Entire Operating Cycle Research Articles

Numerical optimization study on the thermal management of planar sodium nickel chloride battery module

A numerical study is conducted to build up a thermal management strategy for a battery module consisting of stacked planar sodium metal chloride (Na-MCl2) unit cells at the intermediate temperature of 180 °C. Because the sodium metal chloride battery for an energy storage system operates for a long cycle period and maintains a high temperature, a different approach is required considering uniform temperature distribution and efficiency compared with lithium-ion battery. This study starts with a lumped analytical model for preliminary investigation and moves on to a computational fluid dynamics (CFD) analysis for a more sophisticated optimization. In this study, the 2 × 4 and 3 × 3 arrangements of cylinders, each of which represents a 10-cell stack, are considered. From the lumped model in the preliminary design, the insulation thickness and initial approach values of the detailed design are determined by predicting the temperature and heat generation throughout the entire operating cycle of the module. In the detailed CFD analysis, passive thermal management through natural convection has a limitation of cell temperature uniformity. To achieve a uniform cell temperature distribution, case studies are conducted with active fans inside the module. The optimal operating points are proposed based on the overlaid response surface. Finally, for the operating points in this study, the module efficiencies are compared considering the cell failure mode. The efficiencies of optimized module are increased to 26.9 % for 2 × 4 and 21.2 % for 3 × 3 arrangements.

Drilling dynamics measurement of drilling motors and its application in recognition of motor operation states through machine learning

Drilling motors are widely used in unconventional oil and gas exploration. Due to the increased non-productive time and drilling costs brought about by accidental damage to drilling motors, predictive maintenance for drilling motors is necessary to optimize asset utilization. However, service companies face significant challenges in achieving predictive maintenance: operational data acquisition, automated statistics analysis, and drilling state recognition. This paper presents a miniature vibration recorder, an automatic statistical analysis method, and a layered recognition algorithm to resolve these challenges and improve tool maintenance efficiency. The designed recorder can be installed in the catch of a conventional mud motor to record drilling dynamics over a drilling motor's entire operation cycle. Time-series data from the recorder can be used to automatically generate operation statistics, mitigating the costs incurred by manual data analysis. The layered recognition algorithm then enables the automatic identification of drilling operation states, i.e., surface, downhole non-drilling, downhole sliding, and downhole rotation. The solutions were validated by deploying the recorder in drilling field runs and analyzing recorded data using the associated design software, yielding a functional data collection, automatic data statistical analysis, and operation state recognition accuracy of 95%. Through achieving improved data collection and analysis, the recorder and software introduced in this work can notify motor owners of the detailed operation history of their tools and enable informed preventive maintenance.

Installation and test procedure for frequency stability under cyclic loading of metals and alloys

Manufacture of parts operating under difficult conditions of cyclic loading, as well as products with stable dimensions necessitates the use of materials with minimal manifestations of inelastic properties. Study of these materials suggests conducting specialized narrowly focused tests using newly developed machines and installations with appropriate experimental techniques. We present the design, operation and control features of the original electromagnetic installation for testing fatigue and frequency stability and operating in a self- oscillating mode, which provides the equality of the frequency of cyclic loading and natural frequency of the sample. The system of the installation control contains two closed circuits: for excitation of self-oscillations and for stabilization of the oscillation amplitude. The sample is loaded by electromagnetic force, and unloading occurs due to the elastic forces of the material. The methodology and algorithms for calculating the stresses of samples of various geometric shapes for estimating changes in amplitude-frequency characteristics are presented. The calculated relationship between the force applied to the sample and its movement at the point of application of force is derived with subsequent determination of the stress by a known force. The results of calibration tests for the static mode of sample loading are presented and the forces acting on the sample (external, inertia, and elastic forces) are evaluated taking into account the maximum stress and maximum strain amplitude. Static and cyclic loading modes are compared. The frequency characteristics obtained during testing steel samples according to the proposed method are obtained. The experimental results of tests with interruptions in the process of cyclic loading and continuous testing are analyzed. It is shown that interruptions in cyclic tests lead to a jump-like increase in the frequency, whereas continuous tests revealed no jumps. At the same time, a comparative analysis with the results of continuous tests showed that the overall frequency deviation is approximately the same for the entire operating cycle in both cases. It is shown that an increase in the frequency after rest is random and does not depend on the number of operating cycles.

