Case Studies in Thermal Engineering最新文献_第7页

Investigation on dynamic characteristics of droplet impact on surfaces with different rough microstructures based on lattice Boltzmann method 基于晶格玻尔兹曼法研究液滴撞击不同粗糙微结构表面的动态特性

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-09 DOI: 10.1016/j.csite.2024.105252

Constructing microstructures on smooth surfaces is significant for 3D printing technology and surface self-cleaning effects in engineering applications. This paper uses the lattice Boltzmann method (LBM) to study the droplet impact behavior on different microstructured surfaces: right-triangle, semicircular, and rectangular microstructures. The formulas for calculating the surface wetting characteristics of different microstructures are derived theoretically, the difference between simulation results and those from theoretical analyses is less than 5 %. The increase of the microstructure column height h may eventually lead to the disappearance of the Wenzel mode. The droplet impact on the microstructured hydrophilic surface can accelerate the droplet to the stable stage and reduce the excessive impact effect. The droplet impacts on the superhydrophobic microstructured surface can accelerate the rebound separation and shorten the time to reach the stable stage. When droplets impact the superhydrophobic surface of the right-triangle microstructure, a secondary separation phenomenon will occur, resulting in the maximum rebound height and the maximum reduction of the near-wall density. The superhydrophobic right-triangle microstructured surface can more effectively promote self-cleaning.

在光滑表面上构建微结构对于三维打印技术和工程应用中的表面自清洁效果意义重大。本文采用晶格玻尔兹曼法（LBM）研究了液滴在不同微结构表面（直角三角形、半圆形和矩形微结构）上的撞击行为。不同微结构表面润湿特性的计算公式是通过理论推导得出的，模拟结果与理论分析结果的差异小于 5%。微结构柱高 h 的增加可能最终导致温泽尔模式的消失。液滴撞击微结构亲水表面可加速液滴进入稳定阶段，减少过度撞击效应。液滴撞击超疏水微结构表面可加速反弹分离，缩短达到稳定阶段的时间。当液滴撞击直角三角形微结构的超疏水表面时，会发生二次分离现象，导致反弹高度最大，近壁密度降低最大。超疏水的直角三角形微结构表面能更有效地促进自清洁。

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引用次数: 0

Analysis and optimization of a high-speed generator's cooling structure based on Taguchi method 基于田口方法的高速发电机冷却结构分析与优化

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-08 DOI: 10.1016/j.csite.2024.105250

To increase the power density of the original generator, it is desired to boost the generator's power to 1.2 times its original capacity. However, the cooling structure of the original generator cannot meet the heat dissipation requirements of the upgraded power level. It necessitates a redesign of the cooling structure. For the stator, water pipes through the stator core yoke are added; for the rotor, a novel rotor cooling structure is designed. The structure includes the groove bottom vent beneath the rotor excitation winding and the radial auxiliary grooves on the sides. The airflow passes through the groove bottom vent and then follows the radial auxiliary grooves until it reaches the air gap. It can efficiently remove the heat from the rotor excitation winding. The results of the new scheme are discussed. When comparing the new scheme with the original one, the highest temperature of the stator winding decreases by 20.6k, while the one of the rotor excitation winding does by 23.7K. To further improve the cooling structure, the Taguchi method is employed. The optimization variables include the area of the stator back vent, the number of radial auxiliary grooves, and the height of the groove bottom vent. The optimization objectives are the highest temperature of the stator winding, the highest temperature of the rotor excitation winding, the air friction loss, and the inlet-outlet static pressure difference. By analyzing the variance and range of the results, the improved scheme is obtained. Comparing the improved scheme with the new one, the temperature distribution difference between them is negligible. The improved scheme reduces the air frictional loss by 10.7 %, but increases the inlet-outlet static pressure difference by 8.0 %.

