Article
Thermodynamics
Rongji Xu, Xiaona Li, Taoming Lei, Qingping Wu, Ruixiang Wang
Summary: By introducing a gravity pulsating heat pipe (GPHP), the gravity effect of the working fluid (WF) can be enhanced to increase the heat transfer limit and solve the dry-up issue in a conventional pulsating heat pipe (PHP) under high heat input. Experimental investigation of the GPHP using HFE-750 0 as the WF under different heat inputs (30-230 W) revealed three heat transfer stages: low heat-input steady-state operation, transition, and high heat-input steady-state operation. The GPHP exhibited quick and stable heat transfer performance at low heat input, while in the transition stage, the accumulation of liquid WF and the formation of a stable vapor film hindered heat transfer. Under high heat input, the liquid WF returned to the evaporative section, resulting in stable heat transfer with increasing latent heat transfer.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Chemistry, Multidisciplinary
Seyed Masoud Hashemi, Ali Maleki, Mohammad Hossein Ahmadi
Summary: This study investigated the effect of different nanofluids on the performance of heat pipes, showing that nanofluids can improve heat transfer efficiency and reduce thermal resistance in pulsating heat pipes. The nanofluid with a concentration of 0.25 g/L exhibited the best performance, reducing the thermal resistance of the heat pipe by up to 48% at some fluxes.
JOURNAL OF NANOSTRUCTURE IN CHEMISTRY
(2022)
Article
Engineering, Chemical
Yi Zhou, Honghai Yang, Liwei Liu, Miao Zhang, Yaofeng Wang, Yukuan Zhang, Bo Zhou
Summary: Graphene Oxide (GO) nanofluid and filling ratio significantly impact the start-up performance of a water-based PHP. Adding 0.05 wt% GO nanoparticles at filling ratios of 20% and 50% can improve the start-up performance.
Article
Thermodynamics
Sizhuo Li, Haiyue Pei, Dongli Liu, Yunwei Shen, Xuan Tao, Zhihua Gan
Summary: An experimental setup for visualizing a nitrogen pulsating heat pipe (PHP) was developed. The PHP, fabricated using MEMS technology, has a hydraulic diameter of 667 μm and overall dimensions of 70 x 25 x 2 mm³. Six different filling ratios (FRs) ranging from 15% to 94% were measured using visualization images, with the PHP failing to start-up only at a 15% FR. Flow images of nitrogen PHPs were obtained for the first time, revealing four flow patterns. The variations of flow characteristics and fluid motion with heat loads and FRs were analyzed, and the fluid motion diagram and flow pattern proportion were extracted from the visualization results. The study found that large amplitude oscillating motion is rarely observed in the nitrogen PHP, and annular flow dominates in low and medium FR working conditions, suggesting that the one-dimensional slug flow model may have a limited application range for the flat-plate nitrogen PHP.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
A. Esmaeilzadeh, N. Nik-Ghazali, H. S. C. Metselaar, M. S. Naghavi, M. Azuddin, S. Iranmanesh
Summary: The experiments investigated the heat transfer characteristics in a sintered wick heat pipe using stable aqueous dispersions of 1-pyrene carboxylic acid (PCA)-functionalized graphene nanofluid. Results showed that thermal conductivity enhancement of nanofluids ranged from 21% to 40% with increasing concentration and temperature. The tilt angle of the heat pipe was found to have a substantial impact on the thermal properties, enhancing thermal performance by 79%. The use of nanofluids reduced heat pipe thermal resistance, with the most significant enhancement in overall heat transfer coefficient achieved at 0.06 mass% by 13.9 kW/K.m(2).
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Tingsen Chen, Shuli Liu, Yongliang Shen, Binxu Gao, Abdur Rehman Mazhar
Summary: A novel triangular pulsating heat pipe (TPHP) is proposed to solve the starting-up issue in a non-vertical direction. The study investigates the impact of TPHP model structure, heating temperature, and liquid filling ratio on heat transfer performance. The results reveal that a rationalized model structure reduces heat flow resistance by up to 38.04%, and the optimum liquid filling ratio is around 50%. This study is critical for expanding the application of single-loop PHP in buildings.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Engineering, Manufacturing
Ze Wu, Hang Bao, Youqiang Xing, Lei Liu
Summary: By designing a pulsating heat pipe self-cooling tool holder, the cutting temperature can be effectively reduced, wear can be reduced, and tool life can be extended. The experimental results prove the successful application of this new structure.
