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A Subchannel Analysis Code Star for Sodium-Cooled Fast Reactor

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SSRN 2022年

作者： Liang, Yu Zhang, Dalin Zhang, Jing Liu, Xiao Liu, Yapeng Zhou, Lei Chen, Yutong Mikityuk, Konstantin Wang, Xiaoyu Tian, Wenxi Qiu, Suizheng Su, Guanghui 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 Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China Paul Scherrer Institute Villigen PSI5232 Switzerland

The strong coupling heat transfer between subassemblies and inter-wrapper gaps is closely related to the safety of the sodium-cooled fast reactor (SFR). Therefore, it is very important to carry out a detailed thermal hydraulic analysis of the core. In this paper, the inter-wrapper channel is modeled using the subchannel method, and a two-fluid subchannel analysis model is developed based on the staggered grid method. The core thermal-hydraulic analysis code STAR (Subchannel Thermal-hydraulic Analysis code for SFR) is developed by using SIMPLE algorithm. © 2022, The Authors. All rights reserved.

关键词： Sodium-cooled fast reactors

Experimental Studies of Liquid Immersion Cooling for 18650 Lithium-Ion Battery Under Different Discharging Conditions

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SSRN 2022年

作者： Li, Yang Zhou, Zhifu Hu, Leiming Bai, Minli Gao, Linsong Li, Yulong Liu, Xuanyu Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116023 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China Department of Mechanical Engineering Carnegie Mellon University Pittsburgh15213 United States

In this study, the fluorinated liquid immersion cooling as a new cooling scheme has been tested and discussed for cooling the 18650 lithium-ion battery. OpteonTM SF33, with boiling point of 33.4oC, is chosen as the fluid for the immersion cooling. Comparison of the liquid immersion cooling and convective air cooling for a 18650 lithium-ion battery under 2C, 4C and dynamic load conditions are made. It is found that the immersion cooling better cools the battery cell under all these conditions. Under 4C discharging, the maximum cell temperature rise is 14.06°C for the forced air cooling, while is 4.97°C for the liquid immersion cooling. As the cooling fluid’s temperature basically governs the battery cell temperature, the cooling fluid’s temperature should not be too low. This study demonstrates that the lithium-ion battery has non-negligible power losses under cooling liquid temperature of 10oC and 15oC, compared with temperature above 20oC. Lastly, the two-phase boiling heat transfer mechanisms associated with immersion cooling of lithium-ion battery are discussed with bubble dynamics analysis. It is found under higher C rate, more aggressive boiling heat transfer is induced. The battery temperature is controlled to be below 34.5oC even under 7C discharging condition. © 2022, The Authors. All rights reserved.

关键词： Lithium-ion batteries

A 3d Ptco Degradation Model for Long-Term Performance Prediction of a Scaled-Up Pemfc Under Constant Voltage Operation

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SSRN 2023年

作者： Yang, Yunjie Bai, Minli Zhou, Zhifu Wu, Wei-Tao Zhao, Jian Wei, Lei Li, Yang Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Center for Advanced Vehicular Systems Mississippi State University Starkville39762 United States Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China

The non-uniform distribution of reactants, pressure, temperature, and reaction rate, in a scaled-up proton exchange membrane fuel cell (PEMFC) can lead to different catalyst degradation rate, impacting the long-term performance of PEMFCs. However, the local catalyst degradation behaviors in a PEMFC stack have not yet been fully understood due to the lack of experimental approaches and catalyst degradation model. In the present study, a numerical model is established for a 200 cm2 commercial-sized PEMFC stack with realistic anode and cathode flow fields. PtCo is employed as the cathode catalyst, and a 3D PtCo catalyst degradation model is developed to analyze the non-uniform evolution of the electrochemical active surface area (ECSA), current density, and Co2+ in the catalyst layers under the constant voltage conditions. The modeling results demonstrated that catalyst degradation is more severe downstream as well as under land of the cathode flow field, and the cathode catalyst layer (CCL) is the area most contaminated by the Co2+. The non-uniform catalyst degradation as well as Co2+ contamination increased the activation losses and local oxygen transport resistance. The catalyst degradation leads to a total power loss of 43.3% after 80,000 hours operation. The aging model provides a better understanding for large scale PEMFC stacks regarding its nonuniform PtCo degradation and can assist the future design of commercial PEMFCs with better lifetime. © 2023, The Authors. All rights reserved.

