Effect of safety valve types on the gas venting behavior and thermal runaway hazard severity of large-format prismatic lithium iron phosphate batteries

The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the TR hazard severity of LIBs,are not known.In this paper,the TR and gas venting behavior of three 100 A h lithium iron phosphate(LFP)batteries with different safety valves are investigated under overheating.Compared to previous studies,the main contribution of this work is in studying and evaluating the effect of gas venting behavior and TR hazard severity of LFP batteries with three safety valve types.Two significant results are obtained:(Ⅰ)the safety valve type dominates over gas venting pressure of battery during safety venting,the maximum gas venting pressure of LFP batteries with a round safety valve is 3320 Pa,which is one order of magnitude higher than other batteries with oval or cavity safety valve;(Ⅱ)the LFP battery with oval safety valve has the lowest TR hazard as shown by the TR hazard assessment model based on gray-fuzzy analytic hierarchy process.This study reveals the effect of safety valve type on TR and gas venting,providing a clear direction for the safety valve design.

Effect of Dynamic Pressure Feedback Orifice on Stability of Cartridge-Type Hydraulic Pilot-Operated Relief Valve

Current research on pilot-operated relief valve stability is primarily conducted from the perspective of system dynamics or stability criteria,and most of the existing conclusions focus on the spool shape,damping hole size,and pulsation frequency of the pump.However,the essential factors pertaining to the unstable vibration of relief valves remain ambiguous.In this study,the dynamic behavior of a pilot-operated relief valve is investigated using the frequency-domain method.The result suggests that the dynamic pressure feedback orifice is vital to the dynamic characteristics of the valve.A large orifice has a low flow resistance.In this case,the fluid in the main spring chamber flows freely,which is not conducive to the stability of the relief valve.However,a small orifice may create significant flow resistance,thus restricting fluid flow.In this case,the oil inside the main valve spring chamber is equivalent to a high-stiffness liquid spring.The main mass-spring vibration system has a natural frequency that differs significantly from the operating frequency of the relief valve,which is conducive to the stability of the relief valve.Good agreement is obtained between the theoretical analysis and experiments.The results indicate that designing a dynamic pressure feedback orifice of an appropriate size is beneficial to improving the stability of hydraulic pilot-operated relief valves.In addition,the dynamic pressure feedback orifice reduces the response speed of the relief valve.This study comprehensively considers the stability,rapidity,and immunity of relief valves and expands current investigations into the dynamic characteristics of relief valves from the perspective of classical control theory,thus revealing the importance of different parameters.

STUDY ON VARIATION OF SETTING AND STOPPING PRESSURES OF SAFETY VALVE WITH STRUCTURAL MODIFICATION

The possibility of pressure control with the structural change of a safety valve is investigated Safety valve is commonly used as safety devices for numerous applications which include boilers,ships,industrial plants,and piping Setting and stopping pressures of a safety valve, p set and p sto ,are traditionally adjusted with a fine tuning of seat ring and valve ring heights, h sr and h vr However, it is not easy to achieve the proper setting and stopping pressures of a safety valve in practice The depth of inside and outside grooves in a valve, d i and d o are modified and their effects on setting and stopping pressures of a safety vlave are tested The most appropriate values appear 1 0 mm in d i and 0 5～1 0 mm in d o,respectively The valve ring height, h vr ,shows that the best results can be achieved at 2 3 mm for setting pressures of 0 1～0 4 MPa and 1 0 mm for setting pressures of 0 5～1 0 MPa The stopping pressures increases with the increase of seat ring height, h sr , upto certain h sr value and then becomes independent to the seat ring height This implies that there exists the optimum h sr ,which provides the largest flow rate and the proper stopping pressure Stopping pressures of a safety valve are adjusted with the seat ring and valve ring heights This study,however,demonstrated that the modification of value grooves also changes setting and stopping pressures of a safety valve Therefore,the proper selection in dimensions of the inside and outside grooves should be considered for the safety valve design

Properties analysis of a large flow-rate safety valve test device

In order to solve the problem of property test of large flow-rate safety, the property parameter of safety valve test system was analyzed, and a device for property oflarge flow-rate safety valve test was designed.The device used accumulators as power source and a united function cylinder, which can realized the large flow-rate output for the test system.Analyzed the test data and made a particular research on the test device by testing different flow-rate safety valves;it verifies that the test device can be used tode-sign larger flow-rate safety valve test system and can make the flow-rate test and analysis and dynamic characteristics for the large-flow safety valve.

