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Infectious cough droplet dynamics in a makeshift hospital isolation ward

Physics of Fluids 2025年第2期37卷

作者： Norvihoho, Leslie Kojo Liu, Yi Yin, Jing Zhu, Xin-Gang Yu, Hai-Tao Wang, Qi-Di Chen, Bin Zhou, Zhi-Fu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China China Nuclear Power Engineering Co. Ltd. Beijing China

The COVID-19 pandemic highlighted the need for rapidly deployable healthcare facilities, leading to increased use of modular construction methods. Nonetheless, knowledge about airflow patterns and the spread of bioaerosols in these wards remains insufficient, potentially heightening the risk of cross-infection among healthcare workers and patients. This paper presents a ventilation design for a modular negative-pressure ward aimed at reducing the spread of infectious particles. We investigate the effects of various ventilation designs, patient postures (sitting and supine), and air changes per hour (ACH) on the spread of infectious cough droplets in an airborne infection isolation room using large eddy simulation and the Eulerian-Lagrangian model. Findings show that ceiling exhaust grilles (design 2) resulted in the lowest radial dispersion (3.64 m) at 12 ACH, while sidewall exhausts (baseline) performed best at higher ACH levels. Seated patients had quicker droplet evaporation compared to those in a supine position. The best setups for reducing droplet survival included exhaust grilles at the bed's bottom and ceiling, maintaining a minimum of 12 ACH. Cases 5 and 13, with grilles over the patient's head and at the bed's bottom, showed the lowest concentrations of DPM, under 0.008 km−3 near the source and less than 0.001 km−3 mid-room. Sitting posture consistently led to lower DPM concentrations. This research emphasizes the critical role of exhaust placement in reducing droplet re-circulation and transmission risks, ultimately contributing to improved ventilation strategies and infection control in AII rooms. © 2025 Author(s).

关键词： Ceilings

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Experimental and simulation study of H 2 crossover in PEM water electrolysis for high-pressure hydrogen production up to 20 MPa

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International Journal of Hydrogen Energy 2025年 135卷 499-506页

作者： Jiazhe Wu Guoao Zhang Boyu Dong Yuhao Chang Yubin Chen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi 710049 P. R. China

High-pressure proton exchange membrane (PEM) water electrolysis offers considerable advantages, particularly in enabling direct integration with hydrogen storage and transportation systems while eliminating the need for external mechanical compressors. However, H 2 crossover is a bottleneck that induces high H 2 -in-O 2 content and low overall efficiency during high-pressure PEM water electrolysis. This study investigates H 2 crossover in PEM water electrolysis by combining in situ measurements and numerical simulations over a differential pressure range of 0–20 MPa. A linear correlation was observed between hydrogen crossover and current density within the range of 0–1 A cm −2 . The cathodic hydrogen mass transfer coefficient was determined to range from 1.6 to 3.2 mm s −1 , and the hydrogen solubility was estimated as 1.1 × 10 −3 mmol m −3 Pa −1 . The results highlight the importance of optimizing mass transfer and reducing hydrogen solubility within the cathode catalyst layer to mitigate H 2 crossover during high-pressure PEM water electrolysis.

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Experimental Study on Heat Transfer Characteristics of Supercritical Carbon Dioxide in a Vertical Circular Tube

SSRN

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SSRN 2025年

作者： Yang, Haikuo Nie, Ruishan Zhang, Kui Tian, Wenxi State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

Supercritical carbon dioxide (S-CO2) nuclear energy and power systems have garnered significant attention for flow and heat transfer experiments because of their compact design, advanced circulation methods, and high thermal efficiency, aligning with future trends in nuclear power plant development. However, the dramatic change in physical properties of S-CO2 near its pseudo-critical point can lead to heat transfer deterioration (HTD) in heat exchangers, potentially damaging the S-CO2 Brayton system. This paper presents an experimental study on the HTD of S-CO2 in a vertical circular tube under forced circulation, examining how heat flux, inlet temperature, and system pressure influence *** analysis delves into the mechanisms of HTD, focusing on the buoyancy and flow acceleration effects. Additionally, the study explores the impact of heat flux and system pressure on S-CO2 natural circulation. Ultimately, the research summarizes the flow and heat transfer characteristics of S-CO2 and proposes a new heat transfer correlation formula, demonstrating an error margin within ±25%, which meets practical engineering requirements. This experimental study contributes valuable data to the understanding of flow and heat transfer phenomena in S-CO2, offering significant insights for future applications. © 2025, The Authors. All rights reserved.

