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Oxidation of Typical Zr-1nb Alloy in High-Temperature Air Under 700–900 °C

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SSRN 2022年

作者： Jiang, Guanyu Xu, Donghai Liu, Lu Ding, Xin Kuang, Wenjun Wang, Mingjun Key Laboratory of Thermo-Fluid Science & Engineering Ministry of Education School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi Province Xi’an710049 China School of Materials Science and Engineering Xi’an Jiaotong University Shaanxi Province Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi'an Jiaotong University Xi’an China

m-ZrO2 is always the dominant phase, while oxide shapes, the integrity and roughness of oxide films share evident differences. At 900 °C, M5 alloy exhibits kinetics transition and breakaway oxidation at approximately 80 min. The pre-transition oxidation follows a parabola kinetics with the rate exponent n being 1.65. The presence of ZrO and ZrO0.35 sub-oxides accounts for the high reaction activation energy (149.6 kJ/mol). During the kinetics transition, some intergranular cracks turn transgranular, and pores distribute on the oxide layer and O/M interface. Air ingress through the oxide layer is jointly affected by air transport and ion diffusion. © 2022, The Authors. All rights reserved.

关键词： Oxidation

Numerical Study of High-Energy Spark Ignition Characteristics in a Scramjet Combustor

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SSRN 2024年

作者： Gao, Ziyan Zhang, Meng Zhang, Zhibo Wu, Yun Zheng, Xing Miao, Huifeng National Key Lab of Aerospace Power System and Plasma Technology Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong Universiy Xi’an710049 China National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering University Xi’an710038 China Shaanxi Key Laboratory of Environment and Control for Flight Vehicle School of Aerospace Engineering Xi’an Jiaotong University Shaanxi 710049 China

Reliable ignition is a fundamental prerequisite for the scramjet engines. In order to improve the reliability of ignition, further enhance the application of spark ignition in engineering, and improve the ignition ability in the field of supersonic combustion, an innovative long electrode distance high-energy spark igniter (LHSI) system was proposed by our research team. To reveal the instantaneous ignition characteristics of the LHSI, a simulation model of the LHSI is established and verified by experiments. Based on this, the formation and development of the initial fire core of vaporized kerosene and the ignition characteristics of LHSI in a scramjet combustor were simulated and compared with the conventional high-energy spark igniter (HSI). The analysis revealed that the success of the cavity ignition is greatly influenced by the local equivalent ratio of the initial flow field and the penetration depth of the initial flame core. Meanwhile, the fore recirculation zone of the cavity plays a key role in stabilization and development of the initial fire core. Compared with the HSI, the LHSI can produce initial flame core with higher penetration and greater size, which is the main reason for why LHSI has a broader ignition boundary. © 2024, The Authors. All rights reserved.

关键词： Ignition

Thermodynamic Analysis of a Hybrid Energy System Coupling Solar Organic Rankine Cycle and Ground Source Heat Pump: Exploring Heat Cascade Utilization

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SSRN 2023年

作者： Chen, Liangqi Yue, Huifeng Wang, Jiangfeng Lou, Juwei Wang, Shunsen Guo, Yumin Deng, Bohao Sun, Lu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China China United Northwest Institute for Engineering Design & Research Co. Ltd Xi’an710077 China School of Human Settlements and Civil Engineering Xi'an Jiaotong University Xi’an710049 China

The demand for efficient utilization of renewable energy is growing and the hybrid energy system driven by solar and geothermal energy is a significant way to achieve carbon neutrality. This paper presents a hybrid energy system coupling solar organic Rankine cycle (S-ORC) with ground source heat pump (GSHP) for heating and power supply to explore the heat cascade utilization. In the hybrid energy system, the ground heat exchanger (GHE) is shared by the S-ORC and GSHP systems and the waste heat from the condenser of S-ORC is recovered to enhance the coefficient of performance (COP) of GSHP. A mathematical model is optimized to analyze the parametric effects on thermodynamic performance. The results indicate that the COP of the hybrid energy system can be improved up to 6.5 which shows the obvious advantage compared to 2.8 of the stand-alone GSHP system. Furthermore, the hybrid energy system can obtain optimum exergy efficiency by matching ground source temperature and condensation temperature in the ORC unit. For a building of 3000m2 with heating and power supply, multi-objective optimization is carried out to obtain the optimal design performance that the net power output, thermal efficiency and exergy efficiency are 180.0kW, 27.5%, and 9.2% respectively. © 2023, The Authors. All rights reserved.

