Article
Thermodynamics
S. Kalita, Pulak Sen, Dipak Sen, Sudev Das, Ajoy Kumar Das, Bidyut Baran Saha
Summary: This paper investigates pool boiling heat transfer experiments conducted on a microstructured copper surface prepared through chemical etching. Results show significant enhancement in boiling heat transfer coefficient (BHTC) compared to bare copper surface, although the critical heat flux (CHF) is lower. After four repeated tests, the surface's heat transfer coefficient shows a deviation of 4.8%.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2021)
Article
Thermodynamics
Youngsup Song, Hyeongyun Cha, Zhen Liu, Jee Hyun Seong, Lenan Zhang, Daniel J. Preston, Evelyn N. Wang
Summary: This study investigates the effect of surface oxidation on the critical heat flux (CHF) values during boiling. It was found that the CHF values on copper surfaces gradually increased with the duration in saturated water, attributed to the formation of Cu2O nanostructures. On the other hand, the CHF values on nickel surfaces remained relatively stable, except when a highly wetting hydroxide, Ni(OH)2, formed after 24 hours of immersion. These findings provide insights into the fundamental mechanisms causing the wide spread of CHF values on metallic surfaces.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Rishi L. Ramakrishnan, Prasanna Jayaramu, Sateesh Gedupudi, Sarit K. Das
Summary: This study experimentally investigated the effect of copper surface ageing on heat transfer and critical heat flux during flow boiling. The results showed that ageing significantly reduces the heat transfer coefficient on the copper surface, while having an insignificant impact on the critical heat flux. Surface morphology and wettability of copper were found to change after ageing.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Youngsup Song, Lenan Zhang, Carlos D. Diaz-Marin, Samuel S. Cruz, Evelyn N. Wang
Summary: This study investigates the role of structured surfaces in enhancing critical heat flux (CHF) during pool boiling. The results show that CHF enhancement on structured surfaces cannot be solely explained by roughness or wickability. A unified descriptor, representing the combined effects of thin film density and volumetric wicking rate, is derived and shows a reasonable correlation with CHF values.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Pulak Sen, Sanjib Kalita, Dipak Sen, Ajoy Kumar Das, Bidyut Baran Saha
Summary: In this study, hydrophobic copper micro-structured surfaces were prepared through chemical etching and heat treatment, resulting in different micro-structural features. The experimental results showed that the prepared hydrophobic surfaces have a higher heat transfer coefficient, although the critical heat flux is slightly smaller compared to the bare copper surface. Additionally, the micro-porous surface prepared by a combination of two conventional processes significantly improves heat transfer.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Mechanical
Nithyanandam Thangavelu, Senthil Kumar Duraisamy, Vasudevan Devarajan
Summary: An increasing rate of heat generation in electronics equipment has been observed due to its compactness and performance enhancement. Pool boiling is considered as an effective technique for heat recovery, improving safety and prolonging equipment lifespan. This research investigates the performance and safety factors of plain copper surfaces and copper surfaces coated with TiO2 thin films of different thicknesses. The results show that TiO2 coating significantly enhances the critical heat flux and heat transfer coefficient. The hydrophilic nature of the TiO2 thin film creates numerous nucleation sites and improves capillary wicking, leading to better heat transfer.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE
(2023)
Article
Thermodynamics
Atul Ranjan, Israr Ahmad, Rinku Kumar Gouda, Manabendra Pathak, Mohd Kaleem Khan
Summary: This study reports the creation of Cu(OH)2 nanoneedles on a copper surface using an anodization process, which can enhance critical heat flux (CHF) limit in pool boiling applications by improving surface wettability and wickability. Results show that the anodized surface requires higher wall superheat for nucleation and exhibits a higher CHF value compared to the plain surface.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Sayantan Mukherjee, Purna Chandra Mishra, Paritosh Chaudhuri
Summary: The experimental investigation showed significant improvements in boiling heat transfer coefficient and critical heat flux at a mass fraction of 0.1% for Al2O3 and TiO2 nanoparticles in water. An increase in mass fraction improved the surface wettability of nanofluids and reduced the surface roughness of the boiling surface. Al2O3-water nanofluids exhibited better boiling performance compared to TiO2-water nanofluids.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Thermodynamics
S. Y. Guan, Z. H. Zhang, R. Wu, X. K. Gu, C. Y. Zhao
Summary: The impacts of nano-porous structures on boiling heat transfer characteristics are revealed through theoretical and modeling analysis. The results show that the boiling inception time is proportional to the void volume to solid surface area ratio, and the critical heat flux is a power law function of pore size. Molecular dynamics simulations further validate the theoretical analysis, showing a power law relation between boiling inception time and void volume to solid surface area ratio, and an exponent of 1.232 in the power law relation between critical heat flux and pore size.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Chemical
Xu Ma, Yindong Song, Yang Wang, Shouguang Yao, Kambiz Vafai
Summary: In this study, novel hybrid nanoparticles were prepared using Ag modified functionalized GNP, and the boiling heat transfer properties of the nanofluids were investigated. The GNP-Ag hybrid nanofluids with a weight concentration of 0.001% exhibited the best heat transfer performance, with improved structural modification and wetting properties playing a crucial role in enhancing the heat transfer.