关键词： Proton exchange membrane fuel cells (PEMFC)

Development and Assessment of a Novel Air/Water Hybrid Cooling System Coupling Two Units for Energy and Water Saving

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SSRN 2022年

作者： Wang, Jinshi Xue, Kai Zhang, Guilong Chen, Weixiong Li, Gen Zhang, Juntai Zhang, Guozhu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China School of Electric Power Engineering South China University of Technology Guangzhou510641 China Datang Environment Industry Group Co. Ltd. Beijing100097 China

For the purpose of reducing coal consumption, decreasing CO2 emission, and improving economic interests of thermal power plants, a novel air/water hybrid cooling system coupling two units has been developed and assessed. The hybridization is achieved by the heat exchange of the circulating cooling water from two units, which is appropriate for the power plants with both water-cooling units and indirect air-cooling units, such as in North China region. Two schemes with different circulating water returning positions were compared on basis of thermodynamic and economic evaluation. Finally, the scheme that cooled circulating water was introduced to the air-cooling tower outlet was considered as the optimal design, which has the coal saving rate of 1.43 g/kWh at the design condition, with a 3.59-year payback period. In addition, this work focused on operation strategies to obtain optimum operation range, contributing to less coal consumption in summer and less water consumption in winter. The results indicate that annual coal consumption can be reduced by about 1400 tons in the reference power plant, the CO2 emission is decreased by 3490 tons, and 50000 tons of water could be saved. This technology is expected to be further promoted to practical engineering for the sustainable development. © 2022, The Authors. All rights reserved.

关键词： Thermoelectric power plants

Experimental Investigations of Liquid Immersion Cooling for 18650 Lithium-Ion Battery Pack Under Fast Charging Conditions

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SSRN 2022年

作者： Li, Yang Bai, Minli Zhou, Zhifu Wu, Wei-Tao Lv, Jizu Gao, Linsong Huang, Heng Li, Yulong Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116023 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China

In this study, a novel battery thermal management system (BTMS) based on FS49 is proposed and tested for cooling the cylindrical lithium-ion battery (LIB) module under fast charging conditions. Firstly, the temperature response of the battery module under 3 C rate charging with forced air cooling (FAC) and liquid immersion cooling (LIC) is compared. The results indicate that the LIC has excellent heat dissipation performance, and the peak temperature and peak temperature difference of the module are reduced by 19.6 °C and 8.99 °C, respectively, compared with the FAC, while the cooling energy consumption of LIC is only 40.4% of the FAC. It is found that the LIC embraces advantages of efficient cooling and minimizing the temperature non-uniformity in battery pack. Subsequently, the thermal management performance of the proposed LIC is investigated under conventional C rate discharging and different fast charging schemes. Finally, effect of condenser flow rate and cooling water temperature were investigated. This study demonstrates the application prospect of the LIC in the field of LIB fast charging. © 2022, The Authors. All rights reserved.

关键词： Lithium-ion batteries

Nuclear Thermal Coupling Optimization of Baffled Ntp Reactor

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SSRN 2022年

作者： Duan, Zimian Zhang, Jing Han, Zichao Wang, Mingjun Wu, Yingwei He, Yanan Tian, Wenxi Qiu, Siuzheng Su, Guanghui Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi’an710049 China Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Nuclear thermal propulsion (NTP) technology has characteristics of high power and high specific impulse. In particular, CERMET fuel reactor has received a lot of research due to its simple form and structure. A general CERMET fuel reactor model is established by using three-dimensional Monte Carlo neutron dynamics program and commercial CFD program Fluent. After nuclear thermal coupling optimization, three partition schemes of baffled reactor were proposed to reduce the temperature difference between the wall and the coolant and lower the relative spike factor in the inner region. A feasible design of redundant control system was then proposed, with a cold clean excess reactivity greater than $3.44 and a minimum dry shutdown reactivity lower than -$5.95, where there was a high control accuracy of 6.7 pcm/mm. The reactor realized safety of the core temperature lower than 3000K under the conditions of total exit temperature of 2650K and thrust of 25000lb. © 2022, The Authors. All rights reserved.