为了提高原有发电机的功率密度，希望将发电机的功率提升至原来的 1.2 倍。然而，原有发电机的冷却结构无法满足功率升级后的散热要求。这就需要重新设计冷却结构。在定子方面，增加了穿过定子铁芯轭的水管；在转子方面，设计了新颖的转子冷却结构。该结构包括转子励磁绕组下方的槽底通风口和两侧的径向辅助槽。气流穿过槽底通风口，然后沿着径向辅助槽到达气隙。它能有效地去除转子励磁绕组的热量。本文讨论了新方案的结果。新方案与原方案相比，定子绕组的最高温度降低了 20.6 千帕，而转子励磁绕组的最高温度降低了 23.7 千帕。为了进一步改进冷却结构，采用了田口方法。优化变量包括定子后通风口的面积、径向辅助槽的数量和槽底通风口的高度。优化目标是定子绕组的最高温度、转子励磁绕组的最高温度、空气摩擦损耗和入口-出口静压差。通过分析结果的方差和范围，得出了改进方案。将改进方案与新方案进行比较，两者之间的温度分布差异可以忽略不计。改进方案减少了 10.7 % 的空气摩擦损耗，但增加了 8.0 % 的入口-出口静压差。

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引用次数: 0

Experimental study on thermal load characteristics of a U-bend pulse detonation combustor U 形弯曲脉冲爆燃燃烧器热负荷特性实验研究

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-08 DOI: 10.1016/j.csite.2024.105254

The performance of pulse detonation turbine engines (PDTE) surpasses that of conventional turbine engines, primarily due to the pressure gain combustion process inherent in PDTE. A U-bend pulse detonation combustor (PDC) with a compact axial length was designed to meet the requirements of PDTE. However, the PDC introduces complex thermal management challenges. In this study, the wall temperature along the U-bend PDC was experimentally measured under various operating conditions, the thermal load characteristics were investigated. The results indicate that the external wall temperature increases monotonically with prolonged operation, whereas the internal wall temperature exhibits periodic fluctuations corresponding to the periodic filling and combustion process in the PDC. The temperature difference between the internal and external walls increases, then decreases over time, eventually fluctuates within a narrow temperature range. The wall temperature was observed to increase along the flow direction, peaking at 811 °C at 30 Hz at the location where the detonation wave is generated. Similarly, the heat flux of the PDC first increases, then decreases, and eventually reaches a constant value, indicating thermal equilibrium. The heat flux represents a significant energy loss, with the detonation section being the area of highest heat loss, reaching approximately 90.5 kW/m² at 30 Hz.

脉冲爆燃涡轮发动机（PDTE）的性能超过了传统的涡轮发动机，这主要归功于脉冲爆燃涡轮发动机固有的增压燃烧过程。为满足 PDTE 的要求，设计了一种轴向长度紧凑的 U 形弯管脉冲爆燃燃烧器（PDC）。然而，PDC 带来了复杂的热管理挑战。本研究通过实验测量了 U 形弯曲 PDC 在各种工作条件下的壁温，并研究了热负荷特性。结果表明，外壁温度随着长时间运行而单调上升，而内壁温度则呈现周期性波动，这与 PDC 的周期性填充和燃烧过程相对应。内外壁之间的温差先是增大，然后随着时间的推移逐渐减小，最终在一个较窄的温度范围内波动。观察到内壁温度沿流动方向升高，在产生爆轰波的位置，30 Hz 时达到峰值 811 °C。同样，PDC 的热通量先上升后下降，最终达到恒定值，表明热平衡。热通量代表了大量的能量损失，起爆段是热损失最大的区域，在 30 Hz 时达到约 90.5 kW/m2。

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引用次数: 0

Numerical analysis of rack-based data center cooling with rear door heat exchanger (RDHx): Interrelationship between thermal performance and energy efficiency 采用后门热交换器 (RDHx) 的机架式数据中心冷却数值分析：热性能与能效之间的相互关系

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-05 DOI: 10.1016/j.csite.2024.105247

