新能源汽车动力电池散热方式及散热问题的热管理解决方案

新能源电动汽车以更减排、更环保的优势替代传统燃油汽车,成为汽车行业的主流,但新能源电动汽车也存在相应的问题,如电池散热不稳定、部件高温、使用寿命缩短等。为提升动力电池效能,延长新能源汽车的续航能力,针对常用的电池散热方式展开探讨,多种散热系统和散热材料相结合,提出一种更高效、更周全的新能源汽车电池热管理方案,提升电池热管理系统整体的换热效果和系统的实质性发展,以期满足新能源汽车动力电池的散热要求,为动力电池的实际应用提供参考。     

电动汽车动力电池冷却技术的研究进展

新能源汽车在运行时,如何冷却动力电池使其维持在最佳的工作温度是需要重视的问题。合适的冷却技术可以有效提高动力电池的效率,并随着时间的推移降低动力电池老化的速度,延长其使用寿命。综述了几种电池热管理冷却系统,包括传统冷却技术中空气冷却系统、液体冷却系统和直接冷却系统。新型冷却技术中基于相变材料冷却系统、采用热管技术冷却系统和电子元件冷却系统提高汽车动力电池的性能。根据不同技术分析各自的优缺点、适合的工作工况以及经济效益。未来动力电池热管理的发展方向应是无论选择何种技术冷却动力电池,都应保证动力电池处于最佳工作温度,冷却系统稳定、可靠并且能够稳定提高动力电池的转换效率,以期为电池热管理的实际应用提供一定的参考价值。     

基于结构性能连续性的模拟退火算法优化换热网络

换热网络优化是典型的混合整数非线性问题,其整型变量的组合情况(换热网络的结构)对于其优化的走向以及局部最优解的质量具有至关重要的作用.指出换热网络的结构与性能存在连续性,并由此提出以连续性指导整型变量最优搜索的换热网络模拟退火算法,对换热网络的结构进行最优搜索,降低换热网络的综合费用.通过对实际算例的优化,将换热网络的综合费用由1599229美元降至1581165美元.结果表明:换热网络结构与性能的连续性能指导整型变量的优化走向,保证模拟退火算法在换热网络优化过程中的可靠性.     

利用首腔窄化强化折流板型太阳能集热器性能研究

通过数值模拟和实验验证的方法对利用首腔窄化提升折流板型太阳能集热器热性能进行研究。运用数值分析方法分析5种首腔窄化模型的流动换热特性,获得窄化首腔强化集热性能优化的方法。结果表明,首腔宽度对集热器效率有重要影响,而对集热器阻力影响很小,对于特定尺度的折流板型集热器,存在最优窄化宽度。在该文的计算工况范围内,首腔窄化模型相比于折流板均布模型的集热效率增长率最大为16.90%。通过建立1.0∶0.5实验模型对首腔窄化方法的有效性进行验证,实验结果表明首腔窄化方法对于运行工况不敏感,具有较稳定的优化效果,适合向不同应用领域、不同气候地区推广。该文提出的方法为折流板型太阳能空气集热器热性能优化提供了一种新思路。     

上海市新能源汽车动力电池回收现状与发展展望

本文总结分析了国家及上海市新能源汽车动力电池回收利用相关政策、标准和行业现状,对上海市新能源汽车废旧动力电池回收潜力进行了初步预测,并提出废旧动力电池回收利用的三大核心价值链,对上海市动力电池回收领域存在的问题进行总结归纳并提出针对性发展建议,可为上海市新能源汽车废旧动力电池回收利用产业发展和促进减污降碳提供一定支撑。     

混合动力汽车用电池热管理系统的设计与研究

新能源汽车的发展离不开动力电池,且动力电池的性能及寿命与其工作的温度点密切相关,因此设计合理的热管理控制策略保证其工作在最佳工作温度范围对提高整车动力性及经济性具有重要意义。针对平铺水冷电池包的结构布置方案,通过实时采集的电池与冷却液温度信息,实现对外部散热器与压缩机散热控制,并通过2种极端工况进行路试测试。实验表明,该控制方案能保证电池工作在35～48℃(即最佳温度区间)节约能耗,保证整车动力性与经济性,对新能源汽车电池热管理控制策略设计具有重要参考价值。     

