Pub Date : 2024-09-24DOI: 10.1016/j.icheatmasstransfer.2024.108112
Effective de-icing technologies are important to the ships and offshore structures in cold regions and air bubble de-icing method is expected to have great potential for application. To deeply understand the ice melting process under point-source bubble flows, especially the heat transfer characteristics, an experimental set-up is designed to explore the influence of the flow rate. According to the shape of the ice bottom surface and the distribution characteristics of bubbles, the ice melting process is divided into flat, concave, and holed ice stages. The ice melting efficiency decreases with the increasing flow rate and when the flow rate increases from 0.5 L/min to 2.0 L/min, the ice melting efficiency decreases by 58.0 %. The stage-averaged heat transfer coefficients of the flat, concave, and holed ice stages decrease successively and all of them increase with the increase of flow rate. Correlations for central and global heat transfer coefficients are established to describe the ice melting process, which fits well with the experimental data with a deviation less than ±15 %. The findings are helpful to the design and optimization of the air bubble de-icing system.
{"title":"Experimental study on heat transfer characteristics of ice melting processes under point-source bubble flows","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108112","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108112","url":null,"abstract":"<div><div>Effective de-icing technologies are important to the ships and offshore structures in cold regions and air bubble de-icing method is expected to have great potential for application. To deeply understand the ice melting process under point-source bubble flows, especially the heat transfer characteristics, an experimental set-up is designed to explore the influence of the flow rate. According to the shape of the ice bottom surface and the distribution characteristics of bubbles, the ice melting process is divided into flat, concave, and holed ice stages. The ice melting efficiency decreases with the increasing flow rate and when the flow rate increases from 0.5 L/min to 2.0 L/min, the ice melting efficiency decreases by 58.0 %. The stage-averaged heat transfer coefficients of the flat, concave, and holed ice stages decrease successively and all of them increase with the increase of flow rate. Correlations for central and global heat transfer coefficients are established to describe the ice melting process, which fits well with the experimental data with a deviation less than ±15 %. The findings are helpful to the design and optimization of the air bubble de-icing system.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314798","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 : 2024-09-23DOI: 10.1016/j.icheatmasstransfer.2024.108041
Corrugated circular dimple absorber CCD as a heat transfer augmentation is introduced for line focusing solar receiver. It is designed to increase heat transfer performance with minimal increase of pressure drop. Meanwhile, computational fluid dynamics (CFD) analysis which is widely used is conducted by using ANSYS software to study outlet working fluid temperature, absorber temperature distribution, Nusselt number, specific heat loss, specific pressure drop and performance evaluation criteria (PEC). Heat transfer working fluid is Syltherm 800, a thermal oil which is extensively utilized in concentrating solar thermal power plant. The mass flow rate values are between 0.3 kg/s and 4 kg/s, the inlet temperatures of working fluid are 375 K and 650 K and concentrated heat flux is 100,000 W/m. At 375 K inlet working fluid temperature, simulation results showed that corrugated circular dimple absorber can improve outlet working fluid temperature up to 8 K over 4 m absorber length and performance evaluation criteria reaches 3.28. This energy gain is obtained from lower specific heat loss to ambient due to higher Nusselt number. Increasing inlet working fluid temperature to 650 K will reduce thermal energy output since the specific heat loss increases from 137 W/m to 644 W/m due to radiation at higher temperature and emissivity value. Nusselt number rises from 230 to 521 and maximum absorber temperature decreases from 1036 K to 970 K. The specific pressure drop rises from 11 Pa/m in a smooth absorber to 41 Pa/m in a corrugated circular dimple absorber due to surface changes, but the performance evaluation criteria is at 1.31. In conclusion, CCD design can improve heat transfer performance with minimum pressure drop penalty indicated by higher PEC values.
