Pub Date : 2024-11-24DOI: 10.1016/j.icheatmasstransfer.2024.108386
Canan Kandilli , Muhammed Gür , Hakan Yilmaz , Hakan F. Öztop
This study presents an in-depth experimental and numerical analysis of an innovative Composite Trombe Wall (CTW) system utilizing a natural zeolite-perlite composite plate as thermal mass, aimed at advancing sustainable building applications. This novel system uniquely combines the high specific heat capacity of natural zeolite with the low thermal conductivity of perlite, optimizing thermal storage and retention in passive solar energy applications. A comprehensive Computational Fluid Dynamics (CFD) model was developed to simulate natural convection and heat transfer dynamics, and validated against experimental data. Results indicate a maximum temperature differential of 11.5 °C between indoor and ambient conditions, demonstrating the CTW system's potential to enhance energy efficiency and indoor thermal comfort in nearly zero-energy buildings (nZEB). This research contributes a significant advancement by showcasing the practicality of sustainable, locally sourced materials in enhancing passive solar heating systems, thereby establishing a new benchmark in eco-friendly building technology.
{"title":"Experimental and numerical analyses of a model Trombe wall employing the natural zeolite/perlite composite plate as a thermal mass for nearly zero energy buildings","authors":"Canan Kandilli , Muhammed Gür , Hakan Yilmaz , Hakan F. Öztop","doi":"10.1016/j.icheatmasstransfer.2024.108386","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108386","url":null,"abstract":"<div><div>This study presents an in-depth experimental and numerical analysis of an innovative Composite Trombe Wall (CTW) system utilizing a natural zeolite-perlite composite plate as thermal mass, aimed at advancing sustainable building applications. This novel system uniquely combines the high specific heat capacity of natural zeolite with the low thermal conductivity of perlite, optimizing thermal storage and retention in passive solar energy applications. A comprehensive Computational Fluid Dynamics (CFD) model was developed to simulate natural convection and heat transfer dynamics, and validated against experimental data. Results indicate a maximum temperature differential of 11.5 °C between indoor and ambient conditions, demonstrating the CTW system's potential to enhance energy efficiency and indoor thermal comfort in nearly zero-energy buildings (nZEB). This research contributes a significant advancement by showcasing the practicality of sustainable, locally sourced materials in enhancing passive solar heating systems, thereby establishing a new benchmark in eco-friendly building technology.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108386"},"PeriodicalIF":6.4,"publicationDate":"2024-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699643","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}
Pub Date : 2024-11-23DOI: 10.1016/j.icheatmasstransfer.2024.108375
V. Subramanyam , V. Pandurangan , M. Nithyadharan
The paper presents an inverse approach using a micromechanical model for predicting the transverse thermal conductivity of flax fiber, addressing the lack of standard testing protocols for characterizing natural fibers. The model predicts the transverse thermal conductivity of the fiber from experimentally measured properties of the flax-epoxy lamina. The inverse approach was validated using data corresponding to carbon-epoxy composite reported in the literature, with an error of less than 5 %. The transverse thermal conductivity of the flax fiber was estimated to be 0.87 W/m K, which is comparable to other natural fibers. The flax fiber properties were used to evaluate the thermal conductivity of the flax-epoxy lamina for a range of volume fractions, and a simplified non-linear regression equation was proposed. The methodology is further extended to predict the elastic properties of the woven fabric laminate using a multiscale homogenization approach. The proposed framework offers a reliable method for predicting the thermal properties of flax-epoxy composites, which forms the basis for thermo-mechanical analysis and design of automotive and aerospace components.
