Electron Devices Research Articles

HYDRA RoS: Large-Scale Production of a Vacuum Tube Collector With an Innovative Hydraulic Design - Robust Manufacturing Process by Rotary Draw Bending and Induction Brazing

Solar thermal systems, especially in district heating networks, are crucial to achieving climate neutrality in Germany's heat supply by 2045. The joint project HYDRA RoS, funded by the Federal Ministry for Economic Affairs and Climate Protection (Germany), focuses on the development of high-efficiency solar thermal collector concepts for series production with the aim of optimising material and energy use, field hydraulics and control technology. A key component of the project is the use of vacuum tube collectors with CPC (Compound Parabolic Concentrator) reflectors, such as those of Ritter XL Solar. These collectors have proven to deliver high heat yields and can easily reach temperatures of up to 120 °C. The project introduced a new hydraulic register design for these vacuum tube collectors, which improved efficiency and enabled new field interconnection options. However, the new design presented some manufacturing challenges. Finite Element Analysis (FEA) was used to improve the rotary draw bending process and minimise cross-section reductions. Experiments and studies were carried out to achieve a leak-proof connection between the drum connector and the tubes. Computational Fluid Dynamics (CFD) simulations were used to model thermal and fluid dynamic behaviour to guide design optimisation. Prototype collectors were fabricated and tested under controlled conditions to assess their hydraulic and thermal performance. The results show that the new design achieves a significant lower hydraulic loss with the same or a little bit higher thermal efficiencies comparable to the current Ritter XL collector series, while significantly simplifying the manufacturing process.

COMPARATIVE ANALYSIS OF TECHNICAL, ECONOMIC, WEIGHT, AND SIZE CHARACTERISTICS OF HORIZONTAL AND VERTICAL STEAM GENERATORS FOR 1000 MW NUCLEAR POWER PLANT UNITS

A comparative analysis of the technical characteristics and parameters of horizontal and vertical steam generators for reactorinstallations with water coolant in modern 1000 MW NPP power units has been conducted. It is noted that the peculiarities of thedesign schemes and constructions of steam generators in NPP power units with water coolants are significantly influenced by thestrong dependence between the coolant temperature at the steam generator inlet and the pressure in the reactor circuit. Thedependencies of coolant and working substance temperature changes and the amount of heat transferred in steam generatorelements have been considered. The t-Q diagram of a steam generator with a water coolant featuring a non-boiling economizer,evaporator, and superheater is presented. The parameters of water coolants and working substances in nuclear power plant steamgenerators are provided. The t-Q diagram for steam generators without a superheater section is shown, because in modern 1000MW nuclear power plant units with steam generators which use water as the working substance in the steam-turbine cycle,saturated steam without superheating is used. This is because minor superheating of the steam does not significantly increase theefficiency of the steam-turbine cycle but requires significant complexity in the design of the steam generators. It is noted that thecorrect choice of their structural schemes is crucial in the creation of steam generators with water coolants. It has been proven thatthe characteristics determining the structural schemes of steam generators with water coolants are: the scheme of washing the heatexchange surface with the coolant, the form of the heat exchange surface, the layout of steam generator elements, the principle ofworking substance movement, and others. The technical characteristics of a horizontal-type steam generator for 1000 MW nuclearpower plant units are presented, which have proven to be quite effective in operation. However, their designs and characteristicslimit the potential for further improvement of the technical and economic indicators of nuclear power plants. It is noted thatimproving the technical and economic efficiency of 1000 MW nuclear power plant units while simultaneously reducing capitalcosts for their construction is possible by increasing the unit capacity of powerful vertical-type steam generators installed on them.Compared to horizontal steam generators, vertical steam generators allow for a more rational layout of the primary circuitequipment in the reactor department, thus reducing the volume and cost of construction and installation works. The maindimensions and weight characteristics of possible designs of vertical steam generators for nuclear power plants with VVER-1000reactors are provided. It is concluded that once-through vertical steam generators with spiral wound heat exchange tubes and watercoolant in the first circuit tubes weigh approximately 1.5 to 2 times less than vertical steam generators with natural circulation. It isdetermined that once-through vertical steam generators with a hydraulic scheme involving the movement of the working substancein the tubes and the water coolant in the inter-tube space significantly lag behind once-through vertical steam generators with watercoolant in the tubes in terms of dimensional and weight characteristics and also vertical steam generators with natural circulation interms of weight. It is concluded that for VVER-1000 nuclear power plants, the most promising of all options are vertical once-through steam generators with the movement of the water coolant in spiral wound heat exchanger tube bundles. These steamgenerators occupy approximately four times less area in the reactor department than horizontal ones with the same steamproduction, which significantly reduces construction costs for nuclear power plants.

