Start-up Tests Research Articles

Optimization of Power to Gas system with cooled reactor for CO2 methanation: Start-up and shut-down tests with Ru-based and Ni-based kinetics

The dynamic behavior of a methanation process is analyzed in the context of Power to Gas (PtG) technology, to convert carbon dioxide from different sources and hydrogen produced via electrolysis with renewable energy to synthetic methane. The process configuration consists of a single cooled plug flow reactor (PFR) where both ruthenium and nickel-based kinetic models are tested in the Aspen Dynamics simulation environment. In particular, dynamic analyses are performed to study the start-up and shut-down phases and respect injection parameters in the existing gas network. The process consists of three main sections: conditioning, reaction and separation. After the development and optimization of the control system, the start-up and shut-down tests are carried out, to study the trend of composition for the injection in the gas network. The plant size is set according to the following values: 700 Nm3/h of hydrogen and 175 Nm3/h of carbon dioxide, which correspond to the methanation reaction stochiometric ratio. Different cases are considered in both the start-up and shut-down tests, by changing the GHSV values and the catalyst adopted. Moreover, in the shut-down test two different rates are considered to evaluate the behavior of the system.

Techno-economic-environmental optimization of hybrid photovoltaic-thermoelectric generator systems based on data-driven approach

Hybrid photovoltaic-thermoelectric generator (PV-TEG) system combines two types of energy conversion which is an important innovation to advance the development of renewable energy technologies. Hybrid system in practice needs to track the best operating point in real-time with the help of maximum power point tracking (MPPT) technology to ensure the system outputs maximum energy and optimizes performance. To improve the energy conversion efficiency and utilization of hybrid PV-TEG systems, as well as to effectively combat the negative impacts under partial shading conditions (PSC) and non-uniform temperature distribution (NTD), this paper proposes a hybrid system MPPT technique based on the bi-directional long and short-term neural networks (Bi-LSTM). The Bi-LSTM can consider both past and future data information, which will enhance the training process of the network and the accuracy of the model, making the results more comprehensive. It approaches the global maximum power point by searching for the maximum power down in the forward layer and up in the backward layer. The algorithm can effectively prevent from falling into local optimum under PSC and NTD. The case study section tests and explores the feasibility of utilizing Bi-LSTM to obtain the maximum power from a hybrid PV-TEG system under five case study scenarios, namely, start-up test, step change in solar irradiance, stochastic variation, Hong Kong four-season real case, and uncertainty analysis. Comparative analysis with the other five algorithms are also conducted to thoroughly verify the superiority of the proposed technique for hybrid system MPPT applications. The simulation results indicate that the hybrid PV-TEG system with Bi-LSTM achieves the optimal MPPT performance stably and efficiently under different operating conditions. In particular, low irradiate condition in spring, the energy generated by Bi-LSTM exceeds the INC, SAO and P&O energy outputs by 80.51%, 61.22%, and 31.04%, respectively.

MSR Transient Simulation and MSRE Transient Benchmark with SAM and SPECTRA

In recent years, there has been renewed interest in molten salt reactors (MSRs) for their potential advantages compared to reactors that rely on solid fuel. In response to such interest, many methods and codes have been developed to capture the unique features of MSRs. Among them, SPECTRA and SAM are two system analysis codes that have been enhanced to include MSR-specific modeling capabilities, including delayed neutron precursor drift and modified point kinetics equations. This paper discusses the efforts taken to verify and validate these features. A standard MSR system test problem was developed to verify and demonstrate the capability of SPECTRA and SAM on the MSR transient simulation. Sixteen transients were simulated. The results obtained from SPECTRA and SAM show good agreement. The Molten Salt Reactor Experiment transient experiments were reviewed and selected to validate the SPECTRA and SAM codes. The experiments included pump startup and coastdown tests at zero power, reactivity insertion tests at different power levels, frequency tests, and a natural convection test. The simulation results from SPECTRA and SAM show good agreement with the experimental data.

