ASME journal of heat and mass transfer最新文献

Atmospheric Bubbling Fluidized Bed Risers: Effect of Cone Angle on Fluid Dynamics and Heat Transfer 大气气泡流化床上升器：锥角对流体动力学和传热的影响

N/A ENGINEERING, MECHANICAL

ASME journal of heat and mass transfer

Pub Date : 2024-08-08 DOI: 10.1115/1.4066182

H. J. Das, P. Mahanta

In this paper, a comparative study of fluid dynamics and thermal characteristics of sand particles has been carried out numerically and experimentally in bubbling fluidized bed risers for five-cone angles of the riser wall having 0°, 5°, 10°, 15° and 20°. An Eulerian model with a k-e turbulence model is used to explore the numerical analysis, and the findings are compared to those of the experiments. For the study, the inlet air velocity is fixed at 1.5 m/s with sand particles filled up to 30 cm to maintain bubbling conditions in the risers. The results indicate that when the cone angle increases while maintaining the amount of bed materials constant, there is a corresponding reduction in pressure drop. The expansion of particles along the riser is observed to decrease with an increase in cone angle. The radial solid volume fraction profile transforms to a U shape from the W-type profile as the cone angle increases. Correspondingly, the solid velocity is found to have an inverted U-type and W-shaped profile for the risers. The granular temperature is also found to increase with a decrease in the solid percentage at any location. The average bed temperature, interphase, and bed-to-wall heat transfer coefficient at a location of 10 cm axial height also increase with the cone angle. As a result, the conical riser, when designed with a greater cone angle, exhibits more efficiency in terms of heat transfer characteristics.

本文对冒泡流化床立管中砂粒的流体动力学和热特性进行了数值和实验对比研究，立管壁的五个锥角分别为 0°、5°、10°、15° 和 20°。数值分析采用了带有 k-e 湍流模型的欧拉模型，并将分析结果与实验结果进行了比较。在研究中，进气速度固定为 1.5 米/秒，沙粒填充高度为 30 厘米，以保持立管中的气泡条件。结果表明，在保持床层材料数量不变的情况下，当锥角增大时，压降也会相应减小。据观察，随着锥角的增大，颗粒沿立管的膨胀也随之减小。随着锥角的增大，径向固体体积分数剖面从 W 型剖面转变为 U 型。相应地，立管的固体速度也呈倒 U 型和 W 型。在任何位置，颗粒温度也会随着固体百分比的降低而升高。在轴向高度为 10 厘米的位置，床层平均温度、相间和床层到壁面的传热系数也随着锥角的增大而增大。因此，锥形立管在设计时若采用较大的锥角，则在传热特性方面会表现出更高的效率。

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引用次数: 0

Analytic Modelling of 2-D Transient Heat Conduction with Heat Source Under Mixed Boundary Constraints by Symplectic Superposition 用交映叠加法解析混合边界约束下带热源的二维瞬态热传导模型

N/A ENGINEERING, MECHANICAL

ASME journal of heat and mass transfer

Pub Date : 2024-07-22 DOI: 10.1115/1.4066031

Dian Xu, Jinbao Li, Zixuan Wang, Sijun Xiong, Qianqiang He, Rui Li

Many studies have been conducted on 2-D transient heat conduction, but analytic modelling is still uncommon for the cases with complex boundary constraints due to the mathematical challenge. With an unusual symplectic superposition method, this paper reports new analytic solutions to 2-D isotropic transient heat conduction problems with heat source over a rectangular region under mixed boundary constraints at an edge. With the Laplace transform, the Hamiltonian governing equation is derived. The applicable mathematical treatments, e.g., the variable separation and the symplectic eigenvector expansion in the symplectic space, are implemented for the fundamental solutions whose superposition yields the ultimate solutions. Benchmark results obtained by the present method are tabulated, with verification by the finite element solutions. Instead of the conventional Euclidean space, the present symplectic-space solution framework has the superiority on rigorous derivations without pre-determining solution forms, which may be extended to more issues with the complexity caused by mixed boundary constraints.

