Article
Thermodynamics
Ahmet Umit Tepe
Summary: This study investigated the effect of a newly proposed punched triangular ramp vortex generator on heat transfer performance for a fin-tube heat exchanger through numerical simulations. The results showed that the ramp angle had a more significant influence on thermo-hydraulic performance compared to ramp height.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Pongjet Promvonge, Smith Eiamsa-ard, Sompol Skullong, Naoki Maruyama, Masafumi Hirota
Summary: An experiment was conducted to investigate the effectiveness of inserting a louver-punched trapezoidal-winglet into a heat-fluxed tube to create a longitudinal vortex generator. The study aimed to optimize thermal performance and reduce heat exchanger sizes. The experimental results showed significant improvements in friction factor and Nusselt number compared to a plain tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
WeiNa Shi, TengFei Liu, KeWei Song, Qiang Zhang, WanLing Hu, LiangBi Wang
Summary: The research investigated the impact of curved delta winglet vortex generator's longitudinal location on heat transfer in a finned-tube heat exchanger. By adjusting the longitudinal position of the vortex generator, the intensity of longitudinal vortices and heat transfer were significantly affected. Finding the optimal longitudinal location of the vortex generator can achieve maximum heat transfer performance, which is important for the design and optimization of heat exchangers.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Thermodynamics
Suabsakul Gururatana, Rotchana Prapainop, Sathaporn Chuepeng, Sompol Skullong
Summary: The experimental results showed that using the improved NACA0024 vortex generator can produce the best heat transfer enhancement effect inside the tube heat exchanger. The empirical associations for Nusselt number, friction factor, and heat transfer enhancement performance were matched with investigational data.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Prashant Saini, Atul Dhar, Satvasheel Powar
Summary: This study proposes novel configurations of a curved trapezoidal winglet vortex generator to improve heat transfer in fin and tube heat exchangers. By comparing different design configurations, it is found that the curved trapezoidal winglet vortex generator with multiple circular holes performs well in terms of thermohydraulic performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Jiangbo Wang, Ting Fu, Liangcai Zeng, Fue-sang Lien, Xiaolei Deng
Summary: This study investigated the thermal performance of punched rectangular winglet vortex generators in turbulent regime. The results showed that punching holes can reduce heat transfer and friction coefficients, enhance the thermal enhancement factor, and jet flow can improve heat transfer efficiency.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Chunhua Min, Haizhu Li, Xiaomeng Gao, Kun Wang, Liyao Xie
Summary: This paper proposed a novel method to improve heat exchanger thermal performance by combining vortex generators and twisted belts, with numerical studies on circular tube thermo-hydraulic characteristics to determine optimal parameters. The results showed that using a combination of staggered arrangement, optimal twist ratio of 4, attack angle of 75 degrees, and pitch of 1.5D can significantly enhance the heat exchanger performance.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Yuxiao Tang, Konghua Yang, Chunbao Liu, Kunyang Wang, Luquan Ren
Summary: In this study, the thermohydraulic characteristics and enhanced heat transfer mechanism in a water-cooling oil heat exchanger were investigated numerically. The results showed that the vortex generators induced longitudinal and secondary vortices, resulting in enhanced heat transfer regions on the heat exchange fins. However, inhibiting effect between the two still existed, particularly in high attack angle or oil medium. The elliptical winglet vortex generator with 30 degrees in oil medium and 15 degrees in water medium achieved the highest thermal performance factor compared to without vortex generators. The spacing of 4 mm showed the best synergistic heat transfer, elevating the maximum heat flux by 2.2% and 8.6% more than that of a single vortex generator in oil and water medium, respectively.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Yuxiao Tang, Konghua Yang, Chunbao Liu, Kunyang Wang, Luquan Ren
Summary: The thermohydraulic characteristics and enhanced heat transfer mechanism in a water-cooling oil heat exchanger are numerically investigated using various shapes and attack angles of vortex generators (VGs) and spacing of double VGs. The results show that VGs induce longitudinal and secondary vortices, creating tapered and elliptical enhanced heat transfer regions on the heat exchange fins. The best thermal performance is achieved with an elliptical winglet VG with 30 degrees attack angle in oil medium and 15 degrees in water medium. The appropriate configuration of two core heat transfer regions achieves in-depth synergistic heat transfer, with a spacing of 4 mm showing the best performance.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Soheil Asaadi, Hamid Abdi
Summary: The heat transfer enhancement in plate-fin heat exchangers using vortex generators with different nanoparticle volume fractions was numerically simulated. Results showed that using nanofluid can increase heat transfer coefficient by 20% and pressure drop by 18% compared to pure water. Among the vortex generator types, MDWP2 exhibited the highest heat transfer performance but also led to the highest pressure drop in the studied range of Reynolds number.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Thermodynamics
Meng Yuan, Gongmin Liu, Xinyu Zhang, Wenping Zhang, Yifan Yang, JuHun Song, HeeChang Lim
Summary: This study aims to improve and optimize the heat transfer and flow resistance of spiral finned tubes (SFTs) in heat exchangers. Experimental and numerical methods are used to investigate the performance of SFTs with triangular winglets compared to ordinary spiral fin tubes (OSFs) at different Reynolds numbers. An orthogonal experimental design method is employed to calculate the heat transfer and resistance of sixteen different SFTs, and the correlation between Nusselt (Nu) number and fanning friction coefficient (f) for the optimized model is presented.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Green & Sustainable Science & Technology
Yahya Sheikhnejad, Seyed Abdolreza Gandjalikhan Nassab
Summary: The study aims to enhance the performance of planar solar chimneys by using vortex generation technique to convert more solar radiation into air enthalpy, with a passive vortex generator employed for heat transfer enhancement. Numerical results show that the natural vibration of elastic vortex generator induces moving vortices into the flow field, leading to improved natural convection heat transfer and significantly enhancing the performance of the air heater.
