spray strategy are gained for HPR1000 NPP and the proper start-up time for the strategy of containment spray in SAMG are put forward.

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.

Structural Analysis and Optimization of Urban Gas Pressure Regulator Based on Thermo-Hydro-Mechanical Coupling

As a core component in the gas transmission process, the internal wall surface of a gas pressure regulator is prone to failure due to long-term exposure to a high-pressure gas environment, resulting in poor reliability of the regulator. Thus, a thermo-hydro-mechanical coupling model for the FL gas pressure regulator is established in this paper, and the thermo-hydro-mechanical coupling results are verified by engineering data. The effect of valve opening on the parameters (temperature, deformation, and stress) of the gas pressure regulator is studied in detail through simulation. The results show that the stress is greater at the sleeve, valve bore, and outlet valve seat wall under the opening of 20% of the regulator. Finally, the response surface method is used to optimize the regulator to obtain a good fit and high predictive ability of the response surface equation. The optimal parameters for the gas pressure regulator are as follows: the wall thickness of the sleeve is 7.25 mm, the diameter of the valve bore is 25 mm, and the wall thickness of the outlet seat is 31.05 mm. The maximum equivalent stress with this combination of parameters is 135.62 MPa.

Effect of temperature on the fretting wear behavior of Cr-coated Zircaloy cladding in high-temperature pressurized water

Cr-based coatings are promising candidates to protect the claddings on accident-tolerant fuel (ATF) rods in pressurized water reactors (PWRs). In this study, the effect of water temperature on the fretting wear behavior of an N36 Zirconium alloy cladding was investigated. In addition, the effect of applying a protective Cr coating to the cladding was also analyzed. Fretting wear tests were carried out using a unique apparatus that simulated the high-temperature and high-pressure (HTHP) water environment in a real PWR. Results show that changes in temperature alter the wear mechanism of cladding tubes. Furthermore, a Cr-coating improves the wear resistance of an N36 cladding significantly. The main wear mechanisms of Cr-coated cladding in HTHP water were observed to be abrasive and adhesive wear. The protective effect of a Cr coating on the cladding in a low-temperature water environment (25 °C, 90 °C) was less than it was in a high-temperature water environment (260 °C, 315 °C), indicating that Cr coatings can improve wear resistance in HTHP water.

A Facile Way to Fabricate GO-EDA/Al2O3 Tubular Nanofiltration Membranes with Enhanced Desalination Stability via Fine-Tuning the pH of the Membrane-Forming Suspensions.

Pristine graphene oxide (GO)-based membranes have proven promising for molecular and ion separation owing to efficient molecular transport nanochannels, but their separation ability in an aqueous environment is limited by the natural swelling tendency of GO. To obtain a novel membrane with anti-swelling behavior and remarkable desalination capability, we used the Al2O3 tubular membrane with an average pore size of 20 nm as the substrate and fabricated several GO nanofiltration ceramic membranes with different interlayer structures and surface charges by fine-tuning the pH of the GO-EDA membrane-forming suspension (pH = 7, 9, 11). The resultant membranes could maintain desalination stability, whether immersed in water for 680 h or operated under a high-pressure environment. When the pH of the membrane-forming suspension was 11, the prepared GE-11 membrane showed a rejection of 91.5% (measured at 5 bar) towards 1 mM Na2SO4 after soaking in water for 680 h. An increase in the transmembrane pressure to 20 bar resulted in an increase in the rejection towards the 1 mM Na2SO4 solution to 96.3%, and an increase in the permeance to 3.7 L·m-2·h-1·bar-1. The proposed strategy in varying charge repulsion is beneficial to the future development of GO-derived nanofiltration ceramic membranes.