关于二维瞬态热传导的研究很多，但对于具有复杂边界约束的情况，由于数学上的挑战，解析建模仍不常见。本文采用非同寻常的交映叠加法，报告了在边缘混合边界约束下矩形区域热源的二维各向同性瞬态热传导问题的新解析解。通过拉普拉斯变换，得出了哈密顿支配方程。适用的数学处理方法，如变量分离和交映空间中的交映特征向量展开，都是针对基本解实施的，这些基本解的叠加产生了终极解。表中列出了本方法获得的基准结果，并通过有限元解进行了验证。与传统的欧几里得空间相比，本交映空间求解框架在不预先确定求解形式的情况下进行严格推导方面具有优势，可扩展到更多由混合边界约束引起的复杂问题。

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引用次数: 0

Melting Behavior Effect of MXene Nanoenhanced Phase Change Material on Energy and Exergyanalysis of Double and Triplex Tube Latent Heat Thermal Energy Storage MXene 纳米增强相变材料的熔融行为对双管和三联管潜热储能器能量和放能分析的影响

N/A ENGINEERING, MECHANICAL

ASME journal of heat and mass transfer

Pub Date : 2024-07-20 DOI: 10.1115/1.4065997

Utkarsh Srivastava, Rashmi Sahoo

The impacts of melting behaviour on the thermal performance of TT-TES and DT-TES systems employing cetyl alcohol and 3% v/v. MXene nanoenhanced PCM are compared and numerically evaluated in this work. For both the DT-TES and TT-TES systems, the following were investigated in connection to melting time: system efficiency, discharged energy, heat transfer rate, exergy destruction, entropy generation number, exergetic efficiency, melting fraction, and melting temperature contours. In addition, the effect of Stefan, Rayleigh, and Nusselt numbers on Fourier numbers are compared for the DT-TES and TT-TES systems with MXene NEPCM. MXene-based nano-enhanced PCM melting in TT-TES displayed 6.53% more Stefan number than cetyl alcohol. Pure melting of MXene-based nano-enhanced PCM in a TT-TES had 4.16% higher storage exergy than cetyl alcohol. The entropy generation number of pure melting of MXene-based nano-enhanced PCM in TT-TES is 7.93% lower than that of cetyl alcohol. Pure cetyl alcohol has 76.99% optimal system efficiency at 5400 seconds melting time and MXene NEPCM 77.04% at 4800 seconds in DT-TES. The charging temperature for pure cetyl alcohol PCM in TT-TES is 0.7% lower than in DT-TES. Furthermore, pure melting of MXene-based nano-enhanced PCM in a TT-TES has 1.95% lower storage energy than cetyl alcohol. For a given volume of MXene-based nano-enhanced cetyl alcohol PCM, melting occurs more rapidly in a TT-TES system.

熔化行为对采用十六醇和 3% v/v. MXene 纳米增强 PCM 的 TT-TES 和 DT-TES 系统热性能的影响。MXene 纳米增强型 PCM 的热性能的影响进行了比较和数值评估。对于 DT-TES 和 TT-TES 系统，研究了与熔化时间相关的以下内容：系统效率、排出的能量、传热速率、放能破坏、熵生成数、放能效率、熔化率和熔化温度等值线。此外，还比较了使用 MXene NEPCM 的 DT-TES 和 TT-TES 系统的斯蒂芬数、瑞利数和努塞尔数对傅里叶数的影响。在 TT-TES 中熔化的 MXene 纳米增强 PCM 的斯特凡数比鲸蜡醇高出 6.53%。在 TT-TES 中，MXene 纳米增强型 PCM 的纯熔化比十六醇高出 4.16% 的储能。在 TT-TES 中纯熔化的 MXene 纳米增强型 PCM 的熵产生数比十六醇低 7.93%。在 DT-TES 中，纯十六醇在 5400 秒熔化时间内的最佳系统效率为 76.99%，而 MXene NEPCM 在 4800 秒熔化时间内的最佳系统效率为 77.04%。纯十六醇 PCM 在 TT-TES 中的加料温度比 DT-TES 低 0.7%。此外，在 TT-TES 中纯熔化的 MXene 纳米增强 PCM 的存储能比鲸蜡醇低 1.95%。对于一定体积的 MXene 纳米增强鲸蜡醇 PCM，在 TT-TES 系统中熔化的速度更快。

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引用次数: 0

Experimental and Numerical Evaluation of the Film Cooling Characteristics of the Multi-cavity Tip with Inclined Film Holes 带倾斜膜孔的多腔尖端薄膜冷却特性的实验和数值评估

ASME journal of heat and mass transfer

Pub Date : 2024-05-16 DOI: 10.1115/1.4065515

Zhe Jia, Feng Li, Weixin Zhang, Zhao Liu, Zhenping Feng

Due to the complex flow field and the considerable heat load on the turbine blade tip, film cooling is essential to protect the tip from being overheated. In this paper, an experimental work was conducted to compare the film cooling distributions of four tip structures (cavity numbers are one, two, three, and four) with two film hole configurations (perpendicular and 45 degrees inclined to the cavity floor) under three coolant blowing ratios. By using pressure sensitive paint technique, the distributions of film cooling effectiveness were measured. Moreover, a computation with careful validation was executed to obtain the cooling traces in the tip region and compare the aerodynamic performance of these multi-cavity tips. The results showed that the value and uniformity of film cooling effectiveness were improved by the inclined configuration. The tip film cooling was enhanced when using the multi-cavity tips. The aerodynamic loss of the tested tips was compared as well.

