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1.
The low temperature charge and discharge characteristics of experimental MCMB-Li/sub x/Ni/sub y/Co/sub 1-y/O/sub 2/ cells containing different electrolytes were investigated. The use of low ethylene carbonate (EC)-content electrolyte formulations has resulted in good discharge performance to temperatures as low as -40/spl deg/C. The effect of charge voltage and charge current upon the individual electrode potentials at low temperature was investigated using the three electrode cells (containing lithium reference electrodes). In some cases, lithium plating was observed to occur upon low temperature charge, and found to be facilitated by high charge voltages, high charge currents, and poor anode kinetics. Electrochemical characterization of the cells has helped to establish the conditions under which lithium plating can occur by providing information regarding the polarization effects present at each electrode.  相似文献   

2.
Lockheed Martin Missiles & Space (LMMS), Ultralife Batteries, Inc. (UBI), Eagle Picher Technologies, LLC (EPT), Sandia National Laboratories (SNL) and Rentech, Inc. (RTI) are developing lithium ion solid polymer electrolyte (Li-ion SPE) batteries. Under a new Advanced Technology Program (ATP), this team will develop new high-energy density cells and batteries for space and portable electronics applications. These new batteries will utilize new high-energy density anode and cathode active materials developed by SNL and RTI. UBI will incorporate these new materials into an optimized Li-ion SPE electrode laminate. EPT will develop batteries for aerospace applications based on this electrode laminate technology while LMMS will design the battery charge management controller and provide system expertise  相似文献   

3.
Slight differences between the series connected cells in a lithium ion (Lilon) battery pack can produce imbalances in the cell voltages, and this greatly reduces the charge capacity. These batteries cannot be trickle-charged like a lead acid battery since this would slightly overcharge some cells and may cause these cells to ignite. Therefore, an electronic equalizer (EQU) should be used to balance the cell voltages individually. The targeted EQU described herein can be connected to any cell via a set of sealed relays to provide much faster equalization and higher efficiency than previous methods.  相似文献   

4.
采用微观和宏观包覆两种方式制备聚合物固态电解质包覆的硫@碳纤维复合固态电极,利用扫描电镜、元素分析和电化学测试表征电极的微观形貌,研究相应锂硫电池的电池性能。结果表明:微观的聚合物固态电解质包覆活性材料的电极结构有利于离子传输;电极表面宏观构建一层聚合物固态电解质薄膜有助于改善电极的循环稳定性,抑制穿梭效应;利用膜电极结构组装的全固态锂硫电池具有良好的循环性能,循环270次后库仑效率仍保持98%以上。  相似文献   

5.
Eagle-Picher Energy Products (EPEP) has been manufacturing and testing large lithium ion cells (up to 100-Ah) for several years. Recently, work has focused on the testing of different chemistries at variable temperatures and designing and fabricating 100-Ah cylindrical cells. For the aircraft application the largest concern is irreversible capacity loss at elevated temperatures (70°C). In contrast, for the aerospace application shelf-life and cycle life are critical. EPEP has found that the major contributor to the loss in low temperature performance due to high temperature testing, was the positive electrode. EPEP discuss recent results of variable temperature cycling and 100-Ah cell performance  相似文献   

6.
Lithium ion battery technology is being introduced into power supplies used by our armed forces for a variety of applications. In many cases, the same cells and design parameters that support commercial battery packs are being used in military battery packs. This approach is expected to result in a major decrease in the total life cycle cost of the equipment these batteries support. On June 13, 1991, NAVSEA issued INST9310.1B1, which states that all lithium battery powered equipment must undergo safety evaluation and approval prior to fleet use. This safety program governs a process whereby approvals are issued for lithium batteries to be used in specific equipment on ground facilities, surface combatants, air combatants, and/or submarines. The Naval Ordnance Safety and Security Activity (NOSSA) manages the program. The chief technical advisors are Code 644 at NSWC Carderock Division and Code 609A at NSWC Crane Division. This paper describes three battery designs that incorporate lithium ion technology, and the results of battery safety tests conducted in accordance with navy requirements.  相似文献   

7.
NASA requires lightweight rechargeable batteries for future missions to Mars and the outer planets that are capable of operating over a wide range of temperatures, with high specific energy and energy densities. Due to the attractive performance characteristics, lithium-ion batteries have been identified as the battery chemistry of choice for a number of future applications, including Mars rovers and landers. The Mars 2001 Lander (Mars Surveyor Program MSP 01) will be one of the first missions which will utilize lithium-ion technology. This application will require two lithium-ion batteries, each being 28 V (eight cells), 25 Ah and 8 kg. In addition to the requirement of being able to supply at least 200 cycles and 90 days of operation on the surface of Mars, the battery must be capable of operation (both charge and discharge) at temperatures as low as -20°C. To assess the viability of lithium-ion cells for these applications, a number of performance characterization tests have been performed, including: assessing the room temperature cycle life, low temperature cycle life (-20°C), rate capability as a function of temperature, pulse capability, self-discharge and storage characteristics, as well as mission profile capability. This paper describes the Mars 2001 Lander mission battery requirements and contains results of the cell testing conducted to-date in support of the mission,  相似文献   