关键词： Geothermal heat pumps

Hydrodynamic Characteristics Prediction Models for Water-Cooled Wall Under Different Loads Based on Artificial Neural Network

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SSRN 2024年

作者： Yang, Jiahui Zhang, Yong Li, Ruiyu Han, Lei Yue, Yang Wang, Jin Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Yantai Longyuan Power Technology Co. Ltd Yantai264000 China Shunde Institute of Inspection Guangdong Institute of Special Equipment Inspection and Research Foshan528300 China

Real-time monitoring of hydrodynamic characteristics in water-cooled wall is crucial for boiler safety. Comprehensive numerical simulations are employed in this study to determine the heat flux distribution on the water-cooled wall across 38 different operating conditions. The heat flux results are applied to calculate hydrodynamic characteristics. Subsequently, the hydrodynamic characteristics results, along with the corresponding operating parameters, form the dataset for the Artificial Neural Network (ANN) models. The proposed methodology generates high-quality datasets, with a maximum root mean square error (RMSE) of only 6.8 K when comparing the results of working fluid temperature to the measured values. Two dataset partitioning methods are compared. Compared with random partitioning (control group), Considering each working condition as a whole during dataset partitioning (experimental group) reduces the average RMSE of predicted results in the test set by 47.6%, along with a 31.8% decrease in average number of neurons. The developed models exhibit excellent agreement with four working conditions in the test set, both in trends and absolute values, with acceptable error ranges. On the validation and test sets, the maximum RMSEs between the predicted and calculated values for flow rate, pressure, temperature and enthalpy are 0.033 kg s-1, 0.49 MPa, 5.7 K and 89.5 kJ kg-1, respectively, underscoring the reliability and practicality of the predictive models. © 2024, The Authors. All rights reserved.

关键词： Hydrodynamics

Clogging failure in microfilter for blood cell separation and its novel improvements

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Clogging failure in microfilter for blood cell separation an...

International Symposium on Physical & Failure Analysis of Integrated Circuits

作者： Tao Dong Zhaochu Yang Eirik Bentzen Egeland Frank Karlsen Henrik Jakobsen Norwegian Center of Expertise on Micro-and Nanotechnology I.M.S.T. /R. I Vestfold University College Norway State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

Clogging failure is common for microfilter utilizing the flat membrane structure. To reduce clogging failure in microfilters, the turbine blade-like micropillar is introduced in microfilter design. Two improved cross-flow microfilter designs employing the blade-like micropillar barrier are presented, one with varied cross-section channels, and the other with Archimedes' spiral channels. Analogy experimental-data based simulations show that the two aforementioned novel microfilters have good filtrating efficiency and fantastic anti-clogging characteristics. And the commercial value of the turbine blade-like barriers is affirmed by the industry Partners.

关键词： Microfiltration Cells (biology) Filters Biomembranes Filtration Turbines White blood cells Nanotechnology Educational institutions power engineering

Aeroderivative Gas Turbine and Composite Sco2 power Cycle Integrated System: Towards Large-Scale Gas-to-power Efficient Conversion

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SSRN 2023年

作者： Jiang, Yuemao Wang, Shunsen Su, Wen Li, Bo Wang, Zhe State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China School of Energy Science and Engineering Central South University Changsha410083 China National Center for International Research of Subsea Engineering Technology and Equipment Dalian Maritime University Dalian116026 China

power-to-Gas is proving to be an effective means of storing electricity from renewables on a large scale. Nevertheless, there is yet to be a clear technical route for large-scale hydrogen-enriched gas conversion into electricity (Gas-to-power). This paper proposed a novel integrated power system consisting of an aeroderivative gas turbine and a composite supercritical CO2 (sCO2) power cycle. In addition, a new evaluation indicator based on exergy was also proposed to reveal the real waste heat recovery capacity and select the sCO2 cycles. After that, a comprehensive energy, exergy, exergoeconomic, and environment (4E) analysis and global parametric studies were conducted for the integrated system. Finally, an entropy-based TOPSIS decision-maker was combined with the tri-objective optimization algorithm for the combined cycle integrated design. Thermodynamic optimization results show that, unlike the thermal efficiency, the exergy efficiency of the partial heating sCO2 cycle of 48.3% is higher than that of the recuperated one. With the exhaust gas carrying 21% of fuel exergy, the total exergy recovery efficiency is 51.7%, and the fuel efficiency of the integrated system is over 50%. As for the exergoeconomic, the combustor alone is responsible for 77.1% of the total exergy destruction, the initial cost of the bottoming cycle is less than half that of the gas turbine, and the high-pressure turbine has the highest exergoeconomic factor of 91.5%. The key parameters of the gas turbine significantly influence the performance of the sCO2 cycle and the integrated system 4E performance. There is an optimal gas turbine inlet temperature of about 1500 K to minimize the LCOE. After the multi-objective integrated optimization, the overall efficiency, LCOE, and specific gas emissions are 50.2%, 7.8 cents/kWh, and 396.8 g/kWh, respectively, which are all higher than those from optimizing the bottoming cycle alone. It is considered that the technical solutions and research results

关键词： Gas turbines

Enhanced Heat Transfer of flow Boiling Combined with Jet Impingement

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Enhanced Heat Transfer of Flow Boiling Combined with Jet Imp...

第七届天地应用两相系统国际研讨会

作者： J.J.Wei J.F.Zhao D.Guo Y.H.Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University28 Xianning XiluXi’an 710049China 2National Microgravity LaboratoryInstitute of MechanicsChinese Academy of Sciences 15 Beisihuan XiluBeijing 100190China

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

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