Article
Thermodynamics
Vahid Rajabi, Zohreh Mansoori, Hassan Rahimzadeh, Hamed Nasrfard, Goodarz Ahmadi
Summary: The experimental investigation focused on the HTC and pressure loss in horizontal smooth and wire-inserted tubes. Three different coiled wire inserts (CWIs) with varying lengths and thicknesses were studied. The results showed that the use of CWIs significantly improved the HTC compared to smooth tubes. New correlations were developed to accurately predict the condensation HTC in smooth and wire-inserted tubes.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Orhan Keklikcioglu, Veysel Ozceyhan
Summary: The experimental results indicate that adding graphene nanoplatelets to water and combining them with different types of conical wire coils can enhance the thermohydraulic performance of the heat exchanger tube. As expected, the use of conical wire coils increases both the heat transfer rate and fluid friction, while the addition of graphene nanoplatelets significantly increases the heat transfer rate and slightly increases the friction factor.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Review
Green & Sustainable Science & Technology
Mohamed H. Mousa, Nenad Miljkovic, Kashif Nawaz
Summary: Enhancing heat transfer between fluids and walls is crucial for improving performance. By utilizing features that enhance heat transfer, equipment size can be reduced, costs minimized, and safety risks mitigated.
RENEWABLE & SUSTAINABLE ENERGY REVIEWS
(2021)
Article
Thermodynamics
Dogan Akgul, Hatice Mercan, Ahmet Selim Dalkilic
Summary: This study investigates the effects of tube diameter, coil diameter, Reynolds number, Dean number, and flow rate on heat transfer and pressure drop in a helically coiled tube during laminar single-phase flows. The results show that helically coiled tubes have higher heat transfer but also higher pressure drop compared to straight tubes. The heat transfer coefficient increases with increasing Reynolds number, Dean number, tube diameter, and flow rate, while it decreases with increasing coil diameter. On the other hand, the pressure drop increases with increasing Reynolds number, Dean number, and flow rate, but decreases with increasing tube and coil diameter.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Thermodynamics
Saeed Vahidifar, Seyedhadi Banihashemi
Summary: Researchers have conducted numerous studies on active and passive methods to improve thermal performance and increase heat transfer in internal flows. Different geometries and configurations of turbulators have been proposed for optimal performance in heat exchangers. However, there is limited research on turbulators with equal obstruction inside the tube and aerodynamic geometry. This study investigates the effect of stimulating the boundary layer of the internal flow on heat transfer and flow characteristics, using a pipe with ring-shaped turbulators and equal blocking area.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Mingrui Sun, Lunxiang Zhang, Chengzhi Hu, Jiafei Zhao, Dawei Tang, Yongchen Song
Summary: Optimizing the pore structure of metal foam is considered a feasible approach for improving overall heat transfer performance. The study found that throat area could not effectively optimize heat transfer performance, but the area goodness factor j/f was higher than conventional Kelvin cells.
Review
Energy & Fuels
Olga Arsenyeva, Leonid Tovazhnyanskyy, Petro Kapustenko, Jiri Jaromir Klemes, Petar Sabev Varbanov
Summary: A plate heat exchanger (PHE) is a modern and efficient heat transfer equipment, capable of enhancing heat recuperation and energy efficiency. This paper reviews the construction and exploration developments of PHEs, as well as the methods of heat transfer intensification. The use of inclined corrugations on the surface of PHE plates is a common method to improve performance.
Article
Thermodynamics
K. Hata, M. Shibahara
Summary: Systematic measurements were conducted to study the swirl flow heat transfer and pressure drop across a helical coil-wire in a water loop flow. Experimental measurements were performed on the inner surface of a circular test tube, and numerical simulations were also conducted. The results of the experiments and simulations were compared to verify the accuracy of the simulations and establish correlations for heat transfer in swirl flows.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Iyyamperumal Seerangan, Ting-Hsuan Huang, Yao-Hsien Liu
Summary: Enhanced heat transfer and friction factor were observed in a rectangular minichannel heat sink with coiled wire inserts, leading to the proposal of a partially-filled design to reduce pressure drop. The Nusselt number and friction factor increased with wire diameter but decreased with an increase in pitch-to-diameter ratio, resulting in the highest thermal performance with partially-filled coiled wires in the minichannel.
HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
A. Martin Subirana, J. P. Solano, R. Herrero-Martin, A. Garcia, J. Perez-Garcia
Summary: This study investigates the flow and heat transfer in a helical coil under laminar and transitional flow regimes, considering mixed convection conditions. The continuous separation and reattachment of the boundary layer caused by the wire coil, as well as the swirl induced by the helical shape of the insert, are identified as mechanisms for enhancing heat transfer. Simulations in the Reynolds number range 200 < Re < 1500 show the sensitivity of heat transfer to mixed convection, as the flow dynamics is affected by buoyancy forces induced by tube wall heating. The interaction between the secondary swirl flow and buoyancy motion is examined to determine the range where heat transfer may be worsened by the presence of the helical coil. The study considers a helical coil with geometrical characteristics e/D = 0.071 and p/D = 1.5, using water as the working fluid. Experimental validation of friction factor and Nusselt number is also provided.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2023)
Article
Thermodynamics
Marzieh Lotfi, Mohammad Firoozzadeh, Amir Hossein Shiravi, Altynay Sharipova
Summary: Heat transfer enhancement is crucial in thermal systems and researchers have found that adding nanoparticles to fluid can effectively increase the heat transfer rate. However, the effect on pressure drop varies in different cases. In this study, the thermal and hydrodynamic aspects of flowing a TiO2/water nanofluid were investigated at different concentrations. The results showed significant increases in Nusselt number and drag reduction percentage at certain conditions, providing a better understanding of the system.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
Article
Thermodynamics
Mehran Hashemian, Samad Jafarmadar, Hamdi Ayed, Makatar Wae-hayee
Summary: This paper presents a multi-objective experimental study on enhancing the thermal performance of a helically coiled pipe. The study evaluates the hydrothermal behavior of single-phase and two-phase flow through the helically coiled tube, with and without a helical wire insert. The results show that the exergy efficiency is higher by 87% without a turbulator for single-phase flow. The simultaneous use of two-phase flow and turbulator is recommended when pressure drop increment is less important than heat transfer augmentation.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Raad Mohammed Kadhim Ali, Sajida Lafta Ghashim
Summary: This study numerically investigated forced convection heat transfer in a metal foam pipe under uniform heat flux. Water was used as the fluid medium and copper metal foam was used as the test sample. The results showed that partially filling the pipe with metal foam enhanced overall heat transfer, while completely filling the pipe increased flow resistance.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Review
Thermodynamics
Shashank Singh, Anup Malik, Harlal Singh Mali
Summary: This article critically examines the research on modifications in geometry of channels for thermo-hydraulic performance enhancement and aims to determine the best channel configuration with optimal parameters. It explores various designs and their influencing parameters, as well as presents conclusions and potential recommendations for future research.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Hasan Kücük
Summary: Channels with small hydraulic diameters improve the overall heat transfer coefficient and compactness of shell and tube heat exchangers. This study experimentally investigated the effects of mini-channels on the heat transfer coefficient and pressure drop performance. The results showed that mini-channels significantly increased the heat transfer coefficient and had a higher pressure drop.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Cong Li, Jiali Wang, Chenhui Wang, Yanke Jin, Yina Yao, Rui Yang
Summary: This study investigates the impact of NaCl water droplets with various concentrations on a heated surface. The results show that the impact patterns can be categorized into different types, and models are established to predict the spreading behavior of droplets with different concentrations. Additionally, high concentration droplets exhibit more violent boiling and have lower residual energy and rebound time.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
C. Barrera, V. Castro, F. Escudero, J. J. Cruz, I. Verdugo, J. Yon, A. Fuentes
Summary: This study focuses on the characterization of soot maturity and sooting propensity of anisole fuel in a controlled laminar coflow diffusion flame. The results show that the spatial distribution of soot volume fraction is enhanced near the flame centerline, while soot production is promoted near the flame wings. The temperature increase also affects the maturity of soot particles.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Roman W. Morse, Jason Chan, Tiago A. Moreira, Jared J. Valois, Evan T. Hurlburt, Jean-Marie Le Corre, Arganthael Berson, Kristofer M. Dressler, Gregory F. Nellis
Summary: This study investigates the dryout of liquid film and the role of disturbance wave frequency. Experimental results indicate that the heat transfer coefficient associated with optimal boiling conditions is maximized when the surface is dry 5% of the time, independent of pulse amplitude and frequency. Liquid-film measurements, dryout statistics, and direct observation suggest that disturbance-wave frequency can be manipulated by density-wave oscillations in the flow field.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
E. J. Vega, J. M. Montanero
Summary: In this study, we experimentally investigated the bursting of a bubble covered with a surfactant. We found that the bubble bursting time is longer compared to a surfactant-free bubble due to interfacial elasticity. Furthermore, the Marangoni stress drives liquid flow that allows the jet to escape from the end-pinching mechanism within a certain surfactant concentration range.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Guofu Sun, Yi Zhan, Tomio Okawa, Mitsuhiro Aoyagi, Akihiro Uchibori, Yasushi Okano