《促进汽车动力电池产业发展行动方案》印发

<正>工业和信息化部、发展改革委、科技部、财政部日前联合印发《促进汽车动力电池产业发展行动方案》,提出加快提升我国汽车动力电池产业发展能力和水平,推动新能源汽车产业健康可持续发展。方案提出了五大主要目标:一是产品性能大幅提升,2020年动力电池系统比能量力争较现有水平提高一倍达到260瓦时/公斤、成本降至1元/瓦时以下,2025年动力电池单体比能量达500瓦时/公斤;二是产品安全性满足大规模使用需     

水-油连续螺旋折流板换热器热力性能研究

利用计算流体力学(Computational Fluid Dynamic, CFD)方法,针对连续螺旋折流板换热器建立物理模型和数学模型,在管侧介质为水和壳侧介质为原油条件下,研究不同原油流量及螺旋角对螺旋折流板换热器内部流场、换热性能及阻力性能的影响,并拟合了水油换热时螺旋折流板换热器的Nu、f与Re的关联式。结果表明：22°螺旋角的螺旋折流板换热器与其它较小螺旋角换热器对比,壳侧压降和换热系数逐渐减小,综合换热性能最佳。通过对壳侧原油为层流状态下的阻力系数和对流换热系数关系式进行拟合,更好地指导水-油连续螺旋折流板换热器的热力设计。     

三分螺旋折流板换热器壳侧传热特性试验

对倾斜角为20°、24°、28°、32°单头和32°双头周向重叠三分螺旋折流板换热器和作为对照的弓形折流板换热器的水-水传热和压降性能进行了测试;得到了总体传热系数K、壳侧换热系数ho、壳侧压降Δpo等参数和ho/Δpo综合性能指标随壳侧流量的变化曲线。试验结果表明倾斜角20°方案的性能指标均好于其他方案,且其壳侧换热系数和单位压降的壳侧换热系数综合性能指标比弓形折流板换热器方案平均分别高出25%和100%以上。     

新能源汽车未来几年将装配的电池

正近几年,在新能源汽车快速发展的强劲带动下,动力电池的发展速度一路狂飙。1月16日,在"独具匠芯,智创未来"新能源行业峰会暨2018新形势下动力电池发展方向研讨会上,中国汽车技术研究中心方凯正博士介绍:2017年,中国新能源汽车动力电池总配套量373.7亿W·h,同比增长33%。从分析来看,预计未来几年,新能源汽车将更多配套三元电池,购买装配三元电池的新能源车型将成为主流现象。     

开缝布置方式对开缝翅片管换热器 传热与阻力特性的影响

为了获得开缝布置方式对开缝翅片管换热器传热与阻力特性的影响规律,对5种不同翅片管换热器进行了数值模拟研究,并进行了模化试验验证。结果表明：增加开缝会提高翅片管换热器的传热性能,但阻力也随之增加;与开缝位置相比,开缝数量对开缝翅片管换热器传热与阻力特性的影响更大;在Re=4800~7500日时,开缝翅片管换热器综合流动传热性能 随着Re数的增大而增大;在5种翅片中,开缝翅片的综合流动传热性能高于普通平直翅片;数值模拟与试验结果偏差较小,采用数值模拟方法能够比较准确地分析开缝翅片管换热器的传热与阻力特性。     

NUMERICAL DESIGN OF EFFICIENT SLOTTED FIN SURFACE BASED ON THE FIELD SYNERGY PRINCIPLE

In this article, a numerical investigation of the flow and heat transfer in a three-row finned-tube heat exchanger is conducted with a three-dimensional laminar conjugated model. Four types of fin surfaces are studied; one is the whole plain plate fin, and the other three are of slotted type, called slit 1, slit 2, and slit 3. All four fin surfaces have the same global geometry dimensions. The three slotted fin surfaces have the same numbers of strips, which protrude upward and downward alternatively and are positioned along the flow direction according to the rule of “front coarse and rear dense.” The difference in the three slotted fins is in the degree of “coarse” and “dense” along the flow direction. Numerical results show that, compared to the plain plate fin, the three types of slotted fin all have very good heat transfer performance in that the percentage increase in heat transfer is higher than that in the friction factor. Among the three slotted fin surfaces, slit 1 behaves the best, followed by slit 2 and slit 3 in order. Within the Reynolds number range compared ( from 2,100 to 13,500), the Nusselt number of slit 1 is about 112–48% higher than that of the plain plate fin surface under the identical pumping constraint. An analysis of the essence of heat transfer enhancement is conducted from the field synergy principle, which says that the reduction of the intersection angle between the velocity and the temperature gradient is the basic mechanism for enhancing convective heat transfer. It is found that for the three comparison constraints the domain-average synergy angle of slit 1 is always the smallest, while that of the plain plate fin is the largest, with slit 2 and slit 3 being somewhat in between. The results of the present study once again show the feasibility of the field synergy principle and are helpful to the development of new types of enhanced heat transfer surfaces.     

