Pressure Gas Research Articles

Experimental Compressed Liquid Density Measurements and Correlation of the Binary Mixture {n-Pentane (R601) + Trans-1-chloro-3,3,3-trifluoro-1-propene (R1233zd(E))}

Regulations like the F-gas Regulation (EU) 2024/573 and the Kigali Amendment to the Montreal Protocol, along with efforts to mitigate climate change, drive research into alternatives to fluorinated greenhouse gases for high-temperature heat pumps and power generation. Ideal refrigerants should have low GWP, high efficiency, non-flammability, non-toxicity, material compatibility and cost effectiveness. HCFOs have emerged as promising candidates, both as pure fluids and in mixtures with HCs. These blends show efficiency and potential non-flammability for high-temperature applications, but experimental data on their thermophysical properties remain scarce. This study presents the first experimental measurements on the {n-pentane (R601) + trans-1-chloro-3,3,3-trifluoro-1-propene (R1233zd(E))} binary system. In particular, the compressed liquid density of three mixture compositions have been measured employing a vibrating tube densimeter within the temperature range from 283.15 K to 423.15 K and at pressures ranging from 1 MPa to 12 MPa. A novel technique was applied to ensure a combined uncertainty (k=2) not greater than 0.0003 mol·mol-1 in the mixture composition, leading to final combined uncertainty (k=2) on the liquid density of no more than 0.2%. Finally, a new mixture model based on the Helmholtz-energy-explicit Equation of State has been developed from such experimental data. This model accurately represents the behaviour of the binary mixture, enhancing the available understanding of its thermodynamic properties.

Experimental study on multi-scale characterization and damage model of coal particle pores under circulating critical outburst pressure

In the process of coal seam mining, continuous high pressure gas circulation causes accumulating microscopic damage in coal, leading to a decrease in fracture toughness. When pore damage reaches a critical level, the coal body may fracture and become unstable under high pressure gas. Understanding this damage is essential for uncovering the mechanisms of coal and gas outbursts. This study presents experiments on circulating critical outburst pressure desorption using a high pressure desorption device, combined with low temperature liquid nitrogen adsorption tests, to analyze the pore parameters of different coal samples. The experimental results indicate that as the number of high pressure cycles increases, methane desorption generally increases. Bituminous coal exhibits the highest desorption, while lignite shows the lowest. Circulating high pressure significantly impacts the pore characteristics of coal samples. The pores in bituminous coal are well developed, with a liquid nitrogen adsorption growth rate of 50.01%, compared to only 16.49% for anthracite. The growth rate of micropore volume and specific surface area is the highest, indicating that these are the primary sites for gas storage. A comprehensive analysis of the circulating high pressure gas action, gas desorption characteristics, and pore evolution of coal particles led to the development of a quantitative model for pore damage. This model reveals the extent of damage in different coal types after circulating high pressure desorption, providing a theoretical basis for the migration characteristics of coalbed methane.

Pellet-Based Extrusion Additive Manufacturing of Lightweight Parts Using Inflatable Hollow Extrudates

Additive manufacturing (AM) has become a key element of Industry 4.0, particularly the extrusion AM (EAM) of thermoplastic materials, which is recognized as the most widely used technology. Fused Filament Fabrication (FFF), however, depends on expensive commercially available filaments, making pellet extruder-based EAM techniques more desirable. Large-format EAM systems could benefit from printing lightweight objects with reduced material use and lower power consumption by utilizing hollow rather than solid extrudates. In this study, a custom extruder head was designed and an EAM system capable of extruding inflatable hollow extrudates from a variety of materials was developed. By integrating a co-axial nozzle-needle system, a thermoplastic shell was extruded while creating a hollow core using pressurized nitrogen gas. This method allows for the production of objects with gradient part density and varied mechanical properties by controlling the inflation of the hollow extrudates. The effects of process parameters— such as extrusion temperature, extrusion speed, and gas pressure were investigated—using poly-lactic acid (PLA) and styrene-ethylene-butylene-styrene (SEBS) pellets. The preliminary tests identified the optimal range of these parameters for consistent hollow extrudates. We then varied the parameters to determine their impact on the dimensions of the extrudates, supported by analyses of microscopic images taken with an optical microscope. Our findings reveal that pressure is the most influential factor affecting extrudate dimensions. In contrast, variations in temperature and extrusion speed had a relatively minor impact, whereas changes in pressure led to significant alterations in the extrudate’s size and shape.