New operation analysis method for vacuum tube driving a tuned cavity

The rf system of China Spallation Neutron Source (CSNS) Rapid Cycling Synchrotron (RCS) utilizes vacuum tubes to drive the ferrite-loaded cavities. Ensuring stable tube operation in the rf system is crucial for the acceleration of high-intensity beams, as any instability may impede further increases in beam power. Therefore, the operation of the vacuum tube under heavy beam loading has attracted significant attention, particularly in the case of CSNS-II RCS, where the circulating beam current is expected to reach up to 15.25 A, imposing a substantial burden on the vacuum tube for beam loading compensation. Thus, a comprehensive analysis of tube operation is imperative. However, current methods for the tube operation analysis are developed based on wideband rf cavities, which are inadequate when the load of the tube is a narrowband ferrite-loaded cavity equipped with a tuning system. The presence of a tuning system renders the modeling method for wideband rf cavities inapplicable for ferrite-loaded cavities. Therefore, the development of a new method is necessary. This paper introduces a novel method for analyzing operation of vacuum tube driving a tuned cavity. The effectiveness of the method is validated by comparing the analysis results with measurements under beam loading conditions. Furthermore, an estimation of tube operation under 500 kW beam loading for CSNS-II is provided. Published by the American Physical Society 2024

Development of α-ray visualization survey meter in high gamma and neutron background environment.

A survey meter was developed to reliably detect and visualize surface contamination of suits and objects by α-nuclides in high γ/n-rays background radiation environment. The survey meter features a semi-opaque ZnS:Ag scintillator mounted directly onto a multi-anode photomultiplier tube (MA-PMT) and amplification circuits, ensuring output gain equalization for all channels. α-ray events induce localized light emission in thin-film scintillators. By directly mounting the scintillator, diffusion of light before reaching the MA-PMT is suppressed, concentrating it in just a few channels, thereby facilitating discrimination from background radiation. This design also enables clear visualization of the shape of surface contamination. The prototyped survey meter is capable of responding up to 2.1×107cpm, with no γ-ray response even in high-radiation environments exceeding 1Sv/h. In actual environments with high background radiation, contamination of ~1/100th of the surface contamination density limit of 4Bq/cm2 could be reliably detected.

Biogas Production from a Solar-Heated Temperature-Controlled Biogas Digester

This research paper explores biogas production in an underground temperature-controlled fixed dome digester and compares it with a similar uncontrolled digester. Two underground fixed-dome digesters, one fitted with a solar heating system and a stirrer and the other one with an identical stirrer only, were batch-fed with cow dung slurry collected from the University of Fort Hare farm and mixed with water in a ratio of 1:1. The solar heating system consisted of a solar geyser, pex-al-pex tubing, an electric ball valve, a water circulation pump, an Arduino aided temperature control system, and a heat exchanger located at the centre of the digester. Both the digesters were intermittently stirred for 10 min every 4 h. The digester without a heating system was used as a control. Biogas production in the two digesters was compared to assess the effect of solar heating on biogas production. The total solids, volatile solids, and the chemical oxygen demand of the cow dung used as substrate were determined before and after digestion. These were compared together with the cumulative biogas produced and the methane content for the controlled and uncontrolled digesters. It was observed that the temperature control system kept the slurry temperature in the controlled digester within the required range for 82.76% of the retention period, showing an efficiency of 82.76%. Some maximum temperature gradients of 7.0 °C were observed in both the controlled and uncontrolled digesters, showing that the stirrer speed of 30 rpm was not fast enough to create the needed vortex for a uniform mix in the slurry. It was further observed that the heat from the solar geyser and the ground insulation were sufficient to keep the digester temperature within the required temperature range without any additional heat source even at night. Biogas yield was observed to depend on the pH with a strong coefficient of determination of 0.788 and 0.755 for the controlled and uncontrolled digesters, respectively. The cumulative biogas was 26.77 m3 and 18.05 m3 for controlled and uncontrolled digesters, respectively, which was an increase of 33%. The methane content increased by 14% while carbon dioxide decreased by 10% from the uncontrolled to the controlled scenario. The percentage removal of the TS, VS, and COD was 66.26%, 76.81%, and 74.69%, respectively, compared to 47.01%, 60.37%, and 57.86% for the uncontrolled situation. Thus, the percentage removal of TS, VS, and COD increased by 19.25%, 16.44%, and 16.89%, respectively.

