bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of the Heat Transfer Performance of Low Concentration Surfactant Aided Pool Boiling With Electric Field
Authors: Cheng Chung Ki , Ni Song , Lau Kwun Ting , Khan Shahid Ali , Zhao Jiyun 
Published: September 2024

Abstract
Nucleate boiling has been known as one of the efficient methods for transferring large amounts of heat. Such a method has a broad spectrum of applications, for instance, thermal management of power generation and cooling of high-intensity heat flux devices. In the current work, the effect of applying electric field to the bulk solution was experimentally investigated with the presence of surfactants. A number of studies have shown how the electric fields may enhance heat transfer performance with the aid of surfactants. This work focuses on the coupling behavior of the low-concentration surfactant-aided pool boiling with the presence of electric fields and how it will affect the heat transfer performance. On the other hand, two types of surfactants with different electric charges have been chosen in this work. Namely a cationic surfactant, Dodecyl-trimethylammonium bromide (DTAB), and an anionic surfactant, Sodium Dodecyl Sulfate (SDS). The coupling behavior between the surfactant and the electric field is also shown. When only surfactants are present, the critical heat flux (CHF)is reduced by 27% and 25% for 1 mM SDS and 1 mM DTAB, respectively. And the maximum heat transfer coefficient (HTC) is enhanced by 44% and 169% for 1 mM SDS and 1 mM DTAB, respectively. When an electric field is applied to both surfactants at the same concentration, the CHF doesn’t have significant enhancement. Meanwhile, HTC is enhanced by 9.2% and 4% for SDS and DTAB, respectively.
An Experimental Investigation on Characteristics of Liquid Film Thickness of Gas-Liquid Taylor Flow in Rectangular Microchannel
Authors: Fu Dengwei , Hong Sihui 
Published: September 2024

Abstract
Liquid film thickness is one of the most important parameters for understanding two-phase flow in micro-scales. In the present work, experiments were conducted to investigate the variation of liquid film thickness in square tubes with hydraulic diameter Dh = 0.3, 0.5, 0.7, 1.0 mm, and rectangular tubes with a depth of 0.5mm and widths of 0.3, 0.5, 0.7, 1.0 mm. The liquid film thicknesses were measured using a laser focus displacement meter, and visualization images were captured by a high-speed camera. The experiments revealed that at low capillary numbers, surface tension determines the lower limit of the liquid film thickness in either square or rectangular microchannels. At medium capillary numbers, viscous force becomes prominent, and increase the thickness of the liquid film. At high capillary numbers, inertia forces determine the upper limit of the liquid film thickness. The non-uniform distribution of the liquid film thickness in rectangular channels intensifies with the increase in the aspect ratio of channel width to depth.
Molecular Dynamics Investigation of Wettability Transition of Copper and Design of a Durable Superwetting Structure
Authors: Huang Zhigang , Long Jiangyou , Luo Kai 
Published: September 2024

Abstract
Superwettability of clean metal surfaces cannot endure for extended periods in natural atmospheric conditions. Among the various factors that may contribute to the wettability transition of metals, we believe that the adsorption of organics plays a significant role. In this study, we investigate the impact and extent of adsorbed organics on the wettability of copper through Molecular Dynamics simulations of carboxyl acids adsorbing on its surface. We examine the change in surface energy with increasing coverage ratio of organics. The result reveals that a clean metal surface exhibits high surface energy, corresponding to a superwettability nature. However, as the coverage ratio of organics increases, the wettability decreases and changes to hydrophobic at a coverage ratio of about 0.5–0.6. The simulations indicate that this wettability transition is primarily caused by the water-repelling effect originating from the carbon backbone of the organic molecules. Shorter molecules exhibit lower water-repelling strength and form weaker adsorption structures, leading to a less pronounced wettability transition. To achieve durable superwetting, we propose a porous structure composed of sufficiently small voids that allow water molecules to enter while preventing the penetration of organic molecules. Experimental results demonstrate that this structure enables superwetting to persist for several months in urban atmospheric conditions. These superwetting surfaces hold significant potential for various applications across different domains.
Multi-Fidelity Design of Flow Boiling Heat Transfer Processes in Microchannels
Authors: Yuan Yi , Chen Li , Zhang Chuangde , Tao Wen-Quan 
Published: September 2024

