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SSRN 2024年

作者： Yang, Xiaoping Bu, Shichao Jiang, Zhuye Chen, Hongqiang Sun, Zhen Zhang, Yonghai Wei, Jinjia School of Chemical Engineering and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Mobile Network and Mobile Multimedia Technology ZTE Corporation hillsides China

With the continuous development of chip integration and information technology, the heat dissipation has become a major limitation on the performance of electronic devices such as 5G base station, data center and so on, and meanwhile a challenge of conventional single-phase convection cooling methods. Boiling is prospective in high heat flux cooling and energy saving due to the usage of latent heat. R1233zd(E), an environmentally friendly refrigerant (GWP=1, ODP=0) with a freezing point of -107°C, is a potential working fluid in phase-change heat sinks for geographical applications. Nevertheless, the poor boiling performance of R1233zd(E) on plain surface due to the limitation in thermophysical properties must be enhanced. Moreover, conventional heat sinks are mostly copper-based, which are inconvenient for transportation and installation, and costly for production as well. In this work, micro pin fins in the range of 100-500 μm are fabricated on the aluminum surface to enhance the pool boiling of R1233zd(E). Moreover, the influence of their size and saturation pressure on the bubble behavior, critical heat flux (CHF) and heat transfer coefficient (HTC) is experimentally and theoretically investigated. The results show that the increase of pressure, as well as the ensuing various nucleation site and capillary effect to rewet the evaporation region, can lead to an increase in the CHF and HTC. Notably, the 150-200 μm micro pin-finned surfaces reaches the highest CHF and 100 μm one owns the highest HTC, which is 214% and 383% higher than that of plain surface, respectively. BY considering the balance of capillary effect and bubble convolution effect, a model of CHF is proposed to reveal the mechanism of optimum size of the micro pin fins. The predicted CHFs have an inaccuracy of less than ±20% comparing to experimental values. This paper makes up for the lack of basic experimental data on pool boiling of R1233zd(E) on aluminum surface, which thus provides guidance for

关键词： Heat flux

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An Operation Optimization of Cooling System for Reactor Shutdown in Pebble Bed Gas-Cooled Reactor

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SSRN 2024年

作者： Liu, Junfeng Wang, Chenglong Qiu, Suizheng Wang, Boyuan Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Shaanxi Engineering Research Center of Advanced Nuclear Energy Xi’an Jiaotong University Xi’an710049 China Xi’an Thermal Power Research Institute Co. Ltd Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

For the emergency shutdown of a high temperature gas-cooled reactor pebble-bed module (HTR-PM) in its operation conditions, in the current design method with a low-flow auxiliary steam cooling technical solution, there are some security and economic issues, i.e. high thermal shock, long cooling time, and temperature drop rate exceeding the limit. To solve these problems, an optimized design method for the shutdown cooling system is presented. Through a simulation model of the shutdown cooling system based on Matlab/Simulink, the dynamic characteristics of the shutdown cooling system in its operation conditions are obtained, involving shutdown, low flow cooling, and water supply start-up stages. The results showed that with the optimized design method, the safety of the core and steam generator can both be ensured during the cooling process, and the cooling rate is significantly improved. Therefore, the optimized design method is feasible and advanced. © 2024, The Authors. All rights reserved.

关键词： Cooling

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Influence of Bi3+ Doping on the Electrochemical Properties of Ti/Sb-Sno2/Pbo2 Electrode for Zinc Electrowinning

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SSRN 2024年

作者： Wu, Jia Kang, Xuanqi Xu, Shuangwen Wei, Zhen Xu, Shangyuan Liu, Kang Feng, Qing Jia, Bo Wang, Yunhai Xían Taijin New Energy & Materials Sci-Tech CO. Ltd Xi’an710016 China Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiao tong University Xi’an710049 China