A comprehensive modeling framework for coupled electricity and carbon markets

AbstractThe carbon market plays a critical role in promoting the transition toward renewable energy sources and reducing greenhouse gas emissions in the electricity generation and transmission. Extant research has overlooked the dynamic bilateral causality that exists between electricity and carbon markets. Moreover, these studies have frequently treated the macroeconomic effect as exogenous. To bridge this research gap, this paper presents a holistic modeling framework that comprehensively captures the intertwined nature of electricity and carbon markets and their concomitant interactions with the overarching economy. The suggested modeling framework is an integration of three principal modules, namely, a carbon market, an electricity market, and economic system. This synergistic blend provides an exhaustive understanding of the entire market operation cycle. It offers detailed clearance rules, and most importantly, it adopts a macroeconomic systematic modeling approach for evaluating the impact emanating from the interconnected electricity and carbon markets. To illustrate the practicality and effectiveness of the proposed approach, a case study anchored on empirical data sourced from the electricity and carbon markets in China is conducted. The empirical findings underscore the fact that incorporating a green certificate market into the modeling framework can precipitate a reduction in greenhouse gas emissions. Additionally, the results indicate that expanding the scale of the green certificate market from 1.9% in 2021 to 33% by 2023 will increase the generation of green electricity by 10%.

Parametric Design of a New Float-Type Wave Energy Generator and Numerical Simulation of Its Hydrodynamic Performance

A novel float-type device for wave energy power generation, designed specifically for offshore wave environments, is introduced as an innovative technology in wave energy utilization. Herein, we present the design concept, structural composition, and energy conversion process of the device, and conduct mathematical modeling and theoretical research on its kinematic and dynamic characteristics. At the same time, we use a numerical wave pool based on the STAR-CCM+ boundary wave making method and damping dissipation method to analyze the motion response and output power of the wave energy generator in a five-order Stokes wave environment within one wave cycle and the entire operating cycle. Finally, in order to develop the best design strategy, we study the effect of changing the structural parameters of the power generation device on the hydrodynamic performance of the device.

A probabilistic neural network with adaptive capability to optimize fault trees for the intelligent fault diagnosis of rapier loom throughout its operating cycle1

The mechanical structures of the rapier loom are strongly coupled, resulting in faults that are characterized by strong coupling, hierarchy, phase dynamics, and a transient nature. However, current fault diagnosis methods using a single approach are not satisfactory. Additionally, fault diagnosis of the entire operation cycle of the rapier loom equipment is lacking. This paper proposes a fault tree diagnosis method with probabilistic neural network optimization to build a complete fault diagnosis system for rapier looms and improve their intelligent diagnosis capability. The method has strong fault tolerance and self-adaptive capability, allowing for accurate location of the root cause of the fault from multiple fault sources. By accumulating fault samples and continuously improving the diagnosis network, the accuracy of diagnosis can be further enhanced. Initially, the failure mechanism of key subsystems of rapier loom is analyzed. A fault tree model is established for each subsystem based on expert experience and historical data. The model identifies the characteristic sign quantities of typical fault types and serves as the basic input for fault identification. A probabilistic neural network is used to train the fault sample set and complete the diagnosis of the cause of the fault. According to field experiments, the proposed method has demonstrated a significant improvement in the efficiency of locating and identifying fault signs in rapier looms. This improvement allows for accurate and quick identification of faults.

Research on Energy Management Method of Fuel Cell/Supercapacitor Hybrid Trams Based on Optimal Hydrogen Consumption

In this paper, based on the operating states and characteristics of fuel cell/supercapacitor hybrid trams, an optimal hydrogen energy management method is proposed. This method divides the operating states into two parts: traction state and non-traction state. In the traction state, the real-time loss function of the hybrid power system, which is used to obtain the fuel cell optimal output power under the different demand powers and supercapacitor voltage, is established. In the non-traction state, the constant-power charging method, which is obtained by solving the power-voltage charging model, is used to ensure the supercapacitor voltage of the beginning-state and the end-state in an entire operation cycle are the same. The RT-LAB simulation platform is used to verify that the proposed method has the ability to control the hybrid real-time system. Using the comparative experiment between the proposed method and power-follow method, the results show that the proposed method offers a significant improvement in both fuel cell output stability and hydrogen consumption in a full operation cycle.