由于涡轮叶尖上存在复杂的流场和巨大的热负荷，薄膜冷却对保护叶尖不被过热至关重要。本文通过实验比较了四种叶尖结构（腔数分别为 1、2、3 和 4）和两种膜孔结构（垂直于腔底和与腔底倾斜 45 度）在三种冷却剂喷射比下的膜冷却分布。通过压敏涂料技术，测量了薄膜冷却效果的分布。此外，还进行了仔细的验证计算，以获得尖端区域的冷却轨迹，并比较这些多腔尖端的空气动力性能。结果表明，倾斜配置提高了薄膜冷却效果的数值和均匀性。使用多腔针尖时，针尖薄膜冷却效果增强。此外，还比较了测试喷嘴的空气动力损耗。

引用次数: 0

Construction of Short-Time Heat Conduction Solutions in One-Dimensional Finite Rectangular Bodies 构建一维有限矩形体中的短时热传导解决方案

ASME journal of heat and mass transfer

Pub Date : 2024-05-06 DOI: 10.1115/1.4065449

Filippo de Monte, K. Woodbury, Hamidreza Najafi

The concept of both penetration and deviation times for rectangular coordinates along with the principle of superposition for linear problems allow short-time solutions to be constructed for a one-dimensional rectangular finite body from the well-known solutions of a semi-infinite medium. Some adequate physical considerations due to thermal symmetries with respect to the middle plane of a slab to simulate homogeneous boundary conditions of the first and second kinds are also needed. These solutions can be applied at the level of accuracy desired (one part in 10A, with A = 2, 3, …, 15) with respect to the maximum temperature variation (that always occurs at the active surface and at the time of interest) in place of the exact analytical solution to the problem of interest.

根据矩形坐标的穿透时间和偏离时间概念，以及线性问题的叠加原理，可以从已知的半无限介质解构建一维矩形有限体的短时解。此外，还需要对板坯中间平面的热对称性进行一些充分的物理考虑，以模拟第一和第二种均质边界条件。这些解法可根据所需的精度水平（10A 中的一部分，A = 2、3、......、15）应用于最大温度变化（始终发生在活动表面和相关时间），以取代相关问题的精确分析解法。

引用次数: 0

Experiments On Gasketed Plate Heat Exchangers with Segmented Corrugation Pattern 带分段波纹图案的板式热交换器实验

ASME journal of heat and mass transfer

Pub Date : 2024-05-06 DOI: 10.1115/1.4065453

Matheus Strobel, L. Beckedorff, Giovani Martins, J. Oliveira, K. Paiva

Gasket plate heat exchanger (GPHE) is among the most used heat exchanger types, known for its high effectiveness and compact design. Its remarkable feature is the corrugated plate geometry, typically a Chevron pattern. This work aims to analyze another corrugation pattern, which has segments with different angles to the vertical. The strengths and weaknesses of the segmented plate are still unclear, as the studies on this pattern are scarce. To fill this gap, we experimentally assess the pressure drop and heat transfer in a GPHE composed of 31 segmented plates. The plates have four quadrants, and the combination of low-angle and high-angle plates can form up to six channel types. Pressure and temperature data are acquired in 144 sets of experiments. In the pressure drop results, we observe a considerable discrepancy between the two streams, which leads to a discussion of a relevant phenomenon: the elastic deformation of the plates. If the inner pressure of the streams is not equal, the pressure gradient causes the plates to deform and change the channel geometry. The stream with the higher pressure has its channels expanded, while the lower pressure channels will be strangled. This phenomenon is rarely reported in the literature and strongly affects the pressure drop. Moreover, we present friction factor correlations for six channel types using flow data. Based on the generalized Lévêque analogy in the heat transfer experiments, we argue that the plates' deformation also affects the heat transfer.

