Article
Thermodynamics
Qimeng Lv, Yingchun Wu, Xinhao Wang, Lei Zeng, Xuecheng Wu
Summary: This study experimentally investigates the evaporation characteristics of fuel droplets under the combined effects of ambient pressure, temperature, droplet size, and spacing. The results show that the evaporation rate of droplets is influenced by both ambient conditions and droplet interactions. Furthermore, the study reveals the correlations between Nusselt and Sherwood numbers through parametric analysis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Zhaojing Ni, Camille Hespel, Kai Han, Fabrice Foucher
Summary: The evaporation behavior of binary droplets consisting of ethanol and heptane was studied experimentally and through simulation. The study found that the heavier component preferentially evaporates when the lighter component dominates the liquid mixture. The refractive index of the droplets is influenced by temperature and composition, and a linear relationship between the refractive index gradient and the deviations from the center refractive index was proposed. The accuracy of a non-ideal equilibrium model for predicting the diameter, temperature, and concentration of binary droplets was validated for the first time.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2022)
Article
Thermodynamics
Qimeng Lv, Can Li, Yingchun Wu, Xinhao Wang, Xuecheng Wu
Summary: This study investigates the evaporation characteristics of a monodisperse droplet stream of pure ethanol containing aluminum nanoparticles. The results show that droplet evaporation still follows the classical D-2 law under the experimental conditions, and the addition of aluminum nanoparticles gradually decreases the evaporation rate.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Optics
Qimeng Lv, Yingchun Wu, Xuecheng Wu
Summary: Rainbow refractometry is used to measure the temperature and size of transparent spherical particles. However, there are limitations in its application when heating and cooling droplets, as the measured temperature is not the average, surface, or core temperature of the droplet. This study exploits the technique to determine the surface temperature of droplets by measuring the surface tension through detecting the evolution of interference fringes. The relationship between surface tension and temperature enables the study of the surface temperature of evaporating droplets over time. The capabilities and limitations of rainbow refractometry are verified by comparing the directly measured droplet temperature values with the surface temperature.
Article
Optics
Can Li, Wenmin Peng, Yang Kang, Xudong Fan, Xiaolong Huang, Ning Li, Chunsheng Weng, Cameron Tropea
Summary: Rainbow refractometry has been developed for spray measurement applications, allowing simultaneous measurement of refractive index and droplet size. This study investigates the feasibility and accuracy of using incomplete rainbow signals for measurement. The newly defined dimensionless signal partial ratio (SPR) quantifies the degree of incompleteness. Simulation and inversion experiments were conducted, and the results showed that inversion using signal fitting is more accurate than using specific characteristic points. Laboratory experiments also verified these findings. For SPR <= 1, rainbow refractometry achieves errors within 6 x 10-4, 3% for monodisperse droplets and 2 x 10-4, 8% for spray droplets in terms of refractive index and size.
OPTICS AND LASER TECHNOLOGY
(2023)
Article
Engineering, Chemical
Yingchun Wu, Qimeng Lv, Xuecheng Wu, Xinhao Wang, Linghong Chen, Kefa Cen
Summary: The oscillation of micron-sized liquid droplets can be measured using time-resolved rainbow refractometry to determine surface tension and viscosity. The method shows potential for improving experimental validation and reducing measurement errors, with relative errors of less than 5% for surface tension and 10% for viscosity.
Article
Engineering, Chemical
Can Li, Qimeng Lv, Ning Li, Yingchun Wu, Xuecheng Wu, Chunsheng Weng, Cameron Tropea
Summary: There is significant interest and demand for the multi-parameter characterization of colloidal droplets. However, optical in-situ characterization of such droplets poses a challenge due to their heterogeneous and multi-scale nature. This study proposes an analytical model for dual-wavelength extinction rainbow refractometry, which allows for the simultaneous measurement of inclusion concentration, particle size, refractive index, and droplet diameter. Validation experiments demonstrate the effectiveness of this method, and the measurement errors and limitations are analyzed.
Article
Optics
X. I. N. H. A. O. Wang, Y. I. N. G. C. H. U. N. Wu, D. O. N. G. Y. A. N. Xu, B. O. T. O. N. G. Wen, Q. I. M. E. N. G. Lv, X. U. E. C. H. E. N. G. Wu
Summary: This work proposes a synthetic aperture rainbow refractometry (SARR) by synthesizing rainbow signals of the same droplet with dual-wavelength laser beams to increase the aperture of rainbow refractometry. The feasibility and accuracy of SARR are successfully demonstrated for measuring droplet refractive index and size.
