某电动汽车用锂电池散热系统仿真分析与优化

分别利用Hypermesh和Fluent等软件建立某电动汽车锂离子电池组散热系统的仿真模型并进行计算,分析该散热模块及电池组的温度变化。结果表明,冷却通道入口存在明显的高速涡流,在高速流区换热比较明显,但冷却液流动不均匀,电池组及电池单体的温度均匀性较差。对冷板结构进行优化和仿真分析,发现冷却通道进出口处存在的高速流区分布范围较广,每个流场速度分布较均匀,整体换热效果较好,电池组的温差减小,电池组的温度一致性得到明显改善。     

5倍聚光电池散热翅片器件的设计与分析

电池组件的散热设计对于聚光光伏系统十分重要,针对一种5倍聚光电池进行了散热翅片器件的计算与设计,并利用FLUENT软件模拟了该设计方案,根据模拟的结果对该类散热翅片的设计进行了分析与总结。     

蒸汽喷射制冷原理在大型翅片散热上的应用

研究了一种利用喷射制冷原理的翅片散热器散热效率提高装置。创新性地将蒸汽喷射制冷原理应用于翅片散热器,可有效提高翅片散热器散热效率,解决因工况环境等因素导致的设备散热不及时等问题,符合绿色环保节能减排发展理念。     

某数据中心用集装箱发电机组多方案流动传热优化分析

数据中心是国家产业转型,释放经济潜力的重要基础设施。而数据中心用集装箱型发电机组具有保障数据中心电力可靠安全重要设备。本文对某集装箱型发电机组进行数值模拟研究,并提出三种改善散热和流动措施,分别为油箱电缆箱优化,改变进气角度,侧边进气方案。结果表明,改善流动对散热作用较好,不论是优化油箱和电缆箱布局,还是改变进气角度,侧边进气方案,都能改善流动,改善散热。此外,研究侧边进气位置对散热影响,结果表明,尾部侧边进气方案效果最好。对散热和流动的改善能够有效降低高温风险,减少耗油率,提升柴油机以及发电机寿命。     

铜管乐器散热改善音调的数值模拟

铜管乐器吹奏过程中演奏者吹出的湿热气流会使管内空气和铜管本身的温度升高,导致乐器音准偏离。本文提出了对铜管乐器发声前段采用增加散热翅片的方法,增加有效换热面积,即时散发出热量,可改善铜管乐器音准的偏离。根据散热目标要求,设计出了合理的翅片结构参数,并借助FLUENT软件进行了散热效果的数值模拟。结果表明,当环境温度为12℃时,相同条件下加装散热翅片的铜管乐器外表面与环境的温差缩小为原温差的34.2%,散热效果明显,乐器音准得到保证。     

非对称开窗结构对百叶窗翅片散热能力影响分析

为了探索非对称开窗结构对百叶窗翅片散热能力的影响,以8种非对称开窗结构的单周期翅片单元为研究对象,通过STARCCM仿真软件,在6种空气入口速度条件下,对出口温度Tout、进出口压降△P、内部流场和综合评价因子j/f1/3对比分析,得出翅片开窗结构非对称性与散热能力的关系.研究表明,针对同一个非对称开窗结构翅片,不同的...     

封闭空间系统的散热强化仿真研究

结合对流、辐射和传导理论对一个典型的封闭空间系统的热-流场进行了数值仿真研究,提出了三种具体的促散热方案并开展了仿真分析。结果表明:在系统内部,采用强制对流替代自然对流可大幅促进散热;在系统外表面加工微槽,增大与环境的传热面积,可小幅降低中心平台的温度;在封闭空间内填充入氦气有助于系统散热,通过改变空气和氦气的组成比例,可使中心平台处于特定温度。     

列车MPU高速芯片散热设计及仿真研究

热仿真用作电子产品的散热设计,对在不同环境、不同功率下的电子产品温度进行可靠预测,从而进行散热设计,预防高温失效.针对列车MPU高速处理器芯片的结构进行散热仿真研究,并对比仿真结果与实际测试结果,进而进行优化,达到了使用仿真进行散热设计的目的.     