Abstract
Topology optimization (TO) is a powerful method with high degree of design freedom. However, TO is difficult to perform effectively for complex problems represented by flow boiling. This paper builds a framework that avoids time-consuming two-phase simulation and generates structures with high flow boiling heat transfer performance. In this study, the necessary numerical methods are modeled and integrated into a multi-fidelity workflow, including low-fidelity TO and high-fidelity evaluation. Based on these models, the flow boiling heat transfer performance of low-fidelity TO structures is parametrically investigated under different heat flux, subcooling and inlet velocity. The results show that the high temperature at corners of the heat sink leads to accumulation of vapor that severely degrades the heat transfer performance. Based on this result, the high temperature at corners in the low-fidelity temperature field is considered to be a feature with poor high-fidelity performance. This feature is verified by comparing performance of three TO structures, and interestingly, the results show that structures with high low-fidelity performance do not lead to high high-fidelity performance. Then this feature is quantified as an index. By comparing this index under the low-fidelity condition, the performance under the high-fidelity condition can be judged. Twelve TO structures are evaluated by this index, and the results show that there is a significant positive correlation between the index and flow boiling heat transfer performance. The new index can characterize the high-fidelity flow boiling performance of low-fidelity TO structures.
Tunable Electro-Optical Switch in Infrared Communication Band Through Coupling Surface Plasmon Polaritons and Magnetic Polaritons
Authors: Gong Yiquan , Guo Yanming , Chen Shuni , Pan Qinghui , Shuai Yong 
Published: September 2024

Abstract
Optical switch is an essential component in optical communication, which essentially modulates the transmittance in the radiation characteristics of objects. Micro-nano optical switches have the advantage of shorter switching time compared to traditional mechanical optical switches, but their extinction ratio (ER) is lower than that of mechanical optical switches, which seriously restricts the development of micro-nano optical switch. In this article, we achieved an ER of up to 42.6 dB in the infrared communication band (6000cm−1–8000cm−1) based on the electrochromic material lithium titanate (LTO) using the coupling of surface plasmon polariton (SPP) and magnetic polaritons (MP). When the optical switch is in “on” mode, the transmittance can reach 0.967 at wavenumber 6400cm−1, however the transmittance is suppressed to 5.27 × 10−5 at wavenumber 6400cm−1 when the optical switch is in “off” mode. The oblique incidence calculation shows that our optical switch can still maintain good performance under high angle incidence. Our research may contribute to the development of infrared optical communication.
Experimental and Numerical Investigation of the Combustion of a Polymer Infused Fuel Droplet
Authors: Spandan Rimjhim , Bohrey Aayushi , Deka Mandeep , Xia Jun , Ravikrishna R. V. , Panda Pratikash 
Published: September 2024

Abstract
Gelled propellants are a propulsion system fuel whose rheological properties are modified by the addition of a gellant, usually a polymeric or colloidal substance, leading to the liquid fuel having a very viscous liquid, or gel-like consistency. Gelled propellants offer many advantages over conventional liquid pro-pellants such as greater control over the energy density, as well as, ease of transportation and storage (like solid propellants). In this work, we study the combustion dynamics of a single polymer-infused fuel droplet, using both experiments and numerical simulation. The droplet is suspended over a flat flame and different stages of combustion are captured. Using the observations from the experimental data, we formulate a theoretical model for the internal dynamics of the polymer-infused fuel droplet till the end of the initial stage. The resulting partial differential equation is solved numerically and is compared against the experimental data.
Power-Generating Smart Glass With Adjustable Spectral Transmission
Authors: Chen Shuni , Guo Yanming , Gong Yiquan , Shen Chao , Shuai Yong 
Published: September 2024