Article
Optics
Can Li, Qimeng Lv, Ning Li, Yingchun Wu, Xuecheng Wu, Chunsheng Weng, Cameron Tropea
Summary: This study extends traditional rainbow refractometry configurations to measure particle positions in a plane, using a novel calibration method to address challenges. Experimental results demonstrate achieved horizontal and vertical position accuracies, as well as refractive index uncertainty.
Article
Chemistry, Multidisciplinary
Abba Abdulhamid Abubakar, Bekir Sami Yilbas, Hussain Al-Qahtani, Anwaruddin Siddiqui Mohammed
Summary: The presence of minute channels on hydrophobic surfaces can enable unidirectional rolling of droplets by minimizing wobbling. Increasing the channel width leads to higher kinetic energy dissipation and lower rolling speed. The complex flow structures in the droplet fluid modify pressure distribution, but the Laplace pressure still dominates in the upper region of the rolling droplet on channeled hydrophobic surfaces.
Article
Construction & Building Technology
Yang Yang, Yali Zhang, Fan Liu, Yi Wang, Qingfeng Cao, Jia-Ning Fan, Yuming Zhang, Hu Chen
Summary: This study numerically investigates the distribution of sulfuric droplets under two typical general ventilation modes and discusses the effects of evaporation, initial droplet size, air change rate, and outdoor climatic parameters on droplet removal. The results provide a foundation for accurately predicting the distribution of sulfuric droplets in industrial plants and optimizing ventilation.
BUILDING AND ENVIRONMENT
(2022)
Article
Engineering, Aerospace
Jing Yin, Shu-Yan Chen, Dong-Qing Zhu, Shu-Qin Xue, Song-Yang Li, Zhi-Fu Zhou, Bing Liu
Summary: This study conducted experiments to investigate the evaporation characteristics of RP-3 aviation kerosene droplets and found that low-speed evaporation involves transient heating and equilibrium evaporation, while high-speed evaporation only involves equilibrium evaporation. The droplet temperature increases continuously throughout the evaporation process, but never reaches a stable temperature. Increasing ambient pressure and temperature above the critical temperature of the fuel promote heating and evaporation, but the effect of increasing ambient temperature on evaporation is weakened at high ambient pressure.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Multidisciplinary
Can Li, Wenmin Peng, Tianchi Li, Ning Li
Summary: This study investigates the feasibility and accuracy of rainbow refractometry using the incomplete rainbow signal on the right side. Through comprehensive analysis and simulations, the study explores the utilization of refractive index, droplet diameter, and size distributions retrieved from partial rainbow signals. Laboratory experiments confirm the effectiveness of employing right partial rainbow signals in rainbow refractometry.
FRONTIERS IN PHYSICS
(2023)
Article
Thermodynamics
Yumi Uruno, Jaewon Chung, Hyojun Kim, Kihyun Lee
Summary: This study numerically simulated droplet breakup and evaporation in different attemperator design configurations, validated the simulation model, and obtained useful design insights. The simulation results showed that controlling droplet size, using a venturi-type thermal liner, and employing multiple nozzles can improve evaporation efficiency.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Mechanics
M. Mohib Ur Rehman, Alexandros Askounis, Gyoko Nagayama
Summary: The evaporation of droplets in an array is hindered by adjacent droplets due to vapor-mediated interactions. Existing theoretical models neglect the important factor of surface wettability in predicting the evaporation rate. This work develops a model with a contact angle function to accurately predict the evaporation rate of droplets with arbitrary contact angles in the array.
Review
Chemistry, Multidisciplinary
Adithya Balakrishnan, Jan Derk Groeneveld, Suman Pokhrel, Lutz Maedler
Summary: The fascination with increasing efficiency, power, or strength drives the development of new materials and methods, such as higher solar cell conversion efficiencies and lightweight strong materials. By studying past chemical applications, new materials and production methods can be created.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Physical
Jakob Stahl, Jan Ilsemann, Suman Pokhrel, Marco Schowalter, Christian Tessarek, Andreas Rosenauer, Martin Eickhoff, Marcus Baeumer, Lutz Maedler
Summary: The impact of different co-catalytically acting promoters (Pt, ZrOx and SmOx) on alumina supported Co-based model catalysts during COx methanation was studied. Double flame spray pyrolysis was used for synthesis to obtain samples with identical structure and morphology. Promoters (Pt, ZrOx, and SmOx) improved methanation yields within a wide temperature range in CO2 methanation, with zirconia and platinum showing the best performance. In CO methanation, all catalysts deactivated rapidly above 310 degrees C, with Pt exhibiting the best results.