Implementation of dynamic start-up test experimental data as a main part of the nuclear code validation procedure: Developed RELAP5 model for VVER-1000

The main purposes of start-up tests in nuclear power plants (NPPs) are to ensure safe and reliable operation, verify system functionality, comply with regulatory requirements, optimize performance, and establish a foundation for ongoing plant operation and maintenance. However, the start-up tests of NPPs also could be used as a main part of the nuclear code validation procedure for several reasons including: realistic simulation, comprehensive evaluation, detection of code limitations, validation of safety margins and confidence in code predictions. The main purpose of the current study is to define and assess the validation procedure based on actual start-up test data. In this regard, the developed RELAP5 model has been validated against the actual data of VVER-1000 plant during a dynamic start-up test. The results of this full-scale validation show a good agreement between the developed RELAP5 model results and actual plant data. Finally, by defining a step by step validation procedure, it has been recommended to use the start-up phase test data as a more robust validation process which allow for full-scale validation of the nuclear code by comparing its predictions with actual plant measurements and also other advantages which have been demonstrated in the current study.

Evaluation of Reaction Rate Distribution Measurement in the Prototype Fast Reactor Monju

In the prototype fast breeder reactor Monju, reaction rate distributions of the fission reaction rates of 239Pu, 235U, and 238U and the capture reaction rate of 238U were measured using activation foils during its system startup test. The measurements in the core and radial blanket regions were evaluated in detail, and their reliability and usefulness as the validation data for fast reactor neutronics design methodologies were examined through a comparison with calculations. The reaction rate data measured in Monju were confirmed all reliable and useful as the validation data. The fission reactions of 239Pu, 235U, and 238U can be validated with an accuracy of a few percent in the core and blanket regions. The capture reaction of 238U in the core region also can be validated with a similar accuracy, whereas a precise calculation of the foil cross section is necessary to consider the resonance shielding effects of the surrounding fuel pins and a foil.

Development of a new CVAP structural analysis methodology of APR1400 reactor internals using scaled model tests

The U.S. Nuclear Regulatory Commission (NRC) Regulatory Guide (RG) 1.20 provides guidance on the comprehensive vibration assessment program (CVAP) to be performed on reactor internals during pre-operational and startup tests. The purpose of the program is to identify loads that could cause vibration in the reactor internals and to ensure that these vibrations do not affect their structural integrity. The structural vibrational analysis program involves creating finite element analysis models of the reactor internals and calculating their structural responses when subjected to vibration loads. The appropriateness of the structural analysis methodology must be demonstrated through benchmarks or any other reasonable means. Although existing structural analysis methodologies have been proven to be appropriate and are widely used, this paper presents the development of an improved new structural analysis methodology for APR1400 reactor internals using scaled model tests.

The Impact of prototyping on the survival chances of digital early-stage startups: Findings and insights from explorative expert interviews

The products of digital entrepreneurs are highly innovative, and their business models contribute to the prosperity and further development of the economy and society. However, studies indicate that most of all startups fail, particularly during the early stages of their business journey Prototyping as part of Lean Startup or Business Model Testing approaches, can assist digital early-stage startups in navigating uncertainty and achieving successful product launches. However, these methods are applied very individually and there is little empirical research on best practices. We therefore conducted 65 explorative expert interviews and asked successful startups about their prototyping practices. Our results include learnings on the prototyping process and the testing format, the role of the founding team during prototyping practices, the customer focus and the role of networks. Our study adds important details to theory and practice of the innovation and prototyping processes of digital early-stage startups. Our results offer actionable advice and guidance to any current and potential entrepreneur, but especially to first-time founders and less experienced executives in early stage-startups. Additionally, our contribution enhances the theoretical understanding of the Lean Startup approach and prototyping practices.

Startup Tests Ramjet Engine

Startup Tests Ramjet Engine

Wireless Capacitive Energy Transfer System for Mining Applications—Preliminary Results

This paper presents preliminary tests on a capacitively coupled wireless energy-transfer system (C-WET). Significant emphasis has been placed on discerning the fundamental characteristics of the system. This allowed the simulation model to be refined and the parameters of the physical prototype to be fine-tuned. Then, start-up tests of the prototype of the power supply system were presented, up to about 25% of the rated power. Selected simulation and laboratory test results are presented and directions for further work are set. The system is envisaged for underground mining applications, and the work is being carried out as part of the HEET II (High-Efficiency Energy Transfer) project, funded by the Research Fund for Coal and Steel (RFCS).

