离心式压缩机喘振原因及其预防对策

离心压缩机是用高于0.015兆帕的排气来输送空气和其他各种混合气体的径流压缩机,这些空气、工艺气体和混合气体沿着规定的径向流动。喘振是离心式压缩机在流量减少到一定程度时所发生的一种非正常情况下的振动。当离心压缩机系统内的压力过高或者流量吸入不够等都会引发喘振现象,喘振对离心压缩机有着极大的危害,会破坏工艺系统的稳定性运行,烧毁轴承,缩短压缩机的使用寿命。我们可以通过采用固定极限流量的防喘振系统或者在压缩机的出口管线上设置防喘振控制阀等方法防止离心压缩机产生喘振。本文主要分析了离心式压缩机发生喘振的原因和危害,探讨了针对离心式压缩机发生喘振的预防对策。     

双级热泵的应用与技术难点

在分布式能源项目中,用能用户常要求热水供应温度达到60℃。常规的离心式热泵由于蒸发器输入温度过低,无法满足如此高的出水温度要求。采用离心式热泵+空气源热泵的双级热泵设计,空气源热泵可以将离心式热泵蒸发器侧输入温度提高至30~40℃,从而使离心式热泵热水满足供热要求。同时,空气源热泵和离心式热泵单独运行时还需满足制冷工况下的负荷需求。因此,为确保双级热泵系统安全高效运行,空气源热泵与离心式热泵工作特性的匹配是设计中的难点问题,特别是热量、流量的匹配和中间温度的确定等。     

离心式压缩机的喘振原因及控制

在当今的石油化工工业和天然气运输工业中,离心式压缩机发挥着至关重要不可替代的作用,因此保证离心式压缩机正常运行是石油化工行业正常生产的重要前提,而喘振现象是离心式压缩机运行中的常见现象。掌握喘振现象发生的原因以及对喘振现象有效地预防和控制是确保离心式压缩机能够稳定运行的重要前提。本文将对离心式压缩机的喘振原因以及如何防止喘振的发生及对喘振问题该如何控制进行探讨。     

电动汽车电池冷却系统的试验研究

为将空调系统恰当地应用到电动汽车上,并能够更好地与电池冷却系统匹配,减少其对电池的动力性能和续驶里程的影响,本文搭建空调系统试验平台,对单空调系统(以下用"HVAC"表示)充注量、HVAC和chiller(电池热交换器的简称)组成的双蒸发器系统充注量以及压缩机转速进行试验分析,确定空调系统制冷剂的最佳充注量,选出匹配的压缩机转速。结果表明:单chiller系统运行时,压缩机在较低转速下工作即可满足防冻液侧换热能力的要求;双蒸发器系统运行时,chiller换热比随压缩机转速的增加而增加,且chiller的换热能力始终比HVAC系统中蒸发器换热能力大,可以通过调节热力膨胀阀控制chiller的制冷剂流量,改变系统流量分配,提升HVAC中蒸发器的换热量。     

离心式压缩机控制方案的分析与探讨

离心式压缩机是石油化工生产中广泛应用的一种流体输送设备。其优点是体积小，流量大，运行平稳，经济性好。但是，其固有的缺点——喘振现象一旦发生，将会造成严重的后果。因此，正确选择离心式压缩机的控制方案就显得尤为重要!本文结合电化装置氧压机（B-602）的控制方案，阐述了离心式压缩机喘振现象产生的机理，并对控制方案的选择作了初步的分析与探讨。     

离心式制冷压缩机喘振点的分析及解决措施

针对空调系统的实际运行工况,对于离心式制冷压缩机喘振产生的原因进行了深入分析,并且提出了用于中央空调的离心式制冷压缩机的最实用的三种防止喘振措施,对离心式制冷压缩机组的运行达到了较好的防止喘振和节能效果。     

离心式空压机级间喘振的分析

多级离心式压缩机在本身状况或外界条件发生较大改变时,有时在压缩机流量和出口压力等参数都控制在"正常"范围内也会发生喘振。介绍了本单位实际发生过的几次空压机级间喘振现象,分析了产生级间喘振的原因,提出了预防措施。     

空压机防喘振在线监测系统

以透平压缩机的相似理论和防喘振基本理论为基础,以图表的方式实时地在线监测压缩机的实际运行点、当前工况下的防喘振控制线位置,使操作人员实时掌握压缩机的运行状态,及时调整操作,避免喘振的发生,为整个装置的安全、经济的运行提供必要的保障.以大化集团三十万吨合成氨厂轴流-离心式空气压缩机为例,以现有DCS系统数据传输为基础,开发出轴流-离心式压缩机防喘振在线监测系统.实践证明,该系统对于指导操作、预防喘振、高效运行起到了重要作用.     