Article
Chemistry, Physical
Haipeng Li, Collins Erinmwingbovo, Johannes Birkenstock, Marco Schowalter, Andreas Rosenauer, Fabio La Mantia, Lutz Maedler, Suman Pokhrel
Summary: In this study, nanoscale phase-pure and crystalline LiMn2O4 spinel was successfully synthesized by single flame spray pyrolysis, and LiMn2O4 was homogeneously mixed with different percentages of AlPO4 using versatile multiple flame sprays. The LMO nanoparticles of 17.8 nm showed the best electrochemical performance, and the capacity retention was increased to 93% with an initial capacity of 116.1 mA h g(-1) by incorporating 1% AlPO4.
ACS APPLIED ENERGY MATERIALS
(2021)
Article
Energy & Fuels
Dan Sykes, Viacheslav Stetsyuk, Jack Turner, Guillaume de Sercey, Martin Gold, Richard Pearson, Cyril Crua
Summary: Modern engines employ multiple injection and flow rate profiling strategies to achieve significant reductions in NOx and soot emissions, however issues such as fuel residue and inhibited atomisation at the end of injection events persist. Research indicates that fuel films on injector surfaces provide an ideal environment for deposit forming reactions and precursors to adhere onto, requiring further study of these transient processes in order to support mitigation strategies for reducing pollutants and injector deposits.
Article
Thermodynamics
M. F. B. Stodt, Jan Derk Groeneveld, Lutz Maedler, Johannes Kiefer, Udo Fritsching
Summary: This study investigates the occurrence of in-flight droplet microexplosions (mu-explosions) during flame spray pyrolysis and confirms the findings through single drop experiments. It is found that there are distinct mu-explosions happening at high frequencies during the synthesis of iron oxide nanoparticles. This finding is significant for understanding the role and relevance of mu-explosions in the production and formulation of functional nanoparticles.
COMBUSTION AND FLAME
(2022)
Article
Chemistry, Physical
Max Gaessler, Jakob Stahl, Marco Schowalter, Suman Pokhrel, Andreas Rosenauer, Lutz Maedler, Robert Guettel
Summary: This study investigates the impact of catalyst support on the dynamics of methanation and reveals that the support material plays a major role in activity, selectivity, and deactivation behavior. The adsorption of H2O strongly depends on the support material and influences the CH4 formation rate. Changes in selectivity and deactivation are observed in CO2 methanation.
Article
Chemistry, Multidisciplinary
Haipeng Li, Padryk Merkl, Jens Sommertune, Thomas Thersleff, Georgios A. Sotiriou
Summary: This study uses flame aerosol technology to rapidly self-assemble uniform SERS sensing films. By controlling the thickness of the dielectric spacer and the interparticle distance, the Raman hotspots are finely tuned to achieve the highest signal enhancement. The developed SERS sensors demonstrate superior stability and batch-to-batch reproducibility.
Article
Engineering, Chemical
Stefan Christian Endres, Lutz Maedler
Summary: Accurate computation of interface curvature is crucial in simulating surface tension-dominated systems. Prior research has shown that a formulation using discrete differential geometry can find exact equilibrium solutions of surfaces, but fails to provide accurate point-wise estimates for curvatures of particle-particle capillary liquid bridges. This communication elaborates on the use of total curvatures in computing forces of parameterized models and demonstrates the infeasibility of using point-wise estimates on any asymmetric discretization.
CHEMIE INGENIEUR TECHNIK
(2023)
Article
Chemistry, Multidisciplinary
Suman Pokhrel, Jakob Stahl, Jan Derk Groeneveld, Marco Schowalter, Andreas Rosenauer, Johannes Birkenstock, Lutz Maedler
Summary: The development of a novel reactive spray technology based on the gas-phase metal oxide synthesis route opens up opportunities for producing non-oxide nanoparticles. Metal sulfides, including MnS, CoS, Cu2S, ZnS, Ag2S, In2S3, SnS, and Bi2S3, are successfully synthesized in a sulfur-rich environment. The combined approach of flame sprays and single-droplet combustion provides insights into the gas-phase formation of metal sulfides, paving the way for scalable synthesis of functional metal sulfides.