JOURNAL OF MANUFACTURING PROCESSES
(2022)
Article
Thermodynamics
Sizhuo Li, Zhicheng Bu, Tiegen Fang, Yubo Wang, Yunwei Shen, Xuan Tao, Bo Jiao, Zhihua Gan
Summary: A simultaneous thermal and visual experiment was conducted on a silicon-based flat-plate nitrogen pulsating heat pipe (PHP) for the first time. The start-up and quasi-steady state performances were analyzed, revealing two types of start-up processes and different degrees of thermal performance hysteresis phenomenon. The optimal thermal resistance was found to be lower in a lower filling ratio working condition, while a lower filling ratio resulted in a lower heat transfer limit. The latent heat transfer efficiency in the nitrogen PHP was inferred to be higher than that of the sensible heat transfer.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Energy & Fuels
Dongwei Zhang, Erhui Jiang, Zhuantao He, Chao Shen, Junjie Zhou
Summary: This study experimentally investigated the effect of ultrasonic on the heat transfer performance of a pulsating heat pipe (PHP), showing that ultrasonic can enhance heat transfer performance at certain heating powers while also causing deterioration at higher powers. Furthermore, the presence of more vapors confirms that ultrasonic cavitation effectively accelerates phase transition.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2021)
Article
Automation & Control Systems
Ze Wu, Hang Bao, Youqiang Xing, Lei Liu
Summary: The heat transfer performance of open pulsating heat pipe (PHP) was experimentally investigated and a prediction model based on experimental data and boosting integrating learning methods was proposed. The model can be used to select the most suitable open PHP.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2022)
Article
Engineering, Chemical
Haojie Zhang, Wenwen Guo, Long Guo, Guoneng Li, Youqu Zheng, Cong Dong, Haoxiang Zhou
Summary: The combination of nanofluids and pulsation was used to enhance heat transfer in a mini-channel corrugated tube, resulting in a maximum enhancement of 21.8% using distilled water as the medium. When 0.5% Al2O3/DW nanofluids were used as the heat transfer medium, Nunf/Nubf increased by 16% at Re = 1100. A pulsation wave generator was designed and the optimal St for each Re was determined, with lower Re values corresponding to higher optimum St values. The best heat transfer enhancement achieved in this study was 147% at St = 0.034, Re = 747, and A = 3.85.
Article
Thermodynamics
Ji Yeon Kim, Honghyun Cho, Sung Yong Jung
Summary: A cheaper and simpler micro-nano surface treatment method was applied to improve the performance and durability of water-Al PHPs by preventing the production of H-2 gas during Al-water reactions. The modified PHP exhibited flow regeneration and a 45.8% lower thermal resistance compared to the original surface PHP.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Caihang Liang, Xiong Yao, Miaowei Liu, Juan Du, Yuxiang Hong, Lei Zhao
Summary: The heat transfer performances of ultrapure water, n-butanol self-rewetting fluid, multi-walled carbon nanotubes nanofluid, and n-butanol self-rewetting MWCNTs nanofluid were investigated in a pulsating heat pipe. The experimental results showed that all functional working fluids had advantages in thermal transport performances compared to ultrapure water. The advantages of the n-butanol self-rewetting fluid gradually emerged with increasing thermal input, while the advantages of the nanofluid were demonstrated only at higher thermal inputs. The inclination angle and ambient temperature also had significant impacts on the thermal performances.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Energy & Fuels
Omid Mohammadi, Mohammad Behshad Shafii, Abbas Rezaee Shirin-Abadi, Reza Heydarian, Mohammad Hossein Ahmadi
Summary: Utilizing nano-encapsulated phase change material, reduced graphene oxide nanosheets, and their mixture as the working fluid in a pulsating heat pipe can effectively enhance its performance. Nanosheets have a greater impact on the performance of the pulsating heat pipe compared to nano-encapsulated phase change material. Using either nano-encapsulated phase change material or nanosheets alone can improve the performance of the PHP, with nanosheets demonstrating better performance due to their higher thermal conductivity and better mixing with the fluid containing them than pure water.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2021)
Article
Thermodynamics
Mojgan Alishiri, Ali Akbari, Mohammad Hassan Saidi
Summary: This study optimized the concentrations of Fe3O4-MWCNTs/deionized water hybrid nanofluid using NSGA-II and tested its thermal performance in a pulsating heat pipe (PHP). The hybrid nanofluid containing 0.597 vol.% of Fe3O4 and 0.100 vol.% of MWCNTs showed the best thermal performance for the PHP. In comparison, the PHP charged with deionized water exhibited better start-up and lower thermal resistance.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Thermodynamics
Yuduo Li, Hang Li, Chuang Wu, Shoubing Zhang, Guojie Zhang, Liyan Cao, Songzhen Tang, Dongwei Zhang
Summary: This paper proposes a novel multi-functional poly-generation system with high integration and efficiency. It can provide cooling, heating, and hot water services under different operation modes, and exhibits high effectiveness in the combined cooling/hot water mode.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Chemistry, Physical
Junjie Zhou, Shanshan Li, Song-Zhen Tang, Dongwei Zhang, Heqing Tian
Summary: The explosive boiling characteristics of water on the copper surface were studied using molecular dynamics simulation, showing that increasing the size of nanostructures improves heat transfer performance and boiling rate. Additionally, increasing the number of nanostructures at the same volume concentration can also increase the boiling rate of the liquid film. The adoption of cylindrical nanostructures results in higher water heating rates and larger heat flux compared to spherical nanostructures, demonstrating the potential for improving boiling heat transfer performance on copper surfaces.