关键词： Nuclear energy

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Electrochemical evolution of a metal oxyhydroxide surface on two-dimensional layered metal phosphorus trisulfides enables the oxidation of amine to nitrile

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Carbon Energy 2025年第3期7卷 133-147页

作者： Binglan Wu Karim Harrath Marshet Getaye Sendeku Tofik Ahmed Shifa Yuxin Huang Jing Tai Fekadu Tsegaye Dajan Kassa Belay Ibrahim Xueying Zhan Zhenxing Wang Elisa Moretti Ying Yang Fengmei Wang Alberto Vomiero State Key Laboratory of Chemical Resource Engineering College of ChemistryBeijing University of Chemical TechnologyBeijingChina CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology(NCNST)BeijingChina Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of EducationCollege of Chemistry&Materials ScienceNorthwest UniversityXi'anChina State Key Laboratory of Multiphase Flow in Power Engineering International Research Center for Renewable EnergyXi'an Jiaotong UniversityShaanxiChina Fundamental Science Center of Rare Earths Ganjiang Innovation AcademyChinese Academy of ScienceGanzhouChina Ocean Hydrogen Energy R&D Center Research Institute of Tsinghua University in ShenzhenShenzhenChina Department of Molecular Sciences and Nanosystems Ca'Foscari University of VeniceVenezia MestreItaly Testing and Analysis Center Institute of Chemistry Chinese Academy of SciencesBeijingChina Department of Engineering Sciences and Mathematics Division of Materials ScienceLuleåUniversity of TechnologyLuleåSweden

Selective oxidation of amines to imines through electrocatalysis is an attractive and efficient way for the chemical industry to produce nitrile compounds,but it is limited by the difficulty of designing efficient catalysts and lack of understanding the mechanism of ***,we demonstrate a novel strategy by generation of oxyhydroxide layers on two-dimensional iron-doped layered nickel phosphorus trisulfides(Ni1-xFexPS_(3))during the oxidation of benzylamine(BA).In-depth structural and surface chemical characterizations during the electrocatalytic process combined with theoretical calculations reveal that Ni(1-x)FexPS_(3) undergoes surface reconstruction under alkaline conditions to form the metal oxyhydroxide/phosphorus trichalcogenide(NiFeOOH/Ni1-xFexPS_(3))***,the generated heterointerface facilitates BA oxidation with a low onset potential of 1.39 V and Faradaic efficiency of 53%for benzonitrile(BN)*** calculations further indicate that the as-formed NiFeOOH/Ni1-xFexPS_(3) heterostructure could offer optimum free energy for BA adsorption and BN desorption,resulting in promising BN synthesis.

关键词： 2D layered materials benzylamine oxidation metal phosphorus trichalcogenides surfacereconstructed heterostructure

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Molecular dynamics study on bubble nucleation characteristics on rectangular Nano-Grooved surfaces

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Journal of Molecular Liquids 2025年 420卷

作者： Li, Zhibin Lou, Jiacheng Wu, Xiaoyi Li, Xujun Chang, Fucheng Wang, Hengyuan Li, Huixiong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China National Key Lab of Aerospace Power System and Plasma Technology School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China

The micro/nanoscale structures on metal surfaces are of significant research interest for boiling heat transfer and exhibit great application potential in the thermal management of high-power electronic devices. This study employs the molecular dynamics simulation method to investigate the boiling heat transfer characteristics of hydrophilic rectangular shallow nano-groove structures, comparing them with the smooth surface. The phase transition heat transfer characteristics of liquid films on the smooth surface, single rectangular groove (SRG) surface, and overlapping rectangular groove (ORG) surface are revealed by analyzing the variations of parameters such as energy contour diagrams, bubble volume, liquid film temperature, and average potential energy. The research results indicate that water molecules are in a solid-like state within shallow grooves, while the nucleation sites of initial bubbles form randomly outside the grooves. During the initial heating and bubble growth, the initial nucleation time and bubble growth rate of ORG are slower than those of SRG, due to the small rectangular groove on ORG that diminishes the energy transfer efficiency. During bubble formation and growth, the average kinetic energy within the liquid film fluctuates at the nucleation moment in the critical nucleation region, and the average potential energy rises from −0.083 eV. These findings provide a theoretical basis for the micro/nanoscale structure design of vapor-liquid phase transition thermal management devices. © 2024 Elsevier B.V.