Bi3+ doped Ti/Sb-SnO2/PbO2 electrode materials were fabricated by electrodeposition to improve its electrochemical performance in zinc electrowinning. The surface morphology, chemical composition and hydrophilicity of the as-prepared electrodes are characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and contact angle. The electrochemical measurement and the accelerate lifetime experiment are also conduct to investigate the electrocatalytic performance and stability of the electrodes. The results showed that Bi3+ modification electrode has an important effect on the coating morphology, crystal structure, surface hydrophilicity, electrocatalytic activity and stability. The electrode prepared from the solution containing 2 mmol·L-1 Bi(NO3)3 (marked as the Ti/Sb-SnO2/2Bi-PbO2 electrode) exhibits the best hydrophilicity performance (θ=21.6°) and the longest service life (1196 h). During the electrochemical characterization analysis, the Ti/Sb-SnO2/2Bi-PbO2 electrode showed the highest oxygen evolution activity, which can be attributed to the highest electroactive surface (qT*=21.20 C·cm-2) and the best charge transfer efficiency. DFT calculation demonstrate that the doping of Bi lead to the decrease in the OER reaction barrier and increase the DOS of the electrode, which further enhanced the catalytic activity and conductivity of the electrode. Moreover, the simulated zinc electrowinning experiment demonstrate that the Ti/Sb-SnO2/2Bi-PbO2 electrode consume less energy than other electrodes. Therefore, it is expected that the Bi modified electrodes may become a very promising electrode material for zinc electrowinning in the future. © 2024, The Authors. All rights reserved.

关键词： Hydrophilicity

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A simple analytical model to predict liquid unloading in the horizontal gas well

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Journal of Hydrodynamics 2021年第5期33卷 1056-1064页

作者： Zhi-bin Wang Jin-quan Ling Tian-li Sun Hong-yan Shi Guo Zhu State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChendu 610500China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China No 2 Gas Production PlantSouthwest Oil and Gas CompanySINOPECLangzhong 637400China Infrastructure Department Southwest Oil and Gas CompanySINOPECChengdu 610041China

An accurate prediction of the critical gas velocity for the liquid loading is of great importance for operators to select the tubing diameter for the newly drilled gas wells,or to optimize the production rate for production *** is clear from previous experimental studies of the liquid entrainment rate in the gas core that the liquid is mainly carried in the form of film under the critical condition of the liquid loading *** is more reasonable to establish a mathematical model based on the film reversal rather than based on the droplet *** our previous paper entitled“Prediction of the critical gas velocity of liquid unloading in the horizontal gas well”,a new analytical model was established based on the force balance between the gas-liquid interfacial friction force and the bottom film gravity,but the model is not very convenient to use because of the complexity of calculating the average film *** the present study,a new method is proposed to calculate the average film thickness from the bubble drift velocity in the mixture,so the new analytical model becomes much easier to *** new analytical model is evaluated against 103 sets of experimental data,the data in 124 vertical gas wells and one horizontal gas ***,the effect ofthe liquid loading on the production of the horizontal gas well is also analyzed.

关键词： Horizontal gas well inclined annular flow liquid-film thickness liquid unloading

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Model Predictive Control for Automatic Operation of Space Nuclear Reactors: Design, Simulation, and Performance Evaluation

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SSRN 2023年

作者： Fu, Jianghan Jin, Zhao Dai, Zhiwen Su, Guanghui Wang, Chenglong Tian, Wenxi Qiu, Suizheng Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi’an710049 China

Space nuclear reactors possess the inherent benefits of independence from solar energy and the capability to withstand intricate external circumstances. Consequently, the establishment of a dependable automatic control system assumes utmost significance. In this paper, a high-fidelity nonlinear space thermionic nuclear reactor system model is established. An automatic control system with a model predictive control (MPC) controller is designed based on the system. In the case of a nuclear power step response, the MPC controller achieves an overshoot of 0.07% and a settling time of 0.65s. For an electric power step response, the MPC controller yields an overshoot of 0.28% and a settling time of 36.6s. These control performances are better than those achieved by the PID controller. In power tracking control, the MPC controller demonstrates virtually error-free tracking performance. When external reactivity disturbances are introduced, the MPC controller swiftly compensates for the disturbances at the desired level. © 2023, The Authors. All rights reserved.