Abstract
Solar energy is usually difficult to utilize efficiently once it reaches the building through the window glass. Smart glass regulates and utilizes the solar energy spectrum through its material and structural properties, greatly improving the utilization of solar energy. This article offers a multilayers structure smart glass with a metal-particle-doped photovoltaic material layer, which can reach selective transmission of human eye spectral response and relatively high photoelectric conversion efficiency. Four typical doping combinations were calculated and optimized by a multi-island genetic algorithm to obtain structural parameters that give better performance. Under the optimized weighting of 1:1, the average transmittance in the spectral response range of the eye can reach more than 0.75, while the photovoltaic conversion efficiency is between 0.1 and 0.2 or greater than 0.2. The work in this paper provides a reference for the design of smart glass structures to improve the energy efficiency of buildings.
Experimental and Numerical Study on Phase Change Heat Transfer of Ternary Non-Azeotropic Mixture
Authors: Zhang Bo , Tian Peipei , Wang Zhiguo , Sun Zhiwei , Cui Peilin , Liu Zhenyu 
Published: September 2024

Abstract
In this work, one water/1,2-propylene glycol/glycerol ternary solution was constructed to investigate the influences of heating power and solution components on its heat and mass transfer in the phase transition process. The experiment studied the effects of power ranging from 30 W to 70 W, water volume fraction ranging from 30% to 50%, and 1,2-PG volume fraction changing from 5% to 15% on various parameters. Additionally, one corresponding theoretical model was proposed to provide a guidance for the utilization of ternary non-azeotropic mixtures as working fluid. The influential pattern of power on factors, such as the phase change rate and system temperature, has been obtained. The analysis indicates that increasing the volume fraction of low-boiling-point components leads to a decrease in the phase change rate of high-boiling-point components. Furthermore, while increasing the volume fraction of high-boiling-point components elevates their own phase change rate, it does not significantly affect the phase change rate of low-boiling-point components.
Flow Boiling in Microchannels Based Heat Sinks Combined With Micro-Nano Modified Surfaces
Authors: Perez Mariana , Pontes Pedro , Moreira António L. N. , Moita Ana S. 
Published: September 2024

Abstract
The present paper addresses an experimental study on the development of a microchannel based heat sink to cool photovoltaic panels, mainly focusing on the flow instabilities and on the potential effect of surface microstructuring in heat transfer enhancement and in controlling two-phase flow instabilities in a single microchannel. The results include pressure drop and heat flux maps, obtained combining pressure sensors with high-speed imaging and time resolved thermography. After identifying the flow boiling regimes, the observed phenomena are qualitatively and quantitatively described. Results show that surface cavities per se do not promote active nucleation sites. However, a regular pattern of microcavities enhances heat transfer and promotes the occurrence of a more stable flow in the microchannels.
Molecular Dynamic Study on the Nucleation Characteristics of Carbon Dioxide During Pressure Drop
Authors: Wang Xiang , Liu Fang 
Published: September 2024

Abstract
Heterogeneous nucleation is one of the most effective mechanism for initiating phase transformation. Impurities serve as a catalyst in the formation of a new thermodynamic phase by lowering the activation energy necessary for a phase transition and promoting nucleation. This study utilizes molecular dynamics (MD) simulation to examine the heterogeneous nucleation process of CO2 refrigerant during pressure drop phase transformation in the motive flow section of the CO2 ejector. The study results indicate that elevated target pressures in CO2 systems can reduce the minimum Gibbs free energy required for the formation of CO2 clusters of varying sizes, thereby promoting refrigerant nucleation. At a target pressure of 2.70 MPa, the nucleation rate exhibits an increase of 0.34 × 1032 m−2s−1 at 2.86 MPa, 1.11 × 1032 m−2s−1 at 3.14 MPa, and 2.4 × 1032 m−2s−1 at 3.38 MPa. Furthermore, the introduction of PAG lubricating oil into the system decreases the minimum Gibbs free energy necessary for the formation of CO2 clusters of different sizes, while simultaneously enhancing intermolecular forces and facilitating the molecular nucleation of CO2 refrigerants. In comparison to an oil-free CO2 system operating at a target pressure of 3.14 MPa, elevating the mass fraction of PAG oil results in an increased nucleation rate of N3 clusters by 0.43 × 1032 m−2s−1 (2% of PAG), 0.37 × 1032 m−2s−1 (1 % of PAG), and 0.2 × 1032 m−2s−1 (3% of PAG) respectively. This acceleration contributes to the nucleation process of CO2 refrigerants. Nevertheless, it simultaneously leads to a decrease in the mass diffusion coefficient of CO2 molecules within the system. It is worth noting, however, that pressure continues to be the predominant factor influencing CO2 refrigerant nucleation.
Effect of Temperature and Water Content on Thermal Conductivity in Ordered and Amorphous Proton Exchange Membranes: A Molecular Dynamics Study
Authors: Ren Ke , Liu Xinjian , Rao Zhonghao 
Published: September 2024

