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The Journal of Physical Chemistry C 2025年第22期129卷 10083-10093页

作者： Xiong Liu Qulan Zhou Xiaole Chen Shicheng Liu Na Li Zhong Huang Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power Engineering Tsinghua University Beijing 100084 China

Titanium dioxide-based photocatalysts have garnered significant attention for CO2reduction reactions (CO2RR) toward fuel production, with noble metal incorporation markedly enhancing photocatalytic efficiency. However, the development of cost-effective alternatives to expensive metals (e.g., Au, Ag) remains a critical challenge. Herein, amorphous copper nanoparticles (a-Cu NPs) were successfully anchored onto anatase TiO2via a chemical reduction method using Cu(NO3)2·3H2O as the precursor. The optimized 4 wt % a-Cu/TiO2catalyst (4CT) demonstrated remarkable activity, achieving methane and CO production rates of 3.0 and 18.4 μmol·g–1·h–1, respectively, corresponding to 10.0-fold and 7.3-fold enhancements over pristine TiO2. CO2-TPD revealed that the high surface disorder of a-Cu NPs significantly strengthened CO2chemisorption. In situ Fourier transform infrared spectroscopy (FTIR) further indicated that a-Cu loading enabled preferential CO2adsorption over H2O on TiO2surfaces while accelerating the formation of the key intermediate *COOH. This work proposes a synergistic strategy integrating nonprecious metal modification with interfacial engineering, offering a cost-effective pathway to develop high-performance photocatalysts for sustainable CO2conversion.

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Numerical investigation on the drag characteristics of supercritical water flow past a sphere

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Science China(Technological Sciences) 2020年第8期63卷 1509-1519页

作者： WU ZhenQun OU GuoBiao REN YiFei JIN Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi'an 710049China

Numerical simulation has become a useful approach to explore the complex physical and chemical process inside the supercritical water(SCW)fluidized bed *** to the drastic and non-linear variation of water properties near pseudocritical point,the flow field and drag coefficient of SCW flow past a cold particle are considerably different from that of conventional ***,in this work,particle-resolved numerical investigation is conducted to study the flow field and drag characteristics under the influence of the special water properties *** varying the enthalpy corresponding to the particle surface temperature,which will be called the particle surface enthalpy for short,in a wide range,it realizes the study under different properties variation *** simulated results demonstrate that the variations of drag coefficient versus Reynolds number(Re)and particle surface enthalpy are in good regularity when taking the freestream temperature as reference *** drag coefficient is enhanced greatly at high enthalpy difference between particle surface and inflow,and the enhancement is mainly contributed by that of the frictional drag ***,the drag coefficient variations under different pressures are in good agreement when cases are set with the same inflow and particle surface enthalpies,*** fitting the simulated results,a new drag coefficient correlation is developed for Re range of 10–200 with consideration of the influence of the special properties *** fitting quality is good that the maximum deviation between the new correlation and simulated data is 13.92%,and the mean deviation is 3.67%.

关键词： supercritical water numerical simulation sphere drag coefficient

Enhancement of Scr Denitrification Control Strategy Considering Fluegas Temperature Fluctuation: Fundamental Principle and Performance Evaluation

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SSRN 2023年

作者： Gao, Wei Yin, Junjie Liu, Ming Zhao, Yongliang Wang, Chaoyang Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Nitrogen oxides (NOx) is one of the main pollutants in coal-fired power plants, and selective catalytic reduction (SCR) is widely applied to reduce NOx emissions. Coal-fired power plants should frequently change their output power to help the power grid to accommodate high penetration of intermittent renewable power. However, NOx emission transient overshoot often occurs in coal-fired power plants when coal-fired power plants dynamically change their output power. In this study, the dynamic models for a coal-fired power plant and SCR denitrification are developed. The fluegas temperature fluctuation is revealed as a key cause for the NOx emission transient overshoot. The change law of SCR reaction temperature during load cycling processes is obtained, and its prediction model based on neural network algorithm is developed. Then, an enhanced control strategy considering temperature fluctuation of SCR inlet fluegas is proposed, and denitrification performance with the original and enhanced control strategies during load cycling processes are compared. The results show that the transient overshoot of NOx outlet concentration is avoided during load cycling processes, and the maximum value of NOx emissions during loading down and loading up processes with the enhanced control strategy are 48.62 and 49.44 mg m−3, which decreases by 7.36 and 4.63 mg m−3 compared with the original control strategy, respectively. Moreover, when the enhanced control strategy is adopted, the cumulative NH3 consumption decreases by 0.48 and 11.84 g m−3 during loading down and loading up processes, respectively. © 2023, The Authors. All rights reserved.