{"title":"Predicting transverse thermal conductivity of flax-fiber using micromechanical model based inverse framework","authors":"V. Subramanyam , V. Pandurangan , M. Nithyadharan","doi":"10.1016/j.icheatmasstransfer.2024.108375","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108375","url":null,"abstract":"<div><div>The paper presents an inverse approach using a micromechanical model for predicting the transverse thermal conductivity of flax fiber, addressing the lack of standard testing protocols for characterizing natural fibers. The model predicts the transverse thermal conductivity of the fiber from experimentally measured properties of the flax-epoxy lamina. The inverse approach was validated using data corresponding to carbon-epoxy composite reported in the literature, with an error of less than 5 %. The transverse thermal conductivity of the flax fiber was estimated to be 0.87 W/m K, which is comparable to other natural fibers. The flax fiber properties were used to evaluate the thermal conductivity of the flax-epoxy lamina for a range of volume fractions, and a simplified non-linear regression equation was proposed. The methodology is further extended to predict the elastic properties of the woven fabric laminate using a multiscale homogenization approach. The proposed framework offers a reliable method for predicting the thermal properties of flax-epoxy composites, which forms the basis for thermo-mechanical analysis and design of automotive and aerospace components.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108375"},"PeriodicalIF":6.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698789","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}
Pub Date : 2024-11-23DOI: 10.1016/j.icheatmasstransfer.2024.108332
Jiacheng Yuan, Lei Zeng, Yewei Gui
This paper presents an iterative topology optimizer for conductive heat transfer structures based on the Fourier neural operator (FNO). A data-driven model based on FNO is trained to predict the temperature under different material distributions, different boundary conditions, and different thermal loads. A new method is used to generate data, which makes the modeling process of temperature predictor completely independent of the traditional optimization method. Then by coupling the trained temperature predictor with the solid isotropic material with penalization (SIMP) method, a new iterative topology optimizer is formed. Numerical experiments demonstrate that the proposed method can generate heat transfer structures with good performance, and can apply the model trained on low-resolution data to the structural topology optimization with high resolution, which greatly improves the optimization efficiency. In addition to the heat conduction structure optimization problem, the method developed in this paper is expected to be applied to other optimization problems or coupled with other conventional optimization methods
{"title":"Method for predicting conductive heat transfer topologies based on Fourier neural operator","authors":"Jiacheng Yuan, Lei Zeng, Yewei Gui","doi":"10.1016/j.icheatmasstransfer.2024.108332","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108332","url":null,"abstract":"<div><div>This paper presents an iterative topology optimizer for conductive heat transfer structures based on the Fourier neural operator (FNO). A data-driven model based on FNO is trained to predict the temperature under different material distributions, different boundary conditions, and different thermal loads. A new method is used to generate data, which makes the modeling process of temperature predictor completely independent of the traditional optimization method. Then by coupling the trained temperature predictor with the solid isotropic material with penalization (SIMP) method, a new iterative topology optimizer is formed. Numerical experiments demonstrate that the proposed method can generate heat transfer structures with good performance, and can apply the model trained on low-resolution data to the structural topology optimization with high resolution, which greatly improves the optimization efficiency. In addition to the heat conduction structure optimization problem, the method developed in this paper is expected to be applied to other optimization problems or coupled with other conventional optimization methods</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108332"},"PeriodicalIF":6.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698873","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}
Pub Date : 2024-11-23DOI: 10.1016/j.icheatmasstransfer.2024.108373
Zhong Zhou , Yuze Han , Lijuan He , Zhi Li , Lifang Wang , Jianzi Yang , Yunfeng Liu
R41 gas and R1234yf droplets are used in the study as working fluids. Three-dimensional computational fluid dynamics is utilized to investigate the behavior of fluids in single-phase and two-phase vortex tubes, as well as the influence of cold flow fraction on the performance of them. The results show that small addition of droplets does not change the special working mechanism of the vortex tube. Two-phase vortex tubes are effective devices that can separate high pressure flow into cold flow and hot flow. But temperature difference at both cold and hot ends in the case of two-phase vortex tube is less than that of single-phase vortex tube at the same cold flow fraction. The maximum cold temperature differences of the single-phase and two-phase vortex tubes are 11.97 K and 10.54 K respectively when μ = 0.3. A maximum hot temperature difference of 29.54 K is achieved in the single-phase vortex tube when μ = 0.9. In contrast, a two-phase vortex tube exhibits a maximum hot temperature difference of 17.11 K at μ = 0.8. Additionally, the peak refrigerating capacity of the single-phase and two-phase vortex tube are 40.47 W and 38.51 W at μ = 0.7.