Ben Ofori-Okai

Ben Ofori-Okai, a spectroscopist at the SLAC National Accelerator Laboratory, has some big questions about what’s happening at the center of planets. The secret lives of high-pressure and high-temperature environments hold the key to scientists’ long-standing questions about the evolution of our universe and even the elusive chemistry within nuclear reactors. To explore these exotic conditions, Ofori-Okai is taking spectroscopy to the extreme. Ofori-Okai specializes in a field called terahertz spectroscopy, which measures the vibrational energy of molecules as they interact with and emit terahertz radiation. This region of the electromagnetic spectrum, which lies roughly between infrared and microwave wavelengths, captures distinct vibrational modes of molecules that other spectroscopic measurements miss. For example, chemists can use terahertz spectra to reveal the chemical composition of molecular mixtures that might be indistinguishable by nuclear magnetic resonance or infrared spectroscopy, Ofori-Okai says. Yet chemists have been slow to adopt terahertz spectroscopy because “it’s

Study on the effect of injection temperature and nozzle geometry on the flashing transition of liquid ammonia spray

Ammonia is a promising alternative fuel for carbon emission reduction in industry, transport, and power generation. For high-pressure combustion environment applications, direct injection of liquid ammonia (LNH3) is considered. Because of its thermophysical properties, and dependence on the injection and combustion environment conditions, the direct injection of ammonia in its liquid state can lead to flash-boiling, changing drastically the spray characteristics. In this study, we characterized the effect of injection temperature and nozzle geometry on the spray characteristics and transition to flashing using backlit imaging. Flow rates pressure curves and spray angles were obtained in a well-controlled environment and can be used as a database for simulation. Finally, some practical considerations on the design of nozzles are highlighted in the present work.

Design of O-ring with skeleton seal of cutter changing robot storage tank gate for large diameter shield machine

Faced with high pressure and high humidity environment, the seal of the storage cabin gate is the key to ensure the reliable frequent cutter replacing operation for shield machine. In this paper, the design criteria of the gate side seals was proposed. And the numerical analysis model of O-ring seal with skeleton was established. The influence of key structural parameters on the sealing performance was studied. The combination optimization parameters of the seal were obtained. The rationality of the seal structure is verified through the gate sealing performance test. It provides reference for the design and optimization of the sealing structure used in deep-sea tunnel shield.

Formation and Protectiveness of Fe/Ca Carbonate Layer on X80 Steel in High-Pressure CO2 Corrosion Environments

The effect of calcium ions (Ca2+) on the corrosion of API 5L X80 carbon steel in carbon dioxide (CO2)-saturated brines was studied. Tests were performed in brines containing 0 ppm, 1,000 ppm, or 5,000 ppm of calcium ions with a constant chloride ion concentration at temperatures of 35°C and 60°C, and pressure of 80 bar. The corrosion rates were determined by mass loss, and the protective properties of the film were evaluated by performing electrochemical measurements in a separate vessel containing a standard brine. The results showed that adding Ca2+ to the brine slightly reduced the average corrosion rate, even without a crystalline corrosion product scale. For longer exposure times, it promoted the growth of a mixed iron-calcium carbonate (FexCayCO3) scale with increasing calcium molar mass, shifting the scale morphology from prismatic crystals (pure FeCO3) to globular (mixed carbonate). At 35°C the mixed iron-calcium carbonate scale offered better protection when compared to the pure FeCO3 scale counterpart. However, at 60°C, where a thicker carbonate scale was formed, the increased Ca2+ content had a minimal effect on the corrosion rate.

Development of an Antihydropressure Miniature Underwater Robot With Multilocomotion Mode Using Piezoelectric Pulsed-Jet Actuator

The high-pressure environment of deep sea challenges the miniaturization of underwater robots due to assembly of anti-hydropressure devices for protecting electromagnetic motor. Here, inspired by the motion principle of jellyfish, a novel piezoelectric pulsed-jet actuator (PJA) was proposed as power source. Six PJAs were arranged crosswise to form an anti-hydropressure miniature cross-shaped underwater robot (CSUR) with dimensions of Φ10.9 × 6.3 cm³. The numerical simulation method was adopted to analyze the propulsion mechanism, optimize the structure and find the optimal frequency. A robot prototype was fabricated, and its motion performances were tested. The CSUR achieved floating, sinking, hovering motions in the vertical direction and linear, rotary, turning motions in the horizontal direction. The maximum linear velocity reached up to 47.8 mm/s (0.43 BL/s). The robot could move in high-pressure environment of 10 MPa, and the average velocity deviations under different water pressures were less than 10%. Besides, the CSUR could move along S-shaped path to navigate around obstacles. The proposed robot performed merits of miniature structure, good adaptability of high-pressure environment, high agility and maneuverability. It is potential for the CSUR to be applied in exploring, mapping and sampling in narrow areas of deep sea.