Transient simulation of heat and mass transfer in a parallel flow regenerative lime kiln with pulverized coal injection

Quicklime, which is an essential raw material in various industries, is primarily produced by thermally calcinating limestone in kilns. Among the various kiln designs, parallel flow regenerative (PFR) kilns with pulverized coal combustion are the predominant technology. The performance of the PFR kilns is determined by the interactions between the gas, limestone, quicklime, and coal particles inside the chamber. Additionally, the two chambers in the PFR kiln alternate after a short period during the operation. Consequently, the transfer behaviors between the various phases inside the chamber are in a transient state. A three-dimensional transient multiphase model was created to investigate the transient multiphase behavior. The entire operation cycle, which consists of calcination and regeneration processes, was simulated using a coupling method. The predicted CO2 concentration in the exhaust gas was compared with the industrial measurement data, and good agreement was obtained, with an error of less than 6%. Furthermore, variations in the gas and limestone temperatures and limestone concentrations with residence time during each period were obtained. During the calcination period, the gas temperature field stabilized after 100 s. After stabilization, the zone where intensive limestone decomposition occurred was located in the range 0–5 m from the lance tip. The maximum gas temperature in the calcination process was 1845 K, which was approximately 700 K higher than that of a PFR kiln fueled with natural gas. CO2 gradually accumulated in the middle part of the chamber; the average concentration of CO2 in the off-gas was 27.7%. In the regeneration period, the transfer process stabilization required 400 s. Furthermore, the maximum gas temperature was higher than that of a PFR kiln fueled with natural gas, with a difference of approximately 90 K. Contrary to the calcination period, CO2 accumulated in the peripheral region at the end of regeneration. The total CO2 emission is 1.2024 t CO2/t product for the investigated coal-fueled PFR kiln. These transient transfer characteristics, during the PFR operation, could aid the optimization of coal utilization and control of CO2 emissions in the future.

Influence of chlorinated disinfection by-products on transmission of antibiotic resistance genes in biofilms and water of a simulated drinking water distribution system

The spread of antibiotic resistance genes (ARGs) caused by biofilm growth in drinking water distribution systems (DWDSs) poses a serious threat to human health. The influence of disinfection by-products (DBPs) on the distribution of ARGs and mobile genetic elements (MGEs) in different phases (biofilms and water) of DWDSs is unclear. In this study, the characteristics of microbial indices, trihalomethanes (THMs), haloacetic acids (HAAs), ARGs and MGEs in biofilms and effluents of simulated DWDS reactors were detected during 150 d of operation. During the mature biofilm periods of 90 d or 120 d, for both biofilms and effluents, seven categories of ARGs (except tetracycline) and MGEs were at their highest and lowest relative abundance in the entire operation cycle, respectively. The influence of DBPs on ARGs and MGEs in the DWDS was different in different phases. In effluents, DBPs showed a stronger relationship with ARGs compared with MGEs. THMs and HAAs had positive correlations with various ARGs, which indicated that DBPs affected the distribution of resistance genes. In biofilms, the influence of MGEs on ARGs was stronger than that of DBPs on ARGs. Thus, DBPs might be an important contributor to the enrichment and spread of ARGs in water.

Pre-conceptual high temperature gas cooled microreactor design utilizing two-phase composite moderators. Part II: Design space and safety characteristics