{"title":"Numerical analysis on performance of two-phase vortex-tube","authors":"Zhong Zhou , Yuze Han , Lijuan He , Zhi Li , Lifang Wang , Jianzi Yang , Yunfeng Liu","doi":"10.1016/j.icheatmasstransfer.2024.108373","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108373","url":null,"abstract":"<div><div>R41 gas and R1234yf droplets are used in the study as working fluids. Three-dimensional computational fluid dynamics is utilized to investigate the behavior of fluids in single-phase and two-phase vortex tubes, as well as the influence of cold flow fraction on the performance of them. The results show that small addition of droplets does not change the special working mechanism of the vortex tube. Two-phase vortex tubes are effective devices that can separate high pressure flow into cold flow and hot flow. But temperature difference at both cold and hot ends in the case of two-phase vortex tube is less than that of single-phase vortex tube at the same cold flow fraction. The maximum cold temperature differences of the single-phase and two-phase vortex tubes are 11.97 K and 10.54 K respectively when <em>μ</em> = 0.3. A maximum hot temperature difference of 29.54 K is achieved in the single-phase vortex tube when <em>μ</em> = 0.9. In contrast, a two-phase vortex tube exhibits a maximum hot temperature difference of 17.11 K at <em>μ</em> = 0.8. Additionally, the peak refrigerating capacity of the single-phase and two-phase vortex tube are 40.47 W and 38.51 W at <em>μ</em> = 0.7.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108373"},"PeriodicalIF":6.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698788","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}
Pub Date : 2024-11-23DOI: 10.1016/j.icheatmasstransfer.2024.108371
Mohamed Boujelbene , S.A.M. Mehryan , Awatef Abidi , Galal A. Ahmed Alashaari , Sultan Alshehery , Nidhal Ben Khedher , Ibrahim Mahariq , Nehad Ali Shah
This study introduces a novel approach aimed at mechanically influencing and distorting the boundary layer. This is achieved through the utilization of a wide, thin, elongated vibrating turbulator made of latex. The advanced vibrating turbulator continuously sweeps the inner tube perimeter, effectively breaking the boundary layer. Located within the test section is a concentric copper tube, defined by an outer diameter of and an inner diameter of . The effect of a number of parameters on the thermal characteristics of the heat exchanger, including the thickness of the latex turbulator, the width of the latex turbulator, the flow rate through the inner tube and the oscillation frequency, is investigated. The inner diameter of the tube sets the minimum width for the latex turbulator. The findings show a substantial rise in the heat transfer rate, reaching up to 504.5 %, when the rubber strip dimensions and frequency are optimized to a width of , thickness of , and frequency of . Under these conditions, the thermal enhancement factor reaches a peak of 3.39. Moreover, the thermal performance decreases when the rubber thickness is increased.
{"title":"Experimental investigation of a novel approach to enhance heat transfer in double-tube heat exchangers through the utilization of a vibrating latex strip turbulator","authors":"Mohamed Boujelbene , S.A.M. Mehryan , Awatef Abidi , Galal A. Ahmed Alashaari , Sultan Alshehery , Nidhal Ben Khedher , Ibrahim Mahariq , Nehad Ali Shah","doi":"10.1016/j.icheatmasstransfer.2024.108371","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108371","url":null,"abstract":"<div><div>This study introduces a novel approach aimed at mechanically influencing and distorting the boundary layer. This is achieved through the utilization of a wide, thin, elongated vibrating turbulator made of latex. The advanced vibrating turbulator continuously sweeps the inner tube perimeter, effectively breaking the boundary layer. Located within the test section is a concentric copper tube, defined by an outer diameter of <span><math><mn>2.5</mn><mspace></mspace><mi>cm</mi></math></span> and an inner diameter of <span><math><mn>1.6</mn><mspace></mspace><mi>cm</mi></math></span>. The effect of a number of parameters on the thermal characteristics of the heat exchanger, including the thickness of the latex turbulator, the width of the latex turbulator, the flow rate through the inner tube and the oscillation frequency, is investigated. The inner diameter of the tube sets the minimum width for the latex turbulator. The findings show a substantial rise in the heat transfer rate, reaching up to 504.5 %, when the rubber strip dimensions and frequency are optimized to a width of <span><math><mn>22</mn><mspace></mspace><mi>mm</mi></math></span>, thickness of <span><math><mn>0.4</mn><mspace></mspace><mi>mm</mi></math></span>, and frequency of <span><math><mn>40</mn><mspace></mspace><mi>Hz</mi></math></span>. Under these conditions, the thermal enhancement factor reaches a peak of 3.39. Moreover, the thermal performance decreases when the rubber thickness is increased.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108371"},"PeriodicalIF":6.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698874","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}
Pub Date : 2024-11-23DOI: 10.1016/j.icheatmasstransfer.2024.108369
Wei Guo , Junfan Pan , Qinchuan Yang , Qiang Li , Sunhua Deng , Chaofan Zhu
The autothermic pyrolysis in-situ conversion process (ATS) has a considerable advantage in reducing the development costs of oil shale. However, the trigger mechanism of autothermic pyrolysis oxidation reaction in different fractured oil shale formations is not precise. This study conducts a one-dimensional residual carbon oxidation experiment on the oil shale sample, taking into account the overburden pressure. The trigger condition and parameters are determined through the energy analysis during residual carbon oxidation in the fractured oil shale. A trigger simulation model of autothermic pyrolysis oxidation reaction in different fractured oil shale formations is proposed and verified by the temperature field evolution. The results indicate that the heterogeneous oxidation reaction produces a high permeability channel in the oil shale formation, which can further improve the flow conductivity of the oil shale formation. The trigger threshold of the residual carbon oxidation reaction in the fractured oil shale formation was closely associated with the carbon residue concentration (> 2.59 × 104 mol/m3), oxygen content (>15 %), and gas crossflow between the fracture and matrix (0.56–0.78). This study has important theoretical guiding significance for triggering and controlling the ATS.