Abstract
Proton exchange membrane (PEM) is the key component of proton exchange membrane fuel cell. The thermal conductivity of the PEM determines the efficiency of heat dissipation through various cooling methods, directly impacting the fuel cell’s performance. Imparting order to Nafion molecules is a potentially effective method to significantly improve the thermal conductivity of PEM. However, the intrinsic mechanism of this effect as well as the regulatory mechanism is still unclear.
In order to investigate the regulatory mechanism of temperature and water content on the thermal transport mechanism of PEM and to compare the thermal transport properties of ordered and amorphous membranes, this study used reverse non-equilibrium molecular dynamics simulations (RNEMD) to investigate the thermal conductivity of ordered and amorphous membranes at 300 K and 350 K under different water content conditions. The simulation results show that it is effective to improve the thermal conductivity of PEM by imparting order to Nafion molecules, and the thermal conductivity of the ordered membrane is approximately twice that of the amorphous membrane. Furthermore, it was also found that increasing temperature and hydration level can enhance the thermal conductivity of both ordered and amorphous membranes.
Numerical Study of Pool Boiling Heat Transfer on a Heated Cylinder by Lattice Boltzmann Method
Authors: Li Xi , Li Huixiong , Wu Xiaoyi 
Published: September 2024

Abstract
Pool boiling is widely utilized in various industrial applications due to the high heat transfer performance. In the numerical simulations, the pseudopotential LB model is capable of simulating the entire boiling processes, including the bubble nucleation. Under the effect of gravity and surface tension, the distribution of phase fields on the circle surface is nonuniform. The bubble dynamics, and the heat transfer characteristics during the pool boiling processes on the circular surfaces would be unique compared to those on the heated plate. In this study, the bubble dynamics and heat transfer during pool boiling processes at a heated cylinder with different wall superheats were simulated using the MRT pseudopotential model coupled with phase-change model. The bubble dynamics and heat transfer with various orientations of the heated cylinder during pool boiling processes were investigated. In addition, the influence of surface tension and saturated temperature on pool boiling heat transfer was studied. It was found that increasing surface tension could enhance the heat transfer performance for the nucleate boiling with high wall superheat, and CHF is proportional to 0.254 power of surface tension. When Ja is low, the saturated temperature has little influence on heat transfer performance. However, in the nucleate boiling regime with large Ja, heat transfer performance as well as CHF decrease with the increasing saturated temperature.
Experimental Study of Single-Bubble Dynamics and Microlayer Characteristics in Pool Boiling on Different Wettability Surfaces
Authors: Zhao Pengfei , Jamali Jawed Ahmed , Zhu Zihou , He Ying 
Published: September 2024

