Flow Rate Control Research Articles

Numerical study on a new adjustable multi-hole throttling device for natural gas flooding

Natural gas flooding represents a significant technique for the enhancement of oil recovery, thereby facilitating the efficient utilization of oil and gas resources. In the injection and production system, the throttling gas nozzle is a key component that adjust the injection pressure according to the reservoir’s pressure. However, current throttling gas nozzles utilize a fixed structure, which presents a challenge in achieving online control of flow rate and pressure drop. Therefore, a new adjustable multi-hole throttling device was proposed in this paper, allowing for the regulation of pressure loss by changing the number of flowing holes. In order to gain insight into the operational principles and pressure drop characteristics of this new throttling device, the SST k-ω turbulence model and the NIST physical property model were employed to simulate the supercritical natural gas flow in the nozzle. The results demonstrate that there is an uneven distribution of velocity between the channels of the downhole multi-hole throttling device. The velocity in a single nozzle channel exhibits a trend of initially increasing rapidly and then decreasing, while the pressure exhibits an initial decrease, which is then followed by a slight increase. The pressure drops of the nozzle under different flow rates and flowing hole numbers were acquired, revealing that the pressure drop of the multi-hole throttling device is inversely proportional to the number of holes. The adjustment accuracy of pressure drop and flow rate is higher when the number of holes is between 4 and 6. However, a significant increase in pressure drop occurs when the number of holes is less than 3, resulting in poorer regulation accuracy. Furthermore, a pressure drop prediction model was developed based on the numerical results, which provides guidance for the application and design of the throttling device. In this study, a new natural gas flooding throttling device is proposed, offering a new approach for downhole equipment development. Additionally, this research provides guidance for the practical application and iterative improvement of this throttling device in future use.

Physicochemically modified polymer-based fluidic gates with tunable wetting properties for intelligent liquid manipulations

The creation of a selective flow path and the regulation of a flow rate are of critical importance for polymer-based devices that manipulate liquid at the microscale. The formation of a 3D interconnected network of voids (i.e., physical volumetric modification) and the addition of a nonionic surfactant, Silwet L-77, (i.e., chemical volumetric modification) are expected to affect the wetting properties of polymers, thereby achieving selective gating effect in the polymer-based devices as an appropriate technology. Here, a set of polydimethylsiloxane (PDMS)-based fluidic gates (F-gates) were developed to enable selectivity for liquids and flow-rate control of the liquids by tuning the wetting properties of PDMS with the physicochemical volumetric modifications. For water and oil with different surface tensions (STs), the effects of the physical and chemical volumetric modifications on the fluidic gating of PDMS were quantitatively characterized in terms of contact angle, mass flow rate, and liquid absorption speed. The applicability of PDMS-based F-gates to the selective separation of oil and water even from oil-in-water emulsion was demonstrated by fabricating Janus PDMS-based F-gates. Our physicochemical volumetric modifications were also extensively analyzed to examine whether they satisfy the technological, economic, and ecological requirements of appropriate technology. This is the first effort to tailor the wetting properties of PDMS through physicochemical volumetric modifications, thus configuring a set of PDMS-based F-gates that act both as a separator for liquids of different STs and as a switch for fluid flows.

Study on the dynamic characteristics and control strategies of the coupled system of the FHR and SCO2 cycle

The supercritical carbon dioxide (SCO2) Brayton cycle has high efficiency, compactness, and rapid response. Furthermore, the fluoride-salt-cooled high-temperature reactor (FHR), as a Generation IV nuclear reactor, is characterized by compactness, high temperature, and inherent safety. Therefore, the SCO2 cycle as the energy conversion system of the FHR can meet the requirements of modularity and compactness. However, the interaction characteristics between the FHR and SCO2 cycle are unknown, and the system control strategies that can guarantee the safety and flexibility of the coupled system need to be explored. In this study, a dynamic simulation model of the coupled system of the FHR and SCO2 cycle is established. Considering the complexity of the system, the dynamic characteristics of the FHR and SCO2 cycle are investigated separately. Then, the FHR and SCO2 cycle is coupled, and the interaction characteristics between the FHR and SCO2 cycle are further analyzed. It is shown that the coupled system is more flexible under SCO2 mass flow rate disturbance than under FHR reactivity disturbance. Based on that, various SCO2 mass flow rate control strategies are designed and investigated. Among them, the turbine bypass control strategy is the fastest, and system parameters are the most stable.

