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An inverse fault detection and diagnosis (IFDD) strategy for practical application on chiller product

INTERNATIONAL JOURNAL OF REFRIGERATION 2022年 134卷 24-34页

作者： Lu, Hailong Cui, Xiaoyu Han, Hua Liu, Jiangyan Zhang, Yunqian School of Energy and Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Yangpu District Shanghai 200093 PR China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093 PR China CQ Midea General Refrigeration Equipment Co. Ltd. 15 Qiangwei Road Nanan District Chongqing 401336 PR China School of Energy and Power Engineering Chongqing University Chongqing PR China

Current research on chiller fault detection and diagnosis (FDD) is usually based on the multi-classification method for mixed multiple fault types. The establishment of a multi-classification FDD model requires obtaining extensive test data of normal operation and multiple common faults at different fault levels, so the cost-to benefit ratio will not be accepted. In addition, because of the information interference between different types of fault data, FDD model is hard to avoid over-fitting or under-fitting, and there may be an intolerable high false alarm rate existing in product application. Therefore, it is difficult to promote FDD in actual chiller product applications. This paper proposes an inverse fault detection and diagnosis (IFDD) strategy, which is based on the characteristics of the target fault (the fault to be concerned) to establish a two-classification fault diagnosis model. Compared with the multi-classification method, the amount of fault test data required by the two classification methods to realize fault diagnosis can be greatly reduced. With IFDD strategy, the detection and diagnosis are completed simultaneously, while fast calculation speed, high diagnosis accuracy rate and low false alarm rate are achieved. The core of the IFDD strategy is to concentrate resources to capture the characteristics of the target fault, and no longer classify other types of faults and normal operating conditions, so it can avoid the influence of information interference between multiple types of fault data in the fault diagnosis model. In order to verify the feasibility of this strategy, a 200 ton variable-speed screw chiller has been tested on the laboratory, and a database of normal operation, refrigerant leakage, refrigerant overcharge faults, and a new operating condition of insufficient cooling water flow is initially established. Based on the sensors configured by the chiller unit and using the exponentially weighted moving-average (EWMA) control chart for

关键词： Inverse FDD Strategy Practical application Chiller product EWMA

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A Preliminary Study on the Blistering Behavior of Dispersion Plate-Type Fuel Assembly

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SSRN 2024年

作者： Yu, Songjiao Zhang, Kui Yang, Yiming Liu, Yumin Tian, Wenxi Qiu, Suizheng School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The dispersion plate fuel assembly, owing to its favorable characteristics of low temperature gradient, high stability, and excellent thermal conductivity, has become a focal point in the research of novel high-performance fuel elements. However, the current literature lacks a comprehensive understanding of the fuel plate's performance, particularly with regard to the bubbling phenomenon in the fuel plate cladding. In this study, we have implemented a fission gas release model, building upon previous analyses of fuel plate performance under steady-state operation. By comparing our calculation results with the Forsberg-Massih model, we find a close correspondence in trends, thereby validating the accuracy of our computational approach. Furthermore, we utilize the upgraded FROBA-PLATEs code to predict the blistering behavior of fuel plates under specific quasi-steady-state conditions. Our results demonstrate that the occurrence position and threshold temperature of blistering in the fuel assembly can be precisely predicted using this approach. © 2024, The Authors. All rights reserved.

关键词： Fission products

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Low temperature overpressurization analysis for CPR1000

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International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 145-153页

作者： Liang, Yu Wang, Mingjun Li, Zhen Liao, Haoyu Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, G.H. School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Huaneng Shandong ShidaoBay Nuclear Power Plant China

An additional low temperature overpressure protection system which relies on the Pressurizer (PRZ) pressure relief valves has been put forward under the situation in which the Residual Heat Removal System (RHRS) is unavailable or isolated. Taking into account the risk of Reactor Pressure Vessel (RPV) brittle fracture and LOCA under cold overpressurization transients, it is urgent to strengthen the low temperature overpressure protection for in-service Pressurized Water Reactors (PWR) in China. In this paper, the simulation and analysis of two types of overpressure transients at low temperature during the shutdown process are carried out through the detailed Relap5 modeling of CPR1000. The results show that the place where the brittle fracture occurs firstly is the lower plenum. The sensitivities of the system temperature and the opening/closing time of the additional protection system's valve are analyzed. The system set point becomes more restrictive at lower coolant temperature. Additional threshold values of the PRZ pressure relief valve are given under different Effective Full power Years (EFPY). The set point should be less than 5.5 MPa in the case of 5 EFPY and less than 3.7 MPa at 10 *** results can be applied to engineering practice, which can effectively improve the safety of CPR1000. © 2021

关键词： Pressure relief valves

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Co-Optimization for Distributed Multi-Energy System Based on Multi-Objective Robust Stackelberg Game: Energy Management and Multi-Energy Pricing