Analyzing Vacuum Tube Operation for a Wideband Cavity Using a Circuit Simulator

Analyzing Vacuum Tube Operation for a Wideband Cavity Using a Circuit Simulator

Call for Papers: Special Issue on Intelligent Sensor Systems for the IEEE Journal of Electron Devices

Call for Papers: Special Issue on Intelligent Sensor Systems for the IEEE Journal of Electron Devices

IEEE Transactions on Electron Devices Table of Contents

IEEE Transactions on Electron Devices Table of Contents

Call for Papers: Special Issue on Intelligent Sensor Systems for the IEEE Journal of Electron Devices

Call for Papers: Special Issue on Intelligent Sensor Systems for the IEEE Journal of Electron Devices

Special Issue on Intelligent Sensor Systems for the IEEE Journal of Electron Devices

Special Issue on Intelligent Sensor Systems for the IEEE Journal of Electron Devices

Special Issue on Intelligent Sensor Systems for the IEEE Journal of Electron Devices

Special Issue on Intelligent Sensor Systems for the IEEE Journal of Electron Devices

Modulating the Cathode by Back-Gate for Planar Nanoscale Vacuum/Air Channel Electron Tube

Modulating the Cathode by Back-Gate for Planar Nanoscale Vacuum/Air Channel Electron Tube

On the acceptance, commissioning, and quality assurance of electron FLASH units.

FLASH or ultra-high dose rate (UHDR) radiation therapy (RT) has gained attention in recent years for its ability to spare normal tissues relative to conventional dose rate (CDR) RT in various preclinical trials. However, clinical implementation of this promising treatment option has been limited because of the lack of availability of accelerators capable of delivering UHDR RT. Commercial options are finally reaching the market that produce electron beams with average dose rates of up to 1000Gy/s. We established a framework for the acceptance, commissioning, and periodic quality assurance (QA) of electron FLASH units and present an example of commissioning. A protocol for acceptance, commissioning, and QA of UHDR linear accelerators was established by combining and adapting standards and professional recommendations for standard linear accelerators based on the experience with UHDR at four clinical centers that use different UHDR devices. Non-standard dosimetric beam parameters considered included pulse width, pulse repetition frequency, dose per pulse, and instantaneous dose rate, together with recommendations on how to acquire these measurements. The 6- and 9-MeV beams of an UHDR electron device were commissioned by using this developed protocol. Measurements were acquired with a combination of ion chambers, beam current transformers (BCTs), and dose-rate-independent passive dosimeters. The unit was calibrated according to the concept of redundant dosimetry using a reference setup. This study provides detailed recommendations for the acceptance testing, commissioning, and routine QA of low-energy electron UHDR linear accelerators. The proposed framework is not limited to any specific unit, making it applicable to all existing eFLASH units in the market. Through practical insights and theoretical discourse, this document establishes a benchmark for the commissioning of UHDR devices for clinical use.

