Article
Thermodynamics
Andrzej Frackowiak, Agnieszka Wroblewska, Michal Cialkowski
Summary: This paper presents a concept of solving the inverse heat conduction problem using Trefftz functions and provides two examples to validate the effectiveness of the method.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Marcelo Colaco, Fabio Bozzoli, Luca Cattani, Luca Pagliarini
Summary: The paper applies the conjugate gradient method and adjoint operator to the pulsating heat pipe problem, providing interesting experimental results. The CG method with AO is proven to estimate unknown functions more efficiently than other techniques. The main purpose of the paper is to present a robust, efficient, and self-regularized inverse tool for estimating local heat transfer coefficients in pulsating heat pipes, supported by experimental results. The authors also provide all numerical and experimental data used in the paper as supplemental material to enhance its visibility and general use.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2023)
Article
Environmental Sciences
Zhanat Karashbayeva, Julien Berger, Helcio R. B. Orlande, Bolatbek Rysbaiuly
Summary: In this study, the ground diffusivity was indirectly measured by solving an inverse problem. The conjugate gradient method with adjoint problem formulation was used to obtain stable and effective results, which were consistent with literature values.
Article
Thermodynamics
Farzad Mohebbi, Ben Evans, Timon Rabczuk
Summary: This study introduces a numerical approach to address steady-state heat conduction problems in functionally graded materials (FGMs). The method considers two different material gradations and is capable of accurately solving heat conduction equations for irregularly shaped heat conducting bodies with various boundary conditions. The novelty lies in accurately determining material parameters through an inverse analysis and proposing an efficient sensitivity analysis scheme for computing sensitivity coefficients.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Thermodynamics
Parth Sathavara, Ajit Kumar Parwani, Paritosh Chaudhuri
Summary: In this study, the conjugate gradient method with adjoint problem is used to estimate the thermal properties. A scaling factor based on the Levenberg-Marquardt method is applied to overcome divergence and low derivative value issues. Numerical experiments with artificial Gaussian error are conducted to evaluate the accuracy of the modified CGM.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Engineering, Mechanical
Chaokai Yuan, Fanzhao Meng, Xu Liu, Yunfeng Liu, Huan Lian, Yingzheng Liu, Di Peng
Summary: Global heat flux measurement techniques with high spatial resolution are necessary for accurately capturing the peak heat flux and its location in the design of thermal protection systems. However, background radiation from combustion poses a challenge for the application of these techniques. To overcome this problem, a new method suitable for strong combustion radiation environments is introduced, which involves solving a three-dimensional transient inverse heat conduction problem to determine the heat flux on the inner surface of the combustor while measuring the outer surface temperature using temperature-sensitive paint. The configuration of the measurement system, data processing method, and the effect of temperature-sensitive paint layer thickness on the measurement results are discussed in detail. Numerical and experimental results are presented to demonstrate the validity of the new method.
