Article
Thermodynamics
M. Esawy, Amir Hossein Nikoo, M. Reza Malayeri
Summary: The superiority of enhanced boiling on structured heat transfer surfaces is due to excessive bubble generation and behavior as well as the latent heat of evaporation. While these factors lead to higher heat transfer coefficients, they also accelerate fouling for aqueous solutions with inverse solubility. The study finds that Turbo-B tubes demonstrate better anti-fouling behavior compared to plain tubes and low finned tubes.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Vladimir Serdyukov, Sergey Starinskiy, Ivan Malakhov, Alexey Safonov, Anton Surtaev
Summary: Surface modification using laser texturing shows great potential in enhancing heat transfer and increasing critical heat fluxes during pool boiling on metal surfaces. The experiments demonstrate that the laser-textured surface significantly improves heat transfer compared to untreated and polished surfaces. High-speed video recording analysis reveals that laser treatment leads to increased nucleation site density and frequency, as well as reduced bubble departure diameter.
APPLIED THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Siddharth Iyer, Apurv Kumar, Joe Coventry, Wojciech Lipinski
Summary: A mechanistic model is proposed to study the growth of a bubble in pool boiling, considering the change in shape of the bubble as it grows. The model consists of three sub-models for heat transfer, forces acting on the bubble, and the change in shape. The model is validated against experiments and simulations, showing good agreement in the bubble departure time, wall temperature, bubble shape, and microlayer profile.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Sandipan Deb, Mantu Das, Dipak Chandra Das, Sagnik Pal, Ajoy Kumar Das, Ranjan Das
Summary: The experimental study investigated the impact of surface modification on heat transfer phenomena under nucleate pool boiling configuration, showing that modification significantly enhances heat transfer coefficient. The findings were in agreement with existing literature and proposed a mathematical model to predict optimum heat transfer coefficients.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Mechanics
S. Mukherjee, P. C. Mishra, P. Chaudhuri, N. Ali, S. A. Ebrahim
Summary: An experimental study was conducted to investigate the thermal performance of water/titania nanofluid under nucleate pool boiling. The results showed an increase in heat transfer coefficient as heat flux and weight concentration increased, but the enhancement decreased at higher weight concentrations. New correlations with high prediction accuracies were proposed to relate wall superheat temperature with heat flux and heat transfer coefficient.
Article
Thermodynamics
Chao Dang, Yi Ding, Zhuoling Qi, Liaofei Yin, Li Jia
Summary: This study experimentally investigated the saturated nucleate pool boiling heat transfer characteristics of copper foam covered surfaces and plain copper surfaces. The results showed that copper foam coating significantly improved the boiling heat transfer coefficient, while increased roughness of plain copper surfaces had minimal effect. Copper foam covered surfaces triggered nucleation at lower wall superheats, depending on the relationship between the size of the copper foam pores and active nucleation sites.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Jielin Luo, Hongxing Yang
Summary: This study experimentally investigated the nucleate pool boiling enhancement of steroidal bile salts on a copper surface. Four types of bile salts were found effective in improving the heat transfer coefficient (HTC) in aqueous form, with SDC showing the most significant effect. The deposited surface of STGC exhibited simultaneous improvement in critical heat flux (CHF) and HTC with long-term repeatability. The findings of this study can contribute to the development of bio-friendly surfactant-aided energy conversion applications and new-generation green surfactant materials.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Jingwen Li, Longsheng Lin, Shuhao Li, Zhen Yang, Yuanyuan Duan
Summary: This study conducted experimental research on the pool boiling heat transfer characteristics of R32, R1234yf, and their mixtures, obtaining the corresponding heat transfer performance and bubble images. The results showed that the addition of R32 can effectively improve the heat transfer performance of R1234yf and weaken bubble coalescence. The deterioration of heat transfer in mixtures is not only related to vapor-liquid phase equilibrium but also to non-linearly varying physical properties.