This study presents a comprehensive numerical analysis of thermal performance and energy efficiency, IT operating environment, and thermal performance of the RDHx system, a rack-based cooling solution for high-density IT power using air-cooled equipment. A 150 kW IT module and RDHx cooling system were designed and evaluated, and CFD numerical analysis confirmed that RDHx maintains a stable IT environment within ASHRAE standards at a supply air temperature of 24 °C. Additionally, the chilled water supply temperature for the secondary CDU can be increased to 14 °C, and for the primary chiller to 12 °C. A central chilled water system for a 30 MW reference data center was designed and analyzed, showing increased efficiency with a 12 °C supply temperature and varying condenser water return temperatures in winter, resulting in an annual PUE_cooling range of 1.25–1.33, with an average of 1.27. The annual energy consumption distribution for rack-based cooling is approximately 46 % from chillers, 21 % from fans, and 33 % from pumps. These results provide crucial insights into data center cooling and support the application of the RDHx system in high-density data centers, with future validation involving a field mock-up test of a 150 kW IT module.

本研究对 RDHx 系统的热性能和能效、IT 运行环境以及热性能进行了全面的数值分析，RDHx 系统是一种基于机架的冷却解决方案，适用于使用风冷设备的高密度 IT 电源。对 150 千瓦 IT 模块和 RDHx 冷却系统进行了设计和评估，CFD 数值分析证实，在供气温度为 24 °C 的条件下，RDHx 可保持稳定的 IT 环境，符合 ASHRAE 标准。此外，二级 CDU 的冷却水供应温度可提高到 14 °C，一级冷却水供应温度可提高到 12 °C。对一个 30 兆瓦参考数据中心的中央冷却水系统进行了设计和分析，结果表明，在供水温度为 12 °C、冬季冷凝器回水温度不同的情况下，效率有所提高，年 PUEcooling 范围为 1.25-1.33，平均为 1.27。机架式冷却的年能耗分布约为 46% 来自制冷机，21% 来自风扇，33% 来自水泵。这些结果为数据中心冷却提供了重要依据，支持 RDHx 系统在高密度数据中心的应用，未来还将对 150 千瓦 IT 模块进行现场模拟测试验证。

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引用次数: 0

Thermal study of MHD hybrid nano fluids confined between two parallel sheets: Shape factors analysis 限制在两平行板之间的 MHD 混合纳米流体的热研究：形状因素分析

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-05 DOI: 10.1016/j.csite.2024.105229

This article discusses the heat and air transfer characteristics of stable magnetohydrodynamic nanofluid flow between two interconnected sheets under the influence of a magnetic field. The nanofluid is a mixture of equal proportions of ethylene glycol and water. This study examined hybrid nanoparticles containing multi-walled carbon nanotubes (MWCNT) and silver (Ag). This research presents, for the first time, a new method for solving nonlinear equations using HPM Python and AGM Python. In addition, the symbolic solution to HPM and AGM has been attained by employing SymPy and SciPy libraries in Python. The results are presented graphically by comparing them with the fourth-order Runge-Kutta number. The final results reflect a high level of agreement between the analytical and numerical methods on the one hand and HPM Python and AGM Python on the other hand. This examination also investigates the effect of various parameters, including magnetic properties, viscosity coefficients, thermophoretic parameters, Brownian parameters, and nanofluid parameters such as velocity, temperature, and concentration. The results prove that velocity and concentration increase as the magnetic field decreases, whereas the temperature displays an opposite trend. As the Schmidt number increases, both the Nusselt number and concentration decrease. The relationship between concentration and temperature with respect to the Prandtl number indicates that when the Prandtl number decreases, the temperature increases while the concentration declines. It is important to note that the employment of hybrid nanofluids leads to an increase in velocity, temperature, and concentration.