Transition state performance optimization of propfan engine based on DDPG algorithm

As the “heart” of an aircraft, aero-engines work in harsh environments of high temperature and high pressure for a long time. In order to ensure that the engine can operate safely and reliably within the entire flight envelope, a large safety margin needs to be reserved in the design of the control system. This design idea limits the full play of the engine performance, so it is necessary to carry out the research on the performance search control (PSC) of aero-engine. This paper studies the performance optimization control of propfan engine based on deep reinforcement learning algorithm. The Deep Deterministic Policy Gradient (DDPG) algorithm, which is more suitable for continuous action space, is used to optimize the acceleration process of the propfan engine. The simulation results show that, compared with the unoptimized adjustment process, the transition state adjustment time of the engine is reduced by 32.5% under the action of the optimal adjustment law obtained by the DDPG algorithm. Therefore, the DDPG algorithm can be applied to the performance optimization of the engine acceleration process, and has a good transition state performance optimization effect.

Numerical Control Machining Process Parameters of Nickel-based Alloy Casing

As a major component of engine, aviation casing is usually machined from superalloy blanks because it needs to withstand high temperature, high pressure and other environments during use. Surface integrity indexes such as surface roughness and residual stress will seriously restrict the performance and service life of such parts. In this paper, by studying the processing technology of the casing, Deform-3d software was applied to conduct three-dimensional dynamic modelling for the rough milling process of the casing made of nickel-based alloy GH4169, and the milling simulation analysis was carried out. With milling force and milling temperature as evaluation indexes, the variation rules of force and temperature under different coaxial and radial milling depths were obtained through simulation analysis. At the same time, the single factor optimization was carried out for different coaxial and radial milling depths according to evaluation indexes, and a set of optimal milling parameters were obtained, which provided theoretical guidance for practical machining.

Flow accelerated corrosion of X65 steel gradual contraction pipe in high CO2 partial pressure environments

Flow accelerated corrosion (FAC) behavior of X65 steel gradual contraction pipe in high CO2 partial pressure environments was investigated by in situ dynamic high pressure electrochemical measurements with Ag/AgCl reference electrode in FAC loop and microscopic characterization analysis. The corrosion rates in dynamic high CO2 partial pressure environments are obviously enhanced compared with those in dynamic atmospheric pressure and static high pressure environments. The FAC mechanism at gradual contraction pipe in high pressure environments exhibits significant distinction from that in atmospheric pressure environments. The variation of corrosion rates is associated with the hydrodynamics at gradual contraction pipe. The presence of high CO2 partial pressure under fluid flowing accelerates rupture of corrosion product scales.

Evaluation of Inoculation Methods for Determination of Winter Wheat Resistance to Fusarium Head Blight

One of the most severe winter wheat (Triticum aestivum L.) diseases is Fusarium head blight (FHB). It is believed that selection for resistance to FHB is better in high disease pressure environments, for which various methods of artificial inoculation are used. The standard spray method of artificial inoculation is believed to be technically demanding and labour intensive. Therefore, scattering Fusarium-infected maize stalks onto trial plots after wheat emergence is suggested as a suitable alternative. The aim of this study was to compare the mean values and heritability of the visual rating index (VRI) and the percentage of Fusarium-damaged kernels (FDK) between the two abovementioned methods of artificial inoculation and natural infection, and to determine the phenotypic correlations between the three methods for the studied traits. The achieved levels of VRI and FDK were comparable for the two methods of artificial inoculation and considerably lower under natural conditions. Heritability for VRI ranged over four years from 0.68 to 0.91 for the spray method, from 0.73 to 0.95 for the infected maize stalks, and from 0.26 to 0.65 for natural infection, whereas for FDK it ranged from 0.56 to 0.85, 0.38 to 0.83, and 0.11 to 0.44 for the three inoculation methods, respectively. The strong positive correlation between the two applied methods of artificial inoculation for studied traits suggests that scattering infected maize stalks could serve as a reliable supplement for the technically and labor-intensive spray method of artificial inoculation.