Article
Thermodynamics
Pongjet Promvonge, Sompol Skullong
Summary: The article focuses on enhancing the thermohydraulic performance of a solar heat exchanger duct with combined V-shaped baffle-and-groove vortex generators. Experimental results show that using the flapped-baffle and groove VG devices can achieve maximum heat transfer and friction effects, especially for the VU case.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Mehmet Dogan, Atila Abir Igci
Summary: Vortex generators (VGs) play a crucial role in enhancing heat transfer. An experimental comparison between a novel type of vortex generator (NTVG) producing longitudinal vortex (LV) and delta winglet pair (DWP) showed that the NTVG achieved higher thermal enhancement, indicating its effectiveness in improving heat transfer.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Chemical
Lin Sun, Biwei Fu, Menghui Wei, Si Zhang
Summary: This paper proposes three coaxial borehole heat exchangers with vortex generators based on the enhanced heat transfer theory to improve the heat transfer efficiency. The results demonstrate that the vortex generator can enhance the fluid flow's turbulent kinetic energy and improve the mixing characteristics of the fluid flow and heat transfer. Among the heat exchangers studied, the thread vortex generator (TVG) heat exchanger outperforms others in terms of heat exchange performance, extraction temperature, and heat extraction power.
Article
Engineering, Multidisciplinary
Mahmoud Meribout, Faisal Shehzad, Nabil Kharoua, Lyes Khezzar
Article
Thermodynamics
G. Liang, Md. Islam, Md. Mahbub Alam, Imad Barsoum
Summary: The study experimentally investigated the effects of radially-arrayed winglet vortex generators in a circular tube on heat transfer enhancement and pressure drop. It was found that increasing the length or attack angle of the winglets intensified Nu and f, while pitch ratio and inclination angle had the opposite effect. Optimizing pitch ratio was identified as more important for achieving higher thermal enhancement.
HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Multidisciplinary
Mahmoud Meribout, Samir Mekid, Nabil Kharoua, Lyes Khezzar
Summary: This critical review explores the main sensing techniques used for online monitoring of the integrity of alloy steel equipment in the process industry. Despite ongoing research to improve sensitivity and accuracy, challenges such as lack of sensitivity, accuracy, universality, and cost effectiveness persist. Further development efforts are necessary to address these issues.
Article
Acoustics
Idowu Adeyemi, Mahmoud Meribout, Lyes Khezzar, Nabil Kharoua, Khalid AlHammadi
Summary: This study conducted a numerical assessment of binary water droplet coalescence in water-in-oil emulsion and investigated the effects of various parameters on the acoustic pressure and coalescence time. The results showed that the implementation of ultrasound enhanced the coalescence of water droplets, while lower interfacial tension and higher dynamic viscosity reduced the coalescence time.
ULTRASONICS SONOCHEMISTRY
(2022)
Review
Engineering, Chemical
Idowu Adeyemi, Nabil Kharoua, Lyes Khezzar, Mahmoud Meribout, Khalid AlHammadi
Summary: This article summarizes the research progress on confined swirling flows, including two-phase flow and oil-water separation. The research findings are essential for industrial processes such as heat exchange and phase separation.