ACTA MECHANICA SINICA
(2023)
Article
Thermodynamics
T. Helmig, R. Kneer
Summary: Heat transfer at moving bearing interfaces is crucial for the thermal design of high precision machine tools and electrical engines. Traditional methods using tactile sensors have limitations like measurement uncertainties and long investigation times. A novel approach using infrared thermography overcomes these limitations and provides more accurate and efficient results.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Thermodynamics
Shibin Wan, Kun Wang, Peng Xu, Yajin Huang
Summary: In this paper, a single neural adaptive PID (SNA-PID) inverse method is proposed to estimate the thermal boundary condition. Compared with the traditional PID inverse method, SNA-PID can adaptively adjust the weights of PID parameters, thus improving the tuning effect and anti-interference ability.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Cheng-Hung Huang, Kai-Jyun He
Summary: This study estimated the unknown spatially dependent surface heat flux for a three-dimensional steady-state inverse heat conduction-convection conjugated problem (IHCCCP). The conjugate gradient method (CGM) was used for optimization, enabling correction and estimation of a large number of unknowns in each iteration to yield accurate estimates. Experimental verification and analysis of measurement errors were conducted. The accuracy of the estimated heat flux decreases as the plate thickness increases due to the ill-posed nature of the inverse problem.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Matteo Gelain, Marc-Paul Errera, Olivier Gicquel
Summary: This paper aims to evaluate and validate a mathematical coupling model based on normal mode stability analysis for steady conjugate heat transfer problems. The results show that the stability limit and numerical Biot number derived from the coupling model are reliable parameters. Additionally, other physical and numerical aspects of the coupling model are considered, and interesting and promising results are obtained.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Mathematics
Feng Wang, Yan-Cheng Liu, Hui Zheng
Summary: In this study, an efficient localized method of fundamental solution (LMFS) is applied to nonlinear heat conduction with mixed boundary conditions. The Kirchhoff transformation is used to convert the nonlinear partial differential equations into Laplace equations with nonlinear boundary conditions. The LMFS is then used on the governing equation, with the nonlinear equations treated by the fictitious time integration method (FTIM) to verify its effectiveness.
Article
Thermodynamics
Istvan Bozsoki, Balazs Illes, Attila Geczy
Summary: This paper investigates transient condensation and heat transfer on a printed circuit board (PCB) and a surface mounted (SMD) capacitor during a vapour phase reflow soldering (VPS) process, proposing a new method based on finite difference modelling to accurately describe the heat transfer dynamics of the process.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Mathematics, Applied
Baohua Huang
Summary: In this paper, the Moore-Penrose inverse of tensors is studied numerically via the Einstein product, transforming the calculation into solving tensor equations and obtaining an approximate inverse through the conjugate gradient method. Numerical examples demonstrate the efficiency of the proposed methods and confirm the conclusions suggested in the paper.
NUMERICAL ALGORITHMS
(2021)
Article
Engineering, Electrical & Electronic
Jose O. Vargas, Ricardo Adriano
Summary: A subspace-based conjugate-gradient method (S-CGM) is proposed in this article to improve the performance of the linearized CGM. By retrieving the deterministic part of the variational-induced current, the S-CGM estimates the total electric field more accurately, resulting in faster convergence speed and higher accuracy.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2022)
Article
Mathematics
Jose Julio Conde Mones, Carlos Arturo Hernandez Gracidas, Maria Monserrat Morin Castillo, Jose Jacobo Oliveros Oliveros, Lorenzo Hector Juarez Valencia
Summary: This work presents a numerical algorithm to solve the inverse problem of volumetric sources in a non-homogeneous conductive medium. The algorithm allows to recover the complete source and produce stable and accurate numerical solutions.
Article
Thermodynamics
Yi Liu, Ling Li, Yuwen Zhang
APPLIED THERMAL ENGINEERING
(2020)
Article
Thermodynamics
Zhuohuan Hu, Rui Li, Xin Yang, Mo Yang, Yuwen Zhang
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2020)
Article
Thermodynamics
Tingting Chen, Yonggao Yin, Yuwen Zhang, Xiaosong Zhang
APPLIED THERMAL ENGINEERING
(2020)
Article
Thermodynamics
Shahabeddin K. Mohammadian, Yuwen Zhang
JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME
(2020)
Article
Thermodynamics
Jongwook Choi, Yuwen Zhang
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2020)
Article
Engineering, Chemical
Seyed Moein Rassoulinejad-Mousavi, Jafar Azamat, Alireza Khataee, Yuwen Zhang
SEPARATION AND PURIFICATION TECHNOLOGY
(2020)
Article
Energy & Fuels
Zhuohuan Hu, Dongcheng Wang, Wei Lu, Jian Chen, Yuwen Zhang
Summary: A series of inline pico hydropower systems, suitable for confined space and water distribution networks, were designed and investigated. The study utilized numerical simulations and experimental comparisons to find that the standard k-epsilon turbulence model was the most accurate in predicting flow characteristics. The results showed that an opening diameter of 30 mm for the water baffle and a rotor installation angle of 52 degrees achieved the highest efficiency.