垫片板式热交换器（GPHE）是最常用的热交换器类型之一，以其高效和紧凑的设计而著称。其显著特点是波纹板的几何形状，通常为雪佛龙图案。本研究旨在分析另一种波纹模式，即与垂直方向不同角度的分段。由于对这种模式的研究很少，分段板的优缺点尚不清楚。为了填补这一空白，我们通过实验评估了由 31 块分段板组成的 GPHE 的压降和传热情况。板有四个象限，低角度板和高角度板的组合可形成多达六种通道类型。在 144 组实验中获得了压力和温度数据。在压降结果中，我们观察到两股气流之间存在相当大的差异，由此引出了一个相关现象的讨论：板的弹性变形。如果两股水流的内部压力不相等，压力梯度会导致板变形并改变通道的几何形状。压力较高的水流会使其通道扩张，而压力较低的通道则会被勒住。这种现象在文献中很少报道，但对压降影响很大。此外，我们还利用流量数据给出了六种水道类型的摩擦因数相关性。根据传热实验中的广义 Lévêque 类比，我们认为板的变形也会影响传热。

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引用次数: 0

Genetic Algorithm as the Solution of Non-Linear Inverse Heat Conduction Problems: a Novel Sequential Approach 遗传算法作为非线性反热传导问题的解决方案：一种新颖的序列方法

ASME journal of heat and mass transfer

Pub Date : 2024-05-06 DOI: 10.1115/1.4065452

Dominic Allard, Hamidreza Najafi

Direct measurement of surface heat flux could be extremely challenging, or impossible, in numerous applications. In such cases, the use of temperature measurement data from sub-surface locations can facilitate the determination of surface heat flux and temperature through the solution of the inverse heat conduction problem (IHCP). Different techniques have been developed for solving IHCPs. Inspired by the filter coefficient approach, a novel method is presented in this paper for solving one-dimensional IHCPs in a domain with temperature-dependent material properties. A test case is developed in COMSOL Multiphysics where the front side of a slab is subject to known transient heat flux and the temperature distributions within the domain are calculated. The IHCP solution in the form of filter coefficients is defined and a genetic algorithm is used for the calculation of filter matrix. The number of significant filter coefficients required to evaluate surface heat flux at each time step is determined through trial and error and the optimal number is selected for evaluating the solution. The structure of the filter matrix is assessed and discussed. The resulting filter coefficients are used to evaluate the surface heat flux for several cases and the performance of the proposed approach is assessed in detail. The results showed that the presented approach is robust and can result in finding optimal filter coefficients to accurately estimate various types of surface heat flux profiles using temperature data from a limited number of time steps and in a near real-time fashion.

在许多应用中，直接测量表面热通量可能极具挑战性，甚至是不可能的。在这种情况下，利用来自地下位置的温度测量数据，可以通过解决反热传导问题（IHCP）来确定表面热通量和温度。目前已开发出不同的 IHCP 求解技术。受过滤系数方法的启发，本文提出了一种新方法，用于求解具有温度相关材料特性的域中的一维 IHCP。在 COMSOL Multiphysics 中开发了一个测试案例，板的正面受到已知瞬态热通量的影响，并计算域内的温度分布。定义了滤波系数形式的 IHCP 解决方案，并使用遗传算法计算滤波矩阵。通过试验和误差来确定评估每个时间步长的表面热通量所需的重要滤波系数数量，并选择最佳数量来评估解决方案。对滤波矩阵的结构进行了评估和讨论。得出的滤波系数用于评估几种情况下的表面热通量，并详细评估了所提方法的性能。结果表明，所提出的方法是稳健的，能够找到最佳滤波系数，从而利用有限时间步数的温度数据，以接近实时的方式准确估算各种类型的表面热通量剖面。

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引用次数: 0

Estimation of Multiple Contact Conductances in a Silicon-Indium-Silicon Stack 估算硅-铟-硅叠层中的多触点电导

ASME journal of heat and mass transfer

Pub Date : 2024-05-06 DOI: 10.1115/1.4065448

K. Woodbury, Grant Cutler, Hamidreza Najafi, Maya Kota

This report documents evaluation of simultaneous estimation of multiple interfacial heat transfer coefficients (HTCs) using transient measurements from an experiment designed for steady-state operation. The design of a mirror system for directing x-rays under cryogenic conditions requires knowledge of the interfacial HTC (contact conductance) between silicon and indium. An experimental apparatus was constructed to measure temperatures in a stack of five 7.62 mm thick pucks of silicon separated by 0.1 mm thick sheets of indium which is operated under cryogenic temperatures in vacuum. Multiple pucks and interfaces are incorporated into the apparatus to allow evaluation of HTCs for surfaces of different roughness from a single experiment. Analysis of the sensitivity of each of the measured temperatures to each of the unknown HTCs reveals lack of linear independence of these sensitivities and suggests the recovery of the HTCs will be challenging. Artificially noised “data” were created from two different computational models by solving for temperatures and adding random Gaussian noise with a specified standard deviation. These data are subsequently analyzed using two different iterative parameter estimation methods: a Levenberg scheme and a Tikhonov iterative scheme. The required sensitivity matrix is computed using forward finite difference approximations. The results for the heat transfer coefficients for this model problem suggest that coefficients cannot be estimated independently, but the ratios relative to one of the unknowns can be recovered.

