ABSTRACT This paper proposes a cascade multiple‐input–multiple‐output (MIMO) control framework for trajectory tracking of hydraulic robotic manipulators with multi‐closed‐loop kinematic chains. A dynamic modeling method integrating screw theory with reduced system dynamics is first developed to derive standard Lagrangian equations of motion for such manipulators. As large flow‐rate cartridge valves or combined flow control valves are commonly employed in these systems for heavy‐duty operation, a non‐affine nonlinear model is formulated to characterize the hydraulic actuation dynamics. A cascade control algorithm is then proposed, integrating a MIMO approximate nonlinear internal model with a feedback controller to achieve accurate trajectory tracking. The proposed approach tightly couples a computationally efficient screw‐theory‐based dynamic model of the multi‐closed‐loop mechanism with a MIMO approximate internal model control (AIMC) structure tailored to the system's non‐affine actuation characteristics. Whereas existing IMC implementations have predominantly focused on SISO or input‐affine systems, this paper develops a systematic methodology for deriving and implementing discrete‐time MIMO AIMC for non‐affine hydraulic systems, providing a principled framework for handling the inherent nonlinearities and model uncertainties of hydraulic manipulators with non‐affine valve actuation. Experimental results confirm that the proposed controller achieves high trajectory tracking performance on the hydraulic multi‐closed‐loop manipulator platform.

International compendia specify setting the flow for testing dry powder inhalers (DPIs) with the pressure ratio across the flow control valve ≤0.5. This guidance derives from thermodynamic theory, but there is no requirement that the flow control equipment demonstrates adherence to this theory. There is therefore a need to define and test for acceptable flow control valve performance, enabling DPI manufacturers to determine whether their test equipment is achieving the expected flow control. Herein, we present flow control data for two valves common in the inhaler testing community and describe the need for qualification specifications for flow control equipment with such valves. We devised a simple laboratory apparatus and method for determining the mass flow rate through two common flow control valves in their commercial configuration. In the test method, the pressure ratio across the valve is lowered from ∼0.7 to 0.3. This range of pressure ratio covers the standard test requirement that the pressure ratio must be 0.5 or less and maps the transition of compressible flow through the valve to the point where the air flow theoretically remains constant. A common industrial valve, mentioned specifically in Pharm. Eur. 2.9.18 and in earlier editions of United States Pharmacopeia 601, exhibits nearly constant flow when the pressure ratio is <0.5. Another valve in widespread use exhibits a continued slight increase in mass flow rate even as the pressure ratio is decreased below 0.5. Inhaler testing laboratories should test whether their equipment exhibits the constant flow condition that is often assumed when the pressure ratio across the flow control valve is 0.5 or smaller. Quantitative specifications, yet to be developed, for qualifying commercial flow control equipment must account for both the transient start-up and the steady-state flow in DPI testing.

Precise monitoring of control valve performance is essential for regulating combustion outlet temperature, minimising nitrogen oxides emissions, and maintaining stable combustion in natural gas turbines. This study examines the temperature variations of a natural gas flow control valve, taking into account changes in valve stem position and cross-sectional area within a gas turbine power plant. A unique model is introduced to regulate valve area variation and assess performance based on the correlation between upstream and downstream temperatures. The model elucidates the impact of fluctuations in the valve cross-sectional area on the downstream natural gas temperature, taking into account upstream temperature variations between 285.15K and 305.15K. The Joule-Thomson coefficient is obtained from thermodynamic equations by the AGA8-92DC numerical approach. The gas composition, inversion characteristics, upstream and downstream temperature differentials, and the temperature gradient relative to the valve cross-sectional area were computed for two samples of natural gas and pure methane. The results demonstrate the differences in upstream and downstream temperatures at two pressure levels (2MPa and 5.4MPa). The comprehension of the temperature differential between the upstream and downstream areas can act as a crucial metric for condition monitoring and assessing the efficacy of fuel injection in control valves.