MOLECULAR SIMULATION
(2022)
Article
Thermodynamics
Xiuzhen Li, Shijie Liu, Songzhen Tang, Xun Mo, Lin Wang, Dongsheng Zhu
Summary: A novel twisted tube improves the distribution of secondary flow, enhancing convective heat transfer. Experimental results in the low Reynolds number region show that NTT can improve heat transfer performance and reduce thermal resistance.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Xiang Qin, Fan Zhang, Dongwei Zhang, Zhao Gao, Songzhen Tang
Summary: This study investigates the impact of high-pressure control on performance in transcritical CO2 heat pump systems, and examines the effects of compressor frequency, inlet water flow rate, and inlet water temperature on optimal high pressure and performance coefficient through experimental and theoretical analysis. A new method for calculating discharge pressure deviation is proposed, and the occurrence pattern of optimal high pressure is investigated.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Dongwei Zhang, Luotong Fu, Jian Guan, Chao Shen, Songzhen Tang
Summary: This study investigates the fluid flow and heat transfer performance of different extended surfaces in microchannel heat sinks. The results show that the microchannel with the triangular combined cavity exhibits the best heat transfer performance at a low Reynolds number, while the microchannel with 90 degrees fan-shaped and triangular combined cavity has advantages at higher Reynolds numbers. Furthermore, the microchannel with cavity and extended surface shows better heat transfer and energy saving performance compared to the traditional rectangular microchannel.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Energy & Fuels
Songzhen Tang, Junjie Zhou, Chao Shen, Dongwei Zhang
Summary: This study examines the effects of shell-to-tube diameter ratios, fin number, and fin arrangement on the melting performance of a buried tube latent heat storage system, finding that a diameter ratio of 2.0 yields the best overall performance.
JOURNAL OF ENERGY STORAGE
(2022)
Article
Thermodynamics
Songzhen Tang, Liang Ding, Zihao Zhao, Junjie Zhou, Huiting Bian
Summary: This paper focuses on reducing ash deposition in a waste heat boiler in the cement kiln by improving the performance of heat-transfer surfaces through different designs based on the characteristics of the elliptical tube. A detailed CFD model is used to study ash deposition and thermal-hydraulic characteristics, and the dynamic mesh method is employed to simulate the dynamic growth process of the ash deposited layer. The novel designs effectively reduce particle deposition while maintaining easy manufacturing and acceptable thermal-hydraulic performance for waste heat utilization of dust-laden exhaust gas.
APPLIED THERMAL ENGINEERING
(2022)
Article
Chemistry, Applied
Songzhen Tang, Liang Ding, Junjie Zhou, Bo Shen, Hang Li
Summary: A comprehensive CFD model was used to investigate the dynamic deposition behavior of ash particles during Zhundong coal combustion. Different models were used to describe the deposition behavior, and the morphology evolution process of the deposited layer was predicted. The results showed that the novel heating surface had better performance in terms of deposition resistance and thermal-hydraulic performance compared to the typical heating surface, and it could be helpful for the efficient utilization of waste heat from dust-laden flue gases.