Navigating the Intersection of Microgrids and Hydrogen: Evolutionary Trends, Challenges, and Future Strategies

Growing interest in sustainable energy has gathered significant attention for alternative technologies, with hydrogen-based solutions emerging as a crucial component in the transition to cleaner and more resilient energy systems. Following that, hydrogen-based microgrids, integrated with renewable energy sources including wind and solar, have gained substantial attention as an upcoming pathway toward long-term energy sustainability. Hydrogen, produced through processes such as electrolysis and steam methane reforming, can be stored in various forms including compressed gas, liquid, or solid-state hydrides, and later utilized for electricity generation through fuel cells and gas turbines. This dynamic energy system offers highly flexible, scalable, and resilient solutions for various applications. Specifically, hydrogen-based microgrids are particularly suitable for offshore and islanded applications, with geographical factors, adverse environmental conditions, and limited access to conventional energy solutions. This is critical for energy independence, long-term storage capacity, and grid stability. This review explores topological and functional-based classifications of microgrids, advancements in hydrogen generation, storage, and utilization technologies, and their integration with microgrid systems. It also critically evaluates the key challenges of each technology, including cost, efficiency, and scalability, which impact the feasibility of hydrogen microgrids.

Liquid–Solid Coupled Internal Flow Field Analysis of Natural Gas Hydrate Spiral-Swirling Downhole In Situ Separator

This study aims to solve the problem of the recovery efficiency of natural gas hydrate being affected by a large amount of mud and sand in the solid fluidization mining of natural gas hydrate. Therefore, a new method for the separation of in situ sediment and natural gas hydrate in a spiral-swirling downhole is proposed, and the corresponding numerical simulation model is established to realize the analysis and verification of key flow field parameters such as flow velocity, pressure, sediment, and natural gas hydrate phase distribution. The results show that the flow velocity field of the mixed slurry presents an ‘M’-shaped symmetrical distribution, and the slurry near the wall of the separator can obtain a larger flow velocity, which is beneficial to the separation of mud–sand and natural gas hydrate. The static pressure field shows an axisymmetric distribution that decreases first and then increases, indicating that the pressure of the mixed slurry increases with the increase in the radial position, and the closer to the wall, the greater the static pressure of the mixed slurry. Near the wall of the separator, the volume fraction of the sediment phase reaches the maximum. In contrast, the volume fraction of the natural gas hydrate phase reaches the minimum, which confirms the separation effect of the sediment and the natural gas hydrate. The results show that the separation of sediments and natural gas hydrate can be realized, thereby improving the exploitation efficiency of natural gas hydrate. The designed spiral cyclone coupling separator provides a new solution to solving the problem of sand removal in natural gas hydrate exploitation.

Recovery of Bioactive Constituents from Olive Leaf Pruning Waste of Five Different Cultivars: A Comparison of Green Extraction Techniques to Maximize Health Benefits.

Sustainable agro-waste revaluation is critical to enhance the profitability and environmental footprint of the olive oil industry. Herein, the valorization of olive leaf pruning waste from five cultivars ('Caiazzana', 'Carolea', 'Itrana', 'Leccino', and 'Frantoio') employed green extraction methods to recover compounds with potential health benefits. Sequential ultrasound-assisted maceration (UAM) in n-hexane and ethanol was compared with a compressed fluid extraction strategy consisting of supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) for their efficiency in recovering distinct classes of bioactives. Chemical profiling by UHPLC-HR-MS/MS (ultra-high-performance liquid chromatography high-resolution tandem mass spectrometry) and GC-MS (gas chromatography mass spectrometry) showed that UAM-EtOH effectively extracted polyphenols (especially luteolin derivatives) and triterpenes (notably maslinic acid), while PLE yielded the highest amount of secoiridoids (e.g., secologanoside). PLE extracts showed better antiradical activities, putatively due to a higher content of flavonoids, secoiridoids, and HCA derivatives than UAM-EtOH ones, as these latter also contained 20-40% (cultivar-dependent) of triterpenes. SFE extracts with a higher concentration of fatty acids and triterpenes showed moderate antioxidant activities but very high AChE inhibition. This study highlights the importance of selecting appropriate extraction methodologies based on the target bioactive compounds and underscores the potential of olive leaf extracts for sustainable bio-products.