The domestic hot water air-source heat pump has gained great attention recently due to global efforts to decarbonize the energy sector. Its coefficient of performance (COP) falls within the range of 3 to 4, which contributes to significant energy consumption and increased carbon emissions. Addressing these issues, the present study proposes an effective integration between a dual-condenser vapor compression cycle and an ejector to overcome these shortcomings. In the proposed vapor compression–ejector heat pump (VCE-HP), the compressor’s discharge pressure is further exploited to lift extra thermal energy from the ambient and bring it to the low-condenser temperature for water heating. A flow control valve is installed to regulate the amount of the refrigerant flow rate used to power the ejector and the condensers’ heating capacity to be able to achieve the targeted hot water temperature and flow rate over a wide range of operations. An exergoeconomic model estimating the COP, exergetic efficiency (η II), specific cost of hot water (SCHW), and product cost (Cproduct) is built to assess the techno-economic feasibility of the proposed VCE-HP. In addition, the performance of the VCE-HP using low global warming potential (GWP) refrigerants (R1234yf, R290, R1234ze(E), and R717) is assessed and compared with that using R134a. It has been determined that an increase in the ejector entrainment ratio does not inherently translate into an improvement in the COP or a reduction in system cost. Results indicate that the performance of the VCE-HP is always higher than that of traditional heat pumps by 20–50% based on the type of refrigerant. Results conclude that R1234ze(E) can achieve a COP of 5.38, making it a potential alternative to R134a due to its low GWP and zero ozone depletion potential.

Investigation of cavitation-induced failure mechanisms in charging flow control valves for nuclear power plants

The seal of a flow control valve is a critical component in hydraulic systems. Seal failure may cause leakage, reduced energy efficiency, and unplanned shutdowns, posing severe threats to safe system operation. Traditional seal fault diagnosis methods often suffer from strong hysteresis and excessive reliance on expert experience; hence an efficient, real-time online seal monitoring technique is urgently needed. This paper proposes a seal fault diagnosis method for flow control valves based on a Convolutional Neural Network with a Convolutional Block Attention Module (CNN-CBAM). First, a reciprocating seal test rig was established, and seal models with multiple fault modes—including abrasion, aging, scuffing, and poor lubrication—were constructed. Friction force–time series data were collected. Then, time–frequency analysis methods such as the S-transform, Short-Time Fourier Transform (STFT), and Continuous Wavelet Transform (CWT) were used to convert the signals into time–frequency maps, which served as input features to the CNN-CBAM network. On this basis, we analyzed how the three time–frequency methods affect the performance of the CNN-CBAM hybrid architecture. Experimental results show that the S-transform + CNN-CBAM model achieved a test accuracy of 99.33% on 3000 samples and better preserved the frequency-adaptive characteristics of the signal. The proposed method significantly improves diagnostic accuracy and robustness, demonstrating that the CNN-CBAM hybrid architecture can effectively identify reciprocating seal faults.

This paper reports the particle excitation flow control valve using flexural vibration mode. The authors have been developing a compact, light-weight air flow control valve, which can control air flow continuously. This valve controls airflow using particle excitation caused by piezoelectric vibration and the vibration acceleration determines the flow characteristics. In order to reduce the vibration acceleration required for flow control of this control valve mechanism, we proposed a driving principle that uses torsional vibration as a vibration perpendicular to air pressure. However, in the method, the orifice did not open completely, so the controllable flow rate remained low. Therefore, to expand the control flow, we propose a control valve that uses flexural vibration, which is orthogonal to air pressure. In this paper, we present a prototype vibrator that generates flexural vibration mode, and demonstrate the effectiveness of the proposed valve control method through experimentation.