关键词： Kinetic energy

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Operational flexibility enhancement of a combined heat and power plant supplying industrial steam: The integration of sensible or sensible-latent heat storage system

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Journal of Energy Storage 2025年 117卷

作者： Tang, Haiyu Liu, Ming Zhang, Kezhen Wang, Chaoyang Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Xi'an Thermal Power Research Institute Co. Ltd. Xi'an710054 China

The increasing penetration of renewable energy requires greater operational flexibility of thermal power plants, as dispatchable power sources are essential to balance the power supply and demand sides. However, the CHP plant has restricted load cycling range due to its heat dominated operation mode. The Integration of a high-temperature heat storage system is a potential solution to enhance the operational flexibility of the CHP plant that cogenerates industrial steam and power. However, the optimal design of the heat storage system integrated within a CHP plant is complicated due to the changing operation conditions and various heat exchanging mediums. In this study, the design method of the sensible or sensible-latent heat storage system integrated with a CHP plant supplying industrial steam was proposed. The simulation, exergy analysis and economic analysis models were developed, and a case study of 350 MW CHP plant was conducted. The maximum CHP plant output power decrement is 13.59 MW when the heat of flue gas and main steam is stored in the sensible or sensible-latent heat storage system. The exergy-to-exergy efficiencies of sensible and sensible-latent heat storage systems are 71.60 % and 77.76 %, respectively. However, the economic analysis results show that the sensible heat storage system is more cost-effective than the sensible-latent heat storage system. © 2025 Elsevier Ltd

关键词： Latent heat

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Pilot-Scale Photoreforming of Hydrolyzed Polylactic Acid Waste to High-Value Chemicals and H2 via Atomic Ru Integration

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Advanced Energy Materials 2025年第0期

作者： Liu, Feng Zhang, Chunyang Lu, Kejian Yan, Xueli Wang, Yi Jing, Dengwei Guo, Liejin Liu, Maochang International Research Center for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Suzhou Academy of Xi'an Jiaotong University Jiangsu Suzhou215123 China

Photoreforming of polylactic acid (PLA) waste into valuable chemicals offers a promising approach for environmental protection and waste valorization, yet faces challenges of low yields and harsh conditions. Herein, a Cd0.5Zn0.5S nanotwin catalyst decorated with Ru single atoms and clusters is reported, enabling selective photoreforming of PLA into pyruvic acid (PA) and H2. It is demonstrated that Ru single atoms favor PA formation via hydroxyl dissociation, while the further incorporation of Ru clusters serve as active sites for H2 production. This synergistic effect significantly enhances photocatalytic performance, achieving 96.8% PA selectivity and efficient H2 production with a record-breaking apparent quantum efficiency of 83.7% at 400 nm. This approach is scalable for outdoor processes, utilizing direct 1 m2 sunlight irradiation to deliver ≈1191 mL h−1 of H2 and 47.27 mmol h−1 of PA from PLA waste, paving a viable pathway for large-scale simultaneous production of high-value chemicals and H2. © 2025 Wiley-VCH GmbH.

关键词： Photolysis

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Performance comparison investigation on different pulse tube position heat pumps with power recovery displacer

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International Journal of Refrigeration 2025年 176卷 1-16页

作者： Zhu, Shenglin Chen, Xi Zhu, Yifan Qi, Yingxia School of Energy and Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Shanghai200093 China