关键词： Coal fired power plant

An Investigation on Characteristics of Severe Slugging in an Offshore S-Shaped Riser with a Long Pipeline

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SSRN 2023年

作者： Yu, Haiyang Xu, Qiang Huang, Bo Cao, Yeqi Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi 'an Jiaotong University Xi’an710049 China

Long pipelines and risers are essential for transporting oil and gas from the seabed to offshore processing facilities. However, most research focuses on riser systems with short pipelines (≤ 400 m). A 29.1 m high S-shaped riser connecting a 1657 m horizontal pipe, which is comparable to the scale of industrial fields, is utilized for investigating the characteristics of severe slugging. Based on the visual data of gas-liquid interface evolution and the fluctuation of the riser's pressure, the flow pattern map is drawn. Long pipelines delay the liquid accumulation and prolong the severe slugging period. A new correlation for predicting the slugging period is proposed with a deviation of ±15%. The long pipeline provides sufficient compression space and aggravates the blowouts of liquid slugs. The maximum blowout velocity reaches 23 times the mixing velocity. The gas accumulated in the pipeline expands sharply, which causes the instability of the gas-liquid interface in the horizontal pipe and induces a large number of liquid slugs to flow into the riser, where the continuity blowdown of slugs appears. A slug-tracking model considering pressure and liquid holdup is established to precisely forecast the fluctuation of riser pressure during the slug continuity blowdown. © 2023, The Authors. All rights reserved.

关键词： flow patterns

Exergy-Based Control Strategy Design and Dynamic Performance Enhancement for Parabolic Trough Solar Receiver-Reactor of Methanol Decomposition Reaction

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SSRN 2023年

作者： Zhang, Peiye Liu, Ming Mu, Ruiqi Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The parabolic trough solar receiver-reactors of methanol decomposition reaction (PTSRR-MDR) enable efficient hydrogen production with solar energy at users' end. Solar fluctuations affect the solar-to-chemical efficiency, hydrogen yield and system stability, indicating the necessity for an appropriate control strategy. In this study, dynamic and thermodynamic models of PTSRR-MDR with Cu/ZnO/Al2O3 as catalyst were developed. Results of thermodynamic analysis show that an optimal flow rate exists for methanol to achieve the maximum solar-to-chemical exergy efficiency of the PTSRR-MDR. The temperature increases sharply and exceeds the catalyst sintering temperature when the methanol flow rate decreases under its optimal value. Then, control objectives to achieve the maximum efficiency were obtained with a temperature of 3 °C to guarantee the PTSRR-MDR safety. Control strategies based on Dynamic Matrix Control (DMC), Forward-Feedback Control (FFC) and Ramp Control (RC) were evaluated under cloud shading/recovering and real radiation processes. Results show that strategies based on DMC, FFC, and RC increase the solar-to-chemical exergy efficiency from 14.76% to 16.31%, 16.28% and 15.65%, respectively. The Integral Squared Error (ISE) for methanol conversion rate under three methods are 1.46, 0.32 and 5.28, respectively, indicating that strategy based on FFC is considered most suitable for PTSRR-MDR operation control. © 2023, The Authors. All rights reserved.