{"title":"Study of the residual carbon oxidation trigger mechanism in fractured oil shale formation under real condition","authors":"Wei Guo , Junfan Pan , Qinchuan Yang , Qiang Li , Sunhua Deng , Chaofan Zhu","doi":"10.1016/j.icheatmasstransfer.2024.108369","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108369","url":null,"abstract":"<div><div>The autothermic pyrolysis in-situ conversion process (ATS) has a considerable advantage in reducing the development costs of oil shale. However, the trigger mechanism of autothermic pyrolysis oxidation reaction in different fractured oil shale formations is not precise. This study conducts a one-dimensional residual carbon oxidation experiment on the oil shale sample, taking into account the overburden pressure. The trigger condition and parameters are determined through the energy analysis during residual carbon oxidation in the fractured oil shale. A trigger simulation model of autothermic pyrolysis oxidation reaction in different fractured oil shale formations is proposed and verified by the temperature field evolution. The results indicate that the heterogeneous oxidation reaction produces a high permeability channel in the oil shale formation, which can further improve the flow conductivity of the oil shale formation. The trigger threshold of the residual carbon oxidation reaction in the fractured oil shale formation was closely associated with the carbon residue concentration (> 2.59 × 10<sup>4</sup> mol/m<sup>3</sup>), oxygen content (>15 %), and gas crossflow between the fracture and matrix (0.56–0.78). This study has important theoretical guiding significance for triggering and controlling the ATS.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108369"},"PeriodicalIF":6.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698790","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}
Pub Date : 2024-11-23DOI: 10.1016/j.icheatmasstransfer.2024.108387
Wang Wu , Zhaowei Ding , Qixiang Yan , Zechang Zhao
The brine artificial ground freezing (AGF) method is an effective construction technique extensively employed in underground engineering reinforcement. In the numerical simulation of soil temperature field associated with the brine-AGF method, researchers typically impose a constant temperature boundary on the surface of the freezing pipe. This approach circumvents the need to simulate brine flow, thereby simplifying the numerical simulation and enhancing computational efficiency. However, questions arise regarding the accuracy of these simulations: Is the soil temperature field consistent with a constant temperature boundary model when considering brine flow? These concerns remain unresolved at present. Consequently, based on the conjugate heat transfer mechanisms, this paper establishes a numerical model for coupling brine-freezing pipe-soil to analyze variations in soil temperature fields under brine turbulent conditions. Compared to the constant temperature boundary model, it was observed that overall soil temperatures in the brine turbulent flow model are generally lower. However, they are 4 °C higher at the bottom of the freezing pipe. Therefore, this paper proposes a modified temperature boundary that incorporates both Reynold's number of brine and freezing pipe depth considerations. Results indicate that this modified temperature boundary yields a soil temperature field closely aligned with that produced by brine flow models. Furthermore, compared with the model test, the modified temperature boundary can respectively reduce the temperature difference from 3.4 °C to 2.1 °C and from 1.5 °C to 0.3 °C when the different brine flow velocities are considered. The proposed modified temperature boundary not only retains advantages such as simplified modeling and rapid computation inherent in constant temperature boundary but also enhances calculation accuracy significantly. This work provides valuable insights for advancements in brine-AGF engineering.