Analytical Solution and Energy Behavior to a Forced Shock Wave Problem Under Dusty Gas Regime

ABSTRACTIn the presented research work, we have solved a new kind of problem of forced shock waves in a compressible inviscid perfect gas having dirty (dust) particles of small size in a one‐dimensional unsteady adiabatic flow. The approach that we have used is referred to as the generalized geometry approach. Here, we investigated how the density of the zone, which is undisturbed, changes as a function of the position from the point of the source of explosion. In addition, we have obtained analytically a novel solution to the problem in the form of a new rule of power of time and distance. Further, we have investigated the energy behavior of forced shock waves and interaction within the environment containing dust particles. Also, the behavior of the entire energy of a forced shock wave is expounded at different Mach numbers, respectively, for planar geometry, cylindrically symmetric geometry, and spherically symmetric geometry under a dusty gas medium. Furthermore, the findings show that dust particles in a gas produce a more sophisticated representation rather than the standard gas dynamics.

Study on influencing factors and prevention measures of coal-rock-gas compound dynamic disaster in deep coal mine mining

Because coal seam mining with high geostress and high gas pressure is prone to coal–rock–gas compound dynamic disasters, a disaster energy equation considering the influence of roof elastic energy is established, and a disaster energy criterion considering the influence of roof elastic energy is derived and introduced into COMSOL software to conduct numerical simulations of coal seam mining under different geostress and gas pressures. The study revealed that the increase of ground stress reduces the gas pressure required for disaster occurrence. When the gas pressure reaches a certain value, the disaster will occur even if the ground stress is very small. When the ground stress and gas pressure are very low, by changing the magnitude of ground stress or gas pressure, outburst, rockburst and coal‒rock‒gas composite dynamic disasters can transform into each other. As the depth of the excavated coal seam increases, the geostress‒gas pressure increases from 15‒0.5 MPa to 20‒0.74 MPa and 25‒1 MPa, the peak stress and peak gas pressure can reach maximum values of 39.61 MPa and 1.11 MPa, respectively, the difference between the elastic energy of the coal rock body and the expansion energy of the gas is not large, and the energy criterion is greater than 1 and increasing, which indicates that the occurrence of a compound dynamic disaster and the degree of hazard gradually increase. The high-pressure water jet slit technology can increase the average gas extraction volume by 3.6 times, the peak stress is transferred from 7 m away from the coal wall to 10 m, and the peak stress is transferred to the deep coal wall, which can effectively reduce the stress in the coal rock mass and the gas pressure in the coal seam.

Cold Sprayed Copper-Diamond Composites for Thermal Management of Semiconductor Packages

Thermal management is key to enabling increasingly powerful chips and heterogeneous integrated 2.5D/3D systems. Composite materials with high thermal conductivities that can be placed at different levels of proximity to the die provide new solutions for heat dissipation. Here we report the fabrication of thick copper-diamond composite films using cold spray, which is a high-throughput, low-thermal budget deposition technology. In cold spray, feedstock micro powder is accelerated in a specially designed nozzle by a heated pressurized gas and adheres to the substrate upon high-speed impingement. This process achieves higher deposition rates than other methods used in semiconductor manufacturing (such as electroplating). It also produces films which are denser and much less porous than ones produced by conventional thermal spray techniques. In this work, we first use process and thermal simulations to determine the requirements of the micro diamond powder feedstock, including the diamond core size, metal clad thickness, the core-clad interfacial resistance and volume fraction to enable the cold spray of copper-diamond composites with thermal conductivities that are higher than copper’s. Subsequently, we perform systematic characterization of the diamond powders from several suppliers, including the purity, metal oxygen content, particle morphology and metal-clad adhesion. This characterization reveals the challenges of meeting all the specs using currently available diamond powders . Finally, we cold spray copper-diamond composite films on a variety of substrates with tunable thicknesses between 100um -2 mm, achieving a thermal conductivity that is approximately 10% higher than cold sprayed pure copper. Further improvement of the thermal properties relies on continued innovation in powder surface modification and powder packaging/shipping methods.

Novel CO2 loaded nanoparticle ultrasound-activated contrast agent: A potential urinary catheter-free modality to detect vesicoureteral reflux.