{"title":"Corrugated circular dimple absorber for heat transfer augmentation on parabolic trough solar receiver","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108041","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108041","url":null,"abstract":"<div><div>Corrugated circular dimple absorber <span><math><mo>(</mo></math></span>CCD<span><math><mo>)</mo></math></span> as a heat transfer augmentation is introduced for line focusing solar receiver. It is designed to increase heat transfer performance with minimal increase of pressure drop. Meanwhile, computational fluid dynamics (CFD) analysis which is widely used is conducted by using ANSYS software to study outlet working fluid temperature, absorber temperature distribution, Nusselt number, specific heat loss, specific pressure drop and performance evaluation criteria (PEC). Heat transfer working fluid is Syltherm 800, a thermal oil which is extensively utilized in concentrating solar thermal power plant. The mass flow rate values are between 0.3 kg/s and 4 kg/s, the inlet temperatures of working fluid are 375 K and 650 K and concentrated heat flux is 100,000 W/m<span><math><msup><mrow></mrow><mn>2</mn></msup></math></span>. At 375 K inlet working fluid temperature, simulation results showed that corrugated circular dimple absorber can improve outlet working fluid temperature up to 8 K over 4 m absorber length and performance evaluation criteria reaches 3.28. This energy gain is obtained from lower specific heat loss to ambient due to higher Nusselt number. Increasing inlet working fluid temperature to 650 K will reduce thermal energy output since the specific heat loss increases from 137 W/m to 644 W/m due to radiation at higher temperature and emissivity value. Nusselt number rises from 230 to 521 and maximum absorber temperature decreases from 1036 K to 970 K. The specific pressure drop rises from 11 Pa/m in a smooth absorber to 41 Pa/m in a corrugated circular dimple absorber due to surface changes, but the performance evaluation criteria is at 1.31. In conclusion, CCD design can improve heat transfer performance with minimum pressure drop penalty indicated by higher PEC values.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0735193324008030/pdfft?md5=4d9fb295f11990e2a4277edc4fd4a95d&pid=1-s2.0-S0735193324008030-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-23DOI: 10.1016/j.icheatmasstransfer.2024.108093
In the wake of the radically increased development of small electronic devices, the area available for heat dissipation is getting increasingly limited. As a result, ultrathin vapor chambers are commonly utilized for a variety of thermal management systems. Wire meshes are often applied as wicks for ultrathin vapor chambers due to their excellent flexibility and controllable thickness. However, wire mesh suffers from the limitations of shedding and low permeability. In contrast, grooved wicks provide high permeability. Vapor chambers using grooved wicks can be made thinner since the grooves can be machined directly on the copper plate. In this work, the V-shaped micro-grooves with a depth of 110 μm and a width of 40 μm (aspect ratio of 2.8:1) and the V-shaped micro-grooves, trapezoidal micro-grooves and composite micro-grooves with a width of 70 μm and a depth of 50 μm were prepared on the copper plate by an ultrafast laser. Under the same aspect ratio, the capillary rising performance of micro-grooves with different cross-sectional shapes was studied, and the results showed that V-shaped micro-grooves exhibit better capillary rising performance than trapezoidal micro-grooves and composite micro-grooves. The capillary rising performance of V-shaped micro-grooves with an aspect ratio of 1 to 2.8 was further investigated. Both the capillary rising limit and rate increase with the increase of the aspect ratio of the micro-grooves, and the liquid level could rise by 70 mm at about 12 s when the depth-width ratio of the V-shaped micro-groove was 2.8. The thermal performance and temperature uniformity of the vapor chamber is enhanced by the high aspect ratio V-shaped micro-groove wicks. It was found that the minimum thermal resistance of the vapor chambers reached 0.097 °C/W, and the maximum temperature difference in the condenser of the vapor chambers was 0.56 °C.