{"title":"Modification on constant temperature boundary considering conjugate heat transfer of brine turbulent flow in brine artificial ground freezing method","authors":"Wang Wu , Zhaowei Ding , Qixiang Yan , Zechang Zhao","doi":"10.1016/j.icheatmasstransfer.2024.108387","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108387","url":null,"abstract":"<div><div>The brine artificial ground freezing (AGF) method is an effective construction technique extensively employed in underground engineering reinforcement. In the numerical simulation of soil temperature field associated with the brine-AGF method, researchers typically impose a constant temperature boundary on the surface of the freezing pipe. This approach circumvents the need to simulate brine flow, thereby simplifying the numerical simulation and enhancing computational efficiency. However, questions arise regarding the accuracy of these simulations: Is the soil temperature field consistent with a constant temperature boundary model when considering brine flow? These concerns remain unresolved at present. Consequently, based on the conjugate heat transfer mechanisms, this paper establishes a numerical model for coupling brine-freezing pipe-soil to analyze variations in soil temperature fields under brine turbulent conditions. Compared to the constant temperature boundary model, it was observed that overall soil temperatures in the brine turbulent flow model are generally lower. However, they are 4 °C higher at the bottom of the freezing pipe. Therefore, this paper proposes a modified temperature boundary that incorporates both Reynold's number of brine and freezing pipe depth considerations. Results indicate that this modified temperature boundary yields a soil temperature field closely aligned with that produced by brine flow models. Furthermore, compared with the model test, the modified temperature boundary can respectively reduce the temperature difference from 3.4 °C to 2.1 °C and from 1.5 °C to 0.3 °C when the different brine flow velocities are considered. The proposed modified temperature boundary not only retains advantages such as simplified modeling and rapid computation inherent in constant temperature boundary but also enhances calculation accuracy significantly. This work provides valuable insights for advancements in brine-AGF engineering.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108387"},"PeriodicalIF":6.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699572","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}
Pub Date : 2024-11-22DOI: 10.1016/j.icheatmasstransfer.2024.108344
Saurabh Tiwari, Supriyo Ghosh
Spatiotemporal variation of the thermal gradient in the melt pool inherited from different heat input patterns or other non-equilibrium transient effects during additive manufacturing can significantly affect the resulting subgrain microstructure evolution. To examine the impact of this variation, we approximate the thermal gradient by various isotherm patterns that move with constant velocity following directional solidification. We report the first three-dimensional phase-field simulations to investigate the effects of isotherm patterns on the cellular structures typically observed in solidified melt pools. Results indicate that small variations in the isotherm can considerably impact the microstructural features. We use appropriate statistical characterizations of the solid fraction, solid percolation, and solute partitioning behavior to demonstrate the influence of isotherm patterns on the dendritic structures and semisolid mushy zones. Consistent with experimental observations, we find that non-planar isotherms produce finer cells and reduced microsegregation compared to planar isotherms. Also, we note that a tilt of the isotherm leads to a tilted state of the resulting cellular arrays. Our findings will help in understanding the qualitative aspects of the influence of temperature gradient patterns on the evolution of solidification morphologies, mushy zones, and secondary phases, which are crucial for the macroscopic description of the solidified material.
{"title":"Effects of isotherm patterns on cellular interface morphologies of melt pool origin","authors":"Saurabh Tiwari, Supriyo Ghosh","doi":"10.1016/j.icheatmasstransfer.2024.108344","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108344","url":null,"abstract":"<div><div>Spatiotemporal variation of the thermal gradient in the melt pool inherited from different heat input patterns or other non-equilibrium transient effects during additive manufacturing can significantly affect the resulting subgrain microstructure evolution. To examine the impact of this variation, we approximate the thermal gradient by various isotherm patterns that move with constant velocity following directional solidification. We report the first three-dimensional phase-field simulations to investigate the effects of isotherm patterns on the cellular structures typically observed in solidified melt pools. Results indicate that small variations in the isotherm can considerably impact the microstructural features. We use appropriate statistical characterizations of the solid fraction, solid percolation, and solute partitioning behavior to demonstrate the influence of isotherm patterns on the dendritic structures and semisolid mushy zones. Consistent with experimental observations, we find that non-planar isotherms produce finer cells and reduced microsegregation compared to planar isotherms. Also, we note that a tilt of the isotherm leads to a tilted state of the resulting cellular arrays. Our findings will help in understanding the qualitative aspects of the influence of temperature gradient patterns on the evolution of solidification morphologies, mushy zones, and secondary phases, which are crucial for the macroscopic description of the solidified material.