Article
Thermodynamics
Avinash Upadhyay, Brijesh Kumar, Nirbhay Kumar, Rishi Raj
Summary: Two-phase heat transfer processes such as boiling are essential for waste heat management. This study proposes a simple and reliable strategy using aqueous solutions of imidazolium ionic liquids (ImILs) to enhance the critical heat flux (CHF) and heat transfer coefficient (HTC) by improving heater surface wettability. Experimental results show that this method can increase CHF by approximately 1.6 times. The ability to manipulate the surface and fluid properties by tuning the structure of ImILs makes this approach promising for thermal management challenges.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Nithyanandam Thangavelu, Senthil Kumar Duraisamy, Sridharan Mohan, Dinesh Sundaresan
Summary: This work experimentally explores the critical heat flux and heat transfer coefficient in the nucleate boiling regime of a pool boiling system, considering both safety and performance. The study finds that the wetting and rewetting properties of copper nanocoated surfaces significantly increase the critical heat flux and heat transfer coefficient.
Article
Engineering, Chemical
Xu Ma, Yindong Song, Yang Wang, Yuni Zhang, Jingya Xu, Shouguang Yao, Kambiz Vafai
Summary: This study focuses on functionalizing graphene nanoplatelets to improve hydrophobicity while maintaining good thermal properties, and preparing hybrid nanofluids for enhanced heat transfer. Novel GNP-Fe3O4 hybrid nanoparticles with high purity and hydrophilic functional groups were prepared. The addition of metal or non-metal nanoparticles improved the heat transfer characteristics of nanofluids. Experimental results showed significant enhancement in heat transfer properties compared to deionized water, with GNP-Fe3O4 + Al2O3 and GNP-Fe3O4 + SiO2 hybrid nanofluids exhibiting the best heat transfer effects.
Article
Mechanics
Gangtao Liang, Yang Chen, Jiajun Wang, Zhao Wang, Shengqiang Shen
Summary: This study investigates pool boiling heat transfer on hybrid-wettability surfaces, showing that the nucleate boiling heat transfer coefficient is improved on these surfaces compared to the substrate and plain copper reference. However, the critical heat flux (CHF) behavior is complex on the enhanced surface. The difference in contact angles between the pattern and substrate plays a significant role in the CHF enhancement on the hybrid surface, although it affects the nucleate boiling heat transfer coefficient negatively.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Thermodynamics
Mahdi Roodbari, Hasan Alimoradi, Mehrzad Shams, Cyrus Aghanajafi
Summary: This study developed an experimental setup to investigate the pool boiling heat transfer characteristics of dilute dispersions of TiO2 nanoparticles in water-ethylene glycol 50. The results showed that increasing heater surface roughness can enhance BHTC and nucleation site density, while the effect of nanofluid concentration on heat transfer coefficient depends significantly on the surface roughness. Additionally, using TiO2-WEG50 nanofluid was found to increase the surface wettability of the heater.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Engineering, Chemical
Ri Zhang, Shasha Zhang, Mengyan Ding
Summary: A thin liquid film method is proposed to evaluate sand erosion in annular flow. This method considers the direct interaction between the liquid film and gas core, as well as the entrainment and deposition of droplets. The erosion rate is calculated by considering the effects of liquid entrainment and particle velocity decay. The method is fully verified by comparing with experimental data.
Article
Engineering, Chemical
Yu Suo, Xianheng Su, Wenyuan He, Xiaofei Fu, Zhejun Pan
Summary: This research investigates the mechanical properties of sandstone-shale composite through orthogonal experimental method and discrete element simulation. The results show that different lithologies and thickness ratios can affect the strength and fracture mode of the composite rock samples.
Article
Engineering, Chemical
Maurizio Troiano, Andrea El Hassanin, Roberto Solimene, Alessia Teresa Silvestri, Fabrizio Scala, Antonino Squillace, Piero Salatino
Summary: This study investigates the potential of Fluidized Bed Finishing (FBF) for square flat AlSi10Mg specimens manufactured via Laser-Powder Bed Fusion (L-PBF) additive manufacturing technology. The results show that good finishing can be achieved using rotation-assisted tests, with a maximum reduction of surface roughness by 67%. Steel particles are found to be the most effective bed material.
Review
Engineering, Chemical
Ningbo Song, Wanzhong Yin, Jin Yao
Summary: Seawater's dissolved salts and minerals have various effects on the flotation process, including influencing the characteristics and behavior of flotation factors, as well as affecting the surface of sulfide minerals. In most cases, seawater has adverse effects on the flotation of sulfide minerals, but these effects can be mitigated by adjusting the reagents.
Article
Engineering, Chemical
Kaiqiao Wu, Shuxian Jiang, Victor Francia, Marc-Olivier Coppens
Summary: In rectangular and cylindrical annular fluidized beds, pulsating gas flow can create regular bubble patterns, overcoming challenges seen in conventional units. This study provides new opportunities for modularization of fluidized bed operations.