Blood Biomarker Detection Using Integrated Microfluidics with Optical Label-Free Biosensor.

In this study, we developed an optofluidic chip consisting of a guided-mode resonance (GMR) sensor incorporated into a microfluidic chip to achieve simultaneous blood plasma separation and label-free albumin detection. A sedimentation chamber is integrated into the microfluidic chip to achieve plasma separation through differences in density. After a blood sample is loaded into the optofluidic chip in two stages with controlled flow rates, the blood cells are kept in the sedimentation chamber, enabling only the plasma to reach the GMR sensor for albumin detection. This GMR sensor, fabricated using plastic replica molding, achieved a bulk sensitivity of 175.66 nm/RIU. With surface-bound antibodies, the GMR sensor exhibited a limit of detection of 0.16 μg/mL for recombinant albumin in buffer solution. Overall, our findings demonstrate the potential of our integrated chip for use in clinical samples for biomarker detection in point-of-care applications.

Autonomous Inflow Control Devices Help Maximize Life of Wells in Deepwater West Africa

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 35418, “Design Execution and Evaluation of Advanced Completions in Deepwater West Africa,” by Piyush Pankaj, SPE, Matthew S. Jackson, and Lokesh, ExxonMobil, et al. The paper has not been peer reviewed. Copyright 2024 Offshore Technology Conference. _ Deepwater wells offshore West Africa traverse a complicated faulted block with sand bodies that can feature thicknesses of tens of meters. The study described in the complete paper provides insight into designing advanced well completions under various challenging reservoir conditions with autonomous inflow control devices (AICDs) that enable maximizing the producing life of the wells. Introduction The study area for this paper has been a challenging brownfield. Wells have been drilled in difficult deepwater conditions, and the target reservoirs have been lenticular sands with interbedded shale layers. To further complicate production, the sand bodies are poorly consolidated. Openhole wells with standalone screen and gravel packs have become a common approach to address sand control. Water- and gas-injection programs have been used actively in the field during the past 25 years, which further augments production and reservoir management challenges. Water and gas breakthrough in the infill wells has been a major concern for reservoir management. To address the gas buildup in the near-wellbore region and early water production, AICDs have become a popular feature in the lower well-completion designs in high-angled wells that intersect multiple sand bodies along the lateral completion interval. Two case studies are provided in the complete paper; one is included in this synopsis. Flow-Control Technology Although technology that empowers the ability to control the flow of unwanted fluids from zones in the well has been in use since the 1990s, flow-control technology has rapidly evolved, with advancement fueled by the need for long, complex well designs. The two broad categories of these approaches include active and passive flow control. The decision to use inflow-control technologies can be driven by the following economic values: - Balance drawdown along the wellbore - Increase recovery factor and reserves - Improve well cleanup - Reduces risk of erosion or hot-spotting of sandface completion Choice of Inflow Control for West Africa Field of Study Fluidic-diode AICDs were chosen because of their applicability to encountered fluid properties and reservoir conditions and their robustness of design in providing reliable long-term solutions. The reliability is prolonged in such AICDs because they work without any moving parts. Upon changes in viscosity, density, and rate, the fluid flow path will vary to gain the required control of flow rates. This AICD design, with its special geometry, alters the flow path or pattern for preferential fluid restriction. Operational Execution Ultimately, the AICDs were deployed on an inner string. This allowed the standard wire-wrapped screens and gravel pack to function as the traditional sand-control mechanism, while the inner string, deployed inside the lower completion, provides resistance to flow from unwanted gas production.

