International Journal of Heat and Mass Transfer最新文献

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Boiling performance enhancement and self-recovery of nucleate boiling regime on micro- and nanostructured porous surfaces
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-12-02 DOI: 10.1016/j.ijheatmasstransfer.2024.126516
Dong Ju Lee , Young Jae Yang , Dong Eok Kim
{"title":"Boiling performance enhancement and self-recovery of nucleate boiling regime on micro- and nanostructured porous surfaces","authors":"Dong Ju Lee ,&nbsp;Young Jae Yang ,&nbsp;Dong Eok Kim","doi":"10.1016/j.ijheatmasstransfer.2024.126516","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126516","url":null,"abstract":"<div><div>In this paper, we report the pool boiling experimental results for significant enhancements in the boiling heat transfer coefficient (BHTC) and CHF on various microporous surfaces. The microporous surfaces were fabricated by metal (Copper) powder sintering process, and nanostructured porous surfaces were additionally fabricated through the thermal oxidation of the metal porous surfaces. Among the examined substrates, a boiling surface with a thin metal porous layer and millimeter-sized porous pillar structures exhibited optimal boiling performance; the BHTC and CHF of the microporous surface were measured to be approximately 500 % and 270 % higher than those of a smooth reference surface, respectively. We conjecture that the results come from the combined effect of active nucleation site density enhancement, capillary wicking promotion, and separation of liquid-vapor flow paths on the microporous surface with porous pillars. On the other hands, the porous pillar surface with needle-like nanostructures showed the interesting phenomena that can be regarded to the recovery of the boiling regime from transition boiling to nucleate boiling. At the CHF, the temperature increase on the surface was slower than that on the other surfaces. Additionally, at high heat fluxes below the CHF, the overheated surface self-recovered to the nucleate boiling state, indicating the rewetting of local dry spots. We consider that the capillary wicking capability strongly improved by the nanostructures on the surface was presumably responsible for inhibiting the irreversible expansion of local dry spots. From the experimental observations throughout this study, we propose the following key requirements to design an ideal boiling surface: increasing the nucleation site density, ensuring a liquid supply path by capillary wicking, separating the liquid and vapor flow paths, and improving the liquid wettability of the solid surface by forming nanostructures.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126516"},"PeriodicalIF":5.0,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Coupling effects among viscosity, viscous dissipation and convective heat transfer in the microscale flow of polymer melt
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-12-02 DOI: 10.1016/j.ijheatmasstransfer.2024.126491
Jiakun Zhang, Minjie Wang, Hongxia Li, Liangliang Zhang
{"title":"Coupling effects among viscosity, viscous dissipation and convective heat transfer in the microscale flow of polymer melt","authors":"Jiakun Zhang,&nbsp;Minjie Wang,&nbsp;Hongxia Li,&nbsp;Liangliang Zhang","doi":"10.1016/j.ijheatmasstransfer.2024.126491","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126491","url":null,"abstract":"<div><div>The coupling effects among viscosity, viscous dissipation, and convective heat transfer during the polymer melt micro-molding process, influenced by microscale effects, notably impacted the melt's flow characteristics. The scarcity of theoretical exploration into these coupling effects has hindered the evolution of micro-molding. This research initially established the heat transfer coefficient equation at the microscale via experimental approaches, and by integrating multiphysics coupling theories, established a coupled mathematical model encompassing viscosity, viscous dissipation and convective heat transfer at the microscale. Then we computed and analyzed the melt flow characteristics within microchannels of varying characteristic dimensions and validated the temperature variations of the melt along the flow direction through experiments. The results showed that considering coupling effects resulted in a temperature rise along the flow direction that closely matched experimental data, with discrepancies below 0.5 °C, whereas ignoring these effects led to a maximum deviation of up to 2.4 °C. Analysis of velocity, viscosity, and viscous dissipation across radial section revealed that the discrepancies between ignoring and considering coupling escalated with decreasing dimensions. The maximum deviations for velocity, viscosity, and viscous dissipation in PMMA(polymethyl methacrylate) were 19.47 %, 10.71 %, and 39.28 %, respectively. These results emphasized the necessity of considering coupling effects when polymer melt micro-molding.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126491"},"PeriodicalIF":5.0,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The suppression and CO elimination performance of Co3O4 dust cloud for methane-air mixture explosion
