Article
Engineering, Chemical
Haishan Miao, Hao Zhang, Yuhang Wu, Yang Wang, Xizhong An
Summary: Particle-resolved direct numerical simulations (PR-DNS) are used to study the momentum and heat transfer of two interactive non-spherical porous particles. Various parameters of the leading particle, such as aspect ratio, orientation, and porosity, are shown to affect the drag coefficient and average Nusselt number of the trailing particle. The results reveal different trends depending on the specific conditions, such as the shape of the leading particle and the distance between the particles.
Article
Engineering, Chemical
Haishan Miao, Hao Zhang, Xizhong An, Chunhai Ke, Aibing Yu
Summary: This study investigates the combined effect of particle shape and porosity on the momentum and heat transfer of granular matter under laminar flow. It is found that particle shape, characterized by aspect ratio, plays a dominant role in affecting the drag coefficient and Nusselt number, while the influence of porosity becomes significant under high Reynolds number conditions.
Article
Thermodynamics
Haishan Miao, Hao Zhang, Xizhong An, Jiang Chen, Aibing Yu
Summary: This study investigates the distribution of drag coefficient (Cd) and average Nusselt number (Nu) of a porous spheroid in a fluid under different conditions using particle-resolved direct numerical simulations. The results show that the shape, Reynolds number, and porosity have noticeable effects on Cd and Nu, and there are certain trends in their variations within certain ranges. Predictive correlations are established based on the numerical data, which can be used to improve multiphase models and computational fluid dynamics methods.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Environmental
Yong Chen, Pan Jiang, Ting Xiong, Wei Wei, Zhenlong Fang, Bin Wang
Summary: The study utilized the thermal lattice Boltzmann method to calculate drag coefficients and Nusselt numbers for nonspherical particles in uniform flow over a wide range of Reynolds numbers and aspect ratios. The results showed that the drag coefficient for ellipsoids and spherocylinders varied with the incident angle, while the Nusselt number for prolate ellipsoids was affected by the aspect ratio.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Mechanics
P. Suri, A. Verma, S. A. Patel, R. P. Chhabra
Summary: In this study, laminar free convection in power-law fluids with vanishingly small Grashof number (10^4≤Gr≤10) was numerically investigated for an isolated sphere and twin spheres with varying centre-to-centre distance. The effects of Prandtl number and power-law fluid behaviour on drag and heat transfer characteristics were examined in detail. The results showed that the decrease in Grashof number had a tendency to reverse the effect of the power-law index on total drag, and an increase in Prandtl number delayed this effect. The behavior of the twin sphere configurations differed significantly from that of an isolated sphere in terms of drag and Nusselt number values.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2023)
Article
Thermodynamics
Sunil Kumar, Rajneesh Kumar, Varun Goel, Suvanjan Bhattacharyya, Alibek Issakhov
Summary: This study investigates the impact of different roughness geometries on the exergetic efficiency of a solar air heater (SAH), finding that the exergetic efficiency of a semicircular ribbed SAH is 26% higher than that of square roughness. Recommendations are made based on the design plots developed to enhance the efficiency of the SAH.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Thermodynamics
Maruf M. Ikram, Shadman S. Priam, Sumon Saha
Summary: This numerical study analyzes the thermodynamic characteristics of an inclined two-fluid system with variable surface roughness. The study explores the effect of system inclination on thermal transport, entropy generation, and thermal optimization. The results show that the system's average properties are significantly influenced by Rayleigh number and inclination angle, while having a weak dependency on partition roughness. The study also finds that the system orientation regulates the rate of thermal transport, with each Rayleigh number corresponding to a critical angle for highest thermal transport and entropy generation.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Saman Abolfathi, Arash Mirabdolah Lavasani, Peyman Mobedi, Kamran Salehi Afshar
Summary: Experimental study shows that increasing the pitch ratio in mixed tube bundles can lead to higher Nusselt numbers, and cam-shaped tubes in mixed bundles have better performance with thermal-hydraulic performance 2-24% and 4-34% greater than bundles composed of only circular tubes.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Thermodynamics
Vikash Kumar
Summary: This study evaluated the exergetic efficiency of a solar air heater duct system with 3 side concave dimple roughness and compared the results with a 1 side roughened system. The experiments under different parameters showed the influence of Reynolds number and temperature parameter on exergetic efficiency.