随着小型电子设备的迅猛发展，可用于散热的面积越来越有限。因此，超薄蒸发腔通常被用于各种热管理系统。由于金属丝网具有良好的柔韧性和厚度可控性，因此经常被用作超薄蒸气室的灯芯。然而，金属丝网存在脱落和渗透率低的局限性。相比之下，沟纹吸芯具有高渗透性。由于沟槽可以直接在铜板上加工，因此使用沟槽灯芯的蒸气室可以做得更薄。在这项工作中，利用超快激光在铜板上制备了深度为 110 μm、宽度为 40 μm（纵横比为 2.8:1）的 V 形微槽、宽度为 70 μm、深度为 50 μm 的梯形微槽和复合微槽。结果表明，V 形微槽的毛细管上升性能优于梯形微槽和复合微槽。此外，还进一步研究了长宽比为 1 至 2.8 的 V 形微槽的毛细管上升性能。当 V 形微槽的深宽比为 2.8 时，毛细管上升的极限和速率都随微槽长宽比的增加而增加，液面可在 12 秒左右上升 70 毫米。高纵横比 V 型微凹槽灯芯提高了蒸发室的热性能和温度均匀性。研究发现，蒸发室的最小热阻达到 0.097 ℃/W，蒸发室冷凝器中的最大温差为 0.56 ℃。
{"title":"Enhancing the thermal performance of ultrathin vapor chambers by using high capillary performance micro-groove wicks prepared by ultrafast laser micromachining","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108093","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108093","url":null,"abstract":"<div><div>In the wake of the radically increased development of small electronic devices, the area available for heat dissipation is getting increasingly limited. As a result, ultrathin vapor chambers are commonly utilized for a variety of thermal management systems. Wire meshes are often applied as wicks for ultrathin vapor chambers due to their excellent flexibility and controllable thickness. However, wire mesh suffers from the limitations of shedding and low permeability. In contrast, grooved wicks provide high permeability. Vapor chambers using grooved wicks can be made thinner since the grooves can be machined directly on the copper plate. In this work, the V-shaped micro-grooves with a depth of 110 μm and a width of 40 μm (aspect ratio of 2.8:1) and the V-shaped micro-grooves, trapezoidal micro-grooves and composite micro-grooves with a width of 70 μm and a depth of 50 μm were prepared on the copper plate by an ultrafast laser. Under the same aspect ratio, the capillary rising performance of micro-grooves with different cross-sectional shapes was studied, and the results showed that V-shaped micro-grooves exhibit better capillary rising performance than trapezoidal micro-grooves and composite micro-grooves. The capillary rising performance of V-shaped micro-grooves with an aspect ratio of 1 to 2.8 was further investigated. Both the capillary rising limit and rate increase with the increase of the aspect ratio of the micro-grooves, and the liquid level could rise by 70 mm at about 12 s when the depth-width ratio of the V-shaped micro-groove was 2.8. The thermal performance and temperature uniformity of the vapor chamber is enhanced by the high aspect ratio V-shaped micro-groove wicks. It was found that the minimum thermal resistance of the vapor chambers reached 0.097 °C/W, and the maximum temperature difference in the condenser of the vapor chambers was 0.56 °C.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311916","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 : 2024-09-23DOI: 10.1016/j.icheatmasstransfer.2024.108107
Inspired by fractal, two units for infrared-band absorbing metamaterial are proposed in this paper. Unit I uses an additive method which is adding branches based on the cross structure, while Unit II adopts a subtractive method which is etching gaps in the material block. By comparing each construction step of the fractal, it can be confirmed that the fractal can improve the absorption effect without changing the period and thickness of the metamaterial. Then, the two units are put together, and the plane on which Unit 2 is placed is tilted to form an array. This operation is to explore better absorption effects and angle stability. Ultimately, the array achieves good absorption: under normal incident and the polarization angle equal to 45°, the array has an average absorptivity of 94.6 % in the range of 100–2183.3 nm. Under a large incident angle (45°), the TM and TE modes behave differently, but both maintain a fairly high absorptivity. The average absorptivity of TM waves is 96 %, and the average absorptivity of TE waves is 90.9 %, with the lowest point being 84 %. The high absorptivity in the infrared band and the angular stability allow the design to be used as a heat emitter or solar absorber. At 2000 K, this metamaterial can achieve 86.66 % thermal emitting efficiency. For sunlight, the spectral absorption efficiency reaches 94.67 %. Afterward, this work also uses the equivalent circuit to explain the mechanism of absorption, and uses parameter retrieval to obtain the effective impedance and permittivity of the metamaterial. The innovations of this work are listed. First, using the fractal concept to improve the absorption effect without changing the thickness so that the device has an advantage in thickness. Second, by placing some units on the slope, the absorption effect is improved and angular stability is obtained. The advantage of this method of combining two units is that the inclined placement makes the advantages of different units complementary and reduces the requirements for the design of a single unit. This work has potential applications in the fields of thermal radiation and solar energy collection.