This work expands on a pre-conceptual microreactor design based on a High Temperature Gas-Cooled Reactor (HTGR) platform generated in the companion paper of this study. Here, power, coolant inlet temperature, and coolant outlet temperature are varied to outline an operable design space associated maximum allowable component temperatures and coolant pressure drop for a given microreactor design. Calculations show that beryllium- and hydride-based composite moderators have a smaller operating design space than graphite because of a lower allowable moderator temperature under the conservative upper limits employed for this study. Power below 6MWth was considered to be undesirable for all designs because of a limited inlet/outlet temperature range. Reactivity Temperature Coefficients (RTC) are calculated to illustrate an inherent safety feature of HTGRs and are fed into a Depressurized Loss of Forced Coolant (DLOFC) without active intervention accident simulation, considered to be a bounding case for fuel temperatures in a HTGR. RTC calculations showed that all designs would expect to have a negative isothermal coefficient through their entire operating cycle and DLOFC calculations showed no case exceed their maximum temperature limits. An additional accident that simulates the release of fission products is performed to compare expected minimum Emergency Planning Zone (EPZ) size for all designs. EPZ calculations showed a marginally smaller achievable size for the composite moderators because of a lower concentration of relevant nuclides due to a more thermal spectrum

МЕТОДИЧНІ ПІДХОДИ ТА МОДЕЛІ ПРИЙНЯТТЯ АДАПТИВНИХ УПРАВЛІНСЬКИХ РІШЕНЬ У БУДІВНИЦТВІ

The article analyzes the methodological approaches to making adaptive management decisions in construction, taking into account European quality standards for construction products. It was found that the civilizational choice of Ukraine, its main priority of domestic and foreign policy is full-scale integration with the European Union. The «4M» methodology is presented, which directly connects quality management with the use of the whole arsenal of management methods and management decision-making options. It is noted that one of the most important factors in the quality of construction products is effective inventory management, which reduces the duration of the production and the entire operating cycle reducing current costs for their preservation and freeing from current economic turnover of funds by reinvesting them in other assets. Ensuring this efficiency is achieved through the development and implementation of financial policies for inventory management. Emphasis is placed on the fact that one of the modern methods of making adaptive management decisions on the quality of construction products is benchmarking. Its’ application is based on the characteristics of quality management systems, guided by international and national quality management standards. Benchmarking tools have been found in order to make effective management decisions and gain a lasting competitive advantage. It is concluded that taking into account European standards the solution of effective management decisions by the construction companies’ product quality management, is based on the use of operational, marketing and economic tools that address the strategic development of construction companies in Ukraine. In turn, the path chosen by the economy of Ukraine indicates the need to comply with European standards of construction work quality, which is significantly complicated by the current state of domestic production systems.

Development of a Miniature Recorder for Drilling Motors

A recorder is designed to record the vibration data of the drilling motor for health assessment of the motor to improve the drilling efficiency. It is installed in the rotor catch of the drilling motor without increasing the length of the bottom hole assembly(BHA). The recorder is equipped with two triaxial vibration accelerometers with different ranges, a rate gyroscope, a temperature sensor, and an integrated circuit (IC) for timestamps. The recorder can measure and record the vibration data of the entire operation cycle of the ground transportation, rig-side handling and downhole operations of the motor. Vibration recorder does not require any configuration or intervention at rig sides so that it can be easily deployed to motor operations. The Python-based data analysis software was developed for the miniature vibration recorder. The analyzer can make statistics on the recorded data and display it with time plots and histogram. The vibration recorders provided adequate information of a drilling motor to maintenance shops and operator. These statistical data and charts can help users understand transportation, rig-side handling and downhole drilling.

Generation-expansion planning with linearized primary frequency response constraints

As renewable energy resources increasingly penetrate the electric grid, the inertia capability of power systems has become a developmental bottleneck. Nevertheless, the importance of primary frequency response (PFR) when making generation-expansion plans has been largely ignored. In this paper, we propose an optimal generation-expansion planning framework for wind and thermal power plants that takes PFR into account. The model is based on the frequency equivalent model. It includes investment, startup/shutdown, and typical operating costs for both thermal and renewable generators. The linearization constraints of PFR are derived theoretically. Case studies based on the modified IEEE 39-bus system demonstrate the efficiency and effectiveness of the proposed method. Compared with methods that ignore PFR, the method proposed in this paper can effectively reduce the cost of the entire planning and operation cycle, improving the accommodation rate of renewable energy.