A Feedback Control Strategy to Regulate the Temperature in a Nonlinear Solar Receiver

Abstract The substantial energy provided by the sun is a promising substitute for traditional heat sources in various industrial applications. However, the transient nature of solar energy still poses a significant challenge to its widespread utilization. This work presents a methodology for regulating the temperature within a solar receiver by dynamically adjusting incoming sunlight through the aperture using a controlled iris mechanism. The performance of this technique is experimentally compared with the gas flowrate control method, which is typically used in industry. The proposed control system, grounded in the physical model of the solar receiver, underwent experimental testing under varying conditions, including different gas flowrates, simulator power levels, and aperture sizes. The collected data were then analyzed to estimate a simplified model of the solar receiver. A model predictive controller (MPC) is implemented using the model estimations, and its performance was assessed by tracking two set points (335 and 325 °C) over a period of 2 h. The experimental testing of both control systems indicates the superiority of iris mechanism over gas flowrate controller in terms of robustness, settling time, and smoothness. A hybrid control system utilizing both aperture size and gas flowrate is also developed and tested during the operation of the solar receiver via computer simulations.

Modeling and experimental research on adjustable ejector in fuel cell gas circulation system

Fuel cells can be made to operate under a variety of conditions by implementing adjustable ejectors in their anode gas circulation systems. Based on a quasi-two-dimensional model and considering factors such as friction and variable area effects, a theoretical model of ejectors with needles was established to predict their primary and secondary flow rates. Theoretical calculations were used to analyze the variations in internal parameters and flow losses along the ejector, explain the reasons and laws behind the effect of needle position on ejector performance, and explore the control mechanism of different needle shapes on ejector flow rates. Finally, flow control experiments were conducted on three types of adjustable needle shapes–oblique straight, quadratic, and parabolic–to validate the precision of the adjustable ejector theoretical model and the controls of different shapes on the ejector flow rates. The research indicates that the relative errors of the quasi-two-dimensional model in predicting primary and secondary flow rates are within ± 5 % and + 20 % to −5%, respectively. Both the primary and secondary flow rates were impacted by the needle position variation, though the impact on the secondary flow was weaker. The parabolic shape was optimal for the linear control of primary flow rates, followed by the oblique straight shape. The quadratic shape was the weakest, although the quadratic-shaped needle had a wider range of flow rate control. Modeling and experimental research on the adjustable ejector contributes to understanding the influence of the needle on the ejector performance under different working conditions, broadening the application range of the ejector, and providing a basis for flow control in the fuel cell system.

Design and Research of Intelligent Valve Control

The design and research of intelligent valve control system aims to improve the efficiency and accuracy of fluid control in industrial process automation. By integrating advanced sensing technology, communication protocols and intelligent algorithms, the precise control of valve position, pressure and flow rate is achieved. STM32 controller and a variety of sensors are used in the system to realize real-time monitoring and feedback control of valve status. The control strategy based on PID algorithm enables the valve to maintain stable operating performance under complex working conditions. In addition, the safety and reliability of the system are also considered, and the robustness of the system is improved by redundant design and fault detection mechanism. The experimental results show that the designed intelligent valve control system has significant advantages in improving response speed, control precision and energy efficiency, and has a wide range of industrial application prospects.

Operational characteristics and controlling strategies of a novel dual-return-air dehumidification evaporative cooling system (DDEC)

Dehumidification evaporative cooling (DEC) systems exhibit superior environmental adaptability compared to conventional evaporative cooling systems. However, the dehumidification process in DEC is coupled with its cooling process, presenting challenges in adapting to varying environmental conditions. To address this issue, this study proposes a novel dual-return-air dehumidification evaporative cooling system (DDEC) that utilizes two return airflows to control both dehumidification and cooling efficiency. A thermodynamic model based on COMSOL LiveLink with MATLAB for the DDEC has been established and validated, enabling an analysis of the impact of operational parameters on its performance and the identification of key parameters. The results show that there are an optimum inlet flow rate (1100 m3/h) and a third flow rate control factor (0.2) that maximize the coefficient of performance (COP), giving the maximum COP of 0.87 and 0.35 respectively. Moreover, the first and second air flow rate control factors only have a significant influence on the supply air humidity of the DDEC. A higher regenerative temperature can reduce both the temperature and humidity ratio of the supply air but tends to decrease COP. Finally, a single-directional controlling strategy is proposed and analyzed for the DDEC application in different environments.