Abstract Clinical observations from austere environments reveal operational failures in field whole blood transfusion equipment. These failures compromise patient care by impeding blood product delivery due to flow restriction and condensation accumulation within the delivery system. This research investigated the effects of cold exposure on the transfusion kit components, with a specific focus on intravenous (IV) tubing to address an important gap in the current literature regarding the quantitative assessment of cold-induced changes in medical equipment functionality. Fresh whole blood transfusion equipment was exposed to −40 °C in an environmental chamber for 24, 44, 84, and 96 h to simulate cold exposure during transportation in an austere environment. Postcold exposure testing was conducted at room temperature, simulating conditions in a heated field tent, and comprised of two phases: (1) structural deformation assessment using MicroVu camera imaging system and (2) volumetric flowrate measurement using ultrasonic flowrate sensor. Cold exposure induced significant structural alterations in the intravenous (IV) tubing, characterized by patterns of localized indentations and diameter variations. Deformation was most prominent at stress concentration points such as the tubing inlet near flow control valves and downstream of the filter. It was shown that volumetric flowrates decreased substantially from baseline measurements of 165 mL/min to 110–120 mL/min postcold exposure. Plastic, single-use medical equipment, particularly IV tubing, demonstrated poor tolerance to cold exposure of as little as 10 min, resulting in compromised functionality. However, it was demonstrated that increasing the temperature of the infused fluid promotes structural recovery of the tubing and improves functional performance. This recovery mechanism suggests potential interventional strategies: (1) development of prewarming protocols for cold-exposed equipment, (2) incorporation of cold-resistant polymer formulations in transfusion kit components, and (3) design modifications at identified stress concentration points.

Field application of the inline gated pipe equipped with constant flow control valve, case study: Qazvin, Iran

Pressure drops on the working fluid flow control valves in hydraulic drive systems have a decisive impact on high-precision control of hydraulic receivers. The flow rate-dependent characteristics of pressure drop can be used to make informed decisions on the shape of poppet-seat pairs and to improve the operating parameters of the drive system. This fact is of particular importance in the designing of new hydraulic valves which can be manufactured with the use of modern manufacturing technologies (e.g. additive manufacturing). This article presents the results of CFD simulations of hydraulic oil flow through the flow-control valve, verified in experimental tests on a test stand. The tests focus on the flow through small control gaps, within the lift range from 0.25 to 1.5 mm, and indicate a high level of consistency between the CFD model and the experimental results. The research result is a numerical model which enables the representation of flow characteristics in hydraulic valves and thus allows a fast CFD analysis at a certain accuracy level. It also allows the significance of the set numerical parameters, including the mesh parameters and the turbulence model, to be estimated from the perspective of its impact on the calculation accuracy of pressure drops on the valve. The numerical model is a basis for designing further prototypes of modern “green” plastic hydraulic elements to be used in zero-emission drive systems. • The research confirms the possibility of quickly and accurately representing flow characteristics of flow control valves using CFD. • The findings regarding mesh refinement and the advantage of the k-ω SST turbulence model are important in this type of simulations. • The research presents a method of measuring pressure drops and obtaining flow characteristics of lift valves. • The developed model will be instrumental in prototyping new plastic valve designs, especially for “green' hydraulic systems. • This approach, leveraging polymers and additive manufacturing, allows for quick evaluation of pressure drops in new designs.

Research on the steady-state position of the automatic spool of a self-operated flow control valve

To ensure confident molten salt flow operations within Generation 2 concentrating solar power (CSP) and other advanced &gt;700°C molten salt-based power systems, for Gen 3 CSP and Gen 4 Nuclear Energy (NE), an advanced flow control valve is required. This paper investigates development of two molten salt flow control valves (FCV) for operational demonstration of bellows-style and quick-change packing designs. This innovative high-temperature molten salt valve, with nominal operation at 750°C and 11 bar has been demonstrated using FLiNaK and a ternary chloride molten salt. This work details the general design and flow testing of a bellows-seal FCV. This design includes an integrated closed-loop thermal control system to ensure robust design for freeze-thaw cycles. The design of both valves includes advanced thermal management with ceramic fiber (CF) heaters as well as a novel heat pipe valve stem. This investigation details the development of two high-temperature molten salt test systems that tested these valves up to 750°C and at 11 bar operational pressure. The valve test performed within the Flowserve Corp. Villach test loop employed a DOE Gen 3 CSP (20%NaCl/40%MgCl2/40%KCl by mol. wt. %) ternary chloride salt, while the Kairos Power Isothermal batch test system used FLiNaK (LiF-NaF-KF) as the salt chemistry. The results indicated nominal operation for the two valve systems without the heat pipes at 750°C though with the inclusion of the novel valve stem incorporating these, the temperature gradient along the bonnet was reduced by as much as 210°C, to improve thermal management performance and operational reliability.