Enhancement of Heat Transfer for Plate Fin Heat Exchangers Considering the Effects of Fin Arrangements

In the present study, the potential of rectangular fins with different fin types of inner zigzag-flat-outer zigzag (B-type) and outer zigzag-flat-outer zigzag (C-type) and with different fin angles of 30° and 90° for 2 mm fin height and 10 mm offset from the horizontal direction for heat transfer enhancement with the use of a conjugated heat transfer approach and for pressure drop in a plate fin heat exchanger is numerically evaluated. The rectangular fins are located on a flat plate channel (A-type). The numerical computations are performed by solving a steady, three-dimensional Navier–Stokes equation and an energy equation by using FLUENT software program. Air is taken as working fluid. The study is carried out at Reynolds number of 400 and inlet temperatures, velocities of cold and hot air are fixed as 300 K, 600 K and 1.338 m.s^?1, 0.69 m.s^?1, respectively. This study presents new fin geometries which have not been researched in the literature for plate fin heat exchangers. The results show that while the heat transfer is increased by about 10% at the exit of a channel with the fin type of C, it is increased up to 8% for the fin angle of 90° when compared to a channel with A-type under the counter flow. The heat transfer enhancements for different values of Reynolds number and for varying fin heights, fin intervals and also temperature distributions of fluids are investigated for parallel and counter flow.     

几种带冷却结构的双层管换热及流动对比

对相同质量流量下的光管、双层光管、带冷却结构（肋、扰流柱、凹坑、螺旋通道）的双层管等不同结构的管流动进行了流固耦合三维数值模拟,获取了固体壁温的分布特征;对各结构下,外层壁冷热侧温差、冷气温升、流动特性及综合换热效率进行了研究分析。研究结果表明：相同质量流量下,带螺旋通道双层管的外层壁冷热侧温差最小、综合换热效率最高;凹坑结构双层管与双层光管的流动及换热特性相似,流阻较小但换热效果也较差;扰流柱和肋结构双层管的流动换热特性相近,其温度分布均匀性、换热量介于双层光管和螺旋通道双层管之间,其流阻大且综合换热效率低。     

Thermal analysis of plate condensers in presence of flow maldistribution

Flow maldistribution in plate heat exchangers causes deterioration of both thermal and hydraulic performance. The situation becomes more complicated for two-phase flows during condensation where uneven distribution of the liquid to the channels reduces heat transfer due to high liquid flooding. The present study evaluates the thermal performance of falling film plate condensers with flow maldistribution from port to channel considering the heat transfer coefficient inside the channels as a function of channel flow rate. A generalized mathematical model has been developed to investigate the effect of maldistribution on the thermal performance as well as the exit quality of vapor. A wide range of parametric study is presented, which shows the effects of the mass flow rate ratio of cold fluid and two-phase fluid, flow configuration, number of channels and correlation for the heat transfer coefficient. The analysis presented here also suggests an improved method for heat transfer data analysis for plate condensers.     

板式换热器火用传递特性研究

文中运用推导逆流换热器对数平均温度的方法,得到了板式换热器中冷热流体及板上的温度分布.在此基础上运用火用传递理论,推导出了热流体至板、板至冷流体的局部火用传递系数.以某板式换热器为例进行了算例分析,从火用传递角度分析了该换热器的换热性能,此结果可以作为对板式换热器进行优化和改进的一种可行有效的重要参考.     