关键词： Model predictive control

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Efficient Water Recovery and power Generation System Based on Air-Cooled Fuel Cell with Semi-Closed Cathode Circulation Mode

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SSRN 2024年

作者： Yang, Yuchen Wu, Zhen Yao, Jing Wang, Bofei Yang, Fusheng Zhang, Zaoxiao Ren, Jianwei School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Mechanical Engineering Science University of Johannesburg Johannesburg2092 South Africa

Air-cooled proton exchange membrane hydrogen fuel cell with on-line hydrogen production by hydrolysis has potential for portable applications due to its high volumetric power density and self-humidification. However, plenty of reserve water significantly reduces the power density of fuel cell system. Moreover, water recovery from fuel cell tail gas is difficult, because the tail gas humidity is very low due to excess cathode air as coolant. In this work, the dead-ended anode and semi-closed cathode proton exchange membrane fuel cell is proposed to achieve efficient water recovery and energy conversion via semi-closed cathode circulation mode. In this mode, cathode O2-poor tail gas is recycled as coolant instead of fresh air, which helps to enlarge the tail gas humidity by reducing the stoichiometric ratio of cathode to anode gas. The system lumped model with detailed component description is developed for optimization. More than 96% water production can be recycled under atmosphere temperature. The demand of fresh air is greatly reduced from 56 to 2 times of the consumption. Besides, the multi-objective optimization between water recovery and electrochemical performance shows high-efficiency water recovery of 94.70% and high energy conversion efficiency of 54.82%. © 2024, The Authors. All rights reserved.

关键词： Cathodes

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Performance of different flocculants for harvesting Chlorella vulgaris by dissolved air flotation and sedimentation

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Bioresource Technology 2025年 433卷 132743页

作者： Wei, X. Rao, N.R.H. Tyagi, S. Thielemans, W. Cao, W. Guo, L.J. Muylaert, K. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Laboratory of Aquatic Biology KU Leuven Campus Kulak Kortrijk Kortrijk8500 Belgium Sustainable Materials Laboratory Department of Chemical Engineering KU Leuven Campus Kulak Kortrijk Kortrijk8500 Belgium

This study systematically evaluated the performance of dissolved air flotation and sedimentation for harvesting Chlorella vulgaris using eight different flocculants. Significant variation was observed in both the maximum harvesting efficiency and the minimum effective flocculant dose across different flocculant-process combinations. Among the tested flocculants, pyridinium modified cellulose nanocrystals achieved the highest harvesting efficiency of 99 % in both dissolved air flotation and sedimentation, while chitosan required the lowest minimum flocculant dose (∼2 mg·g−1) to induce flocculation. The impact of floc size formed during the flocculation step on harvesting performance was also investigated, revealing that large flocs significantly favored sedimentation-based microalgae harvesting. A preliminary cost analysis highlighted the importance of integrating economic considerations into the selection of both flocculant and harvesting method. The findings suggest that optimal flocculant and process selection should be based not only on harvesting efficiency but also on cost-effectiveness for microalgal biomass recovery. © 2025 Elsevier Ltd

关键词： Cost benefit analysis

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Pani Grafted Onto Waste Poros Polyurethane for Co-Adsorption of Multiple Pollutants in Industrial Wastewater

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SSRN 2023年

作者： Wang, Ning Guo, Yirui Song, Yi Yan, Wei Gong, Xuesong Li, Yunfeng Mu, Ruihua Liu, Yonghong Zhang, Luohong School of Environmental and Chemical Engineering Xi'an Polytechnic University Xi'An710048 China Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China

Up-taking the pollutants simultaneously from industrial wastewater is an urgent in the advanced treatment. In this work, the polyaniline (PANI)-based efficient adsorbent supported by the waste polyurethane(PU) was designed for synchronous adsorption of pollutants (acid red G (ARG), methylene blue (MB), hexavalent chromium Cr(VI), phosphorus (TP), NH4+-N (ammonia nitrogen), NO3-N (nitrate nitrogen) and COD (chemical oxygen demand)). The results showed that the synchronous removal efficiency of ARG, MB, Cr(VI), TP, NH4+-N, NO3-N and COD in simulated wastewater reached 88%, 40%, 90%, 58%, 42%, 30% and 63%, respectively. The adsorption lasted for 1800 min (144 columns) before saturation, and no significant decrease was observed after 5 cycles of regeneration. Combined with the XPS (X-ray photoelectron spectroscopy) and EEM (excitation-emission matrix spectroscopy) analysis, ARG, Cr(VI), NO3-N and TP competed for the same adsorption sites, and the adsorption affinity order was ARG>Cr(Ⅵ)>TP>NO3-. During the adsorption process, Cr(VI) and =N- in PANI chain underwent redox reaction to form Cr(III) and -NH+-, which further promoted the adsorption of anionic pollutants, like H2PO4-. Redox reactions also occurred between Cr(VI) and MB before adsorption forming Cr(III) and small organic fragments. These conclusions prove the feasibility and effectiveness of PU-P/T as a potential engineering adsorbent for co-adsorption of a variety of pollutants. © 2023, The Authors. All rights reserved.