CEFR control rod drop transient simulation using RAST-F code system

This study aimed to verify and validate the transient simulation capability of the hybrid code system RAST-F for fast reactor analysis. For this purpose, control rod (CR) drop experiments involving eight separate CRs and six CR groups in the China Experimental Fast Reactor (CEFR) start-up tests were utilized to simulate the CR drop transient. The RAST-F numerical solution, including the neutron population, time-dependent reactivity, and CR worth, was compared against the measurement values obtained from two out-of-core detectors. Moreover, the time-dependent reactivity and CR worth from RAST-F were verified against the results obtained by the Monte Carlo code Serpent using continuous energy nuclear data. A code-to-code comparison between Serpent and RAST-F showed good agreement in terms of time-dependent reactivity and CR worth. The discrepancy was less than 160 pcm for reactivity and less than 110 pcm for CR worth. RAST-F solution was almost identical to the measurement data in terms of neutron population and reactivity. All the calculated CR worth results agreed with experimental results within two standard deviations of experimental uncertainty for all CRs and CR groups. This work demonstrates that the RAST-F code system can be a potential tool for analyzing time-dependent phenomena in fast reactors.

Uncertainty analysis of the China experimental fast reactor start-up tests based on refined calculation results

In this paper, the numerical calculations of China Experimental Fast Reactor (CEFR) start-up tests were performed by using SARAX code with the improved core model. The results of criticality, control rod worth, and reactivity effect were compared against the experimental data. The numerical results showed the SARAX code could be reliably used for CEFR. Moreover, the sensitivity of the keff value due to the change of input parameters was analyzed. At the same time, the uncertainty quantification of calculated keff value and control rod worth and detailed contribution to the total uncertainty were analyzed. For the reactor loaded with highly enriched UO2 fuel, the uncertainty of keff value could reach more than 2%. Besides, the capture reaction of 235U contributed the most with a value of 1.91%. The uncertainty analysis of the control rod worth showed that the total uncertainty depended on the control rod layout rather than the composition.

Salp swarm optimization algorithm based MPPT design for PV-TEG hybrid system under partial shading conditions

This paper proposes an innovative strategy to integrate thermoelectric generator (TEG) and photovoltaic (PV) systems, aiming to enhance energy production efficiency by addressing the significant waste heat generated during traditional PV system operation. Additionally, photovoltaic-thermoelectric generator (PV-TEG) hybrid system encounters the dual challenge of partial shading conditions (PSC) and non-uniform temperature distribution (NTD). Thus, salp swarm optimization (SSA) is introduced to simultaneously tackle the negative impacts of PSC and NTD. In contrast to alternative meta-heuristic algorithms (MhAs) and conventional mathematical approaches, the streamlined and effective optimization mechanism inherent to SSA affords a shorter optimization time, while mitigating the risk of the PV-TEG hybrid system’s optimization outcomes being confined to local maximum power points (LMPP). Furthermore, the optimization performance of SSA for PV-TEG hybrid systems is assessed via four case studies, including start-up test, stepwise variations in solar irradiation at constant temperature, stochastic change in solar irradiation, and field measured data for typical days in Hong Kong, in which simulation results show that SSA evinces unparalleled global exploration and local search capabilities, yielding heightened energy output (up to 43.75%) and effectively suppressing power fluctuations in the PV-TEG hybrid system (as evidenced by ΔVavg and ΔVmax).