8.
离子发动机羽流特性的数值模拟   总被引:1,自引:1,他引:1  
离子发动机羽流中产生的交换电荷(CEX)离子返流会影响航天器的正常工作.建立离子发动机羽流模型,采用单元内粒子方法(PIC)对羽流场进行数值模拟计算.结合DS-1探测器飞行实验的测量结果,分析了卫星电势、电子温度、卫星几何尺寸、推力器工作特性等对相关因素对CEX离子返流特性的影响.结果表明:从推力器出口附近到卫星背面,CEX离子密度为108~1012m-3.当卫星电势从-15V变化到27V,测量点位置处CEX离子密度从0.65×1012m-3变化到1.5×1012m-3.羽流中CEX离子密度和电势结构随电子温度变化不大,但电势大小随电子温度成比例地变化.同一位置处不同工况下CEX离子的密度可根据CEX离子生成率与工作点参数间的关系式准确地估计.卫星安装推力器的表面起着对CEX离子返流屏蔽和降低的作用.   相似文献   

9.
朱浩  蔡国飙 《航空动力学报》2011,26(10):2346-2351
根据平行层燃烧理论,推导了不同药型燃烧面积和燃烧边界长度随燃去肉厚变化的数学规律;在此基础上,建立了固液火箭发动机系统设计模型,将设计过程转化为数学模型;之后采用遗传算法对不同药型固液火箭发动机进行了优化设计.通过对优化结果的比较和分析,开展了不同药型应用于固液火箭发动机的性能特点及其机理的研究,指出了固液火箭发动机不同于固体火箭发动机的内弹道特性.   相似文献   

10.
张勃  吉洪湖  罗明东  黄伟  蔡旭  高潮 《航空动力学报》2007,22(12):1994-1999
对5组不同宽高比(W/H=1~1)的圆转矩形收敛喷管模型(AR1~AR1) 在尾向可见明火时的红外辐射特性进行了试验研究,并与等出口面积的轴对称喷管(AR0)进行了比较,喷管模型为某型实际喷管缩比4.3倍得到的.研究发现,与轴对称喷管相比,大宽高比矩形喷管减小了红外源的辐射特征,起到了明显的红外抑制作用.在0°~90°范围内,所研究的喷管在3~5 μm波段上的红外辐射信号呈现随探测角度增大逐渐减小的规律.   相似文献   

11.
对航空发动机中央传动杆转子动力学特性进行研究,分析了中央传动杆两端花键套齿联轴器的支承刚度,在此基础上提出了考虑花键套齿联轴器横向刚度和角向刚度的转子动力学设计方法。针对发生碰磨故障的中央传动杆,在试验振动数据详尽分析的基础上,采用该设计方法对其进行了改进设计。发动机整机试验验证表明,改进后的中央传动杆工作稳定,状态良好。通过动力学特性研究以及故障分析,掌握了中央传动杆碰磨故障的简易现象表征,完善了中央传动杆的转子动力学设计技术。  相似文献   

12.
大型民用飞机辅助动力装置性能仿真   总被引:3,自引:2,他引:3  
分析典型辅助动力装置(APU)系统的结构和气动热力学过程,采用面向对象的数值仿真方法,利用C++程序建立了APU各部件类;针对某150座级民用飞机选用的APU型号,将部件类组成具体的APU整机数学模型.依照此型APU的运行工况,完成了气动热力计算和非设计点性能计算,得到其设计点性能参数及用于飞机环境控制和主发起动模式下的工作包线及高度-速度特性、温度特性、负载特性.   相似文献   

13.
The mathematical modeling of gas flow in vane channels of axial compressors in the one-dimensional statement is considered taking into account the radial nonuniformity of flow parameters. Such an approach makes it possible to develop the fast-response algorithms for calculating the characteristics of the axial compressor stage when the working body parameters change at inlet and turn of inlet guide vanes.  相似文献   

14.
大型飞机辅助动力装置与微型涡轮发动机技术特点对比   总被引:9,自引:7,他引:9  
对比分析了这两类动力系统的总体设计和部件技术特点,总结了两者的相似性和不同.分析结果显示:用于150~200座大型飞机的辅助动力装置与推力400 N左右的微型涡轮发动机具有相当的功率;两类动力系统主要部件的设计和制造都具有相似性,微型涡轮发动机的部件性能指标更高,而辅助动力装置通过略保守的设计来获得高可靠性、经济性和长寿命.最后,提出了在已有MTE技术基础上开展APU研制的技术路线.   相似文献   