Safety and effectiveness of neuromuscular electrical stimulation in cardiac surgery:A systematic review

BACKGROUND Lack of mobilization and prolonged stay in the intensive care unit(ICU)are major factors resulting in the development of ICU-acquired muscle weakness(ICUAW).ICUAW is a type of skeletal muscle dysfunction and a common complication of patients after cardiac surgery,and may be a risk factor for prolonged duration of mechanical ventilation,associated with a higher risk of readmission and higher mortality.Early mobilization in the ICU after cardiac surgery has been found to be low with a significant trend to increase over ICU stay and is also associated with a reduced duration of mechanical ventilation and ICU length of stay.Neuromuscular electrical stimulation(NMES)is an alternative modality of exercise in patients with muscle weakness.A major advantage of NMES is that it can be applied even in sedated patients in the ICU,a fact that might enhance early mobilization in these patients.AIM To evaluate safety,feasibility and effectiveness of NMES on functional capacity and muscle strength in patients before and after cardiac surgery.METHODS We performed a search on Pubmed,Physiotherapy Evidence Database(PEDro),Embase and CINAHL databases,selecting papers published between December 2012 and April 2023 and identified published randomized controlled trials(RCTs)that included implementation of NMES in patients before after cardiac surgery.RCTs were assessed for methodological rigor and risk of bias via the PEDro.The primary outcomes were safety and functional capacity and the secondary outcomes were muscle strength and function.RESULTS Ten studies were included in our systematic review,resulting in 703 participants.Almost half of them performed NMES and the other half were included in the control group,treated with usual care.Nine studies investigated patients after cardiac surgery and 1 study before cardiac surgery.Functional capacity was assessed in 8 studies via 6MWT or other indices,and improved only in 1 study before and in 1 after cardiac surgery.Nine studies explored the effects of NMES on muscle strength and function and,most of them,found increase of muscle strength and improvement in muscle function after NMES.NMES was safe in all studies without any significant complication.CONCLUSION NMES is safe,feasible and has beneficial effects on muscle strength and function in patients after cardiac surgery,but has no significant effect on functional capacity.

基于Aspen Plus的Safety Analysis功能计算调节阀故障时的安全阀尺寸

安全阀作为化工生产中的最后一道安全屏障,其选型的准确与否直接关系到生产安全。目前国内大部分设计院计算安全阀时都是基于安全阀设计规范编辑Excel公式,代入手册中查得物性数据得到泄放量及泄放面积。由于安全阀计算涉及的工况、物性参数较多,且各个工况下使用的计算公式均不相同,使得安全阀的选型成为化工设计中的一个难点。通过工程经验总结,以调节阀故障工况为例,利用Aspen Plus软件自带的Safety Analysis功能计算安全阀的泄放量与泄放面积,并核算调节阀入口、出口管径,大幅提高了工作效率与准确性。

单中心经导管主动脉瓣置换术的疗效及安全性分析

目的:回顾南通大学附属医院心脏瓣膜中心经导管主动脉瓣置换术(transcatheter aortic valve replacement,TAVR)的临床数据,总结手术相关经验。方法:2020年10月—2023年6月在本中心接受TAVR手术患者28例,收集患者的病史、实验室检验以及辅助检查等临床资料,对手术成功率、并发症、院内结果以及6个月随访结果进行回顾性分析。结果:28例患者中男女各14例,平均年龄(75.54±6.08)岁,其中重度主动脉瓣狭窄22例,重度单纯主动脉瓣反流6例,美国胸外科医师协会平均积分为(4.05±3.48)分,手术成功率为96.43%,因Ⅲ度房室传导阻滞植入永久起搏器5例(17.86%);术中中度瓣周漏3例(10.71%),其中采用球囊后扩张1例,采用“瓣中瓣”技术2例使瓣膜反流显著减轻;发生瓣膜跳脱1例(3.57%),植入第2个瓣膜使其锚定于升主动脉;术中心包填塞3例(10.71%),2例予心包置管、鱼精蛋白中和肝素后出血终止;另1侧发生瓣环撕脱转行开胸手术后死亡;半年随访期间1例患者因重度贫血再次入院,所有患者生活质量显著提高。结论:TAVR治疗重度主动脉瓣狭窄或反流具有良好的有效性和安全性。