受分形的启发，本文提出了红外波段吸收超材料的两个单元。单元 I 采用加法，即在交叉结构的基础上增加分支；单元 II 采用减法，即在材料块上蚀刻间隙。通过比较分形的各个构造步骤，可以证实分形可以在不改变超材料周期和厚度的情况下提高吸收效果。然后，将两个单元放在一起，并将单元 2 所在的平面倾斜，形成一个阵列。这一操作是为了探索更好的吸收效果和角度稳定性。最终，阵列实现了良好的吸收效果：在正常入射和偏振角等于 45° 的情况下，阵列在 100-2183.3 nm 范围内的平均吸收率为 94.6%。在较大的入射角（45°）下，TM 和 TE 模式的表现不同，但都保持了相当高的吸收率。TM 波的平均吸收率为 96%，TE 波的平均吸收率为 90.9%，最低点为 84%。红外波段的高吸收率和角度稳定性使该设计可用作热发射器或太阳能吸收器。在 2000 K 的温度下，这种超材料的热辐射效率可达 86.66%。对于太阳光，其光谱吸收效率达到 94.67%。随后，这项研究还利用等效电路解释了吸收机制，并通过参数检索获得了超材料的有效阻抗和介电常数。本研究的创新点如下。首先，利用分形概念在不改变厚度的情况下提高吸收效果，使器件在厚度上具有优势。其次，通过在斜面上放置一些单元，改善了吸收效果，并获得了角度稳定性。这种将两个单元组合在一起的方法的优点在于，倾斜放置使不同单元的优势互补，降低了对单个单元设计的要求。这项工作在热辐射和太阳能收集领域具有潜在的应用价值。
{"title":"Large angle stable metamaterial for visible and infrared band absorption and thermal emitter inspired by fractal","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108107","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108107","url":null,"abstract":"<div><div>Inspired by fractal, two units for infrared-band absorbing metamaterial are proposed in this paper. Unit I uses an additive method which is adding branches based on the cross structure, while Unit II adopts a subtractive method which is etching gaps in the material block. By comparing each construction step of the fractal, it can be confirmed that the fractal can improve the absorption effect without changing the period and thickness of the metamaterial. Then, the two units are put together, and the plane on which Unit 2 is placed is tilted to form an array. This operation is to explore better absorption effects and angle stability. Ultimately, the array achieves good absorption: under normal incident and the polarization angle equal to 45°, the array has an average absorptivity of 94.6 % in the range of 100–2183.3 nm. Under a large incident angle (45°), the TM and TE modes behave differently, but both maintain a fairly high absorptivity. The average absorptivity of TM waves is 96 %, and the average absorptivity of TE waves is 90.9 %, with the lowest point being 84 %. The high absorptivity in the infrared band and the angular stability allow the design to be used as a heat emitter or solar absorber. At 2000 K, this metamaterial can achieve 86.66 % thermal emitting efficiency. For sunlight, the spectral absorption efficiency reaches 94.67 %. Afterward, this work also uses the equivalent circuit to explain the mechanism of absorption, and uses parameter retrieval to obtain the effective impedance and permittivity of the metamaterial. The innovations of this work are listed. First, using the fractal concept to improve the absorption effect without changing the thickness so that the device has an advantage in thickness. Second, by placing some units on the slope, the absorption effect is improved and angular stability is obtained. The advantage of this method of combining two units is that the inclined placement makes the advantages of different units complementary and reduces the requirements for the design of a single unit. This work has potential applications in the fields of thermal radiation and solar energy collection.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311915","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 : 2024-09-21DOI: 10.1016/j.icheatmasstransfer.2024.108097
The purpose is to produce a benchmarked commercial Volume of Fluid (VOF)-to-Discrete Phase Modeling (DPM) numerical algorithm using an experimental study of high-viscosity jet fuel blend C-3. Where the mesh resolution was too coarse to resolve sufficient gas-liquid interfacial curvature, the solver automatically converted VOF biofuel phase mass, momentum, and energy into the equivalent DPM biofuel phase at the sub-grid scale level. Particular attention herein was given to the sensitivity of the results to various numerical degrees of freedom related to the local criteria for conversion of a biofuel from VOF to DPM. The proliferation of commercial simulation tools mandates detailed parametric evaluations. It was found that, while instantaneous conversion rates were extremely sensitive to conversion criteria, atomization physics were not sensitive to the conversion rate effects. Also, this flow system exhibited an outstanding dependence on simulated azimuthal angle, rendering lower order models ineffective. Data sampling methods and durations, along with mesh resolution, were explored such that a particular set of parameters provided a validated model.