本文讨论了在磁场影响下，稳定的磁流体纳米流体在两个相互连接的薄片之间流动时的热量和空气传递特性。纳米流体是乙二醇和水的等比例混合物。这项研究考察了含有多壁碳纳米管（MWCNT）和银（Ag）的混合纳米粒子。本研究首次提出了一种使用 HPM Python 和 AGM Python 求解非线性方程的新方法。此外，还利用 Python 中的 SymPy 和 SciPy 库实现了 HPM 和 AGM 的符号解法。通过与四阶 Runge-Kutta 数的比较，以图形方式展示了结果。最终结果反映了分析和数值方法与 HPM Python 和 AGM Python 之间的高度一致。本次研究还考察了各种参数的影响，包括磁性能、粘度系数、热泳参数、布朗参数以及纳米流体参数（如速度、温度和浓度）。结果证明，速度和浓度随着磁场的减小而增加，而温度则呈现相反的趋势。随着施密特数的增加，努赛特数和浓度都会降低。浓度和温度与普朗特数的关系表明，当普朗特数降低时，温度升高而浓度降低。值得注意的是，混合纳米流体的使用会导致速度、温度和浓度的增加。

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引用次数: 0

Thermodynamic behavior of high-power inductively coupled plasma quartz tube wall 大功率电感耦合等离子体石英管壁的热力学行为

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-05 DOI: 10.1016/j.csite.2024.105166

High-power inductively coupled plasmas are commonly used in planetary entry simulations and are increasingly being used in electric propulsion applications. However, during the operation of the system, the walls of the quartz tube will crack and melt. Its thermodynamic behavior is key to ensuring the safe and reliable operation of the system, which is directly related to the distribution of thermal energy within the discharge volume. In this paper, the temperature and stress distribution of the quartz tube wall of an inductively coupled plasma generator at 27 kW–85 kW are described. A numerical simulation model was established to depict the interaction between the plasma and the quartz tube wall. In the field of experimental research, the temperature of the outer wall of the quartz tube was obtained by using a thermal imager, and a non-uniform B-spline difference method was proposed to fit the outer wall temperature of the quartz tube to eliminate the influence of the induction coil. It is found that the numerical simulation and experimental results show that the temperature is stable region, temperature rise area, temperature drop zone, and the high temperature region of the quartz tube wall is located in the coil area, and the high stress area is also located in this region. On this basis, the outer wall temperature and thermal stress of quartz tubes under different heat fluxes are studied. When the heat flux exceeds 18.6 kW/m

^{2}

, the stresses in the coil area and downstream of the coil exceed the limit stress. Mechanical failures may occur in areas where the ultimate stresses are exceeded, and these results can provide theoretical data for the optimal design of high-power inductively coupled plasma generators.

大功率电感耦合等离子体通常用于行星进入模拟，并越来越多地用于电力推进应用。然而，在系统运行期间，石英管的管壁会开裂和熔化。其热力学行为是确保系统安全、可靠运行的关键，与放电体积内的热能分布直接相关。本文描述了功率为 27 kW-85 kW 的电感耦合等离子体发生器石英管管壁的温度和应力分布。建立了一个数值模拟模型来描述等离子体与石英管壁之间的相互作用。在实验研究领域，利用热成像仪获得了石英管外壁的温度，并提出了一种非均匀 B-样条差分法来拟合石英管外壁温度，以消除感应线圈的影响。数值模拟和实验结果表明，温度稳定区、温度上升区、温度下降区、石英管外壁高温区均位于线圈区域，高应力区也位于该区域。在此基础上，研究了不同热通量下石英管的外壁温度和热应力。当热流量超过 18.6 kW/m2 时，线圈区域和线圈下游的应力超过了极限应力。在超过极限应力的区域可能会出现机械故障，这些结果可为大功率电感耦合等离子体发生器的优化设计提供理论数据。