Summary: Experiments were conducted on liquid jets ejected from oval nozzles to investigate the effects of nozzle orifice shape on jet behavior. The study found that the liquid jet exhibited different characteristics at different liquid flow rates. Correlations were established to predict the liquid jet state and characteristics of the secondary droplets produced during jet impact onto a solid surface. This research extended the available knowledge on liquid jet behavior.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Jeonghoon Lee, Laurent Zimmer, Takeshi Saito, Shinji Nakaya, Mitsuhiro Tsue
Summary: This study investigates the effects of spatial resolution on DMD amplitudes and spatial mode strengths, and proposes scaling factors to correct for the resolution differences. The results show that the proposed scaling factors successfully normalize the amplitudes and spatial modes, allowing for quantitative comparison of data obtained with different spatial resolutions. This study is significant for analyzing spatiotemporal data in various fields.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Yanli Zhao, Shibing Kuang, Xiaoliang Zhang, Mingjun Xu
Summary: This study experimentally investigates the dynamic process of water droplet impacting different wood surfaces and analyzes and discusses the impacting phenomena, phenomena distribution, droplet spreading dynamics, and maximum spread factor. The results show that the impacting process can be distinguished by Weber numbers and Reynolds numbers, and can be predicted by mathematical expressions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Aakhash Sundaresan, Atul Srivastava, Callum Atkinson
Summary: This study presents the first-ever application of an advanced methodology, combining two-color laser-induced phosphorescence and particle image velocimetry, to investigate the heat transfer mechanisms on the surface of a cylinder placed inside a confined square duct. The technique allows for simultaneous measurement of velocity and temperature fields, reducing the complexity and costs associated with separately measuring temperature distributions. Experimental observations show that increasing the mass flow rate enhances heat removal from the cylinder surface, and increasing the cylinder heat input enhances heat transfer in the rear portion of the cylinder.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Harish K. Patel, Sukhjeet Arora, Rutuja Chavan, Bimlesh Kumar
Summary: This study experimentally analyzed the multiscale statistical assessment of scour depth surrounding spur dikes with downward seepage. The research found that seepage affects the morphological behavior and hydrodynamic characteristics of the channel bed, leading to changes in scour formation. The rate of scour depth changes initially increases with higher seepage velocity but eventually becomes constant over time.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Justas Sereika, Paulius Vilkinis, Gediminas Skarbalius, Algis Dziugys, Nerijus Pedisius
Summary: This study experimentally investigated the pulsatile flow structure based on a transitional-type cavity. It was found that the pulsation amplitude has a more significant effect on the dynamics of recirculation zone than the pulsation frequency. Pulsatile flow can reduce the size of the recirculation zone.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Merav Arogeti, Eran Sher, Tali Bar-Kohany
Summary: This study provides a detailed exploration of the events that occur when a droplet hits a dry solid surface of various small sizes, with a focus on the deposition, receding breakup, and prompt splash phases. By utilizing non-dimensional analysis and graphical representation, the boundaries between different events are defined, and criteria for differentiation based on target-to-drop ratio, Reynolds, and Webber numbers are presented.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Tianxiong Li, Fei Wen, Yingchun Wu, Botong Wen, Lei Wang, Jinxin Guo, Xuecheng Wu
Summary: This study investigates the structure of the flow field induced by a strut in a scramjet and its influence on flame stabilization. Experimental and numerical analyses reveal that the flow field exhibits features beneficial for flame stabilization, but the asymmetry of the flow poses a challenge to flame establishment.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Syed Ehtisham Gillani, Yasir M. Al-Abdeli
Summary: This study investigates the asymmetry in bluff-body stabilised annular jets and finds that swirl can significantly mitigate the asymmetry and restore the symmetry of the jets. Moreover, increasing the Reynolds number and the swirl intensity can both decrease the asymmetry of the jets.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Utsav Bhardwaj, Rabindra Kumar, Shyama Prasad Das
Summary: This study presents an experimental investigation on flooding phenomenon in a pulsating heat pipe (PHP) unit cell, and analyzes the impact of flooding on the performance of PHP. The study recognizes three different flooding mechanisms and finds that currently accepted correlations for predicting flooding velocity are inaccurate. The study emphasizes the need for further research on flooding in PHPs.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Yunpeng Xue, Yongling Zhao, Shuo-Jun Mei, Yuan Chao, Jan Carmeliet
Summary: This study investigates the impact of building morphology on local climate, air quality, and urban microclimate. The researchers conducted an experimental investigation in a large-scale water tunnel, analyzing heat and flow fields using Laser-induced Fluorescence (LIF) and Particle Image Velocimetry (PIV). The findings show that factors such as canyon configuration, buoyant force, and approaching flow magnitude significantly influence fluid flow in street canyons, and the morphology of the street canyon dominates ventilation rate and heat flux. For example, changing the aspect ratio of a street canyon can lead to a significant change in air ventilation rate, ranging from 0.02 to 1.5 under the same flow conditions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)