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108344"},"PeriodicalIF":6.4,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698867","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}
Pub Date : 2024-11-22DOI: 10.1016/j.icheatmasstransfer.2024.108366
Syed Saqib Shah
This research delves into the intricate influence of magnetohydrodynamic orientation on Soret and Dufour effects within inclined, corrugated triangular cavities containing non-Newtonian fluids, underscoring the impacts of magnetic alignment, cavity inclination, and fluid rheology on convective transport dynamics. By systematically transforming the governing partial differential equations into non-dimensional forms using selected similarity variables, the study applies the finite element method (FEM) for computational analysis. The research intricately dissects the influence of multiple interdependent physical parameters on flow morphology, concentration, isotherms, and local Nusselt numbers, which serve as a barometer for the system's heat transfer efficacy. Critical variables under scrutiny for include magnetohydrodynamics (), buoyancy-driven convective forces (), the non-Newtonian nature of Casson fluid (), as well as the cross-diffusion effects epitomized by the Soret () phenomena. Additional dimensionless parameters, such as the Lewis () and Rayleigh numbers (), further characterize the thermal and concentration fields within the cavity, alongside the role of internal heat generation/absorption () mechanisms for fixed value of Darcy number (). The results show that the Casson parameter subtly affects the distribution of thermal energy and particles, which in turn influences flow patterns and convection. In contrast, the Soret parameter has a direct effect on concentration gradients, regulating the layering of solutes within the fluid. It has been found that inclined MHD orientation effects create variations in magnetic fields, which disrupt fluid velocity and affect heat transfer rates. These effects reshape temperature contours, altering isotherm patterns and local thermal gradients. The study underscores the complex interplay of non-linear factors that collectively govern the efficiency of heat and mass transfer processes in non-Newtonian fluids subjected to magnetothermal and buoyancy forces, with broad implications for optimizing industrial and natural convection systems.
{"title":"Magnetohydrodynamic orientation effects on Soret and Dufour phenomena in inclined corrugated triangular cavities with non-Newtonian fluids","authors":"Syed Saqib Shah","doi":"10.1016/j.icheatmasstransfer.2024.108366","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108366","url":null,"abstract":"<div><div>This research delves into the intricate influence of magnetohydrodynamic orientation on Soret and Dufour effects within inclined, corrugated triangular cavities containing non-Newtonian fluids, underscoring the impacts of magnetic alignment, cavity inclination, and fluid rheology on convective transport dynamics. By systematically transforming the governing partial differential equations into non-dimensional forms using selected similarity variables, the study applies the finite element method (FEM) for computational analysis. The research intricately dissects the influence of multiple interdependent physical parameters on flow morphology, concentration, isotherms, and local Nusselt numbers, which serve as a barometer for the system's heat transfer efficacy. Critical variables under scrutiny for include magnetohydrodynamics (<span><math><mn>0</mn><mo>≤</mo><mi>Ha</mi><mo>≤</mo><msup><mn>10</mn><mn>3</mn></msup></math></span>), buoyancy-driven convective forces (<span><math><mn>0</mn><mo>≤</mo><msub><mi>N</mi><mi>χ</mi></msub><mo>≤</mo><mn>20</mn></math></span>), the non-Newtonian nature of Casson fluid (<span><math><mn>0.1</mn><mo>≤</mo><mi>β</mi><mo>≤</mo><mn>1</mn></math></span>), as well as the cross-diffusion effects epitomized by the Soret (<span><math><mo>−</mo><mn>15</mn><mo>≤</mo><msub><mi>S</mi><mi>χ</mi></msub><mo>≤</mo><mn>15</mn></math></span>) phenomena. Additional dimensionless parameters, such as the Lewis (<span><math><mn>0.1</mn><mo>≤</mo><msub><mi>L</mi><mi>ε</mi></msub><mo>≤</mo><mn>50</mn></math></span>) and Rayleigh numbers (<span><math><msup><mn>10</mn><mn>2</mn></msup><mo>≤</mo><msub><mi>R</mi><mi>a</mi></msub><mo>≤</mo><msup><mn>10</mn><mn>5</mn></msup></math></span>), further