APPLIED THERMAL ENGINEERING
(2022)
Article
Mechanics
Uzair Sajjad, Imtiyaz Hussain, Chi-Chuan Wang
Summary: A high-fidelity deep learning approach has been developed to accurately predict the boiling heat transfer performance of roughened surfaces, taking into account surface characteristics, testing conditions, and liquid thermophysical properties. The model identifies heat flux, surface inclination, surface roughness, among others, as prime factors affecting the nucleate boiling heat transfer coefficient. The final selected model achieved an R-squared of 0.994 and MAE of 0.65, showing high accuracy in estimating the investigated parameter.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Thermodynamics
S. Kalita, Pulak Sen, Dipak Sen, Sudev Das, Ajoy Kumar Das, Bidyut Baran Saha
Summary: This paper investigates pool boiling heat transfer experiments conducted on a microstructured copper surface prepared through chemical etching. Results show significant enhancement in boiling heat transfer coefficient (BHTC) compared to bare copper surface, although the critical heat flux (CHF) is lower. After four repeated tests, the surface's heat transfer coefficient shows a deviation of 4.8%.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2021)
Review
Thermodynamics
Munonyedi Egbo, Mohammad Borumand, Yahya Nasersharifi, Gisuk Hwang
Summary: This paper reviews the effects of surface orientation on pool boiling, including experimental and theoretical approaches to understand the changes in heat transfer coefficient and critical heat flux. The results show that tailored two-phase flow can enhance the performance of pool boiling. This review also discusses future research directions for engineered surfaces under different surface orientations.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Hantao Jiang, Nian Xu, Dongdong Wang, Xinyu Yu, Huaqiang Chu
Summary: The study demonstrates that reducing the spacing between pillars improves boiling heat transfer performance, while reducing the diameter of the pillars enhances heat transfer. More nucleation sites on the wall promote quicker bubble merging, enhanced evaporation, and heat transfer.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Atul Ranjan, Israr Ahmad, Rinku Kumar Gouda, Manabendra Pathak, Mohd Kaleem Khan
Summary: This study reports the creation of Cu(OH)2 nanoneedles on a copper surface using an anodization process, which can enhance critical heat flux (CHF) limit in pool boiling applications by improving surface wettability and wickability. Results show that the anodized surface requires higher wall superheat for nucleation and exhibits a higher CHF value compared to the plain surface.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
L. Surya Narayan, Atul Srivastava
Summary: Experiments were conducted to understand the relationship between dynamics of superheat layer, microlayer evaporation, and bubble growth process during single bubble formation under saturated pool boiling regime. The results showed that the heat flux dissipated in the microlayer region is high during the initial stages of bubble growth, leading to a large temperature drop in that region. As the bubble growth process progresses, the depletion rate of the inner core region of microlayer decreases while the evaporation rate of its peripheral region increases.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Mechanical
Dong Il Shim, Wei-Ting Hsu, Maroosol Yun, Dongwhi Lee, Beom Seok Kim, Hyung Hee Cho
Summary: Surface manipulations have been used to enhance boiling performance by improving the heat transfer coefficient and critical heat flux. In this study, artificially patterned super-biphilic (SBPI) surfaces were utilized to overcome the limitation of liquid supply in hydrophobic regions and enhance boiling performance. The results highlight the importance of considering both wettability and bubble behaviors in designing structured surfaces for boiling.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Engineering, Environmental
Chan Seok Jeong, Chi Young Lee
Summary: The study indicates that the twin-fluid nozzle outperforms the single-fluid nozzle in fire extinguishing performance, being able to extinguish fires faster and more effectively, while using less water. Additionally, the airflow of the twin-fluid nozzle is identified as a critical factor affecting its fire suppression capabilities.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2021)
Article
Thermodynamics
Ji Hyun Yang, Chi Young Lee
Summary: In this experimental study, the interactions between impacting droplets and different liquid surfaces were investigated, leading to the proposal of new correlations for regime transitions based on a dimensionless parameter, which showed good predictions for both present and previous experimental data.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2022)
Article
Instruments & Instrumentation
Justin Neubauer, Zakai J. Olsen, Zachary Frank, Taeseon Hwang, Kwang J. Kim
Summary: This study investigates the sensing properties of polyvinyl chloride (PVC) gels as soft electroactive polymers (EAPs) for soft robotic applications. It demonstrates the high sensitivity of PVC gels in mechanoelectrical transduction and proposes a theoretical framework for this process. The study also uncovers an interesting phenomenon and examines the hysteresis effect. Overall, the research showcases the mechanoelectric ability of PVC gels and provides a foundation for further application development.
SMART MATERIALS AND STRUCTURES
(2022)
Article
Instruments & Instrumentation
Zakai J. Olsen, Kwang J. Kim
Summary: In this study, we investigated the magnitude of field gradients in the ionic polymer-metal composite (IPMC) under large applied voltages and their use for approximating measures of the fields inside the polymer. By using order-of-magnitude based arguments, we were able to accurately quantify the field measures and reconstruct the internal bending moments generated inside the actuator to develop a simplified kinematic model for the steady-state actuator response of the IPMC.
SMART MATERIALS AND STRUCTURES
(2022)
Article
Instruments & Instrumentation
Zakai J. Olsen, Kwang J. Kim
Summary: This study conducts a comprehensive dimensional analysis of IPMC transduction phenomena and builds nonlinear regression models for the transduction response. The validity of the multiphysics model is confirmed with experimental data.
SMART MATERIALS AND STRUCTURES
(2022)
Article
Instruments & Instrumentation
Zachary Frank, Mohammed Al-Rubaiai, Xiaobo Tan, Kwang J. Kim
Summary: The conductivity and dielectric properties of PVC gel actuators are crucial for their electromechanical transduction applications. This study investigates the frequency-dependent properties of PVC gel actuators and reveals the importance of the conductive properties in addition to the dielectric properties. It also proposes a new method for characterizing the actuation performance of PVC gels.