浅析离心式压缩机防喘振控制

中国石油大庆石化公司120万吨乙烯改扩建工程,裂解气压缩机EC-3301为日本三菱重工有限公司(MHI)成套设计制造,由蒸汽透平驱动、离心式五段压缩、三个缸体组成。本文主要针对离心式压缩机防喘振控制进行简要分析。     

风冷热泵的系统仿真

制冷系统仿真器是基于系统中主要部件(如压缩机、冷凝器、蒸发器、膨胀阀等)的特性而设计完成的。它可以模仿系统运行,观察有关系统参数的变化,如系统的温度、压力、空气水的温度、流量等。因此可以节省大量的计算和实验工作。     

板翅式蒸发器液冷系统设计

为了研究板翅式换热器在沸腾相变换热情况下的传热及压降特性,设计一套采用氟里昂蒸气压缩循环的液体冷却试验系统,其中板翅式换热器作为蒸发器,R22作为制冷剂,热水作为被冷却液体提供制冷剂蒸发所需热量。对该系统的运行工况、参数范围及系统各部件（包括压缩机、冷凝器、毛细管、板翅式蒸发器）进行设计及选择,并介绍所搭建的试验台。     

Simulation of a transcritical CO2 heat pump cycle for simultaneous cooling and heating applications

A steady state simulation model has been developed to evaluate the system performance of a transcritical carbon dioxide heat pump for simultaneous heating and cooling. The simulated results are found to be in reasonable agreement with experimental results reported in the literature. Such a system is suitable, for example, in dairy plants where simultaneous cooling at 4 °C and heating at 73 °C are required. The optimal COP was found to be a function of the compressor speed, the coolant inlet temperature to the evaporator and inlet temperature of the fluid to be heated in the gas cooler and compressor discharge pressure. An optimizing study for the best allocation of the fixed total heat exchanger inventory between the evaporator and the gas cooler based on the heat exchanger area has been carried out. Effect of heat transfer in the heat exchangers on system performance has been presented as well. Finally, a novel nomogram has been developed and it is expected to offer useful guidelines for system design and its optimisation.     

理论[火用]分析在冷冻厂高温库中的应用

通过对一定环境温度条件下的高温冷库中的氨蒸汽压缩系统进行[火用]分析,利用线性拟合的方法对氨的物性进行模拟,并对定冷凝温度和变冷凝温度时,制冷系统的各部件的炯损失和系统的[火用]效率进行计算分析,得出在冷库氨蒸汽压缩系统中的蒸发器中的[火用]损失最大,压缩机和冷凝器次之的结果。提出要对冷库氨蒸汽压缩系统的性能进行改进,必须首先考虑提高其蒸发器、压缩机和冷凝器的[火用]效率着手;认为在一定环境温度条件下,降低冷凝温度是提高[火用]效率的较好的改进措施之一．     

用于离心式高温热泵机组研发的模拟模型

为了对所设计的高温热泵机组中各设备进行合理匹配,建立其稳态模拟模型。该模型包括关键部件的子模型:带有经济器的双级离心式压缩机、卧式壳管式冷凝器、浮球膨胀阀、满液式蒸发器和回热器。在模拟算法的设计中,将模块化方法与二分法相结合,所需输入参数易于为设计者所获得,且不会限制系统的运行。利用该模型,对高温热泵进行初步设计;经过多方案比较,确定各换热器的结构参数,并预测该系统的性能和运行参数。     