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-12-02 DOI: 10.1016/j.ijheatmasstransfer.2024.126492
Jia Li , Xiao Wang , Zhiyuan Shen , Sheng He , Junyi Li , Bobo Shi , Jianguo Wu , Lianhe Guan , Xinyu Chen , Xuan Xu , Xiaoyu Chen , Fubao Zhou
{"title":"The suppression and CO elimination performance of Co3O4 dust cloud for methane-air mixture explosion","authors":"Jia Li ,&nbsp;Xiao Wang ,&nbsp;Zhiyuan Shen ,&nbsp;Sheng He ,&nbsp;Junyi Li ,&nbsp;Bobo Shi ,&nbsp;Jianguo Wu ,&nbsp;Lianhe Guan ,&nbsp;Xinyu Chen ,&nbsp;Xuan Xu ,&nbsp;Xiaoyu Chen ,&nbsp;Fubao Zhou","doi":"10.1016/j.ijheatmasstransfer.2024.126492","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126492","url":null,"abstract":"<div><div>This paper experimentally studied the effect of Co<sub>3</sub>O<sub>4</sub> dust clouds on the methane-air mixture explosion characteristics and post-explosion CO concentration, aiming to propose a novel method for simultaneously suppressing explosion and eliminating CO product. The Co<sub>3</sub>O<sub>4</sub> catalyst was synthesized utilizing the co-precipitation method. We varied the methane concentration and Co<sub>3</sub>O<sub>4</sub> dust cloud concentration to investigate their effects on the flame propagation behavior, maximum explosion overpressure (<span><math><msub><mi>P</mi><mi>m</mi></msub></math></span>), flame combustion time (<span><math><msub><mi>t</mi><mi>c</mi></msub></math></span>), and the gaseous product concentration. The hazard of the gaseous product was evaluated by the effective escape time (<span><math><msub><mi>t</mi><mi>e</mi></msub></math></span>) based on the Fraction Effective Dose (FED) mathematical model. The results demonstrated that the Co<sub>3</sub>O<sub>4</sub> dust cloud could significantly reduce the explosion severity and CO concentration. Furthermore, the higher the concentration of Co<sub>3</sub>O<sub>4</sub> dust clouds, the more significant the explosion suppression and CO elimination performance, which was as a result of the significant increase in the contact area and collision probability between the Co<sub>3</sub>O<sub>4</sub> particles and the reaction components increased. Compared to traditional inhibitors that only reduce the severity of an explosion, Co₃O₄ could not only significantly reduce the explosion severity, but also quickly eliminate post-detonation CO. The method proposed in this paper could effectively reduce the hazard of methane-air mixture explosion, which was of great practical significance for ensuring the safety of personnel involved in the risk.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126492"},"PeriodicalIF":5.0,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Predictions of Line Chilldown Boiling Regime Transitions by a Coupled CFD-Subgrid Boiling Model Validated against 1G LN2 Experiments
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-12-02 DOI: 10.1016/j.ijheatmasstransfer.2024.126385
Mohammad Kassemi , Sonya Hylton , Olga Kartuzova , Vineet Ahuja , Ashvin Hosangadi
{"title":"Predictions of Line Chilldown Boiling Regime Transitions by a Coupled CFD-Subgrid Boiling Model Validated against 1G LN2 Experiments","authors":"Mohammad Kassemi ,&nbsp;Sonya Hylton ,&nbsp;Olga Kartuzova ,&nbsp;Vineet Ahuja ,&nbsp;Ashvin Hosangadi","doi":"10.1016/j.ijheatmasstransfer.2024.126385","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126385","url":null,"abstract":"<div><div>Before filling a propellant tank on the ground or in Space, the transfer line between the donor and receiver tanks must be cooled down, preferably while sacrificing the least amount of the cryogenic fluid. The cryogenic line chill-down process involves transitions between different flow boiling regimes, namely film boiling, transition film boiling, and nucleate boiling, which are complex and gravity-dependent. Attempts to capture these boiling phenomena and to predict the transitions between them in a Computational Fluid Dynamics (CFD) framework are new and challenging. The present work addresses this challenge by following an Eulerian approach in which a homogeneous two-phase mixture model is used together with the Lee phase change formulation to capture the chilldown film boiling regime in the framework of the ANSYS Fluent® CFD code. The chilldown nucleate boiling regime is predicted by a mechanistic subgrid model that accounts for the nucleation, growth, departure diameter, and shedding frequency of the bubbles. The subgrid model is encoded and coupled to the CFD model via a user-defined function for the wall-fluid heat flux calculations. The coupled CFD-Subgrid model is validated against published experimental data for the chill-down of a heated stainless-steel pipe in 1g using liquid nitrogen (LN2). The CFD predictions of the wall temperature evolution, rewetting temperature, and transition between film and nucleate boiling agree well with experimental measurements for LN2 flow in a vertical pipe. Physical insights derived from the CFD simulations and validation are described, and the strengths and weaknesses of the modeling approach are presented and discussed. Recommendations for future improvements of the CFD model are also provided.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126385"},"PeriodicalIF":5.0,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Silicon-based square-hole arrays for dual-band nonreciprocal thermal radiation
