An ultra-fast charging strategy for lithium-ion battery at low temperature without lithium plating

Conventional charging methods for lithium-ion battery(LIB)are challenged with vital problems at low temperatures:risk of lithium(Li)plating and low charging speed.This study proposes a fast-charging strategy without Li plating to achieve high-rate charging at low temperatures with bidirectional chargers.The strategy combines the pulsed-heating method and the optimal charging method via precise control of the battery states.A thermo-electric coupled model is developed based on the pseudo-twodimensional(P2D)electrochemical model to derive charging performances.Two current maps of pulsed heating and charging are generated to realize real-time control.Therefore,our proposed strategy achieves a 3 C equivalent rate at 0℃ and 1.5 C at-10℃ without Li plating,which is 10–30 times faster than the traditional methods.The entropy method is employed to balance the charging speed and the energy efficiency,and the charging performance is further enhanced.For practical application,the power limitation of the charger is considered,and a 2.4 C equivalent rate is achieved at 0℃ with a 250 kW maximum power output.This novel strategy significantly expands LIB usage boundary,and increases charging speed and battery safety.

Specific Heat and Charge Density of Quasi-One-Dimensional Interchain Coupling Organic Ferromagnets

On the basis of a generalized SSH model, an organic polymer ferromagnet theory is proposed at the finite temperature in the self-consistent mean field approximation, and the specific heat and charge density of the quasione-dimensional interehain coupling organic ferromagnets are presented. We find that an obvious feature is to present itself the round peak for the specific heat with the temperature. This indicates unambiguously the presence of the phase transition in the system. The transition temperature plays down with increasing of the interchain coupling t2 or decreasing of the electron repulsion u. The curves of charge density with the temperature debase monotonously. This result illustrates that the higher the temperature is, the more electrons are excited.

Time-Temperature Charge Function of a High Dynamic Thermal Heat Storage with Phase Change Material

A thermal heat storage system with an energy content of 40 kWh and a temperature of 58°C will be presented. This storage system is suitable for supporting the use of renewable energies in buildings and for absorbing solar heat, heat from co-generation and heat pumps or electric heat from excess wind and solar power. The storage system is equipped with a plate heat exchanger that is so powerful that even with small temperature differences between the flow temperature and the storage temperature a high load dynamic is achieved. The storage system has a performance of 2.8 kW at 4 K and 10.6 kW at a temperature difference of 10 K. Thus, large performance variations in solar thermal systems or CHP plants can be buffered very well. Further a storage charge function Q(T, t) will be presented to characterize the performance of the storage.

Study on performance of a packed bed latent heat thermal energy storage unit integrated with solar water heating system

In thermal systems such as solar thermal and waste heat recovery systems, the available energy supply does not usually coincide in time with the process demand. Hence some form of thermal energy storage (TES) is necessary for the most effective utilization of the energy source. This study deals with the experimental evaluation of thermal performance of a packed bed latent heat TES unit integrated with solar flat plate collector. The TES unit contains paraffin as phase change material (PCM) filled in spherical capsules, which are packed in an insulated cylindrical storage tank. The water used as heat transfer fluid (HTF) to transfer heat from the solar collector to the storage tank also acts as sensible heat storage material. Charging experiments were carried out at varying inlet fluid temperatures to examine the effects of porosity and HTF flow rate on the storage unit performance. The performance parameters such as instantaneous heat stored, cumulative heat stored, charging rate and system efficiency are studied. Discharging experiments were carried out by both continuous and batchwise processes to recover the stored heat, and the results are presented.

Charging System of ECRH High-Voltage Power Supply and its Control System

High-voltage power supply (HVPS) of Electron Cyclotron Resonance Heating (ECRH) for HT-7 and HT-7U is presently being constructed. The high voltage (100 kV) energy of HVPS is stored in the capacitor banks, and they can power one or two gyrotrons. All the operation of the charging system will be done by the control system, where the field signals are interfaced to programmable logic controller (PLC). The use of PLC not only simplifies the control system, but also enhances the reliability. The software written by using configuration software installed in the master computer allows for remote and multiple operator control, and the status and data information is also remotely available.