The current gold-standard for detecting vesicoureteral reflux (VUR) is the voiding cystourethrogram (VCUG). However, VCUGs require ionizing radiation and bladder catheterization that can be challenging to perform and traumatic for pediatric patients and their parents. To investigate the feasibility of a novel urinary catheter-free modality for diagnosing VUR using invitro and exvivo models. Polyethyleneimine (PEI) and pressurized CO2 gas were utilized to formulate our polymer in a standardized and reproducible method. The CO2-loaded PEI solution was stimulated using moderate intensity ultrasound in latex balloons and ev-vivo porcine bladders. Degassed, deionized water served as the control. A Butterfly iQ ultrasound imaging system connected to a 9th generation iPad was utilized to observe any effervescence (bubbles). In both the balloon and exvivo bladder models, CO2 effervescence is reproducible and visualizable from the CO2-loaded polymer solution under US imaging after stimulation. We have demonstrated the ability to selectively release CO2 from CO2-loaded PEI nanoparticles to serve as an ultrasound contrast agent in both invitro and exvivo models. Future combined kidney-bladder porcine model experiments will be a critical step as we work towards validating and translating this agent as an effective modality for the diagnosis of VUR. In this feasibility study, we evaluated early pre-clinical models of a urinary catheter-free modality for the diagnosis of vesicoureteral reflux. We utilized a novel CO2-loaded nanoparticle solution that creates bubbles when activated with moderate intensity ultrasound. These bubbles were clearly visualizable with regular diagnostic ultrasound imaging in both a latex balloon and porcine bladder model.

A TVD WAF scheme based on an accurate Riemann solver to simulate compressible two-phase flows

PurposeThis study aims to propose a robust total variation diminishing (TVD) weighted average flux (WAF) finite volume scheme for investigating compressible gas–liquid mixture flows.Design/methodology/approachThis study considers a two-phase flow composed of a liquid containing dispersed gas bubbles. To model this two-phase mixture, this paper uses a homogeneous equilibrium model (HEM) defined by two mass conservation laws for the two phases and a momentum conservation equation for the mixture. It is assumed that the velocity is the same for the two phases, and the density of phases is governed by barotropic laws. By applying the theory of hyperbolic equations, this study establishes an exact solution of the Riemann problem associated with the model equations, which allows to construct an exact Riemann solver within the first-order upwind Godunov scheme as well as a robust TVD WAF scheme.FindingsThe ability and robustness of the proposed TVD WAF scheme is validated by testing several two-phase flow problems involving different wave structures of the Riemann problem. Simulation results are compared against analytical solutions and other available numerical methods as well as experimental data in the literature. The proposed approach is much superior to other strategies in terms of the accuracy and ability of reconstruction.Originality/valueThe novelty of this work lies in its methodical extension of a TVD WAF scheme implementing an exact Riemann solver developed for compressible two-phase flows. Furthermore, other novelty lies on the quantitative calculation of different Riemann problem two-phase flows. Simulation results involve the verification of the constructed methods on the exact solutions of HEM without any restriction of variables.

Maximizing the neuroprotection from Citrus aurantium leaves: optimization of a blended extract from a sequential extraction process with compressed fluids and NaDES.

Maximizing the neuroprotection from Citrus aurantium leaves: optimization of a blended extract from a sequential extraction process with compressed fluids and NaDES.

Experimental compressed liquid density measurements and correlation of the binary mixture {3,3,3-trifuoropropene (R1243zf) + isobutane (R600a)}

Experimental compressed liquid density measurements and correlation of the binary mixture {3,3,3-trifuoropropene (R1243zf) + isobutane (R600a)}

Experimental assessment of different compact flow channel geometries on pressurised gas solar receivers

Experimental assessment of different compact flow channel geometries on pressurised gas solar receivers

An Innovative Approach to Mass Measurement of Liquids and Gases in Closed Containers By The Use of Piezo Ceramic Sensor

This article focuses on developing an innovative system for the precise and accurate measurement of the masses of liquids and pressurized gases in sealed containers. The system is based on piezoelectric sensors that detect pressure changes and process these signals to determine the mass of the liquid. The pressure changes detected by the piezoelectric sensors are converted into electrical signals, amplified by an amplifier circuit, and transmitted to a processor. The processor analyses these electrical signals utilizing developed algorithms to determine the mass of the liquid. The sensors used operate in a wide frequency band, adapting to different types of liquids and container shapes. Experimental results show that the developed system offers a great advantage, especially in industrial applications as it measures the liquid mass with high accuracy and does not require direct contact with the liquid. With the developed system, electronic amplifier circuits and digital filtering techniques were used together to minimize signal noise. This way, current voltage gains were increased and measurement accuracy was improved. This project offers an economical, non-contact, and reliable solution for determining the mass of the measured substance and brings an important innovation, especially in areas such as the chemical, food, and pharmaceutical sectors.