关键词： Methanol

Ultrathin curved PdNiRu nanosheets as bifunctional catalysts for oxygen reduction and ethylene glycol oxidation

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Nano Research 2024年第5期17卷 3777-3784页

作者： Xianzeng Li Tingyu Lu Huan Pang Mingyi Zhang Dongdong Xu Lin Xu Min Han Jun Yang Jiangsu Key Laboratory of New Power Batteries Jiangsu Collaborative Innovation Center of Biomedical Functional MaterialsSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China Fujian Cross Strait Institute of Flexible Electronics(Future Technology) Fujian Normal UniversityFuzhou 350117China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China State Key Laboratory of Coordination Chemistry Nanjing UniversityNanjing 210023China School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225009China Key Laboratory for Photonic and Electronic Bandgap Materials Ministry of EducationSchool of Physics and Electronic EngineeringHarbin Normal UniversityHarbin 150025China

Pd-based metallic nanosheets with advanced physicochemical properties have been widely prepared and employed in various electrocatalytic ***,few concerns were focused on their multiple performances in different ***,highly curved and ultrathin PdNiRu nanosheets(NSs)are developed by facile wet-chemistry strategy and exhibit excellent electrocatalytic performance toward both oxygen reduction reaction(ORR)and ethylene glycol oxidation reaction(EGOR).Owing to the synergistically structural(e.g.,ultrathin,curved,defects/steps-rich)and compositional(ternary alloy)advantages,PdNiRu NSs exhibited enhanced ORR and EGOR specific/mass activities and better stability/durability than control *** specific activity(5.52 mA·cm^(−2))and mass activity(1.13 A·mg_(Pd)^(−1))of the PdNiRu NSs in ORR are 4.8 and 3.4 times as the ones of commercial Pt/C,*** mass activity of PdNiRu NSs(3.86 A·mg_(Pd)^(−1))in EGOR is 2.6 times as commercial Pd/C(1.51 A·mg_(Pd)^(−1)).This study is helpful for the development of desired electrocatalysts with multi-functional application in practical fuel cells.

关键词： ultrathin nanosheets noble metal electrocatalysts bifunctional

Experimental Investigation on Heat Transfer of Supercritical Water flowing in a Horizontal Tube with Axially Non-Uniform Heating

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SSRN 2023年

作者： Hou, Zhenghui Huang, Xin Gao, Yu Zhang, Shengjie Wang, Haijun State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

For a heat exchanger, the heat flux is usually non-uniform in the axial direction, and the knowledge about heat transfer of supercritical water with axially non-uniform heating is scarce. To fill the gap, experiments were conducted in a horizontal tube to study the heat transfer characteristics of supercritical water with axially sinusoidal heating. The pressures varied from 23.5 to 26.5 MPa, mass fluxes 200 to 400 kg·m-2·s-1 and average heat fluxes 50 to 150 kW·m-2. Compared with uniform heat flux, the temperature difference between the top and bottom wall is larger than that of the axially sinusoidal heat flux. The inner-wall heat flux is non-uniform along the circumference due to the temperature difference, being higher at the side wall and lower at the top wall. A relative heat flux parameter is defined to describe the relative magnitude of the local heat flux. The relative heat flux parameter of the top generatrix, which is inversely proportional to the average heat flux, decreases linearly with the increase of the temperature difference between the top and side generatrix. The non-uniform degree of heat flux along the circumference is positively correlated with the average heat flux. Additionally, the local heat transfer characteristics should be considered in horizontal tubes. On the one hand, the heat transfer deterioration may occur when the fluid temperature near the top wall is higher than the pseudo-critical temperature and it can be suppressed with increasing Reynolds number. On the other hand, the local heat transfer can be enhanced if the side and bottom wall temperatures exceed the pseudo-critical temperature. © 2023, The Authors. All rights reserved.