基于温度场仿真的干式变压器散热设计

随着国家经济的快速发展,变压器的应用已涉及各个领域,干式变压器因其安全、环保、免维护等优点,而被广泛应用。干式变压器的应用环境千差万别,一旦发生故障,将会引起大范围的停电,给工农业生产和人们生活带来诸多不利,因此,对干式变压器的可靠性要求也随之提升。综合分析各类干式变压器的故障原因,有很大一部分故障原因是干式变压器的局部过热而引发的绝缘失效。在故障发生的前后一段时间内,温度场会随着故障的发生而产生不同的变化。为了解温度场的变化,利用有限元分析,建立干式变压器的三维模型,并对模型的电磁场、温度场和流体场进行计算,得到干式变压器的温度场分布。通过干式变压器的温度场分析出干式变压器易存在过热点的位置,对该位置进行故障模拟,获取变压器的温度场分布变化,再根据分布变化对影响干式变压器的散热的出风口位置进行优化模拟。结果表明,模拟结果与试验结果吻合,通风口位置设置会影响产品的散热效果。     

面向数据中心的储能系统应用研究

[目的]在新基建的背景下,数据中心得到迅猛的发展,数据中心作为高密度负荷,如何最大限度采用清洁能源并降低运行能耗,得到越来越多的关注.[方法]梳理了当前储能系统主流电池技术参数及数据中心供电需求.[结果]通过电池参数分析,给出了适用于数据中心储能系统的电池选型建议,随后提出了面向数据中心储能系统的应用模式以及满足快速切...     

Design and multi-objective optimization of heat exchangers for refrigerators

In this study, a detailed thermodynamic model for a refrigerator based on an irreversible Carnot cycle is developed with the focus on forced-air heat-exchangers. A multi-objective optimization procedure is implemented to find optimal design values for design variables. Minimizations of energy consumption and material cost were the two objectives considered. Since these objectives are conflicting, no single design will satisfy both simultaneously. The result of this research is a set of multiple optimum solutions, which are called ‘Pareto optimal solutions’. Air and refrigerant side correlations were combined with an elemental approach to model the heat exchangers. This paper presents a detailed design model development. A limited validation is presented with experimental test-data obtained from a typical household refrigerator. Detailed simulation models are typically complex and computationally demanding. An optimization algorithm requires several evaluations of such models. Response surface based metamodels for objective functions were used to save computational effort. A genetic-algorithm based optimization tool is used for multi-criteria optimization.     

Molecular dynamics calculation of heat dissipation during sliding friction

A novel method of calculation of heat dissipation during sliding between metals was presented by using molecular dynamics. Temperature distribution in the regions near the contact interface was calculated. The calculation results show that plastic deformation in the near-surface regions accounts for most of the friction heat and the temperature increase. Friction heat was built up in the regions subject to plastic deformation. In the case that no plastic deformation occurred, elastic waves contributed mainly to the energy dissipation so that no large heat buildup could take place in the vicinity of the contact regions.     

Enhanced heat dissipation of V-trough PV modules for better performance

A concentrator photovoltaic (PV) module, in which solar cells are integrated in V-troughs, is designed for better heat dissipation. All channels in the V-trough channels are made using thin single Al metal sheet to achieve better heat dissipation from the cells under concentration. Six PV module strips each containing single row of 6 mono-crystalline Si cells are fabricated and mounted in 6 V-trough channels to get concentrator V-trough PV module of 36 cells with maximum power point under standard test condition (STC) of 44.5 W. The V-trough walls are used for light concentration as well as heat dissipation from the cells which provides 4 times higher heat dissipation area than the case when V-trough walls are not used for cooling. The cell temperature in the V-trough module remains nearly same as that in a flat plate PV module, despite light concentration. The controlled temperature and increased current density in concentrator V-trough cells results in higher V_oc of the module.     

T-shaped assembly of fins with constructal entransy dissipation rate minimization

T-shaped assembly of fins is optimized by adopting an analytical method and taking the minimum mean thermal resistance in terms of entransy as optimization objective. The optimal construct of T-shaped assembly is obtained and compared with the optimal construct with maximum temperature difference minimization. The results show that for the two optimization objectives the thicknesses of the optimized fins are almost equal, but the lengths are different obviously: the former length of the elemental fin is almost half the value of the latter length, and the former length of the first-order fin is almost twice as large as the latter length. Compared with the latter optimal construct, the dimensionless mean thermal resistance corresponding to the former optimal construct decreases by 16.4%, and the corresponding dimensionless maximum thermal resistance increases by 9.74%. Both the minimizations of the EDR and the maximum temperature difference (MTD) should be combined to consider the efficiency and the temperature limitation simultaneously for designing the fins.     