关键词： Cermets

Capillary Limit of a Sodium Screen-Wick Heat Pipe

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SSRN 2022年

作者： Ma, Yugao Wang, Xueqing Yu, Hongxing Huang, Shanfang Zhang, Yingnan Huang, Jian Su, Guanghui Deng, Jian Chai, Xiaoming Hu, Wenzhen School of Nuclear Science and Technology Xi’an Jiaotong University Shanxi Xi’an710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Engineering Physics Tsinghua University Beijing100084 China State Key Laboratory of Multiphase Flow in Power Engineering China

High-temperature alkali-metal heat pipes are passive heat transfer devices, where the capillary pressure created by the menisci in the wick pumps the condensed fluid back to the evaporator. Thus, the heat pipe heat transfer capacity is limited by the maximum capillary pressure at high heat fluxes. This work presents a two-dimensional heat and mass transfer model that includes the capillary and gravitational forces that are used to predict the capillary limit which is then validated by experimental data. The predicted critical heat flux temperature has an error of less than 20℃ and a relative error of 6%. The predicted transient sequences are consistent with the measurements. The model shows that capillary limit is affected by inclination angle, heat flux, and wick structure. For inclinations, the critical heat flux at the capillary limit is linearly related to the inclination angle with the predicted temperature rising 2 ~10℃/s during the early stage of the capillary limit critical heat flux condition. The evaporator temperature oscillates before the capillary limit with positive inclinations. For heat fluxes, increasing the heat flux by 17% increases the temperature increase rate 10 fold with a longer dryout length. The evaporator exhibits hysteresis after the capillary limit due to partial dryout of evaporator. For wick structures, reducing the mesh screen pitch from 80 μm to 15 μm reduces the critical heat flux to 10% of the CHF at 80 μm. This model can accurately predict the heat pipe temperature variations at the capillary limit and can explain the physical mechanisms for the dryout oscillations and recovery hysteresis at the capillary limit. Thus, the measurements and model provide analytical guidelines for designing heat pipe cooling systems. © 2022, The Authors. All rights reserved.

关键词： Heat flux

Optimizing Interfacial Environment of Triphasic Zno-Cu-Zro2 Confined Inside Mesoporous Silica Spheres for Enhancing Co2 Hydrogenation to Methanol

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SSRN 2022年

作者： Chen, Changwei Kosari, Mohammadreza Xi, Shibo Lim, Alvin M.H. He, Chi Zeng, Hua Chun Department of Chemical and Biomolecular Engineering Faculty of Engineering National University of Singapore 10 Kent Ridge Crescent 119260 Singapore State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Shaanxi Xi'An710049 China 1 Pesek Road Jurong Island 627833 Singapore

Herein, the well-known ternary Cu 0 -ZnO-ZrO 2 (CZZ) was spatially sequestered as fine, uniformly-dispersed optimized active interfaces onto an engineered mesoporous silica sphere (MSS), giving rise to Cu 0 -ZnO-ZrO 2 /MSS (CZZ-MSS) with confined binary Cu 0 -ZnO/Cu 0 -ZrO 2 and ternary interfaces that fostered methanol production under moderate conditions. By systematically investigating the CZZ-MSS performance. Besides, the strong metal-support interaction arising from interacting metallic Cu and metal oxides (ZnO and ZrO 2 ) within the confined, ultrasmall nanoparticles ( © 2022, The Authors. All rights reserved.

关键词： Zinc oxide

Numerical Investigations for the Pcm and Liquid Immersion Cooling Effects on Lithium Ion Battery Thermal Runaway Mitigation

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SSRN 2023年

作者： Liu, Xinyu Zhou, Zhifu Wu, Wei-Tao Wei, Lei Wu, Weixiong Li, Yang Gao, Linsong Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China Energy and Electricity Research Center Jinan University Zhuhai519070 China

In this study, a three-dimensional (3D) thermal runaway (TR) model with conjugate heat transfer submodel is adopted. TR behaviors for a battery pack with 12 prismatic LIBs are then simulated. Three thermal safety measures of TR protection from internal shorting in Cell 1 to pack level configuration are compared and evaluated. Paraffin phase change material (PPCM) is firstly proposed to delay the TR propagation between LIBs with solid-liquid phase change as heat transfer mechanism. Different thicknesses of PPCMs are compared to verify the TR mitigation performance of the PPCM under thermal abuse condition. The TR time for the Cell 2 is delayed to be 64 s, 266 s and 414 corresponding to PPCM thickness of 1.8 mm, 3.6 mm and 5.4 mm. As the simulation results shows, this TR time can be further delayed to 798 s by a strategy with combing PPCM with insulation. In addition, this work proposes a novel thermal safety protection based on immersion cooling with pool boiling of fluorinated liquid as heat transfer mechanism. We observe that the average temperature of Cell 2 - Cell 12 tends to be within 34oC under immersive cooling condition, which indicates the possibility to prevent the TR. © 2023, The Authors. All rights reserved.

关键词： Lithium-ion batteries