Article
Engineering, Chemical
Shuo Li, Huili Zhang, Jan Baeyens, Miao Yang, Zehao Li, Yimin Deng
Summary: The paper assesses the behavior of cohesive Geldart C-type particles when fluidized by air with the aid of vibration. It determines that mechanical vibration is a simple and effective method to improve the fluidity of cohesive particles during fluidization.
Article
Engineering, Chemical
Zhenfei Feng, Qingyuan Zhang, Shanpan Liang, Zhenzhou Li, Fangwen Guo, Jinxin Zhang, Ding Yuan
Summary: A new micro/mini-channel heat sink (MCHS) with a combined structure of longitudinal and transverse vortex generators is designed, using Al2O3 nanofluid as the working medium. The study explores the effects of transverse vortex generator shape and longitudinal vortex generator angle on the hydraulic and thermal characteristics, comprehensive performance, entropy generation, and exergy efficiency. The results show that the triangular transverse vortex generator improves the comprehensive performance and exergy efficiency. Combined with the longitudinal vortex generator, the MCHS achieves the best comprehensive performance, entropy generation, and exergy efficiency when the Reynolds number is 742.
Article
Engineering, Chemical
Kostas Giannis, Christoph Thon, Guoqing Yang, Arno Kwade, Carsten Schilde
Summary: This study presents a 3D convolutional neural network (3D-CNN) methodology for generating realistic 3D models of particles. The method trains on 2D projections of particle images to predict their 3D shapes, and evaluates the accuracy of the predictions using Fourier shape descriptors (FSDs). This methodology has wide applications in particle shape analysis.
Article
Engineering, Chemical
Zheng-qing Zhou, Lu-jia Chai, Yu-long Zhang, Ya-bin Wang, Ze-chen Du, Tian-yi Wang, Yu-zhe Liu
Summary: The dynamic oxidation and shell-breaking processes of aluminum nanoparticles (ANPs) during heating were studied using in situ transmission electron microscopy. The results revealed that the changes in shell thickness can be divided into three stages, and the active aluminum content of ANP decreased before shell-breaking.
Article
Engineering, Chemical
Fulei Chen, Huaqing Ma, Zihan Liu, Lianyong Zhou, Yongzhi Zhao
Summary: A particle breakage model based on the particle replacement scheme, using the polyhedral model to describe particles, is proposed in this work to accurately describe the breakage of a large number of particles. Additionally, a fast-cutting algorithm is proposed to reproduce the size distribution of progeny particles determined by the breakage model. The validation and simulation results show satisfactory accuracy, efficiency, and stability of the algorithm.
Review
Engineering, Chemical
Matteo Errigo, Christopher Windows-Yule, Massimiliano Materazzi, Dominik Werner, Paola Lettieri
Summary: Gas-solid fluidized-bed systems have advantages in terms of chemical reaction efficiency and temperature control, making them widely used in industrial applications. However, the design, scale-up, and optimization of these complex units are limited by the lack of deep physical understanding. Non-invasive and non-intrusive diagnostic techniques provide a way for researchers to study these systems without affecting the flow field or directly contacting the medium under study.
Article
Engineering, Chemical
Saeed Fateh, Mohammad Behshad Shafii, Mohammad Najafi, Cyrus Aghanajafi
Summary: Applying a magnetic field to ferrofluids alters their flow characteristics and enhances heat transfer. Through visualization and quantitative investigation, it is found that the magnetic field influences the flow patterns and velocity profiles, improving fluid mixing and vorticity magnitude.
Article
Engineering, Chemical
Lei Gao, Bingbing Wei, Xiaochuan Hu, Zaifeng Yao, Yiwen Fang, Xuejian Gao
Summary: In this study, a numerical model of sand triaxial test was established using discrete element software PFC3D, and an indoor triaxial test was conducted to calibrate the numerical model. The influence of microscopic parameters on the macroscopic mechanical response of sand was analyzed. The results showed that the friction coefficient had the greatest impact on the peak strength and residual strength of the sand's stress-strain curve, and it was positively correlated. The normal tangential stiffness ratio was negatively correlated, while the porosity and boundary flexibility stiffness had minimal influence on it.
Article
Engineering, Chemical
Xuan Liu, Jie Gong, Kai Jiang, Xiaojuan Lai, Yu Tian, Kang Zhang
Summary: This study aimed to improve the performance of lignite coal water slurries (CWSs) by synthesizing a series of three-arm amphiphilic block copolymers. By controlling the relative molecular weight, hydrophilic/hydrophobic ratio, and ionic group content, the apparent viscosity of CWSs was significantly reduced and the static stability was improved. Thermogravimetric testing and XPS analysis were conducted to reveal the mechanism behind the improved performance.
Article
Engineering, Chemical
Lanka Dinushke Weerasiri, Daniel Fabijanic, Subrat Das
Summary: Fluidization at low pressure offers significant benefits for the fine chemical industry. This study investigates the behavior of bubbles and bed expansion under low pressure conditions. It is found that lower pressure leads to larger bubbles, increased bubble quantity, and higher aspect ratio. The predictability is affected by the inhomogeneous fluidization, but low pressure fluidization can generate similar bubble sizes with lower fluidizing mass compared to atmospheric pressure.