ADVANCED MATERIALS
(2023)
Editorial Material
Engineering, Biomedical
Shirin Saberianpour, Gianluca Melotto, Rachel Forss, Lucy Redhead, Jacqueline Elsom, Nadia Terrazzini, Susan Sandeman, Dipak Sarker, Giselda Bucca, Andrew Hesketh, Cyril Crua, Matteo Santin
EXPERT REVIEW OF MEDICAL DEVICES
(2023)
Article
Chemistry, Physical
Tingqiang Yang, Anne Hemeryck, Suman Pokhrel, Wen Chen, Lutz Maedler, Udo Weimar, Nicolae Barsan
Summary: The combination of operando DRIFTS measurement and DFT calculation reveals the counterintuitive HCHO sensing mechanism of In4Sn3O12. At the optimum temperature of 200 degrees C, HCHO undergoes partial oxidation to formate (or HCOOH) with medium activation energy (0.43-0.68 eV) and sufficient electron donation effect, resulting in the generation of sensor signal. The Sn(3a)-connected O acts as the active site, playing crucial roles in both HCHO adsorption and partial oxidation.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Beeke Gerken, Christoph Mahr, Jakob Stahl, Tim Grieb, Marco Schowalter, Florian F. Krause, Thorsten Mehrtens, Lutz Maedler, Andreas Rosenauer
Summary: Hetero-contacts are interfaces between different materials at the nanoscale leading to novel functional properties. In hetero-aggregates, primary particles of at least two different materials are mixed at primary particle or cluster level. Double flame spray pyrolysis (DFSP) is a versatile technique for the controlled synthesis of such materials. Characterization of hetero-aggregates by scanning transmission electron microscopy (STEM) requires acquisition and evaluation of many aggregate images in order to derive statistically significant results. Usually, STEM energy dispersive X-ray spectroscopy (EDXS) is used to acquire elemental maps providing the material distribution of the primary particles within hetero-aggregates. However, the acquisition of a single EDXS map takes up to several minutes. For this reason, determination of material types of primary particles from the intensity in high-angle annular dark field STEM images alone is desirable. These images can be acquired within a couple of seconds. In the present work, a method is suggested which allows for achieving this objective. It can be applied to distinguish materials with a significant difference in their atomic number and hence sufficient material contrast in the STEM images.
PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION
(2023)
Article
Thermodynamics
Arne Witte, Lutz Maedler
Summary: Flame spray pyrolysis (FSP) is a powerful and versatile technique for synthesizing functional nanoparticles. The study of isolated burning FSP droplets is crucial for understanding and improving this technique. In this study, the burning process of single droplets with different sizes and the effect of solvent composition were investigated. The results provide insights into droplet combustion and the use of low-cost precursor-solvent systems in FSP.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
Article
Engineering, Environmental
Haipeng Li, Elodie Dumont, Roman Slipets, Thomas Thersleff, Anja Boisen, Georgios A. Sotiriou
Summary: Pesticide residues in food products are a concern for human health, and their rapid and easy detection is necessary. The surface-enhanced Raman scattering (SERS) technique can detect pesticide residues quickly and reliably, but its application in food safety diagnostics is limited by its high cost, low scalability, and low reproducibility of necessary sensors. In this study, we have developed a low-cost, large-scale, and highly reproducible method for fabricating SERS nano-sensors, based on the direct deposition of plasmonic core-shell structured Ag-SiO2 nanoparticles produced in the gas phase on temperature-controlled inexpensive glass substrates. Our highly sensitive SERS substrates can rapidly and quantitatively detect pesticide residues in fresh orange, demonstrating their practical applicability for food safety diagnostics.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Susana I. L. Gomes, Monica J. B. Amorim, Suman Pokhrel, Lutz Madler, Matteo Fasano, Eliodoro Chiavazzo, Pietro Asinari, Jaak Janes, Kaido Tamm, Jaanus Burk, Janeck J. Scott-Fordsmand
Summary: The study aimed to evaluate the effects of Fe-doped TiO2 NPs on soil invertebrates and investigate the influence of different NPs characteristics on their effects. The findings revealed that toxicity of TiO2 NPs decreased under UV exposure conditions, and short-term water exposure induced lasting biological responses even after longer-term recovery.