Article
Thermodynamics
Tej Pratap Singh, Amitesh Kumar, Ashok Kumar Satapathy
Summary: This study investigates the enhancement of heat transfer rate using a sinusoidal wavy wall surface in a turbulent dual jet. It is found that changes in amplitude and number of cycles of the sinusoidal wavy surface impact turbulent characteristics and heat transfer rate, resulting in nearly 20.70% improvement when N = 7 and A = 0.7.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Emre Mandev, Eyuphan Manay
Summary: This study experimentally investigated the contribution of natural and forced convection effects to total heat transfer in rectangular microchannels, focusing on the effect of surface roughness induced by the manufacturing process. The results showed that surface roughness has a significant effect on mixed convection heat transfer, and the microchannel heat sink with the smallest cross-section and the highest roughness value obtained the best heat transfer results.
APPLIED THERMAL ENGINEERING
(2022)
Review
Engineering, Marine
Franck Schoefs, Arash Bakhtiari, Hamed Ameryoun
Summary: This paper reviews the studies on the effects of biofouling on marine/offshore structures, indicating that factors beyond surface roughness, such as surface coverage ratio, biofouling species, and aggregation, can significantly influence the hydrodynamic force coefficients. Additionally, a new approach is proposed to estimate the drag coefficient of circular members covered by biofouling.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
Chunlai Zhang, Yixiao Yuan, Xueyong Zou, Hongtao Wang, Qing Li, Zhenting Wang, Rende Wang
Summary: This study investigated the aerodynamic characteristics of different land surface types in northern China and analyzed the effects of surface roughness elements on the airflow. The results showed that the roughness length, wind speed pulsation, turbulence intensity, and drag coefficient varied among different land surfaces. Furthermore, the shelter capability of flexible roughness elements increased with increasing wind speed, while that of rigid roughness elements decreased.
Article
Mechanics
Thamali R. Jayawickrama, Nils Erland L. Haugen, Matthaus U. Babler, M. A. Chishty, Kentaro Umeki
Summary: This study investigates the effect of Stefan flow on momentum exchange and heat transfer between a particle and fluid, providing insights into the mechanisms and influencing factors of Stefan flow.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Chemistry, Physical
Karmveer, Naveen Kumar Gupta, Md Irfanul Haque Siddiqui, Dan Dobrota, Tabish Alam, Masood Ashraf Ali, Jamel Orfi
Summary: Artificial roughness on the absorber of the solar air heater improves performance but requires higher pumping power. Thermo-hydraulic performance considers both pumping power and heat gain. The shape, size, and arrangement of artificial roughness are crucial for performance optimization.
Article
Engineering, Environmental
Shi Liu, Zhiwei Ge, Mingming Du, Liejin Guo
Summary: This paper investigates the gasification characteristics and nitrogen distribution in the supercritical water partial oxidation (SCWPO) process of indole. The results reveal the influencing factors on gas product formation and propose an SCWPO mechanism for indole.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Thermodynamics
Lijing Bei, Zhiwei Ge, Changyifan Ren, Di Su, Fei Shang, Yu Wang, Liejin Guo
Summary: Supercritical water partial oxidation (SCWPO) is a promising technology for converting ethanol into hydrogen and energy efficiently. However, traditional SCWPO reactors have limitations in terms of wall material requirements and system efficiency. This numerical study explores the SCWPO of ethanol with auto-thermal operation, analyzing the effects of different parameters. The results show that increasing ethanol concentration, preheated water temperature, and reactor length can enhance the SCWPO efficiency. This study provides valuable insights for reactor scale-up and system optimization.
Article
Engineering, Chemical
Yingdong Wang, Huibo Wang, Hui Jin
Summary: Supercritical water gasification is an efficient and clean energy conversion method. The study of particle-particle and particle-fluid-particle interactions on the particle scale can guide the understanding of gasification performance on the reactor scale.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Engineering, Chemical
Bowei Zhang, Xiao Zhao, Yunan Chen, Zhiwei Ge, Hui Jin
Summary: In this study, the diffusion behavior of H2S in the H2S-H2O system was simulated using the molecular dynamics method. The self-diffusion coefficient of H2S was calculated under different conditions (pressure: 235-280 atm, H2S molar concentration: 1-5%, temperature: 600-1173 K). The results showed that the molar concentration and pressure of H2S had little effect on its self-diffusion coefficient, while temperature and water density had a greater effect. Additionally, the self-diffusion activation energy of the supercritical region of H2S was found to be only 32.58% of the subcritical region. Finally, new parameters of an empirical equation were fitted to predict the self-diffusion coefficient of H2S in the H2S-H2O system, with a mean relative error of 3.05% in the supercritical region.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Energy & Fuels
Pai Peng, Gaoyun Wang, Linhu Li, Hui Ge, Hui Jin, Liejin Guo
Summary: This study investigates the degradation of polymer-containing oily sludge (PCOS) in sub-/supercritical water to find a suitable treatment method. The effects of residence time, temperature, catalysts, and co-solvents on the distribution of end products are studied. Results show that PCOS is hardly gasified under subcritical conditions, while supercritical water has high solubility for PCOS with no solid residues. Organic matter in the liquid phase is classified into nine types, and the increase in temperature greatly changes its composition. The migration of elements (carbon and nitrogen) is also comprehensively studied.