FUEL PROCESSING TECHNOLOGY
(2022)
Article
Energy & Fuels
Chaxiu Guo, Mengxiao Lan, Mingzhi Li, Songzhen Tang, Dongwei Zhang, Jiangbao Song, Hang Li
Summary: This paper proposes a new fin optimization method: the combination of fins of different structures under non-uniform arrangement conditions. By adding fins to the phase change material, the heat transfer area can be expanded and consequently effectively accelerates the heat storage rate. The results indicate that curved fins have the advantage of enhancing heat transfer compared to straight fins.
JOURNAL OF ENERGY STORAGE
(2023)
Article
Thermodynamics
Yinsheng Yu, Songzhen Tang, Heqing Tian
Summary: In this paper, a new Na2CO3/Graphene based phase change material (PCM) with sandwich structure is proposed and designed for thermal energy storage application. The microstructure is established and the thermal transport properties are investigated. The results show that the sandwich structure leads to the limiting effect of ions in the PCM system, reducing the self-diffusion coefficient and increasing the shear viscosity. Moreover, the sandwich structure benefits the enhancement of thermal conductivity, with an average increase of 32.51% and a maximum enhancement of 51.37%, providing a possible strategy for thermal conductivity improvement in molten salt based PCM.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Chemistry, Physical
Junjie Zhou, Zhaochen Sun, Songzhen Tang, Yinsheng Yu
Summary: This paper studied the combustion characteristics of CH4 in a CO2/O-2/N-2 atmosphere subjected to an electric field using molecular dynamics simulation. Conventional and unique pathways were obtained and analyzed the evolution of reactants, main products, and intermediates. The results showed that external electric fields increased conventional responses and species diversity, generating new pathways and accelerating the generation of new species. The applied electric field advanced the reaction start time and strengthened the combustion process, but its effect on the reaction rate was highly nonlinear. At E ≥ 10(5) V/m, the reaction between CH4 and CO2 significantly intensified, while it was suppressed at E = 10(4) V/m. Electric fields also promoted the oxidation degree of CH4, especially at E = 10(6) V/m. These findings provide theoretical guidance for understanding methane combustion under high-concentration CO2 atmosphere and efficient CO2 capture.
MOLECULAR SIMULATION
(2023)
Article
Thermodynamics
Dongwei Zhang, Luotong Fu, Songzhen Tang, Mengxiao Lan, Chao Shen, Songxuan Chen, Hailiang Cao, Jinxing Wu
Summary: This study investigates the influence of high-frequency ultrasound on the heat transfer between fluid and wall by studying different types of microchannels. The comprehensive performance of the microchannel is also analyzed. The results show that at low Reynolds numbers, ultrasonic-induced acoustic streaming effect improves the heat transfer, but with the increase of Reynolds numbers, the flow velocity becomes the dominant factor. The combination of cavity structure and ultrasonic enhances the acoustic wave effect and improves the heat transfer efficiency. The efficiency of using high-frequency ultrasound to enhance microchannel heat transfer is higher than that of pump power.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Chaxiu Guo, Mengxiao Lan, Dongwei Zhang, Xin Wang, Songzhen Tang, Songxuan Chen, Luotong Fu
Summary: This study investigates the influence of the acoustic flow effect on the melting process of phase change material. The position of ultrasonic actuation and the energy of ultrasonic wave on heat storage process enhancement were studied. The results show that the bottom surface of the container with ultrasonic vibration performs the best melting performance for phase change heat storage.