本报告记录了利用设计用于稳态运行的实验的瞬态测量结果，对同时估算多个界面传热系数（HTC）的评估。设计用于在低温条件下引导 X 射线的反射镜系统需要了解硅和铟之间的界面 HTC（接触传导）。我们建造了一个实验装置，用于测量由五个 7.62 毫米厚的硅片组成的堆栈中的温度，这些硅片被 0.1 毫米厚的铟片隔开，在真空中的低温条件下运行。仪器中包含多个硅片和界面，可通过一次实验对不同粗糙度表面的 HTC 进行评估。分析每种测量温度对每种未知 HTC 的灵敏度发现，这些灵敏度缺乏线性独立性，这表明 HTC 的恢复将具有挑战性。通过求解温度并添加具有指定标准偏差的随机高斯噪声，从两个不同的计算模型中创建了人为噪声 "数据"。随后使用两种不同的迭代参数估计方法对这些数据进行分析：一种是 Levenberg 方案，另一种是 Tikhonov 迭代方案。使用前向有限差分近似法计算所需的灵敏度矩阵。该模型问题的传热系数结果表明，无法独立估算系数，但可以恢复相对于其中一个未知数的比率。

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引用次数: 0

Cryogenic Air Supply Feasibility for a Confined Space: Underground Refuge Alternative Case Study. 密闭空间低温供气可行性：地下避难所替代方案案例研究。

0 ENGINEERING, MECHANICAL

ASME journal of heat and mass transfer

Pub Date : 2024-03-01 DOI: 10.1115/1.4064062

Lincan Yan, Dave S Yantek, Cory R DeGennaro, Justin R Srednicki, Brandin Lambie, Jacob Carr

A breathable air source is required for a confined space such as an underground refuge alternative (RA) when it is occupied. To minimize the risk of suffocation, federal regulations require that mechanisms be provided and procedures be included so that, within the refuge alternative, the oxygen concentration is maintained at levels between 18.5% and 23% for 96 h. The regulation also requires that, during use of the RA, the concentration of carbon dioxide should not exceed 1%, and the concentration of carbon monoxide should not exceed 25 ppm. The National Institute for Occupational Safety and Health (NIOSH) evaluated the cryogenic air supply's ability to provide breathable air for a refuge alternative. A propane smoker was used to simulate human breathing by burning propane gas which will consume O₂ and generate CO₂ and H₂O. The rate of propane burned at the smoker was controlled to represent the O₂ consumption rate for the breathing of a certain number of people. Two 96-h tests were conducted in a sealed shipping container, which was used as a surrogate for a refuge alternative. While burning propane gas to simulate human oxygen consumption, cryogenic air was provided to the shipping container to determine if the cryogenic air supply would keep the O₂ level above 18.5% and CO₂ level below 1% inside the shipping container as required by the federal regulations pertaining to refuge alternatives. Both of the 96-h tests simulated the breathing of 21 persons. The first test used the oxygen consumption rate (1.32 cu ft of pure oxygen per hour per person) specified in federal regulations, while the second test used the oxygen consumption rate specified by (Bernard et al. 2018, "Estimation of Metabolic Heat Input for Refuge Alternative Thermal Testing and Simulation," Min. Eng., 70(8), pp. 50-54) (0.67 cu ft of pure oxygen per hour per person). The test data shows that during both 96-h tests, the oxygen level was maintained within a 21-23% range, and the CO₂ level was maintained below 1% (0.2-0.45%). The information in this paper could be useful when applying a cryogenic air supply as a breathable air source for an underground refuge alternative or other confined space. [DOI: 10.1115/1.4064062].