Spacecraft waste heat is dissipated into space primarily by radiation. To improve the heat dissipation efficiency of spacecraft radiators in high-temperature environments and reduce heat wastage in spaceflight thermal control systems, thermoacoustic heat pumps (TAHP) are considered a viable method for increasing radiator cooling temperatures and recovering waste heat. In this study, one-dimensional simulations are used to optimize the geometrical parameters of the 100-watt work recovery thermoacoustic heat pump (WRTAHP) for various pulse tube positions. The performances of the two systems are compared at a cold-end temperature of 293 K and a hot-end temperature of 353 K. The results reveal that a heating capacity of 256 W with a relative Carnot efficiency of 35.01 % is achieved for the pulse tube front-type thermoacoustic heat pump (FTTAHP), whereas the pulse tube back-type thermoacoustic heat pump (BTTAHP) obtains a heating capacity of 225 W with a relative Carnot efficiency of 30.59 %. As the cold-end temperature decreases, the coefficient of performance is reduced for FTTAHP, while the performance of BTTAHP shows a substantial improvement. At a cold end temperature of 233 K and a hot-cold end temperature difference of 60 K, a heating capacity of 268 W with a relative Carnot efficiency of 50.57 % is achieved for BTTAHP. Furthermore, the heating capacity of the BTTAHP is not significantly increased by adopting the active phase adjustment structure. In summary, the FTTAHP is suitable for spacecraft radiator applications and avoids high temperatures affecting compressor operation, whereas the BTTAHP is better suited for low-temperature heating. © 2025 Elsevier Ltd and IIR

关键词： Waste heat utilization

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Decoupling the heating and reduction processes in solar-driven two-step thermochemical cycle by coupling it with thermal power generation

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Energy 2025年 324卷

作者： Zhu, Liya Mao, Jinxin Du, Jinyang Han, Fengshuang Zhao, Kai Lu, Youjun School of Electrical Engineering Zhengzhou University Zhengzhou450001 China School of Energy and Power Engineering North China University of Water Resources and Electric Power Zhengzhou450001 China School of Mechanical and Power Engineering Zhengzhou University Zhengzhou450001 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Solar-driven H2O/CO2 splitting via two-step thermochemical cycle is a promising path for renewable fuel production. However, the energy losses caused by the high solar thermal temperature and the significant technical challenges in oxygen carrier heat recovery have long hindered its efficiency improvement. In this work, the two-step cycle was proposed to couple with a thermal power generation process to recover the process heat, and the electricity generated was proposed to be used in the reduction step, for which the solar heating and reduction processes can be decoupled. Thermodynamic evaluation shows that an efficiency advantage over the traditional cycling mode can be expected even when the solar thermal temperature is 50 K lower. It is 16.1 % at Tred = 1773 K and Tsolar = 1723 K, significantly higher than that of the traditional cycle working at Tred = 1773 K with 95 % gas heat and 40 % solid heat recovered (13.6 %). The novel cycling mode not only provides a practical heat recovery strategy, but also creates a completely new space for further lowering the solar thermal temperature and brings about obvious engineering advantages. It is supposed to be of important implications in promoting the practical application of the technology. © 2025

关键词： Solar heating

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Chromium Promoted the Efficient and Stable Catalytic Degradation of Propane Over Pt/Hzsm-5 Catalyst: Optimization and Reaction Mechanism

SSRN

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SSRN 2025年

作者： Jian, Yanfei Xu, He Wang, Yao Wang, Jingjing Xia, Lianghui Liu, Yujie Yu, Yanke He, Chi State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Shaanxi Xi'An710049 China National Engineering Laboratory for VOCs Pollution Control Material and Technology University of Chinese Academy of Sciences Beijing101408 China Yunnan University China

Light alkanes are a class of ubiquitous volatile organic compounds (VOCs), which bring great environmental hazards and health risks. However, low-temperature degradation of light alkanes is still a great challenge. Herein, a series of Pt/HZSM-5 catalysts without/with additives of Cr were fabricated. Catalytic performance of the catalyst for C3H8 low temperature combustion was investigated. It was found that Cr element had a significant effect on the activity of Pt/HZSM-5. Pt/Cr1/HZSM-5 performed the best activity for C3H8, excellent high temperature stability and water resistance. Characterization results of catalysts indicated that the introduction of Cr element could fix Pt site to promote the dispersion of Pt on the support. Moreover, the interaction between Cr and Pt produced more active Pt species, surface active lattice oxygen and acidic sites, which could promote the activation of C-H bonds in C3H8. Theoretical calculations showed that the interface between Pt and Cr had stronger adsorption for O2 and C3H8, which could accelerate propane oxidation. In this study, the effect of transition metal elements on the promotion of noble metal catalysts in the low-temperature degradation of light alkanes was discussed in depth, and it provided a reference for the design of efficient noble metal molecular sieve catalysts. © 2025, The Authors. All rights reserved.

关键词： Molecular sieves

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