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The existing researches of stepless capacity regulation system by depressing the suction valve for reciprocation compressor always adopt hypothesis that the compressor valves are open or close instantaneously, the valve dynamic has not been taken account into thermal cycle computation, the influence of capacity regulation system on suction valves dynamic performance and cylinder thermal cycle operation has not been considered. This paper focuses on theoretical and experimental analysis of the valve dynamic and thermal cycle for reciprocating compressor in the situation of stepless capacity regulation. The valve dynamics equation, gas forces for normal and back flow, and the cylinder pressure varying with suction valve unloader moment during compression thermal cycle are discussed. A new valve dynamic model based on L-K real gas state equation for reciprocating compressor is first deduced to reduce the calculation errors induced by the ideal gas state equation. The variations of valve dynamic and cylinder pressure during part of compression stroke are calculated numerically. The calculation results reveal the non-normal thermal cycle and operation condition of compressor in stepless capacity regulation situation. The numerical simulation results of the valve dynamic and thermal cycle parameters are also verified by the stepless capacity regulation experiments in the type of 3L-10/8 reciprocating compressor. The experimental results agree with the numerical simulation results, which show that the theoretical models proposed are effective and high-precision. The proposed theoretical models build the theoretical foundation to design the real stepless capacity regulation system. 相似文献
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通过建立新的实验平台,准确测量压缩机各腔体内的气体压力和吸排气阀片的升程量,获取真实的P-V图和阀片运动图。对压缩机P-V图和阀片运动图进行同步研究和分析,得到阀片动作与压缩机内部工作过程的耦合关系,从而为压缩机优化提供方法。实验数据表明:在ASHRAE工况下,该款压缩机循环功耗为66.825W,其中排气压力损失功耗占比为4.254%,吸气压力损失功耗占比为1.2%,吸气阀片位移为2.148mm,排气阀片位移为0.825mm。对压缩机吸排气阀片延时现象进行了分析。 相似文献
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应用小孔喷注噪声原理分析全封闭活塞式制冷压缩机吸排气阀噪声 总被引:1,自引:1,他引:0
制冷剂气体流经压缩机吸、排气阀时,由于气流穿过狭小的阀隙,会产生类似喷注的噪声,将小孔喷注噪声原理应用在吸、排气气阀开启瞬间产生的噪声分析中,并理论定量分析制冷剂蒸气流经吸、排气阀产生气流噪声的机理,着重分析了吸、排气过程转角与压差、转角与声压级、压差与声压级的关系.根据噪声产生原理,指出降低噪声的根本途径是降低气流通过气阀前后的压力损失,并给出降低气流噪声的主要途径是:提出减小阀片刚性、厚度以及扩大排气孔孔径等.并给出了几种通过改善吸、排气阀结构来降低压缩机噪声的方法. 相似文献
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On/off solenoid valves with PWM control are widely used in all types of vehicle electro-hydraulic control systems respecting to their desirable properties of reliable, low cost and fast acting. However, it can hardly achieve a linear hydraulic modulation by using on/off valves mainly due to the nonlinear behaviors of valve dynamics and fluid, which affects the control accuracy significantly. In this paper, a linear relationship between limited pressure difference and coil current of an on/off valve in its critical closed state is proposed and illustrated, which has a great potential to be applied to improve hydraulic control performance. The hydraulic braking system of case study is modeled. The linear correspondence between limited pressure difference and coil current of the inlet valve is simulated and further verified experimentally. Based on validated simulation models, the impacts of key parameters are researched. The limited pressure difference affected by environmental temperatures is experimentally studied, and the amended linear relation is given according to the test data. 相似文献