地下避难所（RA）等密闭空间被占用时，必须有可呼吸的空气源。为了最大限度地降低窒息风险，联邦法规要求提供相应的机制和程序，以便在 96 小时内将地下避难所内的氧气浓度保持在 18.5% 至 23% 之间。美国国家职业安全与健康研究所（NIOSH）评估了低温供气系统为避难所替代方案提供可呼吸空气的能力。使用丙烷燃烧器模拟人的呼吸，丙烷燃烧时会消耗氧气并产生二氧化碳和水。丙烷在烟熏炉中燃烧的速度受到控制，以代表一定人数呼吸时的氧气消耗速度。在一个密封的集装箱内进行了两次 96 小时的测试，该集装箱被用作避难所的替代品。在燃烧丙烷气体模拟人体耗氧量的同时，向集装箱内提供低温空气，以确定低温空气供应是否能使集装箱内的氧气含量保持在 18.5%以上，二氧化碳含量保持在 1%以下，这符合联邦避难替代设施相关法规的要求。两次 96 小时测试都模拟了 21 人的呼吸。第一次测试使用了联邦法规规定的氧气消耗率（每人每小时 1.32 立方英尺纯氧），而第二次测试则使用了（Bernard 等人，2018 年，"避难所替代方案热测试和模拟的代谢热输入估算"，Min.Eng.，70（8），第 50-54 页）（每人每小时 0.67 立方英尺纯氧）。测试数据显示，在两次 96 小时的测试中，氧气水平都保持在 21-23% 的范围内，二氧化碳水平保持在 1% 以下（0.2-0.45%）。在地下避难所或其他密闭空间应用低温供气作为可呼吸空气源时，本文中的信息可能会有所帮助。[doi: 10.1115/1.4064062].

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引用次数: 0

Buoyancy and Velocity Field Synergy Principle in Convective Heat Transfer and its Role in Thermo-Hydraulic Performance Improvement 对流传热中的浮力和速度场协同原理及其在改善热-水力性能中的作用

ASME journal of heat and mass transfer

Pub Date : 2024-02-13 DOI: 10.1115/1.4064734

Dong Yang, Xinyue Hu, Feilong Chen, Yingli Liu

This study proposes the buoyancy and velocity field synergy principle and aims to enhance thermo-hydraulic performance in convective heat transfer. A mechanical energy conservation equation concerning synergy between buoyancy and velocity was derived, which describes the mechanical energy transport and dissipation in convective heat transfer. Two new field synergy numbers, Fsu,g and Fsu,p, were proposed to characterize the degree of synergy between velocity and buoyancy, and the degree of synergy between velocity and pressure gradient over the fluid domain, respectively. The pressure drop of a channel subjected to convective heat transfer is related to not only Gr/Re2 but also Fsu,g. Under a same Gr/Re2, a larger | Fsu,g | leads to a smaller | Fsu,p |, and thus the pressure drop is decreased. Furthermore, the multi-field synergetic relationships among buoyancy, velocity, temperature gradient and pressure gradient were analyzed for convective heat transfer in channels. The correlation between Fsu,p and Fsu,g *Gr/Re2, and the correlation between Fsu,g and a traditional field synergy number characterizing convective heat transfer capability, Fc, were derived, which reveals the coupled mechanisms of mechanical energy dissipation and thermal energy transport. The proposed principle was applied in typical channel flows subjected to convective heat transfer, and its benefits were demonstrated. It is noted that both pressure drop reduction and convective heat transfer enhancement can be achieved in using the proposed principle. This paper provides a new insight for improving thermo-hydraulic performance of heat exchangers.

本研究提出了浮力场和速度场协同原理，旨在提高对流传热中的热液压性能。推导了浮力与速度场协同作用的机械能守恒方程，描述了对流传热中的机械能传输与耗散。提出了两个新的场协同数 Fsu,g 和 Fsu,p，分别表征速度与浮力之间的协同程度，以及速度与流体域上压力梯度之间的协同程度。受对流传热影响的通道压降不仅与 Gr/Re2 有关，还与 Fsu,g 有关。在相同的 Gr/Re2 条件下，Fsu,g 越大，Fsu,p 越小，压降也就越小。此外，还分析了浮力、速度、温度梯度和压力梯度在通道对流传热中的多场协同关系。得出了 Fsu,p 与 Fsu,g *Gr/Re2 之间的相关性，以及 Fsu,g 与表征对流传热能力的传统场协同数 Fc 之间的相关性，揭示了机械能耗散和热能传输的耦合机制。所提出的原理被应用于典型的对流传热的通道流中，并证明了其优势。结果表明，利用所提出的原理，既能减少压降，又能增强对流传热。本文为改善热交换器的热液性能提供了新的见解。

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引用次数: 0