关键词： Heat flux

Dynamic Characteristic Analysis of Sco2 Brayton Cycle Under Different Turbine Back Pressure Modes

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SSRN 2023年

作者： Zhao, Quanbin Xu, Jia yuan Hou, Min Zhang, Dalin Chong, Daotong Wang, Jinshi Chen, Weixiong State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Closed supercritical carbon dioxide Brayton cycle has the advantages of high efficiency and high compactness. The compact structure and completely closed loop with supercritical state makes the dynamic characteristic different from that of steam Rankin cycle. This paper mainly focuses on the dynamic character of SCO2 cycle with different disturbance. Firstly, the dynamic characteristic of isolated heat exchangers is investigated under different disturbances. The response time of HTR and LTR is about 70 seconds, which is much longer than others. Then dynamic characteristics of SCO2 cycle are investigated with different turbine back pressure modes. Under cooled water flow rate disturbance, the operation parameter fluctuation amplitude and the response time with normal back pressure mode are slightly larger than those under fixed back pressure modes, and the effect of pressure iteration is not remarkable when cold water disturbance amplitude is small. But when water flow rate decreases 30%, the discrepancy becomes large and the tendency becomes opposite. Under heat fluoride flow rate disturbance conditions, the parameters iteration in closed loop restrain the non-coordinative of SCO2 pressure and temperatures. © 2023, The Authors. All rights reserved.

关键词： Brayton cycle

CO2 Emission Characteristics Modeling and Low-Carbon Scheduling of Coal-Fired power Units Under Peak Shaving Conditions

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SSRN 2023年

作者： Yuan, Rongsheng Liu, Ming Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

To accommodate the high penetration of renewable power, the operational flexibility of coal-fired power units is highly required by the power system, so coal-fired power units frequently operate under peak shaving conditions. The CO2 emission characteristics of a coal-fired power unit are significantly influenced by the load factor, and also by unit capacity and many other design parameters. Therefore, detailed CO2 emission characteristics of a coal-fired power unit should be modeled and considered in the low-carbon scheduling of coal-fired power units under peak shaving conditions. In this study, coal-fired power units are classified by live steam parameters, unit capacity, reheat stages, cooling mode, and operation mode, and the models of detailed CO2 emission characteristics are developed and validated. An indicator is defined and modeled to evaluate the CO2 emission reduction rate of a coal-fired power unit considering the renewable power accommodation, and an optimization method for low-carbon scheduling is proposed. The proposed optimization method reduces the computational time by ~80%. Finally, a reference case study, including zero, current, and 2030 renewable power accommodation scenarios, is conducted. Results show that the marginal carbon emission of the power system decreases by 123.33 g/kWh in the 2030 renewable power accommodation scenario. © 2023, The Authors. All rights reserved.

关键词： Carbon

Experimental and Kinetic Study of Methanol Reforming and Methanol-Syngas Co-Oxidation at High Pressure

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SSRN 2023年

作者： Zhan, Haochen Li, Shuming Yin, Geyuan Gao, Yibo Hu, Erjiang Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Using engine exhaust heat to improve efficiency by performing co-combustion after partial reforming of methanol to syngas is a favored strategy to address the challenges associated with methanol engine applications. In the present work, experiments of methanol pyrolysis and methanol-syngas oxidation were conducted using high-pressure flow reactors at 1.0-5.0 MPa. The ratio of syngas to methanol varied from 0–50%. Mech15.34 was selected as the most reliable kinetic model to further kinetic analysis, which revealed that pressure decreases the decomposition of CH3OH to CH3, enhances the H-abstraction of CH3OH to CH2OH and CH3O, and increases the yield of H2 and CO. Furthermore, high pressure inhibits CH2OH = CH2O + H, thus reducing CH2O. The effects of blending syngas can be divided into dilution and chemical effects. The dilution effect refers to the reduction of CH3OH, which directly decreases the CH2O formation. The chemical effect refers to the competition of H2 and CO for OH radicals, which decelerates the CH3OH oxidation, decreasing the CH2O generation. Meanwhile, the reaction H2O2 + H = H2 + HO2 proceeds in reverse direction with H2 blending, generating more H radicals, which enhances the CH2O consumption through the reaction CH2O + H = HCO + H2. © 2023, The Authors. All rights reserved.

关键词： Oxidation