Maximal transport of non-Newtonian fluid in an anisotropic rotating porous channel with an inclined magnetic field

This study explores the flow characteristics of a viscous, incompressible, conducting Jeffrey fluid in a rotating channel filled with anisotropic porous medium with an inclined magnetic field. The study has relevance to fluid motion in striated rock formations and seepage flow in rotating systems across insulation or geological layers. The channel's rotation axis and a principal axis of the permeability tensor are perpendicular to the walls. The flow is described by the Darcy–Brinkman model under no-slip boundary conditions, applicable in regenerative heat exchangers. Key parameters include the rotation rate and the lateral permeabilities. They have significant impacts on flow behavior. Fluid velocity consists of a primary component aligned with the pressure gradient and a secondary component influenced by the Coriolis force. The variation in lateral permeabilities affects the convexity of the velocity profile, while the magnetic field allows for control of both velocity and volumetric flow rates. The Jeffrey parameter and the inclination angle further enhance the flow behavior. This study provides comprehensive analysis through tables and figures for various values of the anisotropic Darcy number and the rotation parameter, detailing the model's physical properties. The effects of the product of skin friction and the Reynolds number are also discussed, with results aligning with the existing literature for limiting cases. These findings offer valuable insights into fluid behavior in complex environments where rotation, porous structures, and magnetic fields interact with implications for process optimization, resource recovery, and sustainable engineering practices.

Research on Constant-Flow Water-Saving Device Based on Dynamic Mesh Transient Flow Field Analysis

For the control of the outlet flow rate of a constant-flow water-saving device under different water pressures, this study developed and implemented a custom User-Defined Function (UDF) program to simulate the dynamic motion of the water-saving valve within the Fluent environment. This simulation realistically represents the valve’s behavior under varying water pressures, thereby accurately predicting the valve opening height to comply with national regulatory standards. Firstly, a dynamic grid transient CFD simulation model of the water-saving valve was established using a Fluent UDF program written in C language. The parameters of the elastic elements in the water-saving device flow control system were designed to achieve control of the outlet flow rate. Then, the benchmarking analysis of the aforementioned simulation model was completed based on the flow rate test results of the water-saving device. Finally, the relationship between physical quantities and flow field distribution characteristics of the water-saving valve was analyzed under three different water pressures specified in the national standard. Based on the optimization calculations, the valve opening heights under three different water pressures were obtained, ensuring that the outlet flow rates meet the regulatory standards set by the national authorities. Compared with traditional methods that rely solely on steady-state simulations or empirical data, the method proposed in this paper represents a significant advancement.

Comparison study of two control strategies for the small pressurized water reactor

The control strategy has a significant impact on the control performance of the reactor system. This paper investigates the feedwater flow and steam flow control strategies for small pressurized water reactors. First, the mathematical model of the SPWR Nuclear Steam Supply System is introduced. Second, a dual-constant control strategy was proposed, and the feedwater flow rate and steam pressure control systems under the two control modes were designed. Moreover, a steam bypass control system was designed to avoid excessive steam pressure under the feedwater flow control mode, and the reactor power and pressurize control systems were introduced. Simulation results indicate that the two control modes both meet the SPWR control requirements. However, the feedwater flow control mode has better reactor coolant temperature and steam pressure control performances during the load rejection transient, owing to the timely discharge of heat from the reactor coolant system through the steam bypass system.

Mechanistic insights into how mixing factors govern polyelectrolyte-surfactant complexation in RNA lipid nanoparticle formulation