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-12-02 DOI: 10.1016/j.ijheatmasstransfer.2024.126509
Jiahao Li , Bo Wang
{"title":"Silicon-based square-hole arrays for dual-band nonreciprocal thermal radiation","authors":"Jiahao Li ,&nbsp;Bo Wang","doi":"10.1016/j.ijheatmasstransfer.2024.126509","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126509","url":null,"abstract":"<div><div>Nonreciprocal thermal radiation has many applications in energy harvesting, military camouflage, and other fields. However, in the past, most nonreciprocal devices operated under single polarization, which undoubtedly limited the development of the nonreciprocal thermal radiation. In addition, previous research has focused on single-band nonreciprocal radiation. However, there is little study on dual-band nonreciprocal thermal radiation. We investigate a dual-band nonreciprocal radiation device under dual-polarization, which is composed of a metal layer, magneto-optical layer, and silicon-based square-hole arrays in two-dimensional form. The device can achieve dual-band nonreciprocal radiation at wavelengths of 15.945 μm and 16.475 μm under TE polarization. Under TM polarization, dual-band nonreciprocal radiation can be achieved at wavelengths of 13.956 μm and 14.352 μm. And the electromagnetic field distribution can explain potential physical mechanisms. It indicates that nonreciprocal radiation can be maintained well within a certain range of structural parameters. This work can provide new directions for the study of frequency selective detectors.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126509"},"PeriodicalIF":5.0,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Experimental investigation on gas-liquid two-phase flow patterns and vibration characteristics of an inducer pump
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-12-02 DOI: 10.1016/j.ijheatmasstransfer.2024.126518
Yanhong Mao , Houlin Liu , Giacomo Zanetti , Giovanna Cavazzini , Yong Wang , Jie Chen
{"title":"Experimental investigation on gas-liquid two-phase flow patterns and vibration characteristics of an inducer pump","authors":"Yanhong Mao ,&nbsp;Houlin Liu ,&nbsp;Giacomo Zanetti ,&nbsp;Giovanna Cavazzini ,&nbsp;Yong Wang ,&nbsp;Jie Chen","doi":"10.1016/j.ijheatmasstransfer.2024.126518","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126518","url":null,"abstract":"<div><div>Inducers typically enhance centrifugal pump performance in two-phase flow regimes by producing more uniform mixtures and increasing pressure before the impeller. Their impact is most pronounced under part-load conditions compared to overload situations. This study experimentally investigates air-water two-phase flow behavior within a pump inducer. Using high-speed photography and grayscale image processing, five distinct gas-liquid flow patterns were identified: bubble flow, strip bubble flow, agglomerated bubble flow, gas pocket flow, and segregated flow. The inducer's head and vibration characteristics were also measured. Results show that flow pattern transitions significantly affect performance degradation and vibration. Specifically, the head decreases as the liquid flow rate increases at a constant gas volume fraction (<em>λ</em>) and generally follows a downward trend as <em>λ</em> increases at a constant liquid flow rate. Bubble flow, representing minimal <em>λ</em>, has a negligible effect on performance. However, with higher <em>λ</em>, a sharp decline in head occurs within the agglomerated bubble flow range, followed by a gradual decrease during gas pocket flow under both optimal and overload conditions. In part-load conditions, the head decreases sharply during strip bubble and segregated flow. While bubble flow mitigates vibration fluctuations, increasing GVF leads to higher vibration amplitude, particularly in the range of 2–8 times the inducer's rotational frequency, due to flow pattern instability.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126518"},"PeriodicalIF":5.0,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Numerical simulation and optimization of a high-performance serpentine tube phase change cold storage unit based on high thermal conductivity ice/expanded graphite
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-11-30 DOI: 10.1016/j.ijheatmasstransfer.2024.126497
Tanghan Wu , Weiguan Zhou , Ziye Ling , Zhengguo Zhang , Xiaoming Fang