Holographic heat engine efficiency of hyperbolic charged black holes

We consider a four-dimensional charged hyperbolic black hole as working matter to establish a black hole holographic heat engine,and use the rectangular cycle to obtain the heat engine efficiency.We find that when the increasing of entropy is zero,the heat engine efficiency of the hyperbolic black hole becomes the well-known Carnot efficiency.We also find that less charge corresponds to higher efficiency in the case of˜q>0.Furthermore,we study the efficiency of the flat case and spherical case and compare the efficiency with that of the hyperbolic charged black holes.Finally,we use numerical simulation to study the efficiency in benchmark scheme.

集中供暖建筑不同计费模式对空气品质满意度的影响研究

为了探究寒冷地区不同供暖计费方式下空气品质满意度对热舒适度的影响,对中国河南省焦作地区某居民住宅分别于2018年、2020年两个供暖季进行了现场研究。在测量环境参数时,也采集了受试者的热舒适状况。通过对比、分析发现,在不同热计量方式下,用户的热感觉、空气品质满意度及行为调节均存在统计学上的显著差异。相较于按面积收费,按流量收费住户的热反应与空气品质满意度都更好。本研究旨在揭示空气品质满意度与热感觉、调控行为的关系,并为供暖计费方式的选择提供参考。

微型电动汽车动力电池充电保温系统设计研究

为解决微型电动汽车在低温环境下充电困难的问题,提出了一种动力电池充电保温系统。通过对加热部件-加热膜、电路以及热管理系统控制策略3方面进行设计,实现了充电保温功能和充电保温等待功能,确保充电时保持动力电池温度在适宜范围内的效用。实验结果表明,该充电保温系统可有效实现温度的调节,保证充电的正常运转。

纳米多孔碳孔径对SrBr_(2)化学蓄放热性能的影响

溴化锶(SrBr_(2))被认为是化学蓄热领域最有前景的材料之一。为探究载体孔径大小对SrBr_(2)蓄放热性能的影响,分别以孔径为10、30、50和100 nm的纳米多孔碳(NCP)为载体,采用浸渍法制备多孔碳基SrBr_(2)复合材料。通过XRD、SEM和BET对复合材料的微观形貌结构进行表征,并通过水合实验和同步热分析对其蓄放热性能进行测试。结果表明,复合材料的吸水量和蓄热密度随孔径先增大后减小,存在最优载体孔径。其中,NCP50-SrBr_(2)具有最优的平衡吸水量和蓄热密度,分别为0.703 g/g和1198.62 kJ/kg。NCP50-SrBr_(2)表现出更快的反应速率,在水合反应30min后蓄热密度可达945.34kJ/kg。研究结果可为纳米尺度定向调控化学蓄热材料性能提供理论依据。

内/外隔热复合结构炸药装药快速烤燃热防护效应

为了研究快速烤燃(火烧)条件下炸药装药内/外隔热复合结构(内隔热材料/外阻燃材料)的热防护效应,对多种内/外隔热复合结构的炸药装药进行多点测温快速烤燃试验,得到火焰场和炸药装药各测点的温度-时间曲线及装药点火响应时间。开展内/外隔热复合结构炸药装药快速烤燃数值模拟,获得内/外隔热复合结构对装药快速烤燃点火响应时间的影响规律。研究结果表明:在快速烤燃过程中,外阻燃材料由于火烧变性存在导热增强及隔热减弱效应,在数值模拟中需考虑该效应;无论使用单独的隔热/阻燃材料还是使用内/外隔热复合结构,炸药装药的点火响应时间均随着材料涂覆厚度增加而延后,其中内/外隔热复合结构具有更好的热防护能力;点火位置均发生在装药端面棱角处,装药点火后反应烈度不受内/外隔热复合结构影响,反应等级均为爆燃;对于一定热防护性能范围内的隔热阻燃材料,壳体外表面涂层材料是耐高温纳米隔热材料、壳体内表面涂层材料是高效隔热防护材料时复合结构的隔热效果最好,并且当需求的隔热效果给定时,可考虑优先增加壳体外表面涂层的涂覆厚度,实现以最小涂覆厚度的内/外隔热复合结构满足所需的隔热效果。研究成果可为提升弹药热安全性设计提供参考。