To obtain environmental parameters of production zones during well completion operations, a high-temperature-resistant downhole multi-parameter monitoring system was designed. By enabling remote monitoring of downhole environmental parameters, the system provides a basis for formulating efficient extraction strategies. To address the challenge of electronic equipment failure under high temperatures, the heat transfer mechanism of circuits within the hermetically sealed environment of downhole electrically controlled flow control valves was analyzed. A thermal simulation model of downhole circuits was established, and thermal analysis of downhole acquisition circuits was conducted using specialized simulation software. Through optimized chip layout and heat dissipation design, the system's heat resistance was significantly improved. For communication, the Modbus protocol was selected, and a surface control system was developed using the ForceControl platform. This achieved real-time communication between surface control equipment and downhole acquisition circuits. Multi-node communication tests and high-temperature experiments verified that the monitoring system operates stably at 120°C, with accurate and reliable data transmission among multiple nodes, meeting actual engineering requirements. This system offers a reliable solution for the design of intelligent downhole multi-parameter monitoring systems.

Shut-off and control valves in hydraulic systems are among the primary sources of pressure pulsations in the working fluid. These pulsations propagate throughout the system as acoustic waves or hydrodynamic noise (HDN). This study investigates the potential for reducing HDN in the throttling section of a valve by installing perforated screens downstream of the throttling device. A methodology for selecting the key parameters of these screens is proposed. The paper presents both numerical simulations of fluid flow downstream of the throttling element and supporting experimental data.

Abstract In order to design high-strength downhole flow control valve, realize stratified oil and gas production and dynamic regulation, improve mining efficiency, reduce pollution and promote the development of intelligent completion technology, this paper selects processing materials suitable for electro-hydraulic composite intelligent completion flow control valve based on field working conditions and the working principle of hydraulic control flow control valve. The structure of key components such as valve body, slide sleeve and throttle valve sleeve is designed, and the mechanical properties of key components of flow control valve are modeled and simulated successively by numerical simulation method combined with the actual service conditions of flow control valve in the underground, and the service reliability of flow control valve is clarified. The results show that: Under the coupling conditions of pressure 50 MPa, load 650 KN and temperature 125 °C, the maximum stress value appears on the surface of the throttle valve sleeve is 980 MPa, and the maximum deformation of the parts is controlled within 0.202 mm, and the strength of all parts is lower than the yield strength of the material, fully meeting the requirements of the field working conditions. This tool is of great significance for improving oil field recovery and intelligent well completion development.

Ultra-high-temperature and pressure downhole environments pose challenges for conventional electronic instruments to adapt to high-temperature formations, thereby restricting the application of downhole electronic tool technology in deep and ultra-deep wells. Given the aforementioned limitation of electronic inclination measurement systems, specifically their poor temperature resistance, this study proposes a novel shunt flow control method. This method employs a mechanical structure to overcome temperature constraints: gravitational torque generated by the mechanical structure is utilized to control valve opening and regulate flow rate. By converting sensed well inclination information into changes in flow rate, this approach enables the transformation of well inclination sensing and its associated signals. In this study, a kinetic analysis model of the shunt-regulating valve spool was established. Using computational fluid dynamics (CFD) simulations, the flow characteristics of the regulating spool were analyzed under varying valve openings. The structure of the flow control valve was optimized with the goal of maximizing internal flow. Finally, the reliability of the designed structure for well deviation sensing and flow control was verified using simulation experimental studies and theoretical analyses.