characterize the thermal and concentration fields within the cavity, alongside the role of internal heat generation/absorption (<span><math><mo>−</mo><mn>10</mn><mo>≤</mo><mi>Δ</mi><mo>≤</mo><mn>10</mn></math></span>) mechanisms for fixed value of Darcy number (<span><math><msub><mi>λ</mi><mi>d</mi></msub><mo>=</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></math></span>). The results show that the Casson parameter subtly affects the distribution of thermal energy and particles, which in turn influences flow patterns and convection. In contrast, the Soret parameter has a direct effect on concentration gradients, regulating the layering of solutes within the fluid. It has been found that inclined MHD orientation effects create variations in magnetic fields, which disrupt fluid velocity and affect heat transfer rates. These effects reshape temperature contours, altering isotherm patterns and local thermal gradients. The study underscores the complex interplay of non-linear factors that collectively govern the efficiency of heat and mass transfer processes in non-Newtonian fluids subjected to magnetothermal and buoyancy forces, with broad implications for optimizing industrial and natural convection systems.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108366"},"PeriodicalIF":6.4,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698868","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}
Pub Date : 2024-11-22DOI: 10.1016/j.icheatmasstransfer.2024.108345
Aditya Narkhede, N. Gnanasekaran, Ajay Kumar Yadav
The present research work examined the thermo-fluidic characteristics of a heat sink packed with octet-structured periodic metal foam having varying porosity (0.83–0.93) and unit cell lengths (UCL) of 2.5–5 for electronic cooling application. AlSi10Mg material is considered for the octet lattice structure with water as the cooling medium, with the inlet velocity ranging from 0.02 to 0.05 and a steady heat flux of 10 applied at base of the substrate. The effect of the porosity, unit cell length, and inlet velocity on pressure gradient, friction factor, Nusselt number, wall temperature, heat transfer coefficient, and thermo-hydraulic performance parameter is analyzed. Larger pressure gradients are observed for lower values of porosity and unit cell length, with a maximum value of approximately 5000 for the thermal system having 0.83 porosity, 2.5 UCL, and 0.05 inlet velocity. The wall temperature drops with a rise in inlet velocity and a reduction in porosity and UCL, with the lowest value of 311 for the case of 0.83 porosity, 2.5 UCL, and 0.05 inlet velocity. The case of 0.83 porosity, 5 UCL, and 0.02 velocity was determined as optimum design based on thermo-hydraulic performance parameter.
{"title":"Detailed thermo-hydraulic investigation of 3D octet lattice structure integrated heat sink","authors":"Aditya Narkhede, N. Gnanasekaran, Ajay Kumar Yadav","doi":"10.1016/j.icheatmasstransfer.2024.108345","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108345","url":null,"abstract":"<div><div>The present research work examined the thermo-fluidic characteristics of a heat sink packed with octet-structured periodic metal foam having varying porosity (0.83–0.93) and unit cell lengths (UCL) of 2.5–5 <span><math><mi>mm</mi></math></span> for electronic cooling application. AlSi10Mg material is considered for the octet lattice structure with water as the cooling medium, with the inlet velocity ranging from 0.02 to 0.05 <span><math><mi>m</mi><mo>/</mo><mi>s</mi></math></span> and a steady heat flux of 10 <span><math><mi>W</mi><mo>/</mo><msup><mi>cm</mi><mn>2</mn></msup></math></span> applied at base of the substrate. The effect of the porosity, unit cell length, and inlet velocity on pressure gradient, friction factor, Nusselt number, wall temperature, heat transfer coefficient, and thermo-hydraulic performance parameter is analyzed. Larger pressure gradients are observed for lower values of porosity and unit cell length, with a maximum value of approximately 5000 <span><math><mi>Pa</mi><mo>/</mo><mi>m</mi></math></span> for the thermal system having 0.83 porosity, 2.5 <span><math><mi>mm</mi></math></span> UCL, and 0.05 <span><math><mi>m</mi><mo>/</mo><mi>s</mi></math></span> inlet velocity. The wall temperature drops with a rise in inlet velocity and a reduction in porosity and UCL, with the lowest value of 311 <span><math><mi>K</mi></math></span> for the case of 0.83 porosity, 2.5 <span><math><mi>mm</mi></math></span> UCL, and 0.05 <span><math><mi>m</mi><mo>/</mo><mi>s</mi></math></span> inlet velocity. The case of 0.83 porosity, 5 <span><math><mi>mm</mi></math></span> UCL, and 0.02 <span><math><mi>m</mi><mo>/</mo><mi>s</mi></math></span> velocity was determined as optimum design based on thermo-hydraulic performance parameter.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108345"},"PeriodicalIF":6.4,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698870","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}
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