Simulation model “free-piston engine – electromechatronic converter on the basis of an electrical generator reciprocating”

The analysis of the state and prospects of development of autonomous electric power sources with electric reciprocating motion generators has shown that at present, low-power systems “free-piston engine – electromechanotron сonverter based on an electric reciprocating motion generator” are widely used. Studies of electric reciprocating generators have shown that special attention should be paid to combined generators that can improve the efficiency of such a system. However, until now, the study of the system “free-piston engine – electromechanotron сonverter based on a combined electric reciprocating generator” has not been given due attention. In this regard, a simulation model of the system “free-piston engine – electromechanotron сonverter based on an electric generator of reciprocating motion” was developed, which allows conducting research of this system in various operating modes when changing the parameters of the electrical and mechanical subsystems. A distinctive feature of the developed simulation model is the consideration of the features of simultaneous use in the magnetic system of an electric generator of reciprocating motion of transverse and longitudinal nonlinear changes in magnetic flows. As a result of the simulation model studies, it is shown that the combined electric generator of reciprocating motion allows for continuous conversion of mechanical energy of reciprocating motion into electricity over the entire operating cycle, as well as – to compensate for the mismatch of the forces of the electrical and mechanical subsystems of the system “free-piston engine – electromechanotron converter based on an electric generator of reciprocating motion”.

Coordination of forces of mechanical and electric subsystems of power plant with free piston engine and electric generator of reciprocating type

Autonomous power supply system of modern mobile special-purpose equipment requires the development of electromechanical energy converters with high energy and minimum weight- and size indicators. In industrialized countries, the system “free piston engine – reciprocating electric generator of transverse type” is considered as a promising power plant. The main feature of this kind of power plant is the lack of crank mechanism in the engine design. This allows: increasing the efficiency of the engine up to 50–60 % and overall power by 2.5–3 times while reducing the specific gravity and metal consumption compared to traditional engines; reducing the specific fuel consumption of the engine up to 30 %; increasing the resource to overhaul by 30–50 thousand hours; implementing a modular structure. The main drawbacks of this kind of power plant are high probability of failure when passing the ignition of the working mixture and instability of work with significant load fluctuations. The noted drawbacks are due to the inconsistency of the forces of the electrical and mechanical subsystems of the power plant throughout the operating cycle. The solution for the problem of matching the forces of the electrical and mechanical subsystems of the power plant in the extreme positions of the piston group of the free piston engine is of particular complexity. In this regard, a method for solving the problem of matching the forces of the mechanical and electrical subsystems of the power plant with a free-piston engine throughout the operating cycle was developed, characterized by the use of an electromechanical reciprocating energy converter with transverse- and longitudinal nonlinear changes in the magnetic flux in the electrical subsystem. Coordination of the forces of mechanical and electrical subsystems of the power plant on the entire operating cycle makes it possible to fulfill the conditions of continuous electromechanical energy conversion at all work cycle and to reduce the specific gravity of the electrical subsystems of the plant while improving efficiency.

Expedited method of testing and refinement of refrigeration centrifugal compressors

Currently existing regulatory documents assume that refrigeration compressors are tested as part of test rigs with heat-exchange equipment. Given the high energy intensity of centrifugal compressors, the drive power of which in cooling mode with a cold capacity of up to 8.0 MW can be 2.0 or more MW, the creation of test rigs for preliminary and acceptance tests at the manufacturer’s factory requires a large investment. An alternative to the considered refrigeration centrifugal compressors test method is a test on a test rig in which the agent is partially condensed. In this case, an evaporator and a full-sized condenser are not required. The mathematical model of the refrigeration centrifugal compressors developed by JSC VNIIKHOLODMASH, allows testing of the refrigeration centrifugal compressors in model conditions, when the entire compressor operation cycle at the test rig is carried out in the area of superheated steam. Since the refrigeration centrifugal compressors mathematical model is based on physical simulation of compression processes in model stages at different values of conditional Mach numbers, dimensionless characteristics of model stages can be used to calculate the characteristic of the created compressor when operating under new conditions. The implementation of the model test method provides reduction of testing time due to absence of phase changes of the agent, improves the accuracy of the obtained results, reduces of power consumption, simplifies the test rig, and reduces consumption of the agent for filling the rig and water for cooling the agent.