IGBT水冷基板瞬态启停及变工况运行特性实验研究

为避免绝缘栅双级晶体管(insulated gate bipolar transistor,IGBT)水冷基板在非常情况下导致冷却失效甚至造成系统瘫痪的危险发生,针对设计制作的一种平行微通道水冷基板在多种变工况条件下进行了其传热性能的实验研究;实验研究的变工况条件包括供水系统的瞬态启动或停止条件,质量流量60~330kg/h的波动变化条件以及水冷基板部分流道堵塞的条件,重点研究了实验条件对被冷却器件表面温度及其冷却效果的影响规律。结果表明:瞬态变化条件下高热流密度时会发生危险工况,其反应时间τR10s,流量波动条件下当平均努赛尔数Nu较小时对冷却效果影响较大,水冷基板部分流道堵塞的条件不会导致大幅温升。     

Conjugate heat transfer characterization in cooling channels

Cooling technology of gas turbine blades,primarily ensured via internal forced convection,is aimed towards withdrawing thermal energy from the airfoil.To promote heat exchange,the walls of internal cooling passages are lined with repeated geometrical flow disturbance elements and surface non-uniformities.Raising the heat transfer at the expense of increased pressure loss;the goal is to obtain the highest possible cooling effectiveness at the lowest possible pressure drop penalty.The cooling channel heat transfer problem involves convection in the fluid domain and conduction in the solid.This coupled behavior is known as conjugate heat transfer.This experimental study models the effects of conduction coupling on convective heat transfer by applying iso-heat-flux boundary condition at the external side of a scaled serpentine passage.Investigations involve local temperature measurements performed by Infrared Thermography over flat and ribbed slab configurations.Nusselt number distributions along the wetted surface are obtained by means of heat flux distributions,computed from an energy balance within the metal domain.For the flat plate experiments,the effect of conjugate boundary condition on heat transfer is estimated to be in the order of 3%.In the ribbed channel case,the normalized Nusselt number distributions are compared with the basic flow features.Contrasting the findings with other conjugate and convective iso-heat-flux literature,a high degree of overall correlation is evident.     

Performance of flow and heat transfer in vertical helical baffle condensers

The feed water heaters in power plants are actually the condensers using turbine extracting steam to heat feed water. The vertical feed water heater occupies less area than the horizontal one and convenient to lift tube bundles out in maintenance. However, the lower heat transfer coefficient due to thick condensate film limits its application. A novel trisection helical baffled vertical condenser (feed water heater) is proposed with liquid dams and gaps for facilitating condensate drainage. The flow and condensation heat transfer characters of two vertical condensers with variable angled trisection helical baffles of both single-thread and dual-threads and a variable spanned segmental baffled one were numerically studied with Mixture model of Fluent software. The distributions of velocity, pressure, volume fraction of condensate, and local heat transfer coefficient in these heat exchangers were demonstrated. The simulation results show that the inclined baffles with liquid dam and drainage gaps could drain condensate effectively from tube bundle surfaces and prevent liquid film from entraining into vapor, and that the variable angled trisection helical baffled vertical condenser with dual-threads could greatly improve the condensation heat transfer coefficient up to 35.7% higher than that of the variable spanned segmental baffled one.     

Study of Heat Transfer Distribution in a Channel with Inclined Target Surface Cooled by a Single Array of Staggered Impinging Jets

An experimental investigation has been carried out to study the heat transfer characteristics in a channel with a heated target surface inclined at an angle, cooled by a single array of staggered impinging jets. The work encompasses the effect of three feed channel aspect ratios (5, 7, 9) and three exit outflow orientations (coincident with the entry flow, opposed to the entry flow, and both), and three Reynolds numbers (9400, 14,400, 18,800) on heat transfer. Results show that increasing the Reynolds number increases the heat transfer on the inclined target surface. The outflow orientations affect significantly the local heat transfer charactracistrics, through influencing the jet flow together with the crossflow in the impingement channel. The outflow orientation coincident with the entry flow and the outflow from both sides show better averaged Nusselt number values compared to outflow orientation opposed to the entry flow. The inclined surface affects the local Nusselt number distribution especially for the outflow orientation opposing the entry flow at the narrow region of the impingement channel. In general, the feed channel aspect ratio does not affect the Nusselt number distribution, except for outflow coincident with the entry flow. The local Nusselt number for aspect ratio 9 has been found to be greater than the Nusselt number for aspect ratio 5 by 11%. Additionally, for a given jet-orifice plate with staggered holes, the heat transfer is almost the same throughout the target surface for the outflow exiting in both directions.