{"title":"Thermodynamic behavior of high-power inductively coupled plasma quartz tube wall","authors":"","doi":"10.1016/j.csite.2024.105166","DOIUrl":"10.1016/j.csite.2024.105166","url":null,"abstract":"<div><div>High-power inductively coupled plasmas are commonly used in planetary entry simulations and are increasingly being used in electric propulsion applications. However, during the operation of the system, the walls of the quartz tube will crack and melt. Its thermodynamic behavior is key to ensuring the safe and reliable operation of the system, which is directly related to the distribution of thermal energy within the discharge volume. In this paper, the temperature and stress distribution of the quartz tube wall of an inductively coupled plasma generator at 27 kW–85 kW are described. A numerical simulation model was established to depict the interaction between the plasma and the quartz tube wall. In the field of experimental research, the temperature of the outer wall of the quartz tube was obtained by using a thermal imager, and a non-uniform B-spline difference method was proposed to fit the outer wall temperature of the quartz tube to eliminate the influence of the induction coil. It is found that the numerical simulation and experimental results show that the temperature is stable region, temperature rise area, temperature drop zone, and the high temperature region of the quartz tube wall is located in the coil area, and the high stress area is also located in this region. On this basis, the outer wall temperature and thermal stress of quartz tubes under different heat fluxes are studied. When the heat flux exceeds 18.6 kW/m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span>, the stresses in the coil area and downstream of the coil exceed the limit stress. Mechanical failures may occur in areas where the ultimate stresses are exceeded, and these results can provide theoretical data for the optimal design of high-power inductively coupled plasma generators.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420189","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}

引用次数: 0

Experimental study on physico-mechanical responses and energy characteristics of granite under high temperature and hydro-mechanical coupling 高温和水力机械耦合条件下花岗岩的物理机械响应和能量特性实验研究

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-05 DOI: 10.1016/j.csite.2024.105245

Thermal and hydro-mechanical coupling effects on granite's physico-mechanical responses and energy characteristics can influence its carrying capacity, hydraulic and heat transfer performance. The evolution of these properties is crucial for geothermal reservoir stability assessment and the optimization of deep geothermal energy development techniques. Hence, a variety of physical tests and rock mechanics experiments were conducted. Key findings include: (1) As temperature rises, granite undergoes thermal expansion and structural integrity degradation. The peak strength σ_p, elastic modulus E, total energy density U, and elastic energy density U_e initially rise at 25 °C–150 °C and subsequently decrease above 150 °C, while the proportion of dissipated energy η_d is opposite. Granite also initially experiences hardening, then turns to brittle-ductile transition. (2) The crystallinities of quartz, albite, and orthoclase demonstrate substantial deterioration beyond 450 °C. (3) 150 °C and 450 °C are regarded as the temperature thresholds for mechanical properties. (4) As confining pressure rises, granite experiences hardening, with σ_p, E, U, and U_e increasing, and η_d decreasing. (5) Pore water pressure increases η_d and decreases σ_p, E, U, and U_e, and its effect on the mechanical responses is pronounced when it reaches 80 % of confining pressure or exceeds 450 °C.

热和水文机械耦合效应对花岗岩的物理机械响应和能量特征会影响其承载能力、水力和传热性能。这些特性的演变对于地热储层稳定性评估和深层地热能开发技术的优化至关重要。因此，我们进行了各种物理测试和岩石力学实验。主要发现包括(1) 随着温度的升高，花岗岩会发生热膨胀和结构完整性退化。峰值强度 σp、弹性模量 E、总能量密度 U 和弹性能量密度 Ue 最初在 25 ℃-150 ℃ 时上升，超过 150 ℃ 后下降，而耗散能量比例 ηd 则相反。花岗岩最初也经历了硬化，然后转为脆-韧性转变。(2) 石英、白云石和正长石的结晶度在 450 °C以上出现大幅恶化。(3) 150 °C和450 °C被认为是机械特性的温度临界点。(4) 随着封闭压力的升高，花岗岩发生硬化，σp、E、U 和 Ue 增加，ηd 减少。(5) 孔隙水压力会增加 ηd，降低 σp、E、U 和 Ue，当孔隙水压力达到密闭压力的 80% 或超过 450 °C 时，其对力学响应的影响会非常明显。