关键词： Adsorption

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Effect of ammonium ion on the corrosion behavior of Ni 2 FeCrMo 0.2 high-entropy alloy in simulated haze solution

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Journal of Materials Research and Technology 2025年 37卷 146-156页

作者： Kai Wang Qilong Zhao Yanhui Li Ruidong Li Qipeng Xu State Key Laboratory of Eco-hydraulics in Northwest Arid Region Xi'an University of Technology No.5 Jinhua South Road Xi'an 710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an 710049 China School of Chemical Engineering Northwest University No.229 Taibai North Road Xi'an 710069 China

Various constituents of PM 2.5 in haze can accelerate metal corrosion, but traditional carbon steel and stainless steel perform poorly in such complex corrosive environments, and thus developing new corrosion-resistant materials are of great importance for mitigating haze-induced corrosion. The corrosion behavior of Ni 2 FeCrMo 0.2 alloy in haze-simulating aqueous solutions containing various constituents of PM 2.5 in haze is investigated. By the coupling analysis of electrochemical experiments, corrosion morphology, and corrosion product film, the influence of NH 4 + concentration on the corrosion mechanism related to multi-principal metal elements is revealed. The results show that the Ni 2 FeCrMo 0.2 alloy exhibits superior corrosion resistance compared with 2205 duplex stainless steel. As the NH 4 + concentration increases, the corrosion rate increases initially but then decreases at higher NH 4 + concentrations, and the corrosion morphology also confirms this changing trend. The corrosion prompt is primarily due to the lower solution pH caused by the hydrolysis reaction of NH 4 + . In contrast, the corrosion inhibition at higher NH 4 + concentration is attributed to the passive film on the alloy surface, which is composed of Cr, Fe, Mo, Ni, and their oxides, with the presence of Mo elements forming a unique structure that improved the density and stability of the film, thereby inhibiting the growth of corrosion pits. The changing trend of corrosion film resistance and corrosion product film thickness agrees well with this change in corrosion rate. This study provides an insightful understanding of the corrosion behavior of multi-principal alloy materials in haze environments, which is crucial for the corrosion protection design of metal equipment materials.

关键词： Haze constituents Corrosion High entropy alloy Passive film

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Rate-limiting factors in thin-film evaporative heat transfer processes

arXiv

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arXiv 2024年

作者： Zhao, H. Poole, R. Zhou, Z. Wolfson School of Mechanical Electrical and Manufacturing Engineering Loughborough University Loughborough LeicestershireLE11 3TU United Kingdom State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

In this paper, we present a theoretical study aimed at investigating the rate-limiting factors in thin-film evaporative heat transfer processes, considering the finite-rate evaporation kinetics. The problems of evaporation of a flat thin-film in either pure vapours or vapour-inert-gas mixtures are analysed based on the non-dimensionalised macroscopic transport equations for continuum fluids, coupled with out-of-equilibrium kinetic boundary conditions. Both the full numerical solutions and asymptotic analytical solutions at slow evaporation limit are provided and applied to analyse thin water film evaporation. Existing solutions, assuming negligible heat transfer in the gas domain, or negligible temperature jump across the non-equilibrium kinetic layer, or more boldly a thermodynamically equilibrial interface (i.e. its temperature is at the saturation temperature), can be fully recovered from the more general solutions presented here. Our results show that while these assumptions hold in special cases, they can lead to significant errors in many conditions, especially when the film thickness δ is reduced to a few micrometers or thinner. We show that the conventional views that the rate-limiting factors in thin-film evaporative heat transfer is either the heat diffusion through the liquid film or the mass transfer in the gas domain only apply to thick film (i.e. δ λ where λ is the mean free path in the vapour phase). As δ decreases to a few micrometer or smaller (more precisely when the Knudsen number Kn increases beyond O(1) in an pure vapour environment or when the kinetic Peclet number Pe is reduced below O(1) in inert gases), the interfacial thermal resistance due to the evaporation kinetics can be on the same orders of magnitude as the thermal resistance in the liquid film. The analysis also allow us to compare the heat transfer processes during the evaporation of a thin-film in pure vapours to those in inert gases, providing deeper insight into the effectiveness

关键词： Thin films

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