FRONTIERS IN ENERGY
(2022)
Article
Green & Sustainable Science & Technology
Jianjun Hu, Meng Guo, Jinyong Guo, Guangqiu Zhang, Yuwen Zhang
Article
Thermodynamics
Yubing Li, Mo Yang, Yuwen Zhang
Summary: Numerical simulations were conducted to investigate the effects of Reynolds numbers on the three-dimensional flow and mass transfer of semi-volatile organic compounds in cylindrical and semi-cylindrical chambers. Asymmetric flow and mass transfer were observed in both chambers when Reynolds numbers exceeded critical values, leading to differences in mass transfer efficiency and convective coefficients. Increasing Reynolds numbers resulted in improved mass transfer efficiency, with Chamber B exhibiting stronger convective mass transfer due to its unique structure.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Yubing Li, Mo Yang, Yuwen Zhang
Summary: By systematically investigating the bifurcation phenomenon and the existence of dual asymmetry solutions of double-diffusive convection in a horizontal cavity, it was found that increasing buoyancy destabilizes the symmetric system, while strong couple diffusion effect delays the onset of bifurcation flow, leading to a pair of asymmetric modes under different initial conditions.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Raihan Tayeb, Yuwen Zhang
Summary: A multiscale simulation method is used to investigate and control the self-assembly of charged polymeric nanoparticles in droplet solution deposited on a substrate. The simulation combines finite volume multiphase VOF method, Dissipative Particle Dynamics, and Level Set parameters to reduce spurious current in the droplet. By analyzing the effects of DLVO forces, van der Waals force, substrate friction, and contact angles, the study provides valuable tools for optimizing nanoparticle self-assembly.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Kun Zhang, Yagang Chen, Liangbi Wang, Yuwen Zhang
Summary: A new implicit finite difference method with a compact correction term is proposed for solving unsteady convection-diffusion equations. It improves the accuracies of numerical solutions by connecting classical and compact finite difference formulas. This method has fourth order accuracy and can be used for both uniform and nonuniform grid systems, as well as for one-dimensional to multi-dimensional and steady to unsteady convection-diffusion equations.
NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS
(2022)
Article
Mechanics
J. J. Hu, Z. W. Yang, Y. L. Li, Y. L. Jin, Z. Huang, Y. W. Zhang
Summary: This study investigates the dynamic flowfield of close-range impinging jets using time-resolved particle image velocimetry (TR-PIV). The effects of Reynolds number and nozzle end-profile on vortex generation and migration are studied, and the experimental data are analyzed using vorticity analysis and proper orthogonal decomposition (POD) method. The results show that Reynolds number affects vortex generation and migration differently for different nozzle end-profiles, and the energy distribution and variation in the vortices outside the gap are revealed based on the POD analysis.
Article
Thermodynamics
Wenhua Liu, Mo Yang, Yuwen Zhang, Yubing Li, Xuchen Ying, Weijia Huang
Summary: Numerical investigations were conducted on an opposed-fired boiler to understand the formation and effects of asymmetric phenomenon on combustion characteristics. It was found that increased inlet Reynolds numbers led to the evolution from symmetry to asymmetry in the flow and temperature fields under symmetric combustion conditions. Nonlinearity was used to explain this phenomenon and three asymmetric combustion modes were proposed to optimize the flowfield. The final optimal combustion pattern addressed air stoichiometric ratio and reduction zone heights, resulting in improved combustion performance with reduced NOx emissions and carbon content in fly ash.
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2023)
Article
Thermodynamics
Raihan Tayeb, Yuwen Zhang
Summary: This paper introduces a machine-learned subgrid-scale modeling technique that efficiently and accurately predicts reactants and products in parallel competitive reactions, particularly in a bubble column. The model is based on data generated from a simplified substitute problem with few features. The machine-learned model corrects errors in concentration and concentration gradients caused by linear interpolation and demonstrates good accuracy on a mesh that covers the concentration boundary layer with minimal computational overhead. Therefore, this model offers significant performance improvements for near spherical, ellipsoid, and dimple-ellipsoidal bubbles.