{"title":"Sensitivity analysis of a multi-scale biofuel primary atomization simulation tool","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108097","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108097","url":null,"abstract":"<div><div>The purpose is to produce a benchmarked commercial Volume of Fluid (VOF)-to-Discrete Phase Modeling (DPM) numerical algorithm using an experimental study of high-viscosity jet fuel blend C-3. Where the mesh resolution was too coarse to resolve sufficient gas-liquid interfacial curvature, the solver automatically converted VOF biofuel phase mass, momentum, and energy into the equivalent DPM biofuel phase at the sub-grid scale level. Particular attention herein was given to the sensitivity of the results to various numerical degrees of freedom related to the local criteria for conversion of a biofuel from VOF to DPM. The proliferation of commercial simulation tools mandates detailed parametric evaluations. It was found that, while instantaneous conversion rates were extremely sensitive to conversion criteria, atomization physics were not sensitive to the conversion rate effects. Also, this flow system exhibited an outstanding dependence on simulated azimuthal angle, rendering lower order models ineffective. Data sampling methods and durations, along with mesh resolution, were explored such that a particular set of parameters provided a validated model.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312676","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 : 2024-09-21DOI: 10.1016/j.icheatmasstransfer.2024.108098
Heat transfer in phase change materials (PCMs) is complex because the melting and freezing fronts change as functions of stored or released heat. In prior attempts to optimize heat exchangers (HXs) in one or two dimensions, complex geometry has often been used to maximize the melt and freeze front area. This complex geometry is difficult and hence expensive to construct. This paper proposes a multiple-scale 3D finite element modeling approach to design fin-tube HXs for low-cost latent thermal energy storage applications. The optimal fin and tube designs were determined at three scales (unit-scale, medium-scale, and large-scale) by modeling the melt and freeze front in three dimensions and using measured bulk thermal properties. The finite element model was validated by comparing it with the experimental data for a referenced design of a similar type. The results indicate that commercially available organic PCMs with low conductivity (<0.3 W/m·K) can have charge and discharge times appropriate for building thermal energy storage (i.e., 4–5 h) with fin-tube HX designs at costs <$26/kWh, even when the temperature difference (5.56 °C) between the heat transfer fluid and the PCM phase change temperature is small. However, as the HX increases in length, the temperature reduction along the tube limits some larger-scale designs.
{"title":"Low-cost fin-tube heat exchanger design for building thermal energy storage using phase change material","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108098","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108098","url":null,"abstract":"<div><div>Heat transfer in phase change materials (PCMs) is complex because the melting and freezing fronts change as functions of stored or released heat. In prior attempts to optimize heat exchangers (HXs) in one or two dimensions, complex geometry has often been used to maximize the melt and freeze front area. This complex geometry is difficult and hence expensive to construct. This paper proposes a multiple-scale 3D finite element modeling approach to design fin-tube HXs for low-cost latent thermal energy storage applications. The optimal fin and tube designs were determined at three scales (unit-scale, medium-scale, and large-scale) by modeling the melt and freeze front in three dimensions and using measured bulk thermal properties. The finite element model was validated by comparing it with the experimental data for a referenced design of a similar type. The results indicate that commercially available organic PCMs with low conductivity (<0.3 W/m·K) can have charge and discharge times appropriate for building thermal energy storage (i.e., 4–5 h) with fin-tube HX designs at costs <$26/kWh, even when the temperature difference (5.56 °C) between the heat transfer fluid and the PCM phase change temperature is small. However, as the HX increases in length, the temperature reduction along the tube limits some larger-scale designs.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311913","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 : 2024-09-21DOI: 10.1016/j.icheatmasstransfer.2024.108080
Scale-resolving hybrid RANS-LES models are increasingly being used to numerically simulate wall-bounded turbulent flows. Such models typically display modeled stress depletion within attached turbulent boundary layers, which in turn leads to underprediction of wall shear stress. The interpolated hybrid RANS-LES (IRL) model, recently proposed by Jaiswal et al. (Computers & Fluids, 2023, 106,086), avoids modeled stress depletion by simultaneously evolving the Large Eddy Simulation (LES) equation for filtered velocity and Reynolds Averaged Navier Stokes (RANS) equation for turbulent eddy viscosity on the same computational grid. A hybrid turbulent eddy viscosity, interpolated from RANS eddy viscosity and effective LES eddy viscosity, is used to correct the mean momentum equation near the wall. In this work, IRL has been extended to non-isothermal flows, and a more general formulation, termed as the Interpolated Reynolds-Stress RANS-LES (IRRL) technique, is also presented, in which the full turbulent Reynolds stress/flux is interpolated over the hybrid region. Results from simulations of canonical turbulent flow geometries have been used to evaluate the performance of non-isothermal IRL and IRRL solvers.