Coupled 3D neutronics/thermal-hydraulics analysis of Superphénix start-up tests with DYN3D/ATHLET code system

The capabilities of the DYN3D/ATHLET coupled code system were recently extended to allow for 3D neutron kinetics/thermal hydraulics analyses of Sodium cooled Fast Reactors at reactor system level. In this paper, the DYN3D/ATHLET coupled code system was applied to analyze the Superphenix reactor transient benchmark. The benchmark comprises six operational transients initiated during the SPX reactor start-up tests, covering a wide range of reactor operating states. The peculiarity of these transients is the necessity to consider thermal expansions of major structural elements of the primary system, which significantly influence the transient position of control rods in the core. The paper includes a brief summary of the benchmark specifications, description of the neutron kinetics and thermal hydraulics models, an analysis of the simulation results, and a comparison to the experimental data.

Start-up test of ferrofluid seal based on rheometer

Sealing is one of the most successful applications of ferrofluid. However, the seal often has a sudden change in speed during the start-up process, which causes unstable vibration of the system and may result in accidental failure of the seal. In this work, we designed a ferrofluid seal test equipment based on rheometer to study the start-up characteristics of ferrofluid seal. We scan the rotational speed of the ferrofluid seal to determine the torque range of the fixed torque start, and found that the magnetic field strength and the number of pole teeth will affect the torque value and the slope of the curve. We experimentally analyzed three start-up modes of ferrofluid seal. During the start-up process at a fixed rotating speed, the torque fluctuates periodically, and the fluctuation amplitude increases with the increase of magnetic field strength or the number of pole teeth. During the start-up process of fixed torque, the rotating speed fluctuates periodically, and the fluctuation amplitude declines with the increase of torque. In the process of variable torque start-up, as the number of torque changes increases, the rotation speed increases more slowly and the fluctuation range is smaller, which leads to a more stable start-up of the ferrofluid seal. Ultimately, we believe that variable torque starting will be used to promote the application of ferrofluid seals in high-end precision applications.

Development of a Ru catalyst supported on HY zeolite for the oxidative decomposition of NH3 triggered at room temperature

On-site hydrogen production from the oxidative decomposition of NH3 with a catalyst is highly required in the countryside where external heat is hardly supplied. In this study, Ru-based zeolite catalysts were prepared by impregnation and subsequent washing using RuCl3·3H2O and HY zeolite or H-MOR zeolite for the oxidative decomposition of NH3. The H-MOR-supported Ru catalyst could not be self-heated by feeding 80% NH3/20% O2 to the catalyst bed at room temperature. By contrast, the HY-supported Ru catalyst underwent self-heating to approximately 773 K upon feeding the reactants owing to the heat released by NH3 adsorption and oxidation, leading to excellent performance for the oxidative decomposition of NH3 during five cycles of start-up tests. Characterization results indicated that the Cl-free Ru/HY catalyst exhibited self-heating due to the presence of small well-dispersed Ru metal particles and a large amount of surface acidic sites.

Validating Kraken for VVER-1000 fuel cycle simulations using the X2 benchmark

This article contributes to the validation of the Kraken framework for VVER-1000 fuel cycle modelling. Four fuel cycles from the X2 VVER-1000 benchmark are simulated along with the start-up tests at the beginning of each cycle. Predicted boron letdown curves, power distributions and start-up test results for the four fuel cycles are compared to measured data from the benchmark as well as the results of similar reactor analysis tools. The comparisons to measured data show that Kraken performs well in the task. The accuracy of Kraken is comparable to other nodal diffusion based solvers.

Commissioning of Water Supply and Sanitation Projects- A Case from Nepal

Purpose: Assessment of project commissioning and management transfer of Pakali and Bharaul water supply and sanitation projects were done systematically for assuring smooth operation of the system. Design/Methodology/Approach: Sunsari district with Itahari sub metropolitan and Barahchetra municipality were chosen as the research region because it contains a mixed-race population and is close to the Indian border. Interviews, field perceptions, and surveys were utilized to gather essential information; writing (distribution reports, inspecting reports, records, and information) from both a public and global setting was utilized. The statistical tools used to analyze the adopted process of project commissioning are clustered column, line and bar chart. Findings/Result: Pakali and Bharaul project have been compared on the basis of steps that should be followed for successful project commissioning Both of selected project were found competent in planning and pipe and instrumentation diagrams. In terms of mechanical completion, pre-commissioning, commissioning, start-up, initial operation, and performance testing, none of the chosen projects were deemed competent. Both projects are not handed over yet thus post commissioning is not done. For a successful commissioning, it is recommended a management transfer procedure that involves calibrating and sterilizing the system, having the "water operator's standard" document in place, and training the office staff and members of the water user supply committee. Originality/Value: The novelty of this research is commissioning analyses the nine elements of successful plant commissioning. Paper Type: Research paper

