Article
Thermodynamics
V Scheiff, F. Bergame, J. Sebilleau, P. Ruyer, C. Colin
Summary: This study investigates the heat transfer and flow structure in the fully developed nucleate flow boiling regime in a semi-annular duct. The experiments show that the wall heat flux prediction and bubble diameter variation can be well explained and predicted under different parameter conditions.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Mathematics, Applied
Mihai Bucataru, Liviu Marin
Summary: In this study, we investigate the acceleration of two iterative algorithms for accurate reconstruction of missing temperature and normal heat flux on an inaccessible boundary. The convergence of each algorithm is analyzed by considering the properties of the corresponding operator and determining the optimal value of the relaxation parameter. Numerical experiments confirm the effectiveness of the algorithms in reducing CPU time.
NUMERICAL ALGORITHMS
(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
Tokuma Hikata, Hitoshi Fujimoto
Summary: Water-jet quenching is commonly used in steel-manufacturing industries for cooling hot solids. Evaluating the surface heat flux in the jet-impact region is necessary for precise temperature control. In this study, a method for evaluating the surface heat flux was developed, which showed high spatial resolution and was validated through experiments.
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
Energy & Fuels
Arjun Sivaprasad, Prasenjit Basu
Summary: This paper presents the development of a new soil thermal conductivity measurement device that can simulate soil under different stress conditions and estimate both transient and steady-state thermal conductivity. The results from tests on seven different soils show that the transient-state thermal conductivity increases beyond a certain threshold value of temperature increment rate.
Article
Mathematics, Applied
Piotr Knosalla
Summary: The steady-state system of aerotaxis equations in higher dimensions is studied. It is found that the existence and multiplicity of solutions depend on the total mass of the colony of bacteria, the energy function, and the boundary conditions.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2023)
Article
Thermodynamics
Luca Pagliarini, Luca Cattani, Fabio Bozzoli, Mauro Mameli, Sauro Filippeschi, Sara Rainieri, Marco Marengo
Summary: A Pulsating Heat Pipe (PHP) was tested in microgravity conditions during the 67th Parabolic Flight Campaign, using a high-speed infrared camera to measure the temperature distribution of the external wall, and applying the Inverse Heat Conduction Problem (IHCP) solution to estimate local heat fluxes. A statistical approach was used to study the heat fluxes of the device, showing that it can provide similar information to traditional experimental methods.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Naoko Iwata, Fabio Bozzoli, Luca Pagliarini, Luca Cattani, Pamela Vocale, Matteo Malavasi, Sara Rainieri
Summary: This study focused on the local heat flux distributions and heat transfer behavior of Pulsating Heat Pipes (PHPs), exploring characteristics such as fluid oscillation frequencies under different heat input conditions. The results provide valuable insights into the fundamental governing mechanisms of PHPs.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Feiding Zhu, Jincheng Chen, Yuge Han, Dengfeng Ren
Summary: This study proposed a simple method based on deep learning to estimate thermal boundary condition parameters in the transient inverse heat transfer problem. By combining convolutional neural network (CNN) and long short-term memory networks (LSTM), real-time prediction of multiple time-varying parameters can be achieved. Experimental results showed that the proposed model outperformed standalone models in estimating multiple time-varying parameters.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Mayaram Sahu, Jahar Sarkar, Laltu Chandra
Summary: This study investigates the effects of different assumptions on simulating single-phase natural circulation loops, focusing on Boussinesq approximation, property variation, and heat flux distributions. The results show that Boussinesq approximation under-predicts mass flow rate and effectiveness, while over-predicting entropy generation rate. Fluid and solid conduction are crucial for simulating transient characteristics, with Gaussian heat flux distribution showing the highest mass flow rate and non-linear heat flux showing the highest effectiveness and entropy generation.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Aminul Islam Khan, Md Muhtasim Billah, Chunhua Ying, Jin Liu, Prashanta Dutta
Summary: In this study, a Bayesian inference based inverse technique is used to find local heat transfer coefficient and local steam temperature at the inner surface of a steam header. The calculated outer surface temperatures agree well with experimental measurements in both heating and cooling processes, demonstrating the efficiency of the stochastic based Bayesian technique in estimating unknown boundary conditions at an inaccessible location.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Mustafa Turkyilmazoglu
Summary: This paper extends the classical models for fluid flow, heat transfer, and impulsive acceleration by introducing fractional derivatives. The solutions are represented as steady and transient parts, and alternative solution methods are provided. The findings demonstrate the impact of fractional derivative in different time regimes, contributing to the understanding of diffusion phenomena.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2023)
Article
Optics
Riddhi Ghosh, Ahana Ghoshal, Ujjwal Sen
Summary: We find that transient quantum thermal transistors can have different amplification effects and operating regions for certain initial states. The last type of transient thermal transistor is particularly interesting as it can also operate in the region where the transistor effect is lost.