{"title":"Development of interpolation based RANS-LES solvers for non-isothermal wall-bounded turbulent flows","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108080","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108080","url":null,"abstract":"<div><div>Scale-resolving hybrid RANS-LES models are increasingly being used to numerically simulate wall-bounded turbulent flows. Such models typically display modeled stress depletion within attached turbulent boundary layers, which in turn leads to underprediction of wall shear stress. The interpolated hybrid RANS-LES (IRL) model, recently proposed by Jaiswal et al. (Computers & Fluids, 2023, 106,086), avoids modeled stress depletion by simultaneously evolving the Large Eddy Simulation (LES) equation for filtered velocity and Reynolds Averaged Navier Stokes (RANS) equation for turbulent eddy viscosity on the same computational grid. A hybrid turbulent eddy viscosity, interpolated from RANS eddy viscosity and effective LES eddy viscosity, is used to correct the mean momentum equation near the wall. In this work, IRL has been extended to non-isothermal flows, and a more general formulation, termed as the Interpolated Reynolds-Stress RANS-LES (IRRL) technique, is also presented, in which the full turbulent Reynolds stress/flux is interpolated over the hybrid region. Results from simulations of canonical turbulent flow geometries have been used to evaluate the performance of non-isothermal IRL and IRRL solvers.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311914","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 : 2024-09-21DOI: 10.1016/j.icheatmasstransfer.2024.108091
Studying cracks in aluminum (Al) nanosheets is crucial because it enhances our understanding of their mechanical properties and failure mechanisms, which are vital for applications in lightweight structures, electronics, and nanotechnology. In this study, different levels of an external electric field (EF) (1, 2, 3, and 5 V/Å) were used to see how they affected the growth of nanocracks in Al nanoplates. This investigation was carried out utilizing molecular dynamics simulation and LAMMPS software. Increasing EFA to 2 V/Å increased to maximum (Max) stress from 230.567 to 242.032 GPa. Furthermore, increasing the voltage to 5 V/Å reduced Max stress to 230.567 GPa. Max (Vel) occurred in the presence of 2 V/Å which reached 14.2192 Å/ps. The increase in atomic Vel in Al nanoplates can be attributed to enhanced atomic collisions and energy transfer among atoms as the EFA increases to 5 V/Å, the Vel declined to 11.9908 Å/ps. On the other hand, the outputs predicted the atomic evolution of designed Al nanoplates can manipulate the EF value changes. Numerically, by changing the EF parameter from 1 to 5 V/Å, the nano-crack length value varied from 27.87 to 30.16 Å. Physically, this structural evolution occurred through changes in interaction energy (mean attraction energy) within various regions of Al nanoplates. In industrial cases, this nano-crack length manipulation by EF amplitude parameter can be used to prepare atomic nanoplates with different resistances to the crack growth process.
{"title":"Effects of variable electric field on crack growth of aluminum nanoplate: A molecular dynamics approach","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108091","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108091","url":null,"abstract":"<div><div>Studying cracks in aluminum (Al) nanosheets is crucial because it enhances our understanding of their mechanical properties and failure mechanisms, which are vital for applications in lightweight structures, electronics, and nanotechnology. In this study, different levels of an external electric field (EF) (1, 2, 3, and 5 V/Å) were used to see how they affected the growth of nanocracks in Al nanoplates. This investigation was carried out utilizing molecular dynamics simulation and LAMMPS software. Increasing EFA to 2 V/Å increased to maximum (Max) stress from 230.567 to 242.032 GPa. Furthermore, increasing the voltage to 5 V/Å reduced Max stress to 230.567 GPa. Max (Vel) occurred in the presence of 2 V/Å which reached 14.2192 Å/ps. The increase in atomic Vel in Al nanoplates can be attributed to enhanced atomic collisions and energy transfer among atoms as the EFA increases to 5 V/Å, the Vel declined to 11.9908 Å/ps. On the other hand, the outputs predicted the atomic evolution of designed Al nanoplates can manipulate the EF value changes. Numerically, by changing the EF parameter from 1 to 5 V/Å, the nano-crack length value varied from 27.87 to 30.16 Å. Physically, this structural evolution occurred through changes in interaction energy (mean attraction energy) within various regions of Al nanoplates. In industrial cases, this nano-crack length manipulation by EF amplitude parameter can be used to prepare atomic nanoplates with different resistances to the crack growth process.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312677","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 : 2024-09-21DOI: 10.1016/j.icheatmasstransfer.2024.108065
Thermal contact conductance (TCC) is such a common parameter that is simple to understand but difficult to determine in heat transfer process. TCC can bring a large uncertainty in the thermal analysis of the whole system in many engineering applications, such as the cooling of heat pipe reactors, heat dissipation of the chip and finned-tube heat exchangers; besides, it can also reduce the heat transfer efficiency, thus obtaining accurate TCC and controlling it can be meaningful for high-efficiency thermal management. Although enough attention was paid to TCC in the last few decades, however, there is still a gap needed to fill in TCC research. In this article, a comprehensive review on TCC of macroscale and conforming contact is summarized and commented. The review contains the trend and main progress of TCC, including theoretical analysis, experimental measurement and numerical simulation, and the limitations and advantages of these methods are mentioned and commented. As one of common and conforming contact cases, the TCC at the interface of concentric cylinder surface is mentioned and discussed. Besides, the main methods of controlling TCC is also reviewed. Finally, the prospects and challenges of TCC is addressed.