Hypothesis: Lipid nanoparticle self-assembly is a complex process that relies on ion pairing between nucleic acids and hydrophobic cationic lipid counterions for encapsulation. The chemical factors influencing this process, such as formulation composition, have been the focus of recent research. However, the physical factors, particularly the mixing protocol, which directly modulates these chemical factors, have yet to be mechanistically examined using a reproducible mixing platform comparable to the industry standard. We here utilize Flash NanoPrecipitation (FNP), a scalable rapid mixing platform, to isolate and systematically investigate how mixing factors influence this complexation step, first by using a model polyelectrolyte-surfactant system and then generalizing to a typical RNA lipid nanoparticle formulation.Experiments: Aqueous polystyrene sulfonate (PSS) and cetrimonium bromide (CTAB) solutions are rapidly homogenized using reproducible FNP mixing and controlled flow rates at different stoichiometric ratios and total solids concentrations to form polyelectrolyte-surfactant complexes (PESCs). Then, key mixing factors such as total flow rate, inlet stream relative volumetric flow rate, and magnitude of flow fluctuation are studied using both this PESC system and an RNA lipid nanoparticle formulation.Findings: Fluctuations in flow as low as ± 5 % of the total flow rate are found to severely compromise PESC formation. This result is replicated in the RNA lipid nanoparticle system, which exhibited significant differences in size (132.7 nm vs. 75.6 nm) and RNA encapsulation efficiency (34.0 % vs. 82.8 %) under fluctuating vs. steady flow. We explain these results in light of the chemical variables isolated and studied; slow or nonuniform mixing generates localized concentration gradients that disrupt the balance between the hydrophobic and electrostatic forces that drive complex formation. These experiments contribute to our understanding of the complexation stage of lipid nanoparticle formation and provide practical insights into the importance of developing controlled mixing protocols in industry.

Adsorption and decomposition of perfluorinated compounds using NiSBA-15 and CuSBA-15 catalysts for greenhouse gas reduction

BackgroundThe persistence of the environmental effects of perfluorinated compounds (PFCs) and fluorinated compounds (FCs) has raised concerns due to their widespread use and long-term impact on ecosystems and human health. MethodsIn this study, we investigated the use of NiSBA-15 and CuSBA-15 catalysts for the adsorption and decomposition of PFCs/FCs (CF₄, SF₆, NF₃, C₃F₈, and C₄F₈) by varying parameters such as weight percentage and contact time. The catalysts were synthesized through an impregnation method with stirring at 300 rpm for 24 h, followed by calcination at 550 °C for 6 h. The catalytic decomposition of NF₃ was conducted using a glass reactor with precise flow rate control and FT-IR monitoring. Variations in acid concentration during synthesis led to structural changes, transitioning from elongated rods to doughnut-like shapes and eventually spherical structures. Impregnation with nickel and copper nitrates successfully modified SBA-15, forming NiSBA-15 and CuSBA-15, as confirmed by HR-TEM images displaying black spots. Catalytic PFC decomposition experiments using unmodified SBA-15 showed limited efficiency, achieving only 15 % NF₃ removal at 500 ppm and 500 °C over 1000 min. Subsequent modification with nickel and copper significantly improved NF₃ removal efficiency. Significant ResultsCuSBA-15 exhibited superior performance compared to NiSBA-15, reaching a remarkable 95 % removal efficiency of NF3. Kinetic analysis using a pseudo-first-order reaction model demonstrated the enhanced catalytic efficiency of the modified SBA-15 catalysts, with increased reaction rate constants (K) for NF3 decomposition. This study reveals the potential of NiSBA-15 and CuSBA-15 catalysts for the adsorption and decomposition of specific PFCs/FCs, offering valuable insights into the underlying mechanisms and practical applications of these catalysts.

Применение эволюционных и роевых методов для оптимизации многопараметрического управления процессом нанесения гальванического покрытия

One of the key parameters of the quality of ceramic coatings is its thickness, which must meet technical requirements and provide the necessary degree of corrosion protection, wear resistance and appearance of the coating. Ensuring the uniformity of the galvanic coating is one of the most important and complex tasks of high-tech machine-building production, for which a number of methods have been proposed, such as controlling current modes, the location of electrodes in the bath, and the electrolyte flow rate. However, in most cases, these methods require solving the problem of optimal multiparametric control. Prompt and accurate optimization when changing the conditions of electrolysis (electrode potentials, composition and properties of the electrolyte), as well as, if necessary, taking into account the multi-extreme nature of the dependence of the uniformity coefficient on the process parameters (current density, interelectrode distance, electrolyte flow rate) is a rather complex and ambiguous multifactorial task that limits the use of classical methods for- the claim of a global extreme. The article explores the possibility and expediency of using intelligent heuristic methods, such as evolutionary and swarm methods, to solve this problem. Objective. The objective of this study is to determine the effectiveness of using genetic algorithms and the particle swarm method to solve the problem of optimizing the multiparametric control of the electroplating process. Materials and methods. Methods of mathematical modeling, methods and software environment of numerical modeling and optimization were used to conduct the study. Results. The article investigates the effectiveness of the application of evolutionary and swarm optimization methods in relation to the process of applying chrome plating in a galvanic bath with many anodes with multiparametric control of current density, interelectrode distance and electrolyte flow rate. The best approximation to the extreme of the uniformity coefficient can be achieved by genetic algorithms using the mutation operation and the particle swarm method, while achieving the extreme using the particle swarm method is achieved in fewer iterations. Conclusion. The results of the study substantiate the expediency of using evolutionary and swarm methods to solve the problem of optimizing the multiparametric control of the electroplating process, while it is possible to increase the efficiency of these methods due to additional tuning.