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引用次数: 0

Analysis of microstructure of prefabricated fractured granite under thermal effects based on CT technology 基于 CT 技术的热效应下预制断裂花岗岩微观结构分析

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-05 DOI: 10.1016/j.csite.2024.105243

In this study, Computed Tomography (CT) technology was employed to visually analyze the influence of thermal effects on the microstructure of prefabricated fractured granite. The porosity and heterogeneity of the samples were calculated using three-dimensional reconstruction techniques, and two parameters, crack length and orientation, were introduced to quantitatively evaluate the impact of prefabricated fractures on subsequent crack propagation. The results indicated that at 400 °C–500 °C, numerous microcracks were generated within the samples, but they did not interconnect. Above 600 °C, microcracks gradually propagated, forming well-connected crack networks. Due to the uneven thermal stress distribution caused by the prefabricated fractures, samples subjected to temperatures above 600 °C exhibited higher heterogeneity in the vertical direction. While in other directions, the samples gradually tended to homogenize as the temperature rose. Below 500 °C, crack length was significantly affected by the prefabricated fractures, although this influence diminished with increasing distance from the fractures. When the temperature was below 400 °C, microcracks mainly propagated along the direction of the prefabricated fractures. However, when the temperature exceeded 500 °C, microcracks began to initiate and propagate in the opposite direction of the prefabricated fractures, and anti-wing cracks started to emerge.

本研究采用计算机断层扫描（CT）技术，直观分析了热效应对预制断裂花岗岩微观结构的影响。利用三维重建技术计算了样品的孔隙率和异质性，并引入了裂缝长度和走向两个参数，以定量评估预制裂缝对后续裂缝扩展的影响。结果表明，在 400 ℃-500 ℃ 时，样品内部产生了大量微裂纹，但这些裂纹并不相互连接。在 600 °C 以上，微裂纹逐渐扩展，形成了连接良好的裂纹网络。由于预制裂缝造成的热应力分布不均匀，温度高于 600 °C 的样品在垂直方向表现出较高的异质性。而在其他方向，随着温度的升高，样品逐渐趋于均匀化。低于 500 °C时，裂缝长度受预制裂缝的影响很大，但随着与裂缝距离的增加，这种影响逐渐减弱。当温度低于 400 ℃ 时，微裂缝主要沿着预制裂缝的方向扩展。然而，当温度超过 500 ℃ 时，微裂缝开始沿着预制裂缝的相反方向产生和扩展，并开始出现反翼裂缝。

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引用次数: 0

Thermal characteristics analysis and cooling model optimization of motorized spindle 电动主轴的热特性分析和冷却模型优化

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-05 DOI: 10.1016/j.csite.2024.105238

Aiming at the influence of poor cooling conditions and traditional cooling control strategy on motorized spindle temperature and machining performance. Firstly, the heat transfer model of the motorized spindle cooling system is studied. Secondly, the influence of coolant inlet flow rate and temperature on the thermal characteristics of the motorized spindle is studied. Then, a thermal network model is established to solve the temperature of each temperature measuring point. Finally, the thermal characteristic experiment of the motorized spindle is carried out, and the cooling fluid flow optimization model is established based on the particle swarm optimization algorithm and simulated annealing algorithm. The results show that the temperature difference of the motorized spindle does not exceed 45 °C, the thermal deformation does not exceed 40.2 μm, and the thermal elongation is inhibited by 36 %. The maximum error of the Thermal Network Method and Finite Element Method（FEM）is 14.24 %. The utilization of the average logarithmic temperature difference for assessing the cooling effectiveness of optimal flow rates revealed that the particle swarm optimization algorithm demonstrates a comparatively lower average logarithmic temperature difference in comparison to the simulated annealing algorithm. The heat exchange efficiency of the motorized spindle is higher under the optimal flow rate obtained by the particle swarm algorithm.