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SSRN 2024年

作者： Ren, Xiaoxiao Wang, Jinshi Yang, Sifan Zhao, Quanbin Jia, Yifan Ou, Kejie Hu, Guangtao Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China School of Energy Engineering Yulin University Yulin719000 China

To achieve low-carbon operation of distributed multi-energy system (DMES) and enhance its activity in the energy market, this paper proposes a novel multi-objective Stackelberg game model. The DMES operator (DMEO) acts as the leader, guiding users' behavior through DMES optimal scheduling and multi-energy pricing. The optimization objectives include maximizing DMEO revenues, minimizing DMES primary energy consumption and carbon emissions. The users act as followers, adjusting energy demand based on upper-level energy pricing with the objective of maximizing consumption surplus. To achieve the low-carbon and flexible operation of DMES, carbon trading and demand response mechanisms are introduced. The upper-level model is solved using the non-dominated sorting genetic algorithm III (NSGA-III), while the lower-level model is solved by the Gurobi solver. Furthermore, a robust optimization model with adjustable robust measure is established to mitigate the impact of renewable energy uncertainty. Finally, the validity of the proposed model is verified by a data center in Qinghai. Compared with traditional Stackelberg game model, the proposed model reduces DMEO revenue by 0.63% but decreases carbon emissions by 1.64% and energy consumption by 1.59%. Under this optimization framework, the energy efficiency and exergy efficiency of DMES are 0.798 and 0.535, and the share of renewable energy is 34.6%. Besides, increasing renewable energy uncertainty leads to lower DMEO revenue, higher carbon emissions and energy consumption, while significantly reducing energy efficiency and exergy efficiency. The proposed multi-objective Stackelberg game model may provide some references for multi-stage energy system optimization. © 2024, The Authors. All rights reserved.

关键词： Energy utilization

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Numerical Simulation Investigating the Influence of Varied Stack Parameters on the Energy Conversion in Thermoacoutic Engines

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SSRN 2024年

作者： Yao, Chen Zhou, Yao Liu, Jiping Yan, Junjie MOE Key Laboratory of Thermal Fluid Science Engineering Xi’an Jiaotong Univeristy Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong Univeristy Xi’an710049 China

The stack is a crucial component of the thermoacoustic heat engine, influencing its capacity to generate stable pressure amplitude and enhance efficiency. Utilizing the discontinuous Galerkin (DG) method, fully compressible Navier-Stokes equations were solved to simulate the energy exchange between the stack and surrounding air under various conditions.(1) Simulations were conducted under different stack wall boundary conditions, including linear temperature distribution wall, isothermal wall, and adiabatic wall. The work performed by 1 kg of gas at a specific position during one cycle was defined as local energy density to analyse the effect of different stack spacing, stack length and stack thickness. (2) Too small a stack spacing causes the inability to generate pressure amplitude. Increasing the stack spacing continuously enhances the generated pressure amplitude, with the energy density distribution near the hot heat exchanger becoming more significant. As the stack spacing continues to increase, the energy density decreases at positions farther from the wall, leading to a reduction in pressure amplitude. The generated acoustic streaming intensity diminishes faster with the continuous increase in stack spacing. (3) A smaller stack length results in reduced viscous dissipation at the wall, leading to a larger generated pressure amplitude. However, shorter stack lengths cause increased gas oscillation displacement, resulting in lower energy density concentrate around the stack. This raises the load on the two heat exchangers, consequently reducing the overall efficiency. (4) The pressure amplitude decreases with the increase in stack thickness. The vortex intensity at the gap between the hot heat exchanger and the stack increases with the stack thickness, leading to higher viscous losses for the fluid passing through this region. Consequently, the performance of the thermoacoustic engine declines. These findings provide valuable guidance for the design of thermoa

关键词： Numerical methods

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Data-Driven Surrogate Model for the Dynamic Characteristics of Supercritical Units

Data-Driven Surrogate Model for the Dynamic Characteristics ...

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power System and New Energy Technology Innovation Forum (NPSIF), Boao New power System International Forum -

作者： Shuai Dong An Zheng Junyao Jiang Wei Gao Ming Liu HUANENG YIMIN COAL-POWER CO. LTD. Hulunbuir China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (数字)9798331504557

ISBN: (纸本)9798331504564

Coal-fired power generation units are characterized by large inertia, strong coupling, and high delay, making dynamic characteristic modeling inherently complex and computationally intensive. To address this, this paper utilizes GSE software to explore the dynamic characteristics of supercritical units. Data-driven approaches are then employed to develop surrogate model for these dynamics, comparing neural networks and support vector regression methods in the process. The study indicates that the surrogate model achieves a relative prediction error of less than 1% for live steam temperature, reheater steam outlet temperature, and power output. For live steam pressure and reheater steam outlet pressure, the model maintains a relative error within 10%.