CHEMICAL ENGINEERING RESEARCH & DESIGN
(2022)
Article
Engineering, Mechanical
Hamid Hassan Khan, Md. Islam, Yap Yit Fatt, Isam Janajreh, Md. Mahbub Alam
Summary: The study reveals that increasing the diameter reduction ratio reduces the flow-induced vibrations (FIVs) of the downstream cylinder, while also enhancing its heat transfer performance. This is due to the weaker correlation between lift force and oscillation, modulated oscillation of the cylinder, and distribution of shedding frequency energy to secondary frequency caused by the unequal diameter.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Mechanics
Ussama Ali, Md Islam, Isam Janajreh
Summary: This work numerically studies the heat transfer and wake-induced vibrations of two identical cylinders in the wake of each other at a Reynolds number of 100. The study examines the effects of reduced velocities and spacing ratios on parameters such as lift and drag coefficients, vibrational amplitudes, Nusselt and Strouhal numbers, and vortex shedding patterns. The results indicate that the spacing ratio has a significant influence on the interaction between the cylinders, and a lock-in condition is observed at a reduced velocity of 8.
Article
Energy & Fuels
Yuvraj Sarout, Md Islam, Yap Fatt, Isam Janajreh
Summary: This numerical study investigates flow-induced vibration on non-heated and heated cylinders with different normalized corner radii at different Reynolds numbers. The study finds that the vibration modes of the cylinders are affected by the normalized corner radius and Reynolds number, and the amplitude and Nusselt number of the heated cylinders also show notable changes.
Article
Mechanics
Yuvraj Sarout, Md Islam, Yap Yit Fatt, Isam Janajreh
Summary: This study numerically investigates the flow-induced vibration (FIV) on two tandem cylinders with forced convection at a constant Reynolds number of 150. The effects of corner radii and spacing ratio on flow structure and FIV parameters are observed. The results show that the vibration amplitude and Nusselt number strongly depend on the corner radii and spacing ratio.
Article
Engineering, Mechanical
Md. Mahbub Alam, Guanghao Chen, Yu Zhou, Longjun Wang, Jiasong Wang, M. D. Islam
Summary: This study experimentally investigates the flow-induced vibration of a cantilevered circular cylinder in the wake of another cylinder. Measurements are conducted to simultaneously capture the downstream cylinder's vibration, vortex shedding frequency, surface pressure distribution, and flow structures. It is found that the downstream cylinder with smaller ratios of diameter and spacing is more prone to galloping vibration and hysteresis in the galloping response. The importance of effective mass and damping in initiating and sustaining the vibrations is revealed. The variations in flow structures are discussed in detail in both streamwise and spanwise directions, along with fluid-structure interactions.
JOURNAL OF FLUIDS AND STRUCTURES
(2023)
Article
Engineering, Marine
Sanjeev Kumar, Md Islam, Yap Yit Fatt, Isam Janajreh
Summary: A numerical study was conducted to investigate the effects of angle of incidence, gap ratio, and reduced velocity on flow-induced vibration and heat transfer characteristics in a cluster of staggered cylinders. The results revealed interesting patterns and showed the influence of wake interference on downstream cylinders.
Article
Engineering, Marine
Yuvraj Sarout, Md Islam, Ussama Ali, Yap Yit Fatt, Isam Janajreh
Summary: In this study, the flow-induced vibration (FIV) of two heated cylinders in a tandem arrangement is numerically investigated. The effect of spacing ratio (L/D) and corner radius (r*) is studied, and it is found that the maximum vibrational amplitude is highest for square cylinders and lowest for circular cylinders. The lock-in phenomenon is observed at a specific reduced velocity (Ur) for both square and circular tandem cylinders, and the heat transfer rate is higher for circular cylinders while experiencing lower vibration compared to square cylinders.
Proceedings Paper
Engineering, Multidisciplinary
Nabil Kharoua, Hamza Semmari, Houssem Korichi, Mehdi Haroun
Summary: This study investigates the positive effects of using multiple rows of Vortex Generators in Canadian Wells to enhance heat transfer coefficients, with results showing beneficial effects up to the fifth row of the VGs.
PROCEEDINGS OF ASME 2021 FLUIDS ENGINEERING DIVISION SUMMER MEETING (FEDSM2021), VOL 1
(2021)
Article
Materials Science, Multidisciplinary
Jinli Song, Nabil Kharoua, Lyes Khezzar, Mohamed Alshehhi
Summary: This study simulated turbulent swirling flow inside a short pipe interacting with a conical bluff body using different turbulence models, and investigated the influence of Reynolds number on velocity profiles, swirl decay, and wall pressure on the bluff body.
FDMP-FLUID DYNAMICS & MATERIALS PROCESSING
(2021)
Article
Thermodynamics
Md Islam, A. Nurizki, I Barsoum, Nader Ayish, R. Simmons
Summary: This experiment utilized delta winglet arrays of vortex generators in a tube heat exchanger to study enhanced heat transfer, focusing on the effects of pitch ratios and attack angles on thermal performance. Results indicated significant influences of different pitch ratios and attack angles on heat transfer enhancement.
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)