Advanced Controllers for Heat Transfer Fluid Mass Flow Rate Control in Solar Tower Receivers

Efficient control strategies for managing the mass flow rate (MFR) of heat transfer fluids (HTF) during cloud transients in Solar Tower receivers play a pivotal role in optimizing plant profitability and receiver durability. This study focuses on the performance and durability of Solar Tower receivers during cloud transients. It evaluates adaptive feedback and feedforward control methods, which adjust the flow rate of heat transfer fluids based on real-time measurements of direct normal irradiance (DNI), receiver outlet and receiver panel outlet temperatures. The effectiveness of an aggressive all-sky and conservative clear-sky control strategy is explored against a conventional PI controller, emphasizing energy efficiency and receiver longevity. Simulations using a thermal Modelica model resembling a 100 MWel Crescent Dunes-like solar tower plant reveal that both advanced controllers provide precise setpoint tracking, while the PI controller struggles. The conservative controller which has a cloud standby mode prevents overheating during cloud transients by using a clear sky mass flow rate, while the aggressive controller uses the receiver panel outlet temperatures to correct for upstream tube temperature variations allowing for fast tracking correction and disturbance rejection, albeit with slight overshoots. Furthermore, the controllers significantly decrease the creep-fatigue damage accumulated in the receiver panels during cloudy days, due to limiting the increase in wall temperature spikes when cloud events end. Overall, this study underscores the pivotal role of HTF mass flow rate control systems in influencing receiver system failure modes and longevity and offers a new tool in controller design and operation assessment.

Enhancing π-SnS thin films and fabrication of p-SnS/n-Si heterostructures through flow rate control in ultrasonic spray pyrolysis for improved photovoltaic performance

This study presents findings related to the characterization of cubic SnS (π-SnS) thin films and p-SnS/n-Si heterojunction structures produced simultaneously using the ultrasonic spray pyrolysis technique. In this context, the impact of different spray solution flow rates on the morphological, structural, optical, and electrical characteristics of the films was examined. Morphological analyses revealed that higher flow rates resulted in films with denser and smoother surfaces, approximately 6 nm in roughness. Additionally, it was observed that both the thickness and the growth rate of the films could be adjusted through the modulation of the flow rate. Structural analyses determined that the crystallite size increased and micro-strain values decreased with increasing flow rates. Optical evaluations indicated a decline in the optical band gap of the thin films from about 1.8 eV to 1.7 eV as the flow rates increased. This trend was consistently observed in the data obtained using the Tauc method and the derivative of transmission with respect to wavelength versus photon energy graphs. Electrical analyses revealed that the resistivity values of the thin films increased from 5.24 × 105 Ωcm to 1.64 × 106 Ωcm with increasing flow rates. Furthermore, I-V analyses of the Au/p-SnS/n-Si/Ag heterojunction structures indicated significant variability in key electrical properties. The saturation currents displayed a broad range, suggesting varying efficiencies in charge carrier collection across different samples. Similarly, the change of ideality factors pointed to differences in charge transport mechanisms, while the shifts in barrier heights indicated changes in junction properties with different fabrication conditions. The results of this study offer valuable perspectives for future research.