关键词： Support vector machines Technological innovation Temperature Accuracy Computational modeling power system dynamics Neural networks Predictive models Vectors Load modeling

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Study on the Three-Dimensional flow Control of Two-Phase flow Around a Cylinder by an Attached Cylinder

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SSRN 2023年

作者： Xia, Yizhan Hu, Yu Huang, Shengxian Wang, Ying Shanghai key laboratory of multiphase flow and heat transfer of power engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China

Enhancing the separation of flow, shedding of vortices, and sediment deposition around blunt bodies, particularly in cylindrical flows within the realm of ocean engineering, emerges as a pivotal safety factor. This study delves into the control of two-phase flow encircling a cylinder using an affixed cylinder under three-dimensional real ocean conditions. Employing the SST turbulence model, a two-dimensional incompressible RANS numerical simulation is performed. Initially, the influence of varying gap ratios between the auxiliary small cylinder and the main cylinder is scrutinized. Subsequently, the impact of attached small cylinders on the flow field surrounding the main cylinder is examined under different particle characteristics. Lastly, employing the UDF function, four small cylinders exhibiting distinct vibration modes are defined, and the numerical simulation investigates the effects of Grain flow on particle flow and distribution in the wake region of the main cylinder. © 2023, The Authors. All rights reserved.

关键词： Cylinders (shapes)

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A Novel Multi-Objective Stackelberg Game Model for Multi-Energy Dynamic Pricing and Flexible Scheduling in Distributed Multi-Energy System

SSRN

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SSRN 2024年

In the face of global energy and environmental challenges, distributed multi-energy system (DMES) offers a promising solution. To optimize resource allocation and promote energy market development, this paper proposes a novel multi-energy management and pricing framework based on multi-objective Stackelberg game. The DMES operator (DMEO) acts as the leader by optimizing DMES scheduling and pricing to guide user behavior towards revenue, energy consumption, and carbon emissions goals. Users adjust energy demand based on energy pricing to maximize consumption surplus. To achieve the low-carbon and flexible operation of DMES, carbon trading and demand response mechanisms are introduced. The model is solved using NSGA-III and Gurobi solver, with a robust optimization model with adjustable robust measure is established to address renewable energy uncertainty. The validity of the proposed model is verified by a data center in Qinghai. Compared with traditional Stackelberg game model, the proposed model reduces carbon emissions by 1.64% and energy consumption by 1.59%. Under this optimization framework, the exergy efficiency and energy efficiency of DMES are 0.535 and 0.798, and the share of renewable energy is 34.6%. Increased renewable energy uncertainty leads to lower DMEO revenue, higher carbon emissions and energy consumption, while significantly reducing energy and exergy efficiency. © 2024, The Authors. All rights reserved.

关键词： Energy utilization

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Review, Numerical Validation, and Experiment Verification for Definite Solution Analogy Theory (Dsat) in Thermal-Hydraulic Scaling

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SSRN 2024年

作者： Li, Xinyu Zhang, Dalin Jiang, Dianqiang Zhou, Xingguang Lv, Xindi Tian, Wenxi Qiu, Suizheng Su, Guanghui State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

The new generation of reactor technology: Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR), mainly applied to remote, underground, and arid areas. The design of the heat transport system and Passive Residual Heat Removal System (PRHRS) of FuSTAR has been finished, but the verification still needs to be carried out. In this study, the Definite Solution Analogy Theory (DSAT) was used for scaling analysis, and the scaling experiment platform was built. DSAT was verified through numerical simulation and experiment results. The numerical test results show the similarity of physical fields in dimensionless space on the prototype and experiment under the DSAT framework. The steady-state experiment results show that the prototype of PRHRS can take away more than 1% of the decay heat of the total thermal power. The transient experiment results show that the maximum deviation of dimensionless solutions is less than 4%, which proves the high accuracy of DSAT and the PRHRS based on this framework can effectively remove the decay heat in the reactor. This work can be used to extend the scaling method of thermal-hydraulic in high dimensional space and transient conditions. © 2024, The Authors. All rights reserved.

关键词： Fluorine compounds

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Experimental and Numerical Simulation Study on Critical Heat Flux in Narrow Rectangular Channels

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SSRN 2024年

作者： Lv, Xindi Zhang, Dalin Song, Gongle Su, Guanghui Tian, Wenxi Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

Experimental investigation was performed on the critical heat flux (CHF) in narrow rectangular channels. The rectangular channel adopts single-side heating, the channel gaps were 1.3 and 1.9mm, the system pressure was 1~4Mpa, the inlet subcooling was 20~100K, and the mass flux was 200~1500 kg/(m2⋅s). The variation of CHF in vertical upward flow with different thermal parameters and geometric dimensions was studied. A three-fluid transient model was established to calculate the CHF of vertical upward annular flow in narrow rectangular channel. The calculation model was validated with CHF experimental data and the results were in good agreement. Combining experimental and theoretical research results, it could be concluded that the mass flow rate played an important role in the critical heat flux phenomenon of narrow rectangular channel, and its magnitude directly affected the effect of changes in thermal parameters such as pressure, mass flow rate and inlet subcooling on CHF. © 2024, The Authors. All rights reserved.

关键词： Heat flux

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