SMART MATERIALS AND STRUCTURES
(2022)
Article
Nuclear Science & Technology
Gyeong Seop Hwang, Wang Kee In, Chi Young Lee
Summary: Quenching experiments were conducted on vertical Inconel and Zircaloy tubes in internal water flow to investigate the effects of tube wall temperature, liquid subcooling, and liquid injection velocity on quench temperature, reaching time, and quench front velocity. The experimental results showed that these factors have a significant impact on the quenching process.
ANNALS OF NUCLEAR ENERGY
(2022)
Article
Physics, Multidisciplinary
Alexandrea Washington, Zakai Olsen, Ji Su, Kwang J. Kim
Summary: The focus of this study is to understand the physical phenomenon of the liquid-based electroactive polymer (EAP) actuator known as the Hydraulically Amplified Self-Healing Electrostatic (HASEL) actuator. A two-dimensional model was developed to describe the actuation mechanism and provide data on film material deformation, dielectric liquid dynamics, and electrical conditions within the actuator body. The model predicts fluid dynamic data and phenomena observed in experimentation that previous models did not capture. In summary, this model connects the electrical, mechanical, and fluid systems, providing detailed insight into the dynamics of the actuator system.
JOURNAL OF PHYSICS COMMUNICATIONS
(2022)
Article
Automation & Control Systems
Mohammed Al-Rubaiai, Xinda Qi, Zachary Frank, Ryohei Tsuruta, Umesh Gandhi, Kwang J. Kim, Xiaobo Tan
Summary: This article presents a data-driven approach to modeling the nonlinear dynamics of PVC gel actuators and proposes a control scheme based on the model. Experimental results demonstrate that the proposed control method significantly reduces tracking error.
IEEE-ASME TRANSACTIONS ON MECHATRONICS
(2022)
Article
Engineering, Chemical
Jae Geun Jo, Chi Young Lee
Summary: In this study, the effects of water mist spray characteristics on thermal radiation attenuation were experimentally investigated. The results showed that the water flow rate and droplet size had significant impact on thermal radiation attenuation.
PROCESS SAFETY PROGRESS
(2023)
Article
Instruments & Instrumentation
Justin Neubauer, H. Jeremy Cho, Kwang J. Kim
Summary: Polyvinyl chloride (PVC) gels are investigated for their mechanoelectrical transduction properties, while alternative polymer lattice structure, thermoplastic polyurethane (TPU), is also studied. This study provides further characterization of mechanoelectrical response for varying plasticizers and shows the potential for polymeric gel sensors.
SMART MATERIALS AND STRUCTURES
(2022)
Article
Polymer Science
Justin Neubauer, Kwang J. Kim
Summary: Recent research has discovered that PVC gels can exhibit mechanoelectrical transduction or sensing capabilities under compressive loading conditions. These gels have been found to undergo adsorption-like phenomena in response to different plasticizers. Additionally, a different polymer lattice structure, thermoplastic polyurethane, has shown similar sensing characteristics. This study explores the mechanical and electrical properties of these gel sensors and proposes a mathematical framework to explain the underlying mechanisms of mechanoelectrical transduction using COMSOL Multiphysics.
Article
Engineering, Mechanical
Alexandrea Washington, Ji Su, Kwang J. Kim
Summary: This study focuses on the design and theoretical and experimental investigation of the Hydraulically Amplified Self-Healing Electrostatic (HASEL) actuator in Soft Electrohydraulic (SEH or EH) actuators. By analyzing the electrode closure and conducting experimental testing, dimensional analysis techniques were used to determine the factors influencing the actuator's function. Eight dimensionless p groups were identified, with particular importance placed on those related to the characteristic length, fluid displacement, fluid velocity, fluid pressure, and dielectric constant. Relationships between output force, electrostatic contributions, and other parameters were determined. In conclusion, this type of analysis provides guidance for the development of high-performance HASEL actuators.
Article
Instruments & Instrumentation
Liya Napollion, Kwang J. Kim
Summary: Cracks in polymer composites pose a significant threat to the reliability and safety of polymer-based energy storage devices. Detecting cracks in composite polymers, such as IPMCs, is challenging and affects the performance of these materials.
SMART MATERIALS AND STRUCTURES
(2023)
Article
Engineering, Marine
Min Yeong Park, Chi Young Lee
Summary: The experimental study investigated the effect of fire source location on compartment fire phenomena with a single natural ceiling vent under different vent area and heat release rate conditions. Two cases of fire source location, namely the centre and side of the floor, were tested. The flow patterns and locations of smoke outflow and fresh air inflow differed between the two fire source locations. Empirical correlations were proposed to predict the smoke outflow areas. FSLC exhibited higher outflow velocity and estimated mass flow rate, as well as lower compartment temperatures compared to FSLS. The estimated mass flow rate of the outflow depended more on vent area than on heat release rate, and a previous correlation was found to be more suitable for predicting the mass flow rate of the outflow in FSLS than in FSLC.
SHIPS AND OFFSHORE STRUCTURES
(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)