{"title":"Numerical simulation and optimization of a high-performance serpentine tube phase change cold storage unit based on high thermal conductivity ice/expanded graphite","authors":"Tanghan Wu ,&nbsp;Weiguan Zhou ,&nbsp;Ziye Ling ,&nbsp;Zhengguo Zhang ,&nbsp;Xiaoming Fang","doi":"10.1016/j.ijheatmasstransfer.2024.126497","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126497","url":null,"abstract":"<div><div>To build a high-performance cold storage device integrated into refrigeration, air conditioning, and large energy storage systems, this study presents a high-performance phase change cold storage material based on a combination of expanded graphite (EG) and water and designs a corresponding serpentine tube cold storage unit. By incorporating EG into water, the thermal conductivity of the composite material is significantly enhanced, increasing by more than tenfold, while the phase change enthalpy remains almost unaffected. Utilizing this composite material, a serpentine tube cold storage unit was constructed, and the structural parameters were optimized using numerical simulation methods. The cold storage density exceeds 100 kWh/m³, with a maximum power density exceeding 200 kW/m³, and efficient cold energy release was achieved with an inlet and outlet pressure drop of &lt;30 kPa. Numerical simulation results indicate that different structural parameters have a significant impact on the cold energy release performance of the storage unit. By studying the effects of flow rate, composite material ratio, tube diameter, tube spacing, and flow path length on cold energy release performance, a rapid design method for the structural parameters of serpentine tube structures was summarized. This provides important reference and guidance for the design of high-performance cold storage units in various application scenarios.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126497"},"PeriodicalIF":5.0,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Flow microbubble emission boiling (MEB) in open microchannels for durable and efficient heat dissipation
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-11-30 DOI: 10.1016/j.ijheatmasstransfer.2024.126506
Qi Zhao, Mingxiang Lu, Yuanle Zhang, Qiang Li, Xuemei Chen
{"title":"Flow microbubble emission boiling (MEB) in open microchannels for durable and efficient heat dissipation","authors":"Qi Zhao,&nbsp;Mingxiang Lu,&nbsp;Yuanle Zhang,&nbsp;Qiang Li,&nbsp;Xuemei Chen","doi":"10.1016/j.ijheatmasstransfer.2024.126506","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126506","url":null,"abstract":"<div><div>Microbubble emission boiling (MEB) has been reported to be an advanced heat transfer mechanism due to its significant heat dissipation capacity at high heat flux. Microchannel heat sinks are considered to be effective heat transfer carriers, but MEB is difficult to be triggered in conventional microchannels due to insufficient mainflow subcooling and restriction of narrow channel walls. In this work, we conducted flow MEB experiments in plain and lasered open microchannels with various inlet temperatures (<em>T</em><sub>inlet</sub>) and open gap height (<em>H</em><sub>g</sub>). The open configuration can provide adequate mainflow subcooling and extra flow area to trigger MEB. The results showed that MEB occurred in plain open microchannels as a transition flow pattern between bubbly flow and flow reversal at <em>T</em><sub>inlet</sub> ≤ 25 °C and <em>H</em><sub>g</sub> = 0.3 mm, with a significant temperature drop after a one-time flow reversal, providing abundant vapor composition as MEB evaporation cores; MEB did not happen at higher <em>T</em><sub>inlet</sub> and larger <em>H</em><sub>g</sub> (1 mm). However, in lasered open microchannels, MEB was triggered at the beginning of flow boiling at <em>T</em><sub>inlet</sub> ≤ 65 °C with <em>H</em><sub>g</sub> = 0.3 and 1 mm, without temperature drop or flow reversal. This demonstrated that the required inlet subcooling, heat flux and temperature gradient in vertical direction for MEB initiation were simultaneously reduced in lasered microchannels. The two-phase heat transfer coefficient (<em>h</em><sub>tp</sub>) of MEB was significantly increased (up to 77.8 %) compared to conventional bubbly flow, due to the faster bubble nucleation frequency and rapid impact from the subcooled mainflow to channel walls, and was further enhanced in lasered microchannels. The durability of MEB in plain microchannel was unsatisfactory, as the persistent flow reversal dominated the flow pattern after ∼3750 s at <em>G</em> = 300 ml/min, <em>T</em><sub>inlet</sub> = 25 °C, <em>H</em><sub>g</sub> = 0.3 mm and <em>q</em><sub>eff</sub> ∼1450 kW/m<sup>2</sup>. However, in lasered microchannels, MEB ran steadily for 22500 s at the same working condition. This study provided an effective and accessible method to achieve durable MEB in microchannels with excellent heat dissipation capacity, offering valuable insights for further thermal management engineering applications.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126506"},"PeriodicalIF":5.0,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Three dimensional numerical simulation of slug flow boiling in microchannels