大功率充电连接器相变冷却换热特性研究

直流大功率快充技术可显著缩短电动汽车充电时间,缓解充电焦虑,然而在高电压、大电流下,充电连接器的温度短时间内急剧上升,将降低连接器使用寿命且易引发安全问题。为此,提出一种适用于大功率充电连接器的高效相变冷却技术,分别对单相和相变冷却性能进行数值建模分析,研究了冷却液种类、流量、套管厚度等参数对冷却性能的影响规律。结果表明,充电时长为5 min,加载电流为600 A时,采用40℃水单相冷却可将电缆温度降低至69℃,而采用R134a两相相变冷却则可将电缆温度降低至40℃以下。电缆温度随两相冷却液流量增加而降低,随套管厚度增加而增加,套管厚度相较冷却液流量对电缆温度的影响更为显著。

Exploration of microscopic physical processes of Z-pinch by a modified electrostatic direct implicit particle-in-cell algorithm

For investigating efficiently the stagnation kinetic-process of Z-pinch,we develop a novel modified electrostatic implicit particle-in-cell algorithm in radial one-dimension for Z-pinch simulation in which a small-angle cumulative binary collision algorithm is used.In our algorithm,the electric field in z-direction is solved by a parallel electrode-plate model,the azimuthal magnetic field is obtained by Ampere’s law,and the term for charged particle gyromotion is approximated by the cross product of the averaged velocity and magnetic field.In simulation results of 2 MA deuterium plasma shell Zpinch,the mass-center implosion trajectory agrees generally with that obtained by one-dimensional MHD simulation,and the plasma current also closely aligns with the external current.The phase space diagrams and radial-velocity probability distributions of ions and electrons are obtained.The main kinetic characteristic of electron motion is thermal equilibrium and oscillation,which should be oscillated around the ions,while that of ion motion is implosion inwards.In the region of stagnation radius,the radial-velocity probability distribution of ions transits from the non-equilibrium to equilibrium state with the current increasing,while of electrons is basically the equilibrium state.When the initial ion density and current peak are not high enough,the ions may not reach their thermal equilibrium state through collisions even in its stagnation phase.

小针刀联合中药热封包治疗腰椎间盘突出症的效果分析

目的:分析小针刀联合中药热封包治疗腰椎间盘突出症的效果。方法:选取2021年2月—2023年4月贵州航天医院收治的腰椎间盘突出症患者68例作为研究对象,根据随机数字表法分为研究组和对照组,各34例。对照组采用中药热封包治疗,研究组在对照组基础上联合小针刀治疗。比较两组治疗效果。结果:治疗后,两组疼痛、腰背肌功能评分低于治疗前,且研究组低于对照组,差异有统计学意义(P<0.05)。研究组治疗有效率高于对照组,差异有统计学意义(P=0.031)。结论:腰椎间盘突出症患者应用小针刀联合中药热封包治疗的效果显著,可缓解疼痛,强化腰背肌功能。

The thermal analysis of the heat dissipation system of the charging module integrated with ultra-thin heat pipes

Electric vehicles(EV)played an important role fighting greenhouse gas emissions that contributed to global warming.The construction of the charging pile,which was called as the"gas station"of EV,developed rapidly.The charging speed of the charging piles was shorted rapidly,which was a challenge for the heat dissipation system of the charging pile.In order to reduce the operation temperature of the charging pile,this paper proposed a fin and ultra-thin heat pipes(UTHPs)hybrid heat dissipation system for the direct-current(DC)charging pile.The L-shaped ultra-thin flattened heat pipe with ultra-high thermal conductivity was adopted to reduce the spreading thermal resistance.ICEPAK software was used to simulate the temperature and flow profiles of the new design.And various factors that affected the heat dissipation performance of the system were explored.Simulation results showed that the system had excellent heat dissipation capacity and achieved good temperature uniformity.Rather than solely relied on the fans,this new design efficiently dissipated heat with a lower fan load and less energy consumption.