Distinct modes of meltwater drainage and landform development beneath the last Barents Sea ice sheet

The flow of glacial ice is impacted by basal meltwater drainage systems that fluctuate on a continuum from distributed, high-pressure environments to channelized, lower pressure networks. Understanding the long-term development of dominant drainage modes and impacts on ice flow and landform development is a crucial step in predicting palaeo and contemporary ice-mass response to changes in climate. The spatial and temporal scales at which different drainage modes operate are largely unknown, and the geomorphological legacy of subglacial meltwater networks that evolve over a glaciation provide composite records of drainage system development. Here, we use high-resolution bathymetric data from shallow banks in the central Barents Sea to map the geomorphological imprint of meltwater drainage beneath the collapsing marine-based Barents Sea Ice Sheet (BSIS). We observe a succession of distinct meltwater landforms that provide relative timing constraints for subglacial drainage modes, indicating that extensive networks of channelized drainage were in operation during deglaciation. Interlinked basins and channels suggest that meltwater availability and drainage system development was influenced by filling and draining cycles in subglacial lakes. Networks of eskers also indicate near-margin meltwater conduits incised into basal ice during late-stage deglaciation, and we suggest that these systems were supplemented by increased inputs from supraglacial melting. The abundance of meltwater during the late stages of BSIS deglaciation likely contributed to elevated erosion of the sedimentary substrate and the mobilisation of subglacial sediments, providing a sediment source for the relatively abundant eskers found deposited across bank areas. A newly discovered beaded esker system over 67 km long in Hopendjupet constrains a fluctuating, but generally decelerating, pace of ice retreat from ∼1,600 m a−1 to ∼620 m a−1 over central Barents Sea bank areas during a 91-year timespan.

Different augmentations of absorbed hydrogen under elastic straining in high-pressure gaseous hydrogen environment by as-quenched and as-tempered martensitic steels: combined experimental and simulation study

Hydrogen embrittlement (HE) behavior of as-quenched and as-tempered martensitic steels under elastic straining in a high-pressure gaseous hydrogen environment was studied for the first time. The difference in the total content of defects acting as H trap sites has the highest contribution to the increase in absorbed hydrogen content under the elastic loading. The hydrogen-induced fracture occurred in the as-quenched specimen during elastic straining in hydrogen environment, while the tempered specimen did not fracture under the elastic loading. Higher accumulation of the dislocations near the main crack initiation sites (prior austenite grain boundaries (PAGBs)) in the as-quenched specimen will be the main source of the hydrogen to the potential flaw to crack to initiate. H accumulated near PAGBs enhances dislocation slip along {011} planes and helps transgranular crack propagation. Due to less possibility to provide the critical local amount of hydrogen at PAGBs for the crack to initiate, the as-tempered specimen remained unfractured.