15.
为了获得带斜孔肋大宽高比矩形通道的强化传热特性,并寻求最佳的孔排倾斜角度,调节孔排倾斜角度和通道雷诺数,使其分别在0°~30°和3×104~9×104范围内变化,通过数值计算系统分析了通道摩擦因数和带肋壁努塞尔数等参数的变化规律.研究发现:相比于常规肋片,新型斜孔肋有效改善了肋片后方紧邻肋片的局部区域的壁面换热,并降低通道的摩擦因数,但传热增强因子有所减小;随着孔排倾斜角度的增大,通道的相对摩擦因子单调升高,传热增强因子则呈现出先升高后降低的变化过程,因此存在着最优孔排倾斜角度为15°,此时斜孔肋的强化传热综合指标达到最大值;随着通道雷诺数的增大,斜孔肋通道的摩擦因数小幅减小,换热则逐渐增强.   相似文献   

16.
基于现有大尺寸过冷水滴(supercooled large droplet, SLD)动力学特性,分析水滴变形对阻力的影响.并根据几种典型的反弹/飞溅模型,分析了SLD的阻力变化、反弹、飞溅等对水滴撞击特性的影响,采用软件FENSAP-ICE的飞溅模型和LEWICE 2.0的反弹模型研究了反弹及飞溅现象对冰形的影响.计算结果显示:水滴撞击前的破碎现象对水滴尺寸分布有较大的影响,进行撞击特性以及冰形计算的时候需进行考虑;SLD破碎、飞溅、反弹降低了局部水收集系数、减小了水滴撞击范围;飞溅现象主要发生在机翼前缘附近区域,反弹主要在撞击边缘区域;水滴直径增加,飞溅现象逐渐减弱,但边缘位置的反弹现象一直很明显.SLD变形带来的阻力影响对冰形及结冰区域影响很小;与未考虑飞溅及反弹现象得到的冰形比较,考虑飞溅及反弹得到冰形前缘区域形状变化不大,但是整体结冰区域减小.   相似文献   

17.
采用 VOF 方法建立了大水滴撞击壁面的计算模型,模拟了大水滴以不同直径、不同速度撞击光滑壁面的动态撞击过程和撞击特性。计算结果表明:在大韦伯数情况下,水滴撞击光滑壁面会在铺展过程中发生边缘水滴飞溅;在水滴撞击壁面的收缩阶段,随着水滴直径的减小和水滴速度的提高,会发生液膜缓慢收缩、边缘液环和液膜分离、中心处部分液膜和边缘液膜分离、液膜完全破裂等不同结果;当水滴直径和撞击速度增大时,同一时刻水滴的铺展半径、最大铺展半径、最大铺展系数增大;水滴在壁面上达到最大铺展系数所用的无量纲时间随水滴直径增大而增大,同一直径水滴不同初始速度下达到最大铺展系数所用的无量纲时间变化较小。  相似文献   

18.
Hydrogen peroxide as a monopropellant and an oxidizer has been used for well over 60 years. Although much public information has been known on the silver catalyst and its characteristics there is a dearth of specific information on the design of catalyst bed based on silver screen. In this paper activation method that can be adopted easily on silver catalyst is contrived. The experiment data and evaluation results from the fire tests with five catalyst beds are presented including the efficiency of characteristic exhaust velocity, pressure drop at catalyst. A scheme of catalyst arrangement is presented for high concentrated hydrogen peroxide.  相似文献   

19.
In this tutorial we evaluate the present status and future direction of fuel cell development. The three most promising types of fuel cells being evaluated for electric vehicle propulsion are: (1) direct hydrogen-consuming fuel cells; (2) methanol-consuming fuel cells; and (3) zinc-air fuel cells. The author evaluates the advantages and disadvantages of each type.  相似文献   

20.
利用数值计算的方法研究了绕任意轴旋转的方形截面大曲率弯管内的粘性流动情况,分析了在不同人口距离处离心力和科氏力共同作用下的二次流动、轴向主流的发展变化情况。计算结果表明:当F接近-1时,二次流呈现6-涡结构;F≥0时流场内流场随,变化依次呈现2涡-4涡-6涡-4涡-2涡-4涡结构,并且随着F的增大,流动在距入口更近的地方便达到充分发展;F=4.0流场呈现6-涡结构时,只有两个轴向速度极值区,分别位于靠近管道外侧的上下角处。  相似文献   

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