ENERGY SOURCES PART A-RECOVERY UTILIZATION AND ENVIRONMENTAL EFFECTS
(2023)
Article
Energy & Fuels
Libo Lu, Wenwen Wei, Fan Liu, Zhiwei Ge, Hui Jin, Yunan Chen, Liejin Guo
Summary: Supercritical water gasification (SCWG) is a promising technology for the treatment of black liquor and energy recycling. However, the transformation of sulfur during the SCWG process is not well understood. In this study, the effects of different parameters on gasification and sulfur transformation were investigated. The results showed that reaction temperature played a crucial role, and H-2 was the most important gaseous product. After SCWG treatment, sulfur mainly existed in the form of sulfide. The findings of this study provide a basis for the resource utilization of black liquor and a promising method for sodium sulfide production.
Article
Chemistry, Multidisciplinary
Hanbing Li, Hongyan Zhang, Wenquan Liu, Jie Huang, Kejian Lu, Jinwen Shi, Hui Jin, Wenshuai Chen, Maochang Liu
Summary: In recent years, solar-powered photocatalytic water splitting for hydrogen production has gained significant attention as a renewable and environmentally friendly method to generate clean energy. This paper explores the process of photocatalytic hydrogen evolution using Pt-loaded commercial titanium dioxide as the photocatalyst and presents a simple experimental demonstration of integrating photocatalytic hydrogen production with a hydrogen fuel cell system. The principles, reaction mechanisms, and experimental design linking photocatalysis with fuel cells are systematically discussed.
JOURNAL OF CHEMICAL EDUCATION
(2023)
Article
Green & Sustainable Science & Technology
Bin Bai, Peng Liu, Hui Jin
Summary: This study investigates the settlement of plastic particles in hydrothermal conditions. The experimental results show that the particles undergo a swelling stage and increase in size by absorbing the fluid under hydrothermal conditions. The falling trajectory of particles displays an irregular spatial curve, and the eccentric position of the particles during settlement also affects their size. The drag coefficient of swelling particles in the tube is significantly larger than that of rigid particles, and it gradually decreases with the Reynolds number, especially for small particles.
JOURNAL OF CLEANER PRODUCTION
(2023)
Article
Mechanics
Peitong Li, Huibo Wang, Xiaoyu Li, Liejin Guo, Hui Jin
Summary: This paper aims to find a convenient method to calculate the friction coefficient on a flat plate in supercritical water (SCW) laminar flow using a pseudo-critical incoming state. Direct numerical simulation (DNS) is used to study the velocity profile characteristics in the SCW boundary layer and apply them to derive a semi-analytical formula for plate friction in the SCW fluid field. The method of obtaining a dimensionless parameter G(mu)* by DNS is given, and the dependence between G(mu)* and boundary conditions is derived by numerical experiments. The accuracy of this method is proved by comparing the results with DNS results.
Article
Mechanics
Kun Jiang, Qiuyang Zhao, Haocheng Yu, Jinwen Shi, Hui Jin
Summary: In this study, particle resolve-direct numerical simulation is used to investigate the flow of high-temperature supercritical CO2 over a low-temperature stationary sphere. It is found that the presence of Stefan flow reduces flow resistance but inhibits heat transfer performance compared to cases without Stefan flow.