SuFEx‐based Transparent Polysulfates and their Applications in Tunable Resistant Electrical Memory Materials

AbstractVisibly transparent electron devices are current research highlights, which are found at the “neotype” stage of technical development for the usage in the next generation “see‐through” electronic devices. However, less attention is paid to transparent semiconductor memory devices, and hence, achieving such “see‐through” electronic devices are still partially limited by lacking the easily achievable and cost‐effective transparent memory materials. Herein, three visible light transparent polysulfate‐based memory devices are reported, e.g. ITO/P‐BPS/Al, ITO/P‐TPA/Al, and ITO/P‐TPABPS/Al, that displayed DRAM, WORM, and FLASH effects, respectively. The mechanisms of the observed memory behavior of each memory material are proposed on the basis of computational simulation. Remarkably, these polysulfates‐based memory materials are obtained by simply using different main‐chain repeating units, suggesting a wide application potential of polysulfate as functionalized materials.

A novel perspective of addressing the hydraulic dynamic imbalance in district heating network: The application of nonlinear programming

Hydraulic balance within the heating system's pipeline network is essential for efficient operation. Hydraulic imbalances can result in increased energy consumption and heat loss. Accordingly, a new dynamic hydraulic model has been developed, leveraging the topological structure of the network. This model incorporates the nonlinear constraints associated with flow coupling between electric valves and variable frequency pumps, with the objective of minimizing energy used in pump operation. It determines the optimal pump frequency and valve settings for operational adjustments. The model's predictive accuracy was validated using real operational data from a campus heating system. Additionally, it calculates the campus's ideal load and evaluates the potential for energy savings. Three adjustment strategies were established based on different temporal scales: hourly, day-and-night, and daily. Findings indicate that the optimized system offers substantial energy savings, particularly the hourly adjustment, which reduces pump energy consumption by 38.2 % and total system flow by 9.0 %. The day-and-night variable frequency was the next most effective, reducing pump energy consumption by 32.8 %, and total system flow by 7.6 %. The daily variable frequency strategy showed the least energy savings, with pump energy consumption by 25.0 %, and total system flow by 5.5 %. This dynamic hydraulic regulation optimization model serves as a valuable tool for developing intelligent heating systems.

Simulation and experimental study on the performance of vacuum tube phase change collector with combined heat exchange of flat tubes and fins

This paper establishes a solar vacuum tube collector with flat tubes and fins as the heat transfer unit, and the thermal performance was tested under different environmental conditions. The results indicate that the paraffin in the vacuum tube collector showed the phenomenon of temperature stratification at the region of the high and low temperature when the system absorbed heat. Secondly, the daily average heat-taking efficiency can reach 30–45 % when the irradiance is 822.5 W/m2, 555.0 W/m2, and it only about 6 % under the irradiance 111.6 W/m2. In addition, the energy storage system was simulated, and the thermal storage stage was analyzed according to the different temperature distribution curves, temperature distribution nephogram and liquid fraction. The results show that when the running time is about 2500 s, the paraffin temperature reached the melting point, the paraffin begins to melt; when to 4500 s, the solid–liquid phase conversion is complete, after this time the temperature rise is relatively smooth; when the time is run to 14,000 s, energy-storage type solar vacuum collector has reached a stable state, the temperature tends to level off, then the temperature increase is not obvious. It will provide some theoretical and data support for the later combination of solar phase change energy storage technology and heat pump technology.

Increasing the Efficiency of Thermoelectric Conversion of Solar Energy

The article considers the latest achievements in the field of thermionic conversion of solar energy. The key aspects of thermionic emission, the problems of reducing the electrode work function and increasing the efficiency of devices are analyzed. It is shown that diamonds doped with phosphorus can be an attractive material for the purposes of thermionic emission. In this case, the presence of donor states can significantly narrow the space charge region, and at the same time reduce the potential barrier in the work function. The studies also found that the most successful and widely used method for overcoming the space charge effect is filling the interelectrode gap with cesium. The efficiency of thermionic conversion devices for solar energy increases by 1.6 times. Particular attention is paid to the use of new materials, such as nanostructures and carbon nanotubes, as well as promising technologies, such as photonic enhancement of thermionic processes. The analysis of the results showed that the photonic enhancement of the electron yield due to illumination is greater in p-type silicon, as predicted by theoretical models. The thermionic current increases by 1.7 times compared to silicon. The distance between the quasi-Fermi level and the Fermi level in n-type silicon is less than this distance in p-type silicon. As a consequence, the number of electrons in the conduction band is smaller. Methods for combating the space charge effect and optimizing the configuration of energy conversion systems are discussed.