Constructing uniform oxygen defect engineering on primary particle level for high-stability lithium-rich cathode materials

Lithium-rich layered cathode materials are considered to be research focus of cathode candidates for next-generation lithium-ion batteries due to their high specific capacity and low cost. However, lattice deoxidation associated with elemental migration and internal local shrinkage usually results in deteriorated cyclic performance and notorious voltage attenuation, severely limiting its application. In this paper, we have successfully injected uniform oxygen defects into surface region of Li1.2Ni0.13Co0.13Mn0.54O2 primary particles under the high-pressure and weak carbonate environment. Various experimental investigations indicate that the injected robust oxygen defects can not only mitigate detrimental interfacial reactions but also suppress unfavorable lattice variation and particle breakage. More importantly, theoretical calculations unravel the critical roles of oxygen defects in regulating energy band structure for strengthened anionic reversibility. Owing to stabilization effects of unique oxygen defect engineering, the modified Li1.2Ni0.13Co0.13Mn0.54O2 cathode has harvested dramatically enhanced electrochemical performance including a high initial coulombic efficiency of 96.6%, an outstanding capacity retention of 91.96% (1C, 200 cycles) and suppressed voltage decay of only 1.62 mV per cycle. Therefore, this facile and effective defect engineering strategy could establish new guidance for promoting practical application of Li-rich Mn-based cathode material.

An Ultrahighly Pressure Sensitive Electronic Fish Skin for Underwater Wave Sensing

Underwater flexible sensors have a future for wide application, which is promising for attaching them to underwater creatures to monitor vital signals and biomechanical analysis of their motion and perceive tiny environmental disturbances. However, the pressure waves induced by biological swimming are extremely weak and susceptible to undercurrents, making them difficult to sense. Here, we report an ultrahighly sensitive biomimetic electronic fish skin designed by embedding an artificial pseudocapacitive-based hair cell into a simulated canal neuromast encapsulation structure, in which the artificial hair cell, as the key sensitive unit, is assembled from hybrid film electrodes and polyurethane-acidic electrolyte foam. Such a film is prepared by inter-cross-linking MXene and holey reduced graphene oxide with the assistance of l-cysteine, effectively increasing the interfacial capacitance and alleviating the oxidation issues of MXene. Meanwhile, the acidic foam with high porosity shows great compressibility to adapt to a high-pressure underwater environment. Consequently, the device exhibits ultrahighly sensitivity (maximum sensitivity ∼173688 kPa-1) over a wide range of depths (0-100 m) and remains stable after 10000 repeated tests. As an example case, the device is integrated as a motion monitoring system to identify the minor disturbances triggered by instantaneous postural changes of fish. The electronic fish skin is expected to demonstrate enormous potentials in flow field monitoring, ocean current detecting, and even seismic waves warning.

Energy analysis and research on injection control parameter influence mechanism of air assisted spray system

Air assisted spray system is a two-phase flow spray technology, which consists of fuel injector and gas injector. High pressure gas is injected into the air assisted spray system to maintain the high pressure environment. When using, fuel is injected into the system to mix with high pressure gas, and then the mixture is sprayed out through gas injector to complete the atomization process. Because the air assisted spray system can achieve better atomization of high viscosity liquid under lower injection pressure (below 10 bar), it has attracted more attention recently. A geometric model of the air assisted spray system with a complete air assisted nozzle is established. Based on this model, working process of air assisted spray system is investigated by energy analysis method, and influence mechanisms of different injection control parameters are analyzed. As discovered, the energy provided by fuel injection promotes droplet breakup after interacting with gas inside nozzle. Simultaneously, droplet transfers kinetic energy to gas. Afterwards, kinetic energy of gas and droplet is consumed during their interaction, thereby weakening gas–liquid interaction and reducing droplet breakup. After opening needle valve of gas injector, gas can obtain more kinetic energy due to the pressure difference inside and outside the nozzle, which plays a dominant role in the gas–liquid interaction, and promotes the breakup of droplets. However, the kinetic energy of gas and droplets is subsequently transferred to ambient gas, thus weakening the gas–liquid interaction and hindering the breakup of droplets. The fuel injection duration indirectly affects the consumption of gas kinetic energy in gas–liquid interaction by affecting the total amount of droplets, and then affects the characteristics of air assisted spray. The fuel-gas injection interval directly affects the consumption of gas kinetic energy in gas–liquid interaction, and then affects the characteristics of air assisted spray. The influence of gas injection duration on the characteristics of air assisted spray is determined by the influence of the flow inside the nozzle on the external spray.