APPLIED THERMAL ENGINEERING
(2023)
Article
Chemistry, Physical
Dongwei Zhang, Jian Guan, Chao Shen, Songzhen Tang, Junjie Zhou
Summary: In this work, molecular dynamics simulation was used to study the formation and development mechanisms of near-surface nanobubbles and analyze the effects of wettability on their dynamic behaviors. The results showed the presence of nanobubbles and a gas-enriched layer in the system. The formation of nanobubbles can be divided into two stages, namely, the initial stage and steady stage. Wettability was found to have a significant impact on the formation of nanobubbles. During the coalescence process, vapor molecules from small bubbles actively moved into larger ones, leading to continuous changes in the shape of the coalesced bubbles. Hydrophobic walls were found to be more favorable for gaseous molecules, making it easier to form surface nanobubbles. This work provides theoretical guidance for the practical application of near-surface nanobubbles.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyang Xu, Fangjun Hong, Chaoyang Zhang
Summary: This study introduces a self-induced jet impingement device for enhancing pool boiling performance in high power electronic cooling. Through visualization and parametric investigations, the effects of this device on pool boiling performance are studied, revealing the promotion of additional liquid supply and vapor exhausting. The flow rate of the liquid jet is found to positively impact boiling performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Wenchao Ke, Yuan Liu, Fissha Biruke Teshome, Zhi Zeng
Summary: Underwater wet laser welding (UWLW) is a promising and labor-saving repair technique. A thermal multi-phase flow model was developed to study the heat transfer, fluid dynamics, and phase transitions during UWLW. The results show that UWLW creates a water keyhole, making the welding environment similar to in air laser welding.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Xingrong Lian, Lin Tian, Zengyao Li, Xinpeng Zhao
Summary: This study investigates the heat transfer mechanisms in natural fiber-derived porous structures and finds that thermal radiation has a significant impact on the thermal conductivity in low-density regions, while natural convection rarely occurs. Insulation materials derived from micron-sized natural fibers can achieve minimum thermal conductivity at specific densities. Strategies to lower the thermal conductivity include increasing porosity and incorporating nanoscale pores using nanosize fibers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Yasir A. Malik, Kilian Koebschall, Stephan Bansmer, Cameron Tropea, Jeanette Hussong, Philippe Villedieu
Summary: Ice crystal icing is a significant hazard in aviation, and accurate modeling of sticking efficiency is essential. In this study, icing wind tunnel experiments were conducted to quantify the volumetric liquid water fraction, sticking efficiency, and maximum thickness of ice layers. Two measurement techniques, calorimetry and capacitive measurements, were used to measure the liquid water content and distribution in the ice layers. The experiments showed that increasing wet bulb temperatures and substrate heat flux significantly increased sticking efficiency and maximum ice layer thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Dan-Dan Su, Xiao-Bin Li, Hong-Na Zhang, Feng-Chen Li
Summary: The boiling heat transfer of low-boiling-point working fluid is a common heat dissipation technology in electronic equipment cooling. This study analyzed the interfacial boiling behavior of R134a under different conditions and found that factors such as the initial thickness of the liquid film, solid-liquid interaction force, and initial temperature significantly affect the boiling mode and thermal resistance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyi Wu, Dongke Sun, Wei Chen, Zhenhua Chai
Summary: A unified lattice Boltzmann-phase field scheme is proposed to simulate dendrite growth of binary alloys in the presence of melt convection. The effects of various factors on the growth are investigated numerically, and the model is validated through comparisons and examinations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shaokun Ge, Ya Ni, Fubao Zhou, Wangzhaonan Shen, Jia Li, Fengqi Guo, Bobo Shi
Summary: This study investigated the temperature distribution of main cables in a suspension bridge during fire scenarios and proposed a prediction model for the maximum temperature of cables in different lane fires. The results showed that vehicle fires in the emergency lane posed a greater thermal threat to the cables.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shuang-Ying Wu, Shi-Yao Zhou, Lan Xiao, Jia Luo
Summary: This paper investigates the two-phase flow and heat transfer characteristics of low-velocity jet impacting on a cylindrical surface. The study reveals that the heat transfer regimes are non-phase transition and nucleate boiling with the increase of heat transfer rate. The effects of jet impact height and outlet velocity on local surface temperatures are pronounced at the non-phase transition stage. The growth rates of heat transfer rate and liquid loss rate increase significantly from the non-phase transition to nucleate boiling stage.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Feriel Yahiat, Pascale Bouvier, Antoine Beauvillier, Serge Russeil, Christophe Andre, Daniel Bougeard
Summary: This study explores the enhancement of mixing performance in laminar flow equipment by investigating the generation of chaotic advection using wall deformations in annular geometries. The findings demonstrate that the combined geometry can achieve perfect mixing at various Reynolds numbers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Liangyuan Cheng, Qingyang Wang, Jinliang Xu
Summary: In this study, we investigated the supercritical heat transfer of CO2 in a horizontal tube with a diameter of 10.0 mm, covering a wide range of pressures, mass fluxes, and heat fluxes. The study revealed a non-monotonic increase in wall temperatures along the flow direction and observed both positive and negative wall temperature differences between the bottom and top tube. The findings were explained by the thermal conduction in the solid wall interacting with the stratified-wavy flow in the tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