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-11-30 DOI: 10.1016/j.ijheatmasstransfer.2024.126505
Zheng Zhang , Guanmin Zhang , Xiaoxu Ma , Maocheng Tian
{"title":"Three dimensional numerical simulation of slug flow boiling in microchannels","authors":"Zheng Zhang ,&nbsp;Guanmin Zhang ,&nbsp;Xiaoxu Ma ,&nbsp;Maocheng Tian","doi":"10.1016/j.ijheatmasstransfer.2024.126505","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126505","url":null,"abstract":"<div><div>In recent years, flow boiling heat transfer in microchannels has been extensively studied as an efficient cooling solution, with slug flow considered the optimal operating condition for microchannels. Current research on slug flow boiling primarily focuses on circular channels and isolated bubbles modeled with 2D axisymmetric geometries. This paper investigates flow boiling in three-dimensional rectangular microchannels based on conjugate heat transfer. Superheat, velocity, and bubble generation frequency affect slug flow heat transfer by influencing the internal circulation within the liquid slug, the length and thickness of the liquid film, dry patches, and bubble length. In this study, the two-phase flow with a Peclet number (Pe) ranging from 355 to 1780 is in the transition zone, where the diffusion effects between the fluids cannot be ignored. The main mechanism for enhancing heat transfer within the liquid slug is the internal recirculation flow. In comparison to the heat transfer of single-phase flow within the channel, the average Nusselt number for two-phase flow boiling exhibits a significant enhancement, increasing by as much as 85 % and not less than 62 % concomitant with the increase in superheat. Accompanying the increment in inlet velocity, there is a notable augmentation in the Nusselt number for two-phase flow boiling, escalating by as much as 63 % and at a minimum of 29 %. Consequent to the elevation in bubble generation frequency, a substantial rise is observed in the heat transfer coefficient, surging by up to 80 % and not falling below 28 %. When the length of the liquid slug equals the width of the channel, slug flow achieves the highest heat transfer coefficient. This study provides theoretical guidance for flow pattern control within microchannels.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126505"},"PeriodicalIF":5.0,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The influence of external action on the dynamics of elastic, thermal and concentration waves propagation
IF 5 2区 工程技术
International Journal of Heat and Mass Transfer Pub Date : 2024-11-30 DOI: 10.1016/j.ijheatmasstransfer.2024.126486
Elena S. Parfenova, Anna G. Knyazeva
{"title":"The influence of external action on the dynamics of elastic, thermal and concentration waves propagation","authors":"Elena S. Parfenova,&nbsp;Anna G. Knyazeva","doi":"10.1016/j.ijheatmasstransfer.2024.126486","DOIUrl":"10.1016/j.ijheatmasstransfer.2024.126486","url":null,"abstract":"<div><div>This paper presents the nonlinear coupled mathematical model allowing investigating the interrelation between the mechanical, thermal and diffusion processes in solid body. The model takes into account the finiteness of relaxation times of mass and heat fluxes. This is of interest for dynamical processes with characteristic times comparable to relaxation times, when the changes in the temperature and impurity concentration are described by hyperbolic thermal conductivity and diffusion equations. Additionally, the model takes into account the temperature and concentration dependencies of the diffusion coefficients; it gives rise to additional nonlinearity. The model is thermodynamically consistent and follows from the nonlinear equations of the thermoelastic diffusion theory. The implicit difference scheme of second approximation order in time and spatial steps, linearization relatively to known time moment and double-sweep method are used for the numerical implementation of the equation system. Examples of interrelating wave propagating under external actions are considered. The results show that distortions in the strain/stress and temperature distributions appear due to the interaction between the phenomena of different physical nature. The specific rates of different physical processes are different. Although diffusion is the slowest of them all, the influence of the diffusion wave is reflected in stress and strain waves far beyond the diffusion wave front. It is shown that regardless of the external action character and impulse form, the influence of the considered processes on each other does not change, but the wave picture becomes much more complicated with increasing number of actions.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"238 ","pages":"Article 126486"},"PeriodicalIF":5.0,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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