Background: Radon (&lt;sup&gt;222&lt;/sup&gt;Rn) and thoron (&lt;sup&gt;220&lt;/sup&gt;Rn) are naturally occurring radioactive gases with significant differences in half-life, influencing their indoor behavior. Radon has well-documented health risks and mitigation strategies, but thoron has received less attention. This study explores thoron behavior in relation to air flow dynamics and ventilation conditions used to mitigate radon levels.Materials and Methods: Controlled experiments were conducted from February to June 2021 in an empty basement room and a laboratory simulation. Radon and thoron activity concentrations were measured using Durridge RAD7 radon monitors. Forced air movement was achieved through a fan, and ventilation conditions were simulated in the laboratory using air pumps with inline flow control valves. The exhaust state varied between closed and open air systems.Results and Discussion: The experiments revealed that while radon concentrations were stable or decreased under both forced air movement and increased ventilation rates, thoron concentrations displayed an inverse relationship with forced air movement, irrespective of an open or closed air system. Additionally, thoron required much higher ventilation rates (&gt;50 air changes per hour [ACPH]) to reduce concentration levels that radon achieved with much lower rates (1–10 ACPH). This suggests certain ventilation strategies might inadvertently elevate thoron levels despite reducing radon levels, indicating a nuanced interaction between thoron concentration and air flow dynamics.Conclusion: This study underscores the importance of considering thoron’s unique behavior when implementing ventilation strategies for indoor radioactive gas mitigation. It calls for a nuanced approach to managing air flow dynamics to effectively reduce both radon and thoron levels. Further research is needed to refine models for ventilation strategies in radiation hazard mitigation for radon and thoron.

The energy-efficient control of heating systems is a highly perspective issue. Retrofitting old heating systems require flow control valves which can provide linear control of flowrate; therefore, an accurate model is needed to be able to use simulation methods to efficiently optimize these systems. The Simscape toolbox of MATLAB/Simulink, widely used in engineering practice, includes a ball valve model that can be used as a throttle; however, the model may not be sufficiently accurate. In this research, a comprehensive mathematical model describing the flow cross-section of a ball valve is presented. An experimental system was built to be able to verify simulated data, thus validate the developed model. The developed and Simscape model is compared to measured data which shows a significant accuracy improvement. This study presents a new improved ball-valve model that considers the real geometry of the valve providing accurate simulation results, making it possible to simulate retrofitted systems with ball-valves.

Abstract Precision flow control valves play a critical role in pipeline transportation systems by dynamically regulating medium flow. However, existing research lacks comprehensive analysis of flow characteristics and erosion prevention strategies for specific valve configurations. This study employs a fluid-structure interaction approach to systematically investigate the flow behavior and spool force distribution in a precision flow control valve. Results reveal that the outlet flow increases with relative valve opening up to 0.8, beyond which choked flow conditions induce a 6.3% reduction in discharge rate. Notably, counter-impacting jets formed by bilateral throttling ports cause significant flow deflection towards one sidewall. Erosion analysis identifies the spool bottom region as the most vulnerable area. Through comprehensive performance evaluation, the optimal relative opening range of 0.4-0.8 is determined to balance flow regulation accuracy and service life extension. These findings provide valuable insights for the structural optimization of industrial flow control valves and contribute to the development of intelligent manufacturing solutions in fluid system management.

ABSTRACT Pneumatic systems are widely used in industrial applications such as palletising, labelling, embossing, material transfer, turning and inverting parts, packaging, and end of the line inspection. This study builds a test rig to examine how input parameters, such as pressure, cylinder orientation, flow control valve setting, and load magnitude, and the interactions between them affect the stopping accuracy and response time of a double-acting, single-rod pneumatic cylinder. The inquiry collects and analyses data using the Design of Experiments (DOE) technique. The best stopping accuracy and response time is achieved by tweaking the pressures at blank end and rod end definitely, but they are not the sole factors determining the stopping accuracy and response time. Rightly manipulating the flow control valve setting which control the amount of air exiting the cylinder, weight of attached loads and cylinder orientations also influence the stopping accuracy and response time significantly. This study acts as a guideline on how to improve stopping accuracy and response time without the intervention of expensive linear and nonlinear control system techniques for low-cost automation industries. The results show that the horizontal orientation of the pneumatic cylinder provides the best stopping accuracy of 9 mm at a response time of 2.29 seconds at higher pressures settings in the test rig. Furthermore, the best stopping accuracy and response time for each orientation of cylinder, is presented along with respective pressure and flow control valve settings. The experimental results are subjected to the boundary conditions of the developed test rig.