有轨电车地面充电装置内循环散热系统优化方案

[目的]为解决现有有轨电车地面充电装置存在外壳防护性能不稳定、散热系统装置复杂、散热效率低等问题,设计了一种有轨电车地面充电装置内循环散热系统。[方法]介绍了地面充电装置的组成及散热原理,分析了其散热效率低的原因;针对密闭柜体整体内循环的散热系统,介绍了内循环散热系统优化方案,利用FLOTHERM仿真软件对原方案与优化方案散热系统的风速及温升情况进行对比,并进行了试验验证。[结果及结论]基于空调冷却整体内循环的散热系统无法有效解决大功率高热损耗集中发热器件的散热问题,这与制冷系统的制冷量大小无关,而与散热系统的风道回路有关。所提内循环散热系统优化方案在空调出风口、电抗器及空调回风口之间形成闭环风道回路,大幅降低了大功率集中发热器件的温升,有效提升了散热系统的散热性能,优化后充电装置中的电抗器温升降低约20.1%。所提优化方案能够满足内循环散热系统的温升要求。

可燃制冷剂在轨道交通车辆空调中的应用

[目的]为分析轨道交通车辆空调中的可燃制冷剂允许充注量,需研究可燃性环保制冷剂在轨道交通车辆空调中安全应用的可行性及方案。[方法]分析空调的安装场所及访问类别,结合不同可燃制冷剂热物性,计算当前轨道交通车辆空调中制冷剂的允许充注量。进一步通过空调间接换热系统的设计,提高轨道交通车辆空调中可燃制冷剂充注量限值,并就不同制冷剂的空调性能进行对比分析。[结果及结论]不同燃烧等级的制冷剂在轨道交通车辆空调中的允许充注量不尽相同,基于制冷剂燃烧下限的限制,可燃制冷剂在轨道交通车辆空调中难以直接使用,而通过间接换热设计可以有效提高可燃制冷剂在空调中的允许充注量,解决制冷剂燃烧性带来的安全风险问题,实现环保制冷剂在轨道交通车辆空调上的应用。

热连轧加热炉控制系统及升温曲线的优化研究

为解决当前热连轧加热炉在实际生产中由于对温度控制精度不够而导致的轧制产品质量不好和能耗偏高的问题,在对热连轧加热炉进行综合概述的基础上,采用可兼容通讯模块对控制系统进行改造,对加热炉升温曲线进行优化。优化改造后,对在炉时间、装炉温度和能耗等指标进行综合评估,不仅提升了产品质量,而且降低了能耗。

基于CFD数值模拟的汽车中冷器流动均匀性研究

针对汽车中冷器内流道气体流动均匀性差的问题,提出了一种在中冷器气室安装导流板的中冷器结构优化方案。基于CFD数值模拟,对中冷器内部气体质量流量分布、速度场和压力场进行了分析,通过风洞试验验证了仿真模型的有效性。在此基础上,研究了气室导流板对中冷器内流道气体流动均匀性的影响。研究结果表明:合理设置导流板,中冷器各散热管气体平均质量流量偏差由7.66%减小到3.20%,中冷器许用环境温度提高了0.84℃,气室压力损失减少了37.4%,改善了中冷器内流道气体流动均匀性,提高了散热性能,避免了芯体热应力集中,减少了可靠性失效风险。此中冷器结构优化方案可为中冷器流动均匀性研究提供参考。

纯电动汽车锂离子电池低温充电方法对温升速率的影响分析

为了解决锂离子电池在寒冷环境中充电能力下降导致充电时间大幅增加的问题,分析了锂离子电池的低温充电方法,并针对纯电动车用锂离子电池在低温下充电方法的差异对电池温升速率的影响展开研究,对改善电池低温充电速率和提升纯电动车低温充电能力提出建议。

厚板线加热炉节能技术改造

针对莱钢厚板线加热炉能耗偏高的现状,依靠热平衡搭建能耗桥对加热炉诊断分析后并实施技术改造。现场对炉门进行了节能技术改造,优化了步进梁、装钢机、出钢机连锁程序,解决了厚规格钢坯因热送温度偏高无法连续热送装钢技术难题;通过试验试轧拓展了热送坯型,优化了热送钢坯加热控制工艺。厚板线加热炉技术改造后,节能效果显著,煤耗指标由1.491 GJ/t降到1.474 GJ/t。