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《流体机械》2015,(7):47-50
基于主动控制进气阀的气量调节系统具有调节范围大、节能效果好等优点,适用于工艺流程中大型压缩机。本文依据热、动力学理论建立了耦合阀片运动的往复压缩机热力学模型,模拟了气缸内气体瞬态压力变化规律及进气阀片运动特性。研究结果表明:调节工况下自动阀和强制阀方式同时存在,执行机构延迟关闭进气阀,使压力升高过程延迟,实现压缩机流量及功率的降低。执行机构在气阀完全打开后作用,不影响气阀打开过程,仅利用撤销时间控制压缩机气量。调节工况下阀片打开速度不变,但关闭速度增大,且阀片与阀座间的最大撞击速度随执行机构撤销角度的增大而增大。由于气阀打开及关闭存在时间延迟,执行机构撤销时间在主轴转角为160°~295°范围内变化时,已实现气量0~100%范围调节。 相似文献
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针对目前往复压缩机气阀故障诊断中存在的问题,提出了基于小波包变换与能量算子相结合的包络解调技术对其振动信号进行包络分析,解决了对信号包络解调前需要人为确定载波带对信号进行带通滤波的问题.并将其用于往复压缩机气阀的故障诊断,实例数据的分析表明,把包络信号的歪度值和峭度值作为特征指标较好地区分了气阀的不同故障,并且表现出抑噪特性. 相似文献
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余隙容积的合理设计是保证压缩机正常工作的必备条件。相较于传统的高压压缩机,微型高压压缩机体积小、结构紧凑,活塞行程短且高压级活塞的直径较小,因而其工作性能对余隙容积更为敏感。为研究余隙容积对微型高压压缩机各级工作腔容积效率的影响,在微型高压压缩机关键结构参数和压力参数的基础上,结合能量和质量守恒定律、气阀运动以及活塞运动规律,搭建了工作腔热力学仿真模型。分析不同余隙容积下各级工作腔内气体压力、质量的瞬态变化过程,得出各级工作腔内容积效率的变化规律,从而为微型高压压缩机缸体和气阀关键结构参数的设计和优化提供指导意义。 相似文献
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研究分析了应用于中国石油乌鲁木齐石化加氢裂化压缩机上的HydroCOM无级气量调节系统的工作原理和控制逻辑,该系统基于部分行程顶开进气阀调节理论,核心部件是液压执行机构和电磁阀,通过压叉强制顶开进气阀片控制进气阀的打开时间,从而只压缩工艺所需要的气量。计算比较了该系统在压缩机组中实际使用中的节能效果,该系统调节下的往复压缩机轴功率与排气量成正比,实现了连续无级气量调节,并对该系统执行机构密封室出现的填料损坏问题的原因进行了探讨和分析,发现工况恶劣与装配不合适是引发密封填料损坏的主要原因。HydroCOM系统对于往复压缩机的控制快速而精准,节能效果明显,避免了起动、停机过程中较大的压力波动,同时也能够使压缩机的各项运行参数更稳定。 相似文献
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Young Joon An Byeong Jin Kim Byeong Rog Shin 《Journal of Mechanical Science and Technology》2008,22(10):1998-2005
A numerical analysis of three dimensional incompressible turbulent flows through high pressure drop control valves was carried
out by using a CFD-ACE code to develop anti-cavitation control valve used in LNG marine system. For this, numerical simulation
was performed on several models of control valve that have different orifice diameters of anti-trim and the size of valve
discharge. In this study, flow characteristics of control valves with complex flow fields including pressure drop, cavitation
effect and variation of flow coefficient as well as correlation of discharge coefficient were investigated and analyzed. Comparing
with conventional control valves, newly designed valves by using the CFD analysis showed an improved flow pattern with reduced
cavitation and an anticipated performance characteristic.
This paper was presented at the 9th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007. 相似文献
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为研究强振动环境对二通插装阀工作性能的影响,建立了振动环境下的二通插装阀结构模型及AMESim仿真模型,分别分析振动条件及插装阀结构参数对其动态特性的影响规律。研究表明:基础振动会引起插装阀阀口流量及阀芯开度出现波动现象;阀芯在稳态时的波动程度随基础振动幅值线性增加,振动频率大于20Hz后,波动程度明显。较小的阻尼孔径会使流量上升至最大值的时间增加,但通过阀口的流量更平稳;插装阀在开启状态时,阀芯波动值与阀芯质量呈正相关关系;改变插装阀的面积对改善流量波动现象效果有限;增加弹簧刚度可以改善流量波动现象,但会使通过阀口的流量减小。 相似文献
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针对波浪能液压系统自吸回路单向阀需要加压开启或内部无序流动的问题,提出了零重力无压开启策略。通过对比分析单向直通阀不同阀芯形式的优缺点,说明了球阀的可行性。为提升球阀的流动特性,优化单向阀的弹簧力与阀芯重力差,实现吸油回路阀芯的零重力和无压开启,结合液压回路短程设计,改善了液压系统效率。通过实验室在不同流量下的效率测试和海试运行的状态,结果显示该方案具有可行性,不仅减小了沿程损失,也保证了工程化的安全性。 相似文献