华龙一号安注系统电动截止阀可靠性试验及评估研究

作为核反应堆系统中的关键设备,阀门在核反应堆系统中起着至关重要的作用,其可靠性直接决定着核反应堆安全以及人员安全。本文针对华龙一号安注系统电动截止阀,采用3个试验样机开展可靠性试验,通过模拟使用工况下的冷热态寿命试验,获得了该型阀门的典型失效——阀座内漏,并基于试验数据采用小子样试验的半经验评估方法完成了可靠性评估,确定该安注系统电动截止阀全寿期无故障动作360次的可靠度大于0.99。

应用于井下安全阀试验的高压气源控制系统设计

井下安全阀试验需要有能够稳定输出气体、人机交互性强以及自动化控制程度高的气源,针对这一问题,从研究气体流动特性入手。首先,对气源系统整体结构进行设计,包括关键部件的分析计算和选型;其次,基于S7-200 SMART PLC和LabVIEW软件进行控制程序编写和主控界面设计,实现数据存储和显示以及绘制气源系统各工作参数随时间变化的功能曲线;最后,搭建实验平台进行测试,实验结果验证了系统设计的合理性,得到输出过程中气体输出流量波动在2.8%、压力波动在5%、温度波动在6%左右,能够简单、高效、精确地控制气体输出,使设计的高压气源系统达到井下安全阀试验需求。

核级典型电动截止阀FMECA及试验验证

作为核反应堆系统中的关键能动设备,阀门在核反应堆系统中起着至关重要的作用,其安全性直接决定着核反应堆安全及人员安全。本文针对安注系统电动截止阀,基于使用特点对其开展故障模式、影响及危害性分析(FMECA),找出其结构中潜在的故障模式及其原因与影响,并根据失效分析结果有针对性地开展寿命试验,以激发潜在的故障,验证分析结果并获得该阀最为典型的失效模式。

弹簧式安全阀启闭动态过程仿真与分析

为研究安全阀的启闭性能,采用数学建模方法对其性能进行仿真分析。首先,根据安全阀工作原理将其内部主要活动部件分别建立成等效模型,然后采用数值模拟方法对部件刚度进行求解,再通过流体分析及数据拟合来获得阀瓣推力,建立数学公式并采用龙格库塔法进行方程求解,以获得启闭过程的运动曲线。结果表明,根据数学模型求解出的运动曲线趋势与安全阀实际运动趋势相同。由此可知,数学建模结果为安全阀性能分析提供理论依据。

矿用液压支架大流量安全阀卸荷性能分析

针对液压支架大流量安全阀在冲击载荷作用下不稳定的问题,以矿用液压支架上的FAD500/50型大流量安全阀作为研究对象,依据其结构和工作原理,利用AMESim软件对安全阀过载时的卸荷性能进行仿真分析,得到安全阀溢流时压力与流量动态输出特性以及阀芯运动规律特性。结果表明:在冲击载荷下,安全阀压力超调量和压力超调率分别为5.9 MPa和15%;安全阀开启瞬间阀芯会产生震荡,突变载荷是阀芯产生震荡的主要因素。最后通过试验证明了安全阀回路压力损失随着乳化液流量的增大而增大,但在0~320 L/min公称流量下,安全阀的压力损失低于7 MPa,系统整体运行稳定。

安全阀排放的动响应分析

安全阀排放冲击与响应是振动工程中典型的瞬态响应问题。根据阀后直管段长度L与特征长*度L的关系,讨论了四种可能的冲击形式;利用Laplace变换和逆变换,给出了四种冲击的瞬态响应解析解,表明冲击响应的最大幅值是关于安全阀全开时间与系统自振周期之比的函数;据此对安全阀排放系统的动载系数DFL取值给了分析和建议。

安全阀校验系统不确定度评定及实验室间能力验证评估

为更好实现对安全阀校验实验室的质量控制,提升实验室校验能力和专业技术人员校验水平。本文应用定量试验方法,对主导实验室安全阀校验系统进行不确定度评定,根据评定结果确定参考测量值;通过多个实验室间量值比对,实现准确一致的校验传递和可靠的量值溯源,对比对结果应用En值进行评价,验证各实验室安全阀校验能力,依据评价结论采取优化措施改进实验室校验质量。

直动式安全阀启闭特性分析与优化

针对某安全阀启闭特性影响无法满足设计需求的问题,需要对液流力进行分析。首先进行流场仿真与分析,研究安全阀内部流体的流动特性与液流力作用规律,得到安全阀启闭特性不足的主要原因是安全阀出口结构不合理;基于动力学分析与CFD仿真结果构建AMESim仿真模型并复现实验曲线,通过提高出口位置以及扩大出口直径实现安全阀的结构优化。结果表明该方法可以有效改善安全阀的启闭特性,使其关闭压力达到正常关闭要求。