ASME JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Yunxia Ma, Fei Liu, Honggang Pan, Hongjian Zhang, Shuxia Yan, Ailing Zhang
Summary: This paper proposes a dynamically tunable and switchable perfect infrared absorber that exhibits excellent electrical regulation performance and high absorptance. The absorption mechanism is explained using a multiple interference model, and it is proven to be polarization insensitive.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
F. J. dos Santos, G. S. M. Martins, M. Strobel, L. Beckedorff, K. V. de Paiva, J. L. G. Oliveira
Summary: This study investigates the effects of inlet conditions and plate's features on the thermal-flow performance of a gasket plate heat exchanger (GPHE) and assesses the impact of a modified tightening distance on its performance. No systematic study on the combined effects of inlet conditions and assembly accuracy on GPHE performance has been conducted before.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Alok K. Ray, Dibakar Rakshit, K. Ravi Kumar, Hal Gurgenci
Summary: The low thermal conductivity of phase change materials limits the heat transfer rate and application of latent heat storage systems. This numerical study examines the impact of two passive heat transfer enhancement techniques on the thermal performance of a latent heat storage system. The results show that the orientation and position of the heat transfer fluid tube have significant effects on the charging duration, while the discharging duration remains unchanged. The combined effect of orientation and eccentricity reduces the charging duration, but increases the discharging duration compared to the concentric domain.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Yalu Han, Yanlong Wang, Chenyang Liu, Xinmin Hu, Yin An, Zhengcai Li, Jiaxun Jiang, Lizhi Du
Summary: This paper investigates the calculation method of thermal conductivity in NAPLs-contaminated soils. By establishing NAPLs-contaminated soil models and using the Lattice Boltzmann Method (LBM) for calculation, an optimized three-dimensional model with high computational accuracy and efficiency is obtained. The study also finds that saturation and Nz parameters have a significant impact on calculation time, while the thermal conductivity of the two-dimensional model is more sensitive to anisotropy. The influence of porosity and NAPLs content on thermal conductivity should be considered during in-situ thermal desorption.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Mostafa Taha, Song Zhao, Aymeric Lamorlette, Jean-Louis Consalvi, Pierre Boivin
Summary: For the first time, large-eddy simulations (LES) of the near-field region of large-scale fire plumes were performed using a pressure-based Lattice Boltzmann method (LBM) with low-Mach number approximation. The simulations showed quantitative agreement with experimental data and were consistent with previously-published numerical studies. The study demonstrated the computational efficiency of the proposed LBM solver in tackling fire-induced flows, suggesting LBMs as a good alternative candidate for modeling fire-related problems.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Weixin Zhang, Yehang Xie, Yuqiang Ding, Zhao Liu, Zhenping Feng
Summary: This study investigated the impact of upstream slot leakage on the endwall film cooling characteristics of turbine blades. Pressure Sensitive Paint (PSP) technology was used to measure the film cooling characteristics, and numerical analysis was conducted to evaluate the aerodynamic performance. It was found that increasing the mass flow ratio of the upstream slot enhanced film cooling, decreased aerodynamic losses, and reduced the strength of passage vortex. However, reducing the distance between the slot and the blade leading edge only enhanced film cooling without affecting the leakage coverage area.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Rui Zhang, Zhen-lei Li, Yan-sheng Zhang, Dong Chen, Guo Yuan
Summary: This study discusses the heat transfer behavior of different jet forms on steel tubes. The results show that the annular jet performs better in terms of cooling intensity and uniformity. The cooling performances of the two jet forms are similar when the steel tube size is small. Therefore, the planar jet can be considered for smaller diameters due to its simplicity, low cost, and convenience in application.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
A. R. Khoei, A. M. Orvati Movaffagh, A. Rezaei Sameti