Editorial Material
Chemistry, Multidisciplinary
Hui Jin, Qingang Xiong, Xiaolei Zhang, Yaning Zhang
ACS SUSTAINABLE CHEMISTRY & ENGINEERING
(2023)
Article
Engineering, Chemical
Qiuyang Zhao, Baercheng Bawaa, Tian Xie, Yu Dong, Weizuo Wang, Hui Jin, Liejin Guo
Summary: The study investigates the hydrocarbon generation characteristics of pure kerogen in supercritical water by removing inorganic minerals using acid-pickling. Results show that increasing temperature favors high-quality oil production with more light distillates, while gas yield continues to increase. The main gas products are methane, hydrogen, carbon dioxide, and C2+ hydrocarbons, with hydrogen proportion increasing with temperature and methane proportion peaking at 600 degrees C. Elevated temperatures in a supercritical water atmosphere lead to ring-opening processes and the cleavage of branched side chains, promoting kerogen maturation.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Engineering, Chemical
Rui Zhang, Shuaiqi Zhao, Chengzhen Sun, Hui Jin, Kunpeng Zhao, Bofeng Bai
Summary: This study investigates the morphology evolution of lignite particles during supercritical water gasification, and finds that the sharpness of the particles has a significant impact on the gasification efficiency. The presence of high-sharpness structures promotes a particle conversion rate of up to 86.21%. Additionally, an optimized particle morphology of C-s < 0.74 and size D-0 < 1.5 mm achieves an average mass conversion rate of approximately 79.12% without the use of a catalyst.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Engineering, Environmental
Gaoyun Wang, Jiasunle Li, Xujun Li, Jiajing Kou, Zhiwei Ge, Linhu Li, Pai Peng, Liejin Guo
Summary: Supercritical water gasification (SCWG) technology is able to convert oily sludge into hydrogen-rich gas. A two-step method involving a desorption process and a catalytic gasification process using Raney-Ni catalyst was investigated to achieve high gasification efficiency of oily sludge with a high oil concentration under mild conditions. The research revealed that the two-step method outperformed the single-step method, and provided valuable insights into the effective SCWG of oily sludge at a low temperature.
JOURNAL OF HAZARDOUS MATERIALS
(2023)
Article
Mathematics, Applied
Junfeng Cao, Ke Chen, Huan Han
Summary: This paper proposes a two-stage image segmentation model based on structure tensor and fractional-order regularization. In the first stage, fractional-order regularization is used to approximate the Hausdorff measure of the MS model. The solution is found using the ADI scheme. In the second stage, thresholding is used for target segmentation. The proposed model demonstrates superior performance compared to state-of-the-art methods.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Dylan J. Oliver, Ian W. Turner, Elliot J. Carr
Summary: This paper discusses a projection-based framework for numerical computation of advection-diffusion-reaction (ADR) equations in heterogeneous media with multiple layers or complex geometric structures. By obtaining approximate solutions on a coarse grid and reconstructing solutions on a fine grid, the computational cost is significantly reduced while accurately approximating complex solutions.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Nathan V. Roberts, Sean T. Miller, Stephen D. Bond, Eric C. Cyr
Summary: In this study, the time-marching discontinuous Petrov-Galerkin (DPG) method is applied to the Vlasov equation for the first time, using backward Euler for a Vlasov-Poisson discretization. Adaptive mesh refinement is demonstrated on two problems: the two-stream instability problem and a cold diode problem.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Yizhi Sun, Zhilin Sun
Summary: This work investigates the convexity of a specific class of positive definite probability measures and demonstrates the preservation of convexity under multiplication and intertwining product. The study reveals that any integrable function on an interval with a polynomial expansion of fast absolute convergence can be decomposed into a pair of positive convex interval probabilities, simplifying the study of interval distributions and discontinuous probabilistic Galerkin schemes.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Bhagwan Singh, Komal Jangid, Santwana Mukhopadhyay
Summary: This paper examines the prediction of bending characteristics of nanoscale materials using the Moore-Gibson-Thompson thermoelasticity theory in conjunction with the nonlocal strain gradient theory. The study finds that the stiffness of the materials can be affected by nonlocal and length-scale parameters, and the aspect ratios of the beam structure play a significant role in bending simulations.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Guoliang Wang, Bo Zheng, Yueqiang Shang
Summary: This paper presents and analyzes a parallel finite element post-processing algorithm for the simulation of Stokes equations with a nonlinear damping term, which integrates the algorithmic advantages of the two-level approach, the partition of unity method, and the post-processing technique. The algorithm generates a global continuous approximate solution using the partition of unity method and improves the smoothness of the solution by adding an extra coarse grid correction step. It has good parallel performance and is validated through theoretical error estimates and numerical test examples.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Hao Xu, Zeng-Qi Wang
Summary: Fluid flow control problems are crucial in industrial applications, and solving the optimal control of Navier-Stokes equations is challenging. By using Oseen's approximation and matrix splitting preconditioners, we can efficiently solve the linear systems and improve convergence.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Zhengya Yang, Xuejuan Chen, Yanping Chen, Jing Wang
Summary: This paper focuses on the high-order stable numerical solutions of the time-space fractional diffusion equation. The Fourier spectral method is used for spatial discretization and the Spectral Deferred Correction (SDC) method is used for numerical solutions in time. As a result, a high-precision numerical discretization scheme for solving the fractional diffusion equation is obtained, and the convergence and stability of the scheme are proved. Several numerical examples are presented to demonstrate the effectiveness and feasibility of the proposed numerical scheme.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