Novel heat dissipation design incorporating heat pipes for DC combiner boxes of a PV system

In a Photovoltaic (PV) system, heat is generated by an operating diode. Because DC combiner boxes are waterproof, dustproof, air tight and made of heat-insulating material, thermal energy is easily accumulated, affecting the performance and safety of power cables and other electronic components near the diodes in the DC combiner box. This study utilizes a heat pipe as a channel for heat dissipation to conduct the heat out of a DC combiner box without destroying the air-tightness of the box. An existing DC combiner box was improved upon using this method of heat dissipation. The measured heat flow and temperature demonstrate that the proposed method is feasible. The influence of the condensation section temperature on the maximum heat transfer of the heat pipe was also investigated by experiment. The maximum heat transfer rate of the heat pipe was found to increase with the condensation section temperature of the heat pipe. When the condensation temperature was 20 °C, 30 °C and 40 °C, the maximum heat transfer rate of the heat pipe was 21.6 W, 29.6 W and 39.7 W, respectively.     

MHD-conjugate heat transfer analysis for a vertical flat plate in presence of viscous dissipation and heat generation

In this paper, the effects of magnetic field, viscous dissipation and heat generation on natural convection flow of an incompressible, viscous and electrically conducting fluid along a vertical flat plate in the presence of conduction are investigated. Numerical solutions for the governing momentum and energy equations are given. A discussion is provided for the effects of magnetic parameter, viscous dissipation parameter and heat generation parameter on two-dimensional flow. Detailed analysis of the velocity profile, temperature distribution, skin friction, rate of heat transfer and the surface temperature distribution are shown graphically.     

数据中心超高效冷源系统能效评价与设计探讨

从数据中心冷源系统高能耗分析入手,探讨国内外冷源系统能耗评价体系,注重分析数据中心超高效冷源系统设计特征和建设流程,为实现提升数据中心能效水平提供技术参考。     

户内主变压器室通风散热优化设计研究

建立某110 kV户内主变压器室通风散热三维模型,利用计算流体力学方法研究了变压器室自然通风临界温度,机械排风速率,进、出风口位置及大小对其散热特性的影响,并分析了原始方案与优化后方案中变压器室内的流动特性。结果表明：原始方案中变压器自然通风临界温度约为22℃,且随着室外环境温度升高,自然通风时室内变压器靠近底部区域易出现热量堆积,造成变压器散热量无法及时排出,进而对变压器的安全、稳定运行造成危害。在自然通风临界温度为22℃时,所需最小机械排风速率为2.56 m·s^-1。增大进、出风口面积以及降低出风口位置均有利于增强变压器室内散热效果,使变压器室排风温度显著降低。将两个风机位置调低可使出风口平均温度降低1～2℃。与原始方案(风量2.56 kg·s^-1)相比,优化后方案(风量降低至1.50～2.00 kg·s^-1)可满足该变压器室通风散热需求,从而达到优化风量、降低噪声的目的。     

Design of a large-scale metal hydride based hydrogen storage reactor: Simulation and heat transfer optimization

An optimized design for a 210 kg alloy, TiMn alloy based hydrogen storage system for stationary application is presented. A majority of the studies on metal hydride hydrogen systems reported in literature are based on system scale less than 10 kg, leaving questions on the design and performance of large-scale systems unanswered. On the basis of sensitivity to various design and operating parameters such as thermal conductivity, porosity, heat transfer coefficient etc., a comprehensive design methodology is suggested. Following a series of performance analyses, a multi-tubular shell and tube type storage system is selected for the present application which completes the absorption process in 900 s and the desorption process in 2000 s at a system gravimetric capacity of 0.7% which is a vast improvement over similar studies. The study also indicates that after fifty percent reaction completion, heat transfer ceases to be the major controlling factor in the reaction. This could help prevent over-designing systems on the basis of heat transfer, and ensure optimum system weight.     

氟泵供液式散热系统试验研究

利用一个氟泵供液式散热系统,分别研究了室外环境温度变化对散热量和能效比的影响;通过变频调节氟泵功率改变散热工质流量,分析并讨论散热工质流量的变化对散热量和能效比的影响。试验结果表明,随着室外环境温度的降低,系统散热量和能效比均显著提高;随着散热工质流量的增大,散热量先升高后基本保持不变,能效比则先升高后降低,即存在最佳散热工质流量使得系统的能效比达到最大值。系统优化后在实际应用时,在室内外温差为11～26℃时,测算的能效比可达8.5～16.5。