{"title":"A review of thermal contact conductance research of conforming contact surfaces","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108065","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108065","url":null,"abstract":"<div><div>Thermal contact conductance (TCC) is such a common parameter that is simple to understand but difficult to determine in heat transfer process. TCC can bring a large uncertainty in the thermal analysis of the whole system in many engineering applications, such as the cooling of heat pipe reactors, heat dissipation of the chip and finned-tube heat exchangers; besides, it can also reduce the heat transfer efficiency, thus obtaining accurate TCC and controlling it can be meaningful for high-efficiency thermal management. Although enough attention was paid to TCC in the last few decades, however, there is still a gap needed to fill in TCC research. In this article, a comprehensive review on TCC of macroscale and conforming contact is summarized and commented. The review contains the trend and main progress of TCC, including theoretical analysis, experimental measurement and numerical simulation, and the limitations and advantages of these methods are mentioned and commented. As one of common and conforming contact cases, the TCC at the interface of concentric cylinder surface is mentioned and discussed. Besides, the main methods of controlling TCC is also reviewed. Finally, the prospects and challenges of TCC is addressed.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311912","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 : 2024-09-20DOI: 10.1016/j.icheatmasstransfer.2024.108096
Phase change materials (PCMs) play a crucial role in energy storage and heat transfer applications by allowing for the storage and release of significant amounts of energy during phase changes. However, the PCM suffers from an inherent low thermal conductivity, suppressing the transported heat during the charging and discharging process. The fins are considered a significant technique for augmenting the thermal features of PCM storage systems. This review explores the novel application of “L,” T,“ and “Y” shapes fins to improve heat transmission in PCM systems. The review aimed to examine how various fin shapes and orientations affect the overall efficiency of PCM systems. It is reported that substantial enhancements in melting time, thermal performance, and heat transfer efficiency result from the inclusion of fins. By optimizing the dimensions and orientations of these fins, significant enhancements were noticed in both the melting/solidification efficiency and the performance of the PCM thermal system. This review paper is of great significance as it brings together and combines existing research findings, providing insights into the potential of new fin designs to transform PCM applications. This article provides a detailed analysis of the advantages of fins shaped like alphabets, which can lead to the creation of thermal energy storage systems that are both more effective and environmentally friendly.
{"title":"Heat transfer enhancement of phase change materials using letters-shaped fins: A review","authors":"","doi":"10.1016/j.icheatmasstransfer.2024.108096","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108096","url":null,"abstract":"<div><div>Phase change materials (PCMs) play a crucial role in energy storage and heat transfer applications by allowing for the storage and release of significant amounts of energy during phase changes. However, the PCM suffers from an inherent low thermal conductivity, suppressing the transported heat during the charging and discharging process. The fins are considered a significant technique for augmenting the thermal features of PCM storage systems. This review explores the novel application of “L,” T,“ and “Y” shapes fins to improve heat transmission in PCM systems. The review aimed to examine how various fin shapes and orientations affect the overall efficiency of PCM systems. It is reported that substantial enhancements in melting time, thermal performance, and heat transfer efficiency result from the inclusion of fins. By optimizing the dimensions and orientations of these fins, significant enhancements were noticed in both the melting/solidification efficiency and the performance of the PCM thermal system. This review paper is of great significance as it brings together and combines existing research findings, providing insights into the potential of new fin designs to transform PCM applications. This article provides a detailed analysis of the advantages of fins shaped like alphabets, which can lead to the creation of thermal energy storage systems that are both more effective and environmentally friendly.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311919","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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