针对冷却条件差和传统冷却控制策略对电主轴温度和加工性能的影响。首先，研究了电主轴冷却系统的传热模型。其次，研究冷却液入口流速和温度对电主轴热特性的影响。然后，建立热网络模型，求解各测温点的温度。最后，进行了电主轴的热特性实验，并基于粒子群优化算法和模拟退火算法建立了冷却液流量优化模型。结果表明，电主轴的温差不超过 45 °C，热变形不超过 40.2 μm，热伸长率抑制了 36%。热网法和有限元法（FEM）的最大误差为 14.24 %。利用平均对数温差评估最佳流速的冷却效果时发现，与模拟退火算法相比，粒子群优化算法的平均对数温差更小。在粒子群算法得到的最佳流速下，电主轴的热交换效率更高。

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引用次数: 0

A thermal performance study on magnetic dipole based viscoplastic nanomaterial deploying distinct rheological aspects 基于磁偶极的粘塑性纳米材料的热性能研究，涉及不同的流变学方面

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering

Pub Date : 2024-10-05 DOI: 10.1016/j.csite.2024.105237

Magnetic nanoliquids stand inimitable when compared with conventional liquids as their distinctive magnetic attributes can be regulated utilizing magnetic fields. For this reason, heat transference can be stimulated or regulated subjected to externally imposed magnetic fields. Magnetic nanoliquids are useful in comparison to orthodox or non-magnetic nanoliquids. These encompasses, energy conversion, electronics, hydraulics, thermal engineering and bioengineering. This study elaborates the magnetic dipole impact on convectively heated rheological nanomaterial confined by stretchy surface. Mathematical modeling is based on thermally radiative viscoplastic (Casson) model. Porous medium features are scrutinized through Darcian Forchheimer (DF) relation. Two-component Buongiorno nanomaterial model which captures Brownian diffusive together with thermophoretic diffusion is under consideration. Energy and solutal transportation expressions capture thermal source and chemical reaction effects. The dimensionalized nanomaterial flow model for stretching flow is obtained by deploying similarity variables. Numerical solutions are computed through Bvp4c scheme. The physical outcomes are elucidated graphically and arithmetically on dimensionless quantities (i.e., Nusselt number, temperature, skin-friction, velocity, Sherwood number and concentration streams). A benchmark is reported to authenticate the acquired numeric solutions. It is further visualized that nanomaterial temperature escalates subject to higher estimations of thermal Biot number, Curie temperature factor, radiation factor, thermophoresis parameter, heat source, ferrohydrodynamic interaction factor and Brownian diffusive parameter while it diminishes with Prandtl number and dissipation factor.

与传统液体相比，磁性纳米液体具有独特的磁性，可以利用磁场对其进行调节。因此，可以通过外部强加的磁场来刺激或调节热传递。与正统或非磁性纳米液体相比，磁性纳米液体非常有用。这些领域包括能源转换、电子学、水力学、热能工程和生物工程。本研究阐述了磁偶极对对流加热流变纳米材料的影响。数学建模基于热辐射粘塑性（Casson）模型。多孔介质特征通过达尔西安-福赫海默（Darcian Forchheimer，DF）关系进行研究。双组分 Buongiorno 纳米材料模型可捕捉布朗扩散和热泳扩散。能量和溶质传输表达式捕捉了热源和化学反应效应。通过使用相似变量，获得了用于拉伸流动的尺寸化纳米材料流动模型。通过 Bvp4c 方案计算数值解。物理结果以图形和算术方式阐明了无量纲量（即努塞尔特数、温度、表皮摩擦、速度、舍伍德数和浓度流）。报告了一个基准，以验证所获得的数值解决方案。结果进一步表明，纳米材料的温度会随着热比奥特数、居里温度系数、辐射系数、热泳参数、热源、铁流体力学相互作用系数和布朗扩散参数的升高而升高，同时会随着普朗特数和耗散系数的降低而降低。

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引用次数: 0