Summary: This paper presents a comprehensive study on the thermo-mechanical characteristics of oxide-coated aluminum nano-powder. It is found that the thermal conductivity of oxide-coated aluminum nano-powder is significantly lower than that of the bulk aluminum, and it is affected by the density and temperature.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Yanjin Wang, Jintao Xiong, Lingyu Chen, Zhihai Lv, Qian Wang
Summary: A solar radiation transfer model for spray cooling double skin facade (SC-DSF) is proposed in this study. The model is validated by experimental results and various influence factors are analyzed. The effectiveness of adjusting droplet coverage rate and size is also evaluated.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Bostjan Zajec, Blaz Mikuz, Anil Kumar Basavaraj, Marko Matkovic, Matej Tekavcic, Martin Draksler, Leon Cizelj, Bostjan Koncar
Summary: We have developed an advanced experimental setup to investigate flow and heat transfer in an annular channel. The setup allows heat transfer measurements and flow visualization using a temperature-controlled inner tube. Measurements can be conducted in both single-phase and two-phase flow regimes. The setup ensures a uniform velocity field in the annular channel using specially designed inlet and outlet headers. The inner copper tube is heated by water and contains turbulators for enhanced heat transfer and thermocouples for temperature measurement. A three-dimensional conjugate heat transfer CFD model has been developed and validated to accurately estimate heat losses in the setup. This study demonstrates the importance of numerical simulations in improving the interpretation of complex experimental results.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Weijie Chen, Ke Wang, Yongqing Wang, Shantung Tu, Zunchao Liu, Huijuan Su
Summary: In this study, a novel gradient porosity transpiration cooling plate structure (GP-TCPS) is proposed to alleviate heat transfer deterioration caused by non-uniform temperature distribution in transpiration cooling plate structure (TCPS). Computational fluid dynamics (CFD) and response surface method (RSM) were used for qualitative and quantitative analysis of the flow and heat transfer of GP-TCPS. The optimized structure of GP-TCPS significantly improves temperature uniformity, injection pressure, and average cooling efficiency compared to traditional TCPS.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
R. Essam, A. Elsaid, W. K. Zahra
Summary: This study presents a novel bioheat model for simulating heat transfer in skin tissue. The model offers an improved representation of thermal dynamics in the skin and has been validated using numerical solutions and experimental measurements. The study highlights the importance of incorporating vascular inlet parameters and thermal relaxation effects in the thermal profile, and suggests potential applications in thermal therapy and wound healing.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Dongbo Shi, Tao Xu, Zifeng Chen, Di Zhang, Yonghui Xie
Summary: The cooling structure design of turbine blades is crucial for the safety and reliability of the gas turbine set. This research investigates different arrangement schemes, including dimple/protrusion arrangements, to enhance the cooling performance. The results show that the arrangement scheme with both passes arranged by dimples has the best comprehensive thermal performance.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Emrehan Guersoy, Hayati Kadir Pazarlioglu, Mehmet Guerdal, Engin Gedik, Kamil Arslan
Summary: The thermo-hydraulic performance of Al2O3/H2O nanofluid with different nanoparticle shapes flowing in a sudden expansion tube with variable sudden expansion inclination angles and elliptical dimpled fins with different diameters were numerically investigated. The results showed that the nanoparticle shapes, sudden expansion inclination angles, and elliptical dimpled fin have significant impact on the thermo-hydraulic performance. This study reveals the novelty and importance of these factors in the research.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Thermodynamics
Rukun Hu, Xinyu Huang, Xinyu Gao, Liu Lu, Xiaohu Yang, Bengt Sund
Summary: This study examines the impact of applying bottom cross-cut on PCM's spatial distribution in a horizontal LHTES unit using numerical simulation. The findings show that bottom cross-cut can improve the heat storage rate and natural convection heat transfer gain.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