离心式空压机防喘振控制策略的研究

压缩空气系统是火力发电机组中非常重要的公用系统,其主要作用是为机组自动控制系统中的气动执行机构、吹扫及冷却系统提供安全可靠的气源。因此,空压机的运行工况直接关系到机组的安全稳定运行。但是,喘振是离心式空压机的固有属性,如何避免离心式空压机在运行过程中发生喘振,使空压机运行在稳定工况区是空压机控制系统需要解决的问题。本文采用OMRONCJ系列PLC控制器,对系统压力和流量采用双PID控制,利用入口门、旁路门“快开慢关”原则,有效的避免了喘振的发生。该控制系统已经在华能国际上安电厂应用,运行结果良好。     

满液式水冷冷水机组换热器设计参数选取的经济性分析

针对选定的压缩机匹配换热器时,设计参数选取的不同往往使得冷凝器和蒸发器的成本不同。本文选定一款压缩机,在不同设计参数下进行冷凝器和蒸发器设计,并核算相应成本,以此分析换热器经济性最佳时的设计参数。     

R32经济器系统涡旋压缩机中间补气参数的分析与优化

为了优化带经济器的R32空气源热泵系统的制热性能,结合涡旋压缩机的结构以及实际运行特点,本文利用MATLAB建立了系统的数学模型,并通过实验数据验证了仿真结果,研究了在不同环境温度下系统的补气压力、准一级压缩内容积比对相对喷气量的影响.研究结果表明:经济器系统较普通热泵系统,更适宜在环境温度低于-10 ℃的工况下运行;...     

Effect of jet length and ambient temperature on the performance of a two-phase jet impingement heat sink refrigeration system

The jet impingement heat sink integrated with a compact oil-free R-134a vapor compression refrigeration system introduced in a previous work (Oliveira and Barbosa, 2017) is now further evaluated in terms of the influence of the compressor piston stroke, applied thermal load, orifice-to-heater distance (jet length) and ambient (hot end) temperature. The proposed heat sink is a compact active thermal solution for concentrated heat loads because it integrates the evaporator and the expansion device into a single unit, making use of a single two-phase impinging jet as the cooling mechanism. The present analysis is based on the coefficient of performance and other steady-state heat transfer parameters associated with the impinging jet (heat transfer coefficient and heater surface temperature). A reduction of the jet length promoted a more vigorous splattering of the jet on the heated surface, enhancing the droplet breakup, which in turn reduced significantly the critical heat flux. An increase of the hot reservoir temperature increased the jet impingement heat transfer coefficient.     

Boiling of ammonia/lubricant mixture on a horizontal enhanced tube in a flooded evaporator with inlet vapor quality

In a flooded evaporator of an ammonia vapor-compression refrigeration system, boiling commonly takes place with ammonia mixed with compressor lubricant and subjected to a vapor quality at the inlet of the evaporator. In the present study, flooded boiling tests of ammonia on an enhanced tube under simultaneous influence of a miscible lubricant and inlet quality were conducted. The results suggest that the boiling heat transfer coefficient increases with both saturation temperature and heat flux. The coefficient slightly increases or does not significantly vary with the inlet quality. The coefficient in general is decreased by adding lubricant to the refrigerant, but the coefficient does not necessarily decrease as the lubricant concentration increases. The lubricant effect is generally more significant than the inlet quality effect. A correlation was developed based on the present data for flooded boiling of lubricant/ammonia mixture on an enhanced horizontal tube under the influence of inlet quality.     

Hybrid vapor compression refrigeration system with an integrated ejector cooling cycle

A refrigeration system was developed which combines a basic vapor compression refrigeration cycle with an ejector cooling cycle. The ejector cooling cycle is driven by the waste heat from the condenser in the vapor compression refrigeration cycle. The additional cooling capacity from the ejector cycle is directly input into the evaporator of the vapor compression refrigeration cycle. The governing equations are derived based on energy and mass conservation in each component including the compressor, ejector, generator, booster and heat exchangers. The system performance is first analyzed for the on-design conditions. The results show that the COP is improved by 9.1% for R22 system. The system is then compared with a basic refrigeration system for variations of five important variables. The system analysis shows that this refrigeration system can effectively improve the COP by the ejector cycle with the refrigerant which has high compressor discharge temperature.