Abstract
Nucleate boiling is the most effective mode of heat transfer in pool boiling, exploring the morphological changes of bubbles under different conditions is of great help in improving the heat transfer mechanism of nucleate boiling. This study obtains hydrophilic, smooth, and hydrophobic surfaces with contact angles of 40.3°, 69.3°, and 90° by grinding, oxidizing, and corroding copper surface with 276 um machined cavity, respectively, and then build a boiling experimental bench that can stably generate single-bubble, and the PIV technique is used to carry out single-bubble experiments on heat transfer surfaces with different wettability to observe the morphology of single-bubble and the trend of their surrounding fluids. The experimental results show that as the hydrophobicity of the heat transfer surface increases, the volume, the base circle radius, etc., and the thickness of the microlayer beneath the bubble will increase, the heat carried away by the single bubble will be more, and the replenishment rate of liquid due to the evaporation of microlayer at the moment of bubble detachment will also be faster, which will lead to the formation of a new bubble and help it detach from the surface and enhance the heat transfer.
A New Model for Capillary Imbibition With Asymmetric Wettability Walls
Authors: Zhu Chenyue , Yan Yuying , Alston Mark 
Published: September 2024

Abstract
The imbibition dynamics is controlled by energy dissipation mechanisms and influenced by asymmetric wettability in a nanochannel. This work proposes a new theoretical model for capillary imbibition while the imbibition dynamics are described by a combined model of the Lucas-Washburn equation and the Cox-Voinov law considering velocity-dependent contact angles. Most of previous studies on capillary imbibition have focused on channels with walls of homogeneous and symmetric wettability. The imbibition dynamics in channels with asymmetric wettability is not well understood. Meanwhile, the energy dissipation mechanism in capillary imbibition also remains to be elucidated. Here, theoretical analysis and molecular dynamics simulations are combined to investigate the energy dissipation mechanism of capillary imbibition in nanochannels. The model may have a wide range of applications, for example, in development of novel materials and microfluidic chips, control of transport of water molecules and ions in cement-based materials, and regulating the spontaneous imbibition of hydraulicfracturing fluids in shale reservoirs.
Two-Dimensional Numerical Simulation on Bubble Growth in Microchannel Boiling Flow
Authors: Gao Hongtao , Zhai Jianrong , Niu Dong , Liu Huaqiang , Yan Yuying 
Published: September 2024

Abstract
In this paper, a gradient constraint algorithm is proposed to study the boiling flow mechanism of lithium bromide solution in microchannels. The numerical results obtained using this method demonstrate good agreement with the experimental results. In this study, the growing process of a single refrigerant bubble and the merging of two lateral bubbles in a two-dimensional microchannel were examined. The impact of various factors, such as wall superheat, Reynolds number, surface tension, and double bubble merging on wall heat transfer were investigated. The results show that increases in both wall superheat and inflow Reynolds number improve the heat flux at the heated wall. The effects of changes in surface tension on the heat flux at the heated wall surface differ in the pre- and post-bubble growth periods. The algorithm is still able to keep the interface clear and sharp during multi-bubble merging, and it is found that multi-bubble merging also improves the heat flux at the heated wall.
Experimental Study on the Heat Transfer Performance of a Cesium Oscillating Heat Pipe
Authors: Feng Yanmin , Ji Yulong , Liu Zhonghao , Wu Mengke , Liu Huaqiang 
Published: September 2024

Abstract
Due to the active chemical properties, explosive risk and high price of cesium metal, research on high-temperature oscillating heat pipe (HOHP) with cesium as a working fluid has not been reported. In view of the application of HOHPs and the need for systematic academic research, a high-temperature heat pipe with cesium as the working fluid was fabricated in this paper and the filling ratio was 50 %. The start-up and operating characteristics of the Cs-HOHP at an operating temperature of 80°C were investigated experimentally, and the effects of different inclination angles (90°, 60°, 30°, 0°) and different input powers on the heat transfer performance were analysed. The experimental results show that: (1) when the inclination angle was 90°, 60°, and 30°, the start-up temperature of Cs-HOHP was lower compared with that of HOHP with sodium, potassium, and sodium-potassium alloys as the working fluids, whereas the start-up of Cs-HOHP could not be started or had a poor start-up performance when the inclination angle was 0°. (2) At an inclination angle of 60°–90°, the heat transfer performance of Cs-HOHP was insensitive to the inclination angle, and when the inclination angle was 30°, the thermal resistance increased significantly, especially when the input power was low. (3) At an inclination angle of 90° and an input power of 3373 W, the thermal resistance was the smallest, with a value of 0.17 °C/W.