Design and Implementation of a Low-Voltage Photovoltaic System Integrated with Battery Energy Storage

In this paper, the simulation and design of a power converter suitable for a low-voltage photovoltaic (PV) battery energy storage converter was investigated. The converter was suitable for sources and loads with near voltage levels and were aimed at efficiency improvement. The converter was called a series partial power converter (SPPC). A continuous current and a boost SPPC topology based on an isolated Cûk converter was constructed. The operation modes of the converter were analyzed. The efficiency verification test of the SPPC in a laboratory environment was completed using an outdoor start-up test, a photovoltaic full cover test and a steady-state operation test under different power levels. The results show that the SPPC can achieve 95–98% converter efficiency within the 87 W–242 W power range. The incremental conductance method based on the SPPC can realize the dynamic MPPT under constant illumination and changing meteorological conditions.

Experimental study on rapid cold start-up performance of PEMFC system

The cold start-up of a proton exchange membrane fuel cell is considered one of the main factors affecting the commercialization of fuel cell vehicles. In this study, an automotive fuel cell system was designed and tested for cold start-up at low temperatures. In the absence of PTC (Positive Temperature Coefficient) heating device, the stack was directly loaded to generate heat, which provided the cold start-up characteristics of system at low temperatures. Cold start-up process and purging control strategies were analyzed at −20 °C and −30 °C. It was found that the fuel cell system could produce 50% power in 25 s at −20 °C, the coolant temperature's heating rate was 0.78 °C/s, the coolant outlet temperature could reach 20 °C within 40 s and no apparent low voltage of single cell occurred. While, the cell close to the end plate had low cell voltage and reverse polar phenomena throughout the −30 °C cold start-up process. The heating rate of the coolant temperature was 0.44 °C/s, and the temperature of coolant outlet reached 20 °C within 90 s. The purging time ranged from 180 to 260 s according to the voltage drop value of stack and the ohmic resistance of stack was 360–470 mΩ after the high-volume air purging at different tests. After 30 cold start-up tests, the rated point performance of the stack declined by about 1%, and the consistency of cell voltages did not change significantly. Future work will focus on optimizing cold start-up strategy and speeding up purging time to minimize the performance impact of the cold start-up.

Novel Multibus Multivoltage Concept for DC-Microgrids in Buildings: Modeling, Design and Local Control

In this paper, a novel microgrid (MG) concept suitable for direct current (DC) multibus architectures is depicted. Multibus feature is improved in order to distribute power in DC using a number of buses at different voltage level. A teachers offices building that houses several kinds of loads, including a charging station for electric vehicles (EV), is considered to validate the strategy. Several topologies of power electronics converters (PECs) are included in the system to perform specific tasks and providing isolation between bus and final loads. In order to develop the PECs, first, a switching function is used to obtain average model of each converter. Then, converters design is done by using well known methods that allow to obtain parameter values of all the devices in every version of each kind of converter. A hierarchical control is selected to govern the direct current microgrid (DCMG). At a lower control level, local control stage is implemented and tuned using models and designs obtained, with linear controllers in some PECs and classic strategies in others. In higher control level, there is a supervisory strategy that prioritizes the use of generated power to supply the building’s loads. This energy management system (EMS) is based in Petri net theory; it consists of a start-up test, then source condition synchronous algorithm and load condition synchronous algorithm operate the DCMG according to the mentioned priority. Finally, PECs are tested on standalone, performing in closed loop, facing load changes to verify the adequate operation. Some trajectories of a simplified version of the CDMG are tested with local control in order to validate the multibus multivoltage concept. In order to verify coordinated control, some events managed by EMS are presented.