The effect of solar thermal energy storage on natural gas heating systems: An experimental and techno-economic investigation

This study investigates the storage of solar thermal energy using thermal oils in Kilis, Türkiye, a region characterized by high solar potential. Both experimental and modeling studies were conducted. Mobiltherm 605 and PO Heat Transfer Oil 32 were tested as alternatives to commonly used oils. PO Heat Transfer Oil 32 was introduced to the literature for the first time. The impact of operating temperature, water flow rate, and outdoor temperature on the efficiency of stored thermal energy in the water heating system was examined. The findings revealed that system efficiency averaged 42 % at a nighttime outdoor temperature of 9 °C but decreased to 36 % at 13.5 °C. Efficiency was also 36 % at a flow rate of 0.7 m/s, decreasing to 24 % at 0.24 m/s. Mobiltherm 605 cooled down later than PO 32 in the thermal tank, indicating a higher heat transfer coefficient for PO 32. Based on experimental data, a model of the thermal storage system was developed, and its techno-economic feasibility was assessed. Using this model, a techno-economic analysis was performed and the potential for this clean energy to reduce reliance on natural gas combi boilers for heating was discussed. For a building with a maximum indoor-outdoor temperature difference of 20 °C and a heating requirement of 467 kWh over 14 h, the thermal energy cost was estimated to be $0.029/kWh. This implementation reduced carbon emissions by 130 kg/day. The total equipment cost for the thermal storage system, with a U-type Vacuum Tube Collector (U-VTC) area of approximately 380 m2, was $295,697. In conclusion, both Mobiltherm 605 and PO Heat Transfer Oil 32 demonstrated comparable price/performance ratios relative to common oils.

Reduced ultimate-bound of tracking error convergence for ETV system with unknown upper-bound mismatched perturbation

The electronic throttle valve (ETV) is widely used in automobile engines to obtain efficient fuel combustion, improved fuel economy, and reduced emissions. The control of the ETV system is a challenging problem due to the unmatched structure of perturbation and its unknown upper bound. As such, deep control concerns are required. For such a system, recent control approaches could partially solve the ultimate boundedness of convergence error, but they have failed to find a solution in the presence of unknown upper-bound perturbation. The contribution of this study is to develop a novel backstepping-based barrier function integral sliding mode controller (BS-BFISMC) to find a solution for the ETV system without the pre-knowledge of the upper bound of perturbation. The proposed control scheme gets the benefits of the backstepping algorithm (BS) and barrier function integral sliding mode control (BFISMC), and the combined scheme could lead to reduced ultimate-bound convergence of tracking error and result in chattering-free control action. A rigorous stability analysis has been conducted to prove the finding reached by the proposed control approach. The efficacy and effectiveness of the proposed controller have been shown by conducting a comparison study with other existing control methods; namely, conventional backstepping controller, robust continuous backstepping (CRBS), and backstepping-based quasi-integral sliding mode controller (BS-QISMC). The numerical results showed that the proposed BS-BFISMC yields the lowest level of ultimate bound of tracking errors and the least control efforts as compared to other controllers. Also, it has been shown that the proposed controller does not require the upper bound of perturbation, which is a pre-requisition of all compared controllers.

Solar Organic Rankine Cycle (ORC) Systems: A Review of Technologies, Parameters, and Applications

The Organic Rankine Cycle (ORC) is a widely utilized technology for generating electricity from various sources, including geothermal energy, waste heat, biomass, and solar energy. Harnessing solar radiation to drive ORC is a promising renewable energy technology due to the high compatibility of solar collector operating temperatures with the thermal requirements of the cycle. The aim of this review article is to present and discuss the principles of solar-ORC technology and the broad range of solar-ORC systems that have been explored in the literature. Various solar energy technologies capable of powering ORC are investigated, including flat plate collectors, vacuum tube collectors, compound parabolic collectors, and parabolic trough collectors. The review places significant emphasis on the operating parameters of technology.