输气管道工程放空系统的模拟计算

放空泄压在输气管道工程中是不可缺少的操作,如生产运行过程中设备或阀门的检维修、管道疲劳导致泄漏以及火灾等情况,需对线路或站场中的天然气快速泄压并安全的排放到大气中。安全阀的关键选型及利用TG NET和HYSYS软件对天然气管道进行放空模拟计算,可以分析并确定放空过程中放空量、放空时间和限流孔板的尺寸等重要数据。通过对天然气管道的深入计算分析,能够大幅度降低天然气的损耗并缩短放空时间,降低环境噪音,适用于长距离输气管道降压放空操作,同时也对实现站场及线路的日常管理,节约建设成本提供帮助。

机器人辅助二尖瓣置换术治疗二尖瓣病变的临床疗效及安全性分析

目的分析机器人辅助二尖瓣置换术治疗二尖瓣病变的临床疗效及安全性。方法回顾性分析2020年7月至2023年2月在香港大学深圳医院接受手术治疗的60例二尖瓣病变患者的临床资料。其中接受机器人辅助二尖瓣置换术30例为观察组,传统正中开胸二尖瓣置换术30例为对照组,比较两组疗效结局指标、临床结局以及并发症发生情况。结果两组转机时间、主动脉开放后并行时间、呼吸机使用时间比较差异无统计学意义(P>0.05)。观察组阻断时间、手术时间长于对照组,引流量、术中出血量少于对照组,创面愈合时间短于对照组,差异有统计学意义(P<0.05)。观察组临床结局的好转率为96.67%,对照组为93.33%,两组比较差异无统计学意义(P>0.05)。观察组并发症总发生率为13.33%,对照组为10.00%,两组比较差异无统计学意义(P>0.05)。结论二尖瓣病变经机器人辅助二尖瓣置换术治疗能够有效改善患者的疗效结局指标,安全性较好,值得推广。

煤矿液压支架安全阀性能分析仿真与试验研究

基于安全阀压力梯度理论,介绍一种适用于煤矿弹簧式液压支架安全阀的仿真分析方法。此方法主要采用AMESim软件构建安全阀仿真模型,并根据模型实施安全阀内部结构仿真安全阀冲击加载试验系统仿真。为验证液压支架安全阀仿真分析方法的应用效果,将仿真分析方法与安全阀冲击压力安全性试验进行匹配对比,根据对比分析结果确认仿真分析方法具有较强应用可行性。

新型柱塞式安全阀设计优化及仿真分析

针对导弹气路系统用安全阀小型化、大流量、高可靠性的发展要求,设计一种新型柱塞式安全阀。绘制安全阀的流场的几何模型,基于Fluent仿真分析平台建立新型柱塞式安全阀流道的数学模型。对其进行详细的流场分析,明确了安全阀气穴气蚀的产生机制和影响因素,并提出流道优化方法。利用AMESim软件分析了优化后柱塞式安全阀动态特性。最后,利用测试系统进行了安全阀的启闭特性试验,试验结果满足设计要求,验证了理论分析和设计方法的正确性。

基于动态仿真的火炬气回收系统超压保护措施

油气田火炬气回收是碳减排的重要手段,但目前针对火炬气回收系统(FGRS)尤其是超压保护方面还缺乏系统性研究。以文昌9-7海上钻井生产平台为例,采用K-Spice软件搭建了火炬气回收系统动态仿真模型,研究确定火炬气回收系统在不同放空工况下的超压保护措施。结果表明:火炬气回收系统分液罐的压力高高关断(PAHH)设定值应根据连续放空气量变化确定,参照现行规范设定的PAHH值(210 kPa)明显偏高,应调至38.5 kPa,以确保超压值不高于分液罐设计压力又满足平台低压设备的泄放背压要求;应急放空工况下,为确保一级保护和二级保护相互独立,火炬支路快速开关阀(ESD)的开阀时间应小于27 s;火炬支路ESD故障时,为确保应急放空过程中分液罐内压力不超过设计压力,同时考虑爆破膜泄压对上游设备泄放背压的影响,最终选择Z型爆破膜。目前该平台已结合上述关键参数形成了一套完整的火炬气回收方案,预期回收火炬气可达13万立方米/年以上,碳减排效果显著。本研究为火炬气回收系统超压保护措施关键参数确定提供了定量分析手段,为火炬气回收系统的设计提供了参考。