Approximating printed circuit heat exchangers dynamics in a sCO2 RCBC as a low-order system via an optimal time constant

The low-order approximation emerges as a promising method for capturing the dynamic behavior of Printed Circuit Heat Exchangers (PCHEs) in sCO2 Recompression Closed Brayton Cycles (RCBCs). However, two primary challenges hinder widespread adoption: concerns regarding feasibility and the determination of key parameters, such as the time constant. To address these challenges, this study first affirms the feasibility of approximating PCHE's dynamic behaviors with a low-order system. In specific, the validity of first-order approximation on the dynamics of high-temperature recuperator (HTR) with mild non-linear property variations is initially assumed. However, a discrepancy is noticed under various operating conditions by employing the same time constant after being compared with the reference model (SCOPE). Then, a novel concept of the optimal time constant, τop, is introduced to underscore the influence of operating conditions on parameter accuracy. Through extensive parameter sweeping, the impact of operating conditions on approximation error is evaluated from two perspectives. First, utilizing τop effectively reduces approximation errors to acceptable levels. The mean squared error remains below 2°C2 for mass flow rate fluctuations below 32.5 kg/s, and below 4°C2 for temperature variations below 40°C. Second, the optimal time constant is significantly influenced by mass flow rate, notably affected by geometry configuration, and minimally influenced by hot inlet temperature. Additionally, this study provides insights for design optimization and control strategy selection, as the findings highlight the trade-off between response speed and thermal performance, and the relatively rapid response of sCO2-PCHEs to temperature control, compared with mass flow rate control.

Clinical efficacy and safety study of Loratadine combined with glucocorticoid nasal spray in the treatment of pediatric bronchial asthma with seasonal allergic rhinitis

Objective To investigate the clinical efficacy and safety of Loratadine combined with Glucocorticoid nasal spray in the treatment of pediatric bronchial asthma with seasonal allergic rhinitis. Methods A total of 100 pediatric patients with moderate to severe bronchial asthma and seasonal allergic rhinitis admitted to our hospital between January 2020 and January 2023 were included in this study. All patients met the complete inclusion and exclusion criteria. Based on different treatment interventions, they were divided into the control group (n = 50) and the observation group (n = 50). Patients in the control group received treatment with glucocorticoid nasal spray, while patients in the observation group received combined intervention with Loratadine in addition to the treatment received by the control group. The clinical treatment outcomes, incidence of adverse reactions, as well as the scores of nasal symptoms, asthma control, and peak expiratory flow rates at different treatment time points (baseline, T1: 30 days after treatment, T2: 60 days after treatment, T3: 90 days after treatment) were compared between the two groups. The combined treatment of Loratadine with Glucocorticoid nasal spray demonstrates significant clinical efficacy in the treatment of pediatric bronchial asthma with seasonal allergic rhinitis. It further promotes the recovery of peak expiratory flow rates, improves symptoms of rhinitis and asthma in pediatric patients. Importantly, the application of this combined treatment does not increase the risk of adverse reactions in pediatric patients, indicating its high safety profile. This treatment approach is worthy of clinical application and further promotion.

Development of performance analysis model with numerical and dynamic energy modeling for an integrated PVT-HP system

This study delivers a comprehensive numerical analysis of an integrated photovoltaic/thermal-heat pump (PVT-HP) system, underscored by an innovative three-dimensional thermal energy storage (TES) model. Addressing the limitations of conventional one-dimensional TES models, which struggled with accurately simulating horizontal flows and the fluid state at various facility inlets, this research marks a significant advancement. Our development of a 3D TES model optimizes finite elements to reduce computation time and enhance accuracy, vital for precise energy analysis in buildings and air conditioning systems. The integration of this model with a network model allows for detailed analysis of flow rate changes and their impacts on heat transfer, crucial for the integrated PVT-HP system. Key findings include a 30 % increase in the temperature difference between the top and bottom layers of the TES when the flow rate is reduced from 50 LPM to 20 LPM, and a 1 % decrease in the heat pump's coefficient of performance (COP) with a 10 LPM reduction in flow rate. The study emphasizes that managing the flow rate is key to optimizing temperature gradients and system efficiency. Strategic adjustments in flow rate significantly affect thermal storage and transfer capabilities, proving essential in system performance. This research offers vital insights into optimizing PVT-HP systems, focusing on the importance of flow rate control in improving temperature management and overall system performance.