Reactor core power mapping based on Bayesian inference

Bayesian inference provides a coherent probabilistic approach for combining information from measurements of in-core neutron detectors and numerical neutronics simulation results, and thus is an appropriate framework for reactor core power mapping which has been implemented in this paper. Measurements from DayaBay Unit 1 PWR are used to verify the accuracy of the Bayesian inference method, and comparisons are made among the Bayesian inference method, the Kalman filter method and the very-often-used coupling coefficients method. The root mean square errors (RMSE), the maximum relative errors (MRE), and the power peak reconstruction error (PPRE) of the Bayesian inference method are less than 0.31%, 1.64% and 0.07% for the entire operating cycle separately. The reconstructed assembly power distribution results and the calculation speed show that the Bayesian inference method is a promising candidate for on-line core power distribution monitoring system.

High-frequency measurement of N2O emissions from a full-scale vertical subsurface flow constructed wetland

In the last few years, the emission of nitrous oxide (N2O) from constructed wetlands has become a topic of increased interest. Most N2O emission measurements made so far are based on limited grab-samples, leading to sparse temporal resolution in the data. Using a high sampling frequency strategy, gaseous and dissolved N2O emissions from a two-stage vertical subsurface flow constructed wetland, treating domestic raw wastewater, were investigated. The monitoring period that lasted 3 weeks corresponded to an entire operation cycle of the filters including the feeding and rest periods.Gaseous N2O fluxes exhibited remarkable temporal fluctuations with contrasted emission rates between the feeding and rest periods, as well as high variability within a given period. Total potential emission rates (gaseous+dissolvedN2O fluxes) were found to be similar in both stages, with a mean value over the entire operation cycle of 1.50 and 1.78mgN/m2/h in Stage 1 and Stage 2, respectively. The dynamic behavior of the emissions was found to be correlated to the changes in the biogeochemical conditions within the filters. A positive relationship between gaseous N2O emissions and oxygen concentrations in filter media was observed during conditions favoring nitrification and denitrification, suggesting that N2O can be emitted from both processes.

A new power mapping method based on ordinary kriging and determination of optimal detector location strategy

The Ordinary Kriging (OK) method is presented that is designed for a core power mapping calculation of pressurized water reactors (PWRs). Measurements from DayaBay Unit 1 PWR are used to verify the accuracy of the OK method. The root mean square (RMS) reconstruction errors are kept at less than 0.35%, and the maximum reconstruction relative errors (RE) are kept at less than 1.02% for the entire operating cycle. The reconstructed assembly power distribution results show that the OK method is fit for core power distribution monitoring. The quality of power distribution obtained by the OK method is partly determined by the neutron detector locations, and the OK method is also applied to solve the optimal neutron detector location problem. The spatially averaged ordinary kriging variance (AOKV) is minimized using simulated annealing, and then, the optimal in-core neutron detector locations are obtained. The result shows that the current neutron detector location of DayaBay Unit 1 reactor is near-optimal.

Investigation on the Fatigue Characteristic in Support Structure of HL-2M Tokamak

In order to obtain enhanced plasma parameters a complete new tokamak HL-2M is now under construction in Southwestern Institute of Physics. To assure the structural safety of the device for the entire operation cycle, one of the most important issues is the lifetime-limiting effects due to the pulsed operation mode. Fatigue is one of the major failure modes to be considered in mechanical design, and pulsed operation imposes stress with significant alternating components on the support structure (SS). Therefore, the reliability of the whole device is strongly affected by the stress and fatigue characteristic of the SS as the interface structure. This article introduces the SS design and details the fatigue life calculation methods based on the different characteristics of the sub-structures. The fatigue life in hazardous areas of the toroidal field coils anti-torque structure (TFCs-ATs) has been determined by non-linear analysis results. And with the stress-time history data of the vacuum vessel & poloidal field coils support structure (VV&PFCs SS), the fatigue analysis of the hot spots has been completed based on rain-flow counting method and linear cumulative damage method. The calculated minimum fatigue life on TFCs-ATs and VV&PFCs SS is 4.743E+05 and 1.805E+06 cycles, respectively. And the calculated fatigue life on sub-structures can meet the required life for HL-2M tokamak: 1.0E+05 cycles.