Article
Mathematics, Applied
Lexiang Yan, Rong An
Summary: In this paper, two-level finite element methods are proposed for the steady bio-convection flows problem. The MINI element is used to approximate the velocity and pressure, while the piecewise linear element is used to approximate the concentration. Error estimates of the finite element solutions are derived for the one-level method using the Aubin-Nitsche method. Two-level Stokes/Oseen/Newton finite element methods are proposed by combining two-level discretization technique, and optimal error estimates for the velocity and concentration in L1-norm and the pressure in L2-norm are obtained. Numerical results are provided to validate the theoretical analysis and assess the efficiency of the two-level methods.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2023)
Article
Engineering, Multidisciplinary
T. Gomboc, J. Iljaz, J. Ravnik, M. Hribersek
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2019)
Article
Computer Science, Interdisciplinary Applications
Yan Cui, Jure Ravnik, Matjaz Hribersek, Paul Steinmann
COMPUTERS & FLUIDS
(2020)
Article
Mathematics, Applied
J. Iljaz, L. C. Wrobel, T. Gomboc, M. Hribersek, J. Marn
Review
Chemistry, Physical
Amadeus C. S. Alcantara, Israel Assis, Daniel Prada, Konrad Mehle, Stefan Schwan, Lucia Costa-Paiva, Munir S. Skaf, Luiz C. Wrobel, Paulo Sollero
Article
Physics, Multidisciplinary
Tibor Besenic, Milan Vujanovic, Jakov Baleta, Klaus Pachler, Niko Samec, Matjaz Hribersek
Article
Thermodynamics
Damijan Cerinski, Milan Vujanovic, Zvonimir Petranovic, Jakov Baleta, Niko Samec, Matjaz Hribersek
ENERGY CONVERSION AND MANAGEMENT
(2020)
Article
Engineering, Multidisciplinary
O. Verhnjak, M. Hribersek, P. Steinmann, J. Ravnik
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2020)
Article
Chemistry, Multidisciplinary
Thiago Santos, Luiz C. Wrobel, Nick Hopper, Maria Kolokotroni
Summary: The heat transfer between encapsulated PCM panels and air in PCM-Air heat exchangers was studied, leading to the development of a new encapsulation panel design. Through simulations and laboratory testing, it was found that the new design significantly improved heat transfer efficiency, increased material capacity, and allowed the fan to overcome the increased pressure drop.
APPLIED SCIENCES-BASEL
(2021)
Article
Computer Science, Interdisciplinary Applications
Andres F. Galvis, Daniel M. Prada, Lucas S. Moura, Cecilia Zavaglia, Jamie M. Foster, Paulo Sollero, Luiz C. Wrobel
Summary: BESLE is an open-source code for analyzing the mechanical behavior of heterogeneous materials using the boundary element method in 3D with both elastostatic and elastodynamic capabilities. It can simulate isotropic and anisotropic materials comprised of single or multiple domains, with results described by displacement and traction fields, as well as stress and strain tensors available for post-processing. The software is implemented in Fortran-MPI and is best suited for multi-core architectures for efficient parallelization.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Thermodynamics
Filip Juric, Marija Stipic, Niko Samec, Matjaz Hribersek, Stanislav Honus, Milan Vujanovic
Summary: The study compares and validates the flamelet generated manifold (FGM) and Three-zones extended coherent flame model (ECFM-3Z) for multiphase reactive processes inside compression ignition engines. Both models show differences in predicting ignition delay and combustion processes for single and multiple injection strategies, and demonstrate good predictive capabilities on nitric oxide emission trends.
ENERGY CONVERSION AND MANAGEMENT
(2021)
Article
Engineering, Multidisciplinary
Henrique C. C. de Andrade, Fernando L. B. Ribeiro, Luiz Carlos Wrobel
Summary: This article presents a parallel formulation of the finite volume method for solving three-dimensional, turbulent, mixed, reactive, and slightly compressible flows. It can also be used for incompressible laminar/turbulent flows. The method is designed for nonorthogonal meshes and uses a deferred correction technique to handle oscillations caused by advective terms. The chosen finite volume scheme is cell centered. The study focuses on gas mixtures with predominance of N2, specifically the combustion process in the air. The mathematical model uses an approximation for low Mach numbers and the coupling between fluid dynamic equations is solved using nonlinear Picard's method and the SIMPLE algorithm. The parallel strategy uses the MPI and OpenMP standards.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING
(2022)
Article
Engineering, Chemical
Aljaz Klasinc, Gregor Drago Zupancic, Matjaz Hribersek, Ales Hribernik, Aleksandra Lobnik, Matej Zadravec
Summary: The objective of this study was to determine the density of anaerobic granules at different heights in a full-scale Upflow Anaerobic Sludge Bed reactor. The density was calculated using measured settling velocities and a mathematical model based on the Stokes model. The results showed that the granule densities at different heights were independent of the reactor height.
Article
Energy & Fuels
Jure Ravnik, Gorazd Bombek, Ales Hribernik, Timi Gomboc, Matej Zadravec, Aleks Kapun, Grega Hrovat, Jure Gradisek, Matjaz Hribersek
Summary: This article investigates the energy consumption of membrane microfiltration in intermittent operation mode. By conducting experiments and computational analysis, an energy intake model is developed and evaluated for different types and conditions (clean and partially clogged) of filters. The results show that the clean filter case has the highest energy intake.
Article
Engineering, Civil
Emerson Bastos, Eder Lima de Albuquerque, Lucas Silveira Campos, Luiz Carlos Wrobel
Summary: This study presents two fast isogeometric formulations of the Boundary Element Method (BEM) accelerated by the Fast Multipole Method (FMM) and Hierarchical Matrices respectively. Both formulations use NURBS as shape functions and reduce computational cost through decomposition. Validation is performed by comparing with the conventional BEM formulation and the advantages in large scale problems are demonstrated.
LATIN AMERICAN JOURNAL OF SOLIDS AND STRUCTURES
(2022)
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)