Teaching Practice to Enhance Safety Awareness of Students in Welding Processing Professional Training

As an important part of cultivating students’ practical skills, the safety of welding processing professional training cannot be ignored. Students' safety awareness is directly related to their training effectiveness and personal safety in complex environments such as high temperatures, high pressure, and harmful gasses. Therefore, enhancing students' safety awareness in welding processing professional training is not only a guarantee of teaching quality but also a responsibility for students’ life safety. This article will explore effective teaching strategies and practical methods based on this. By strengthening safety education, simulating real-scene drills, and building a safety culture, we can comprehensively enhance students’ safety awareness and self-protection abilities, escorting their professional growth.

Analysing Recurring Failures: Case Study of a Pressurized Gas Supply Pipeline

This paper presents a case study of an in-service failure occurred in a pressurized gas supply pipeline, which has been recurring in recent years, particularly during the winter season. The investigation focused on two pipe coupons extracted from a DN 300 pipeline, which had sustained damage while in operation as part of a natural gas pipeline. Through the implementation of mechanical and non-destructive testing methods on the pipe couplings and their welds, multiple non-conformities were identified. These non-conformities were found to be the root causes of failures that occurred after welding and during operation. The findings of this investigation have led to several valuable comments and recommendations, which are beneficial for manufacturing companies and clients alike. Implementing these suggestions can contribute to enhanced safety and operational efficiency in gas pipeline systems.

COMPUTATION OF UNSTEADY SWIRLING FLOWS IN NOZZLES AND PIPES BY APPLYING A NEW LOCALLY IMPLICIT GODUNOV-TYPE SCHEME

A new class of numerical schemes for calculating unsteady swirling flows in nozzles and pipes based on compressible inviscid gas equations is presented. The main advantage of these schemes is their ability to efficiently handle unsteady problems with multiple scales. The construction of such schemes is based on the well-known Godunov approach, which involves calculating fluxes at the faces of computational cells (volumes) by solving auxiliary one-dimensional problems in the vicinity of each face and approximating conservation laws. The scheme switches from an explicit method to an implicit one for flux calculation based on an analysis of the current solution near the cell face. The scheme is absolutely stable and does not generate spurious oscillations. Its effectiveness is demonstrated in the calculation of unsteady swirling flows in nozzles and pipes. Specifics of setting up problems of this type are investigated, and options for proper problem formulation are proposed. Properties of the solution for swirling flows with a central body covering only part of the symmetry axis in the computational domain are also studied.

Performance Evaluation of Common Rail Direct Injection Engine Run on Biodiesel of Used Temple Oil Using Response Surface Methodology

<div>Diesel engines produce more smoke and nitrogen oxide (NOx) emissions. Hence, one has to develop a new technique that reduces these emissions besides works satisfactorily with alternative fuels in place of diesel. In this work, used temple oil biodiesel (BTO) is a candidate to replace diesel to run diesel engine. Also, common rail direction injection (CRDi) is a technique that injects fuel at a higher pressure than conventional injectors of diesel engines that produce fine fuel droplets suitable for highly viscous biodiesel. This work also uses the design of experiments (DOE) and response surface methodology (RSM) modeling approach to evaluate the performance of CRDi engine with three operating parameters namely injection timing (IT), injection pressure (IP), and exhaust gas recirculation (EGR). From the study, it could be concluded that CRDi engine showed better performance at IT of 9°bTDC, IP of 855 bar with EGR of 20% but with little reduction in thermal efficiency. The study has reported good agreement between predicted values and experimental results.</div>

Fluorescence imaging of individual ions and molecules in pressurized noble gases for barium tagging in 136Xe

The imaging of individual Ba2+ ions in high pressure xenon gas is one possible way to attain background-free sensitivity to neutrinoless double beta decay and hence establish the Majorana nature of the neutrino. In this paper we demonstrate selective single Ba2+ ion imaging inside a high-pressure xenon gas environment. Ba2+ ions chelated with molecular chemosensors are resolved at the gas-solid interface using a diffraction-limited imaging system with scan area of 1 × 1 cm2 located inside 10 bar of xenon gas. This form of microscopy represents key ingredient in the development of barium tagging for neutrinoless double beta decay searches in 136Xe. This also provides a new tool for studying the photophysics of fluorescent molecules and chemosensors at the solid-gas interface to enable bottom-up design of catalysts and sensors.