变频风机优化控制方法

针对采用变频风机和变频压缩机的风冷螺杆式冷水机组,提出一种优化制冷系统综合部分负荷性能系数的控制方法。此控制方法将风机转速与变频压缩机的转速、压缩机的供油压差、制冷系统的吸/排气压差以及压缩机的排气压力进行关联,建立一套变频风机的效率优化和可靠性优化的控制模型,并在机组的全工况IPLV和NPLV性能测试中得到验证,具有很好的应用意义。     

美国艾默生公司压缩机应用技术讲座：第二十三讲 热气旁通阀的原理和应用

1原理 制冷系统的能量调节一般由以下几种方式构成：①压缩机并联-多级控制；②变转速压缩机-变频等；③带有卸载装置的压缩机；④热气旁通。对于自身没有能量调节装置的单压缩机制冷系统，使用热气旁通来进行系统的能量调节是非常经济的。     

变频压缩机及变频空调控制器项目可行性分析

在空调行业的发展过程中,变频技术是行业中较为核心的技术之一。该文从介绍变频压缩机及变频空调控制器应用领域入手,对目前国内市场变频器市场进行分析,提出了开发新低压变频器技术,将新旧变频器的散热问题进行对比,在该基础上对新项目进行风险性分析,目的是通过专业技术的研究,提高项目的经济性及科学性,保证变频压缩机及变频空调控制器项目使用的安全性,为行业的稳步运行及持续发展提供参考。     

变频螺杆式制冷压缩机的应用现状及研究进展

变频技术作为一种容积流量调节方式,具有调节范围大、结构简单、启动电流平稳等优点,越来越多地应用于螺杆式制冷压缩机。本文从产品的角度介绍变频螺杆式制冷压缩机的应用现状,并从变频技术、压缩机性能预测、控制优化、电机及变频器的冷却、噪声与振动以及油路优化等方面介绍变频螺杆式制冷压缩机的研究进展,最后阐明变频螺杆式制冷压缩机的未来发展趋势。     

变频技术在超市制冷机组中的应用分析

针对超市制冷系统常用的半封闭活塞式压缩机组,分析利用变频技术调节压缩机电机的转速,以调节压缩机组的能量输出。对压缩机采用变频控制可以使并联机组始终以适宜末端负载的高效率运行,从而达到节能的目的,并能够在优化并联机组能量调节级别的条件下减少机组的机头数量,降低用户的初期投入成本。     

格力推出“中国造”磁悬浮压缩机及机组

正2014年3月7日,经专家组鉴定,由格力电器自主研发的"磁悬浮变频离心式制冷压缩机及冷水机组"再获"国际领先"认定。这是在离心式冷水机组项目上,继温湿度独立控制高效离心机组、永磁同步变频离心机组、光伏直驱变频离心机组之后,格力电器获得的又一项"国际领先"科技成果。在传统的制冷压缩机中,机械轴承是必需的部件,并且需要有润滑油以及润滑油循环系统来保证机械轴承的工作。数据显示:在所有烧毁的压缩机中,有90%是由于润滑的失效而引起的。而机械     

空分装置压缩机防喘振优化控制及应用

本文分析了传统空分装置压缩机防喘振控制的基本方法及其局限性,提出采用压缩机通用特性曲线防喘振控制方法,该方法与入口条件及工况无关,可以实现压缩机组变工况运行,拓宽了压缩机安全运行范围,减少了放空,实现系统节能。     

BEPC Ⅱ超导腔低温氦制冷压缩机压力控制

结合双螺杆变频调速压缩机在BEPCⅡ低温系统上的应用,研究压缩机吸气压力和排气压力控制方法。根据制冷机控制系统的PLC程序,得出压缩机吸气压力和排气压力的控制方法,并通过BEPCⅡ低温系统的实际运行情况对研究结论进行验证。     

我国螺杆冷水机组的能量调节亟待推广使用VSD法

螺杆冷水机广泛应用于中央空调中 ,鉴于其长期工作在部分负荷下的特点 ,本文在分析了滑阀及变速调节螺杆制冷压缩机负荷的基础上 ,提出借变频调速装置来实现滑阀、压缩机转速及内容积比的优化匹配控制的VSD法 ,并进行了实测 ,分析了其节能效果。     

采用变频技术的制冷装置的优势分析

文章通过分析采用变频技术制冷装置性能 ,说明了采用变频技术的制冷装置具有能够大幅节能 ,迅速达到设定温度 ,实现高精度温控、压缩机软启动 ,以及可实现系统的多种运行方式等技术优势的原理     

自动可调内容积比螺杆机组的PLC控制系统

介绍了自动可调内容积比机组的控制原理和方法。并对以西门子(SIEMENS)S7-200可编程控制器(PLC)作为控制核心的控制系统、硬件结构和特点以及软件的设计做了相应的介绍。     

Advanced control systems for single compressor chiller units

In this paper the problem of designing advanced control systems for increasing the performances of low capacity HVAC system with single scroll compressor is addressed. In particular, a simulation environment based on Matlab/Simulink that has been validated on a state-of-the-art experimental facility and used to design an adaptive controller for single scroll compressor, packaged air-cooled water chillers is presented. The capability of the controller to substantially increase the energy performance of the system, as well as to achieve excellent regulation performances in process applications is demonstrated.     

螺杆式制冷机组运行初始阶段油温控制分析及改进

对螺杆式制冷机组运行初始阶段的油温控制特点进行分析,发现开机时过低的冷冻油温度会使其溶解制冷剂的能力增强,从而使冷冻油黏度和润滑能力降低,加速螺杆式压缩机运动部件的机械磨损。而目前使用热力膨胀阀的油冷却系统会使供油温度不断大幅波动,并超出使用范围。采用带有加热器的油气分离器,并通过PLC控制器利用PID调节方式对电子膨胀阀开度进行自动调节,从而控制冷冻油温度,可使上述问题得到解决。     

离心式压缩机转子系统稳定性控制方法研究

针对离心压缩机转子失稳已成高效长周期运转主要障碍问题,通过分析失稳机理及影响因素,研究压缩机转子系统稳定性控制方法。结合工程案例,采用有限元方法对转子进行瞬态动力学分析,研究转速及因密封等部件交叉刚度对转子稳定性影响。研究转子振动位移反馈与速度反馈方法对转子失稳振动的控制效果。结果表明,两种方法均能有效提高转子系统稳定性。对比在达到相同控制效果时执行机构能量消耗表明,通过位移反馈方式能以更低能耗达到控制效果。该结果可为离心压缩机转子稳定性控制与提高提供新的思路及可行性。     

A model-driven multivariable controller for vapor compression refrigeration systems

A model-driven controller for vapor compression refrigeration systems is presented herein. Mathematical sub-models were developed for each of the system components: heat exchangers (condenser and evaporator), variable-speed compressor and variable-orifice electric expansion device. The overall system simulation model was used to design a MIMO controller based on the linear-quadratic Gaussian method using a state observer of the Kalman filter type. A purpose-built testing apparatus comprised of a variable-speed compressor and a pulse-width modulated expansion valve was used to collect data for the system identification and model validation exercises. It was found that the model reproduces the experimental trends of the working pressures in conditions far from the operation point (±30%) with a maximum deviation of ±5%. Additional experiments were also performed to verify the ability of the controller of tracking reference changes and rejecting thermal load disturbances as high as 15%.     

动车组太阳能空调系统压缩机的矢量控制

采用矢量控制策略的变频控制方法对动车组太阳能空调系统压缩机进行控制,在Matlab/Simu-link环节下仿真动车组太阳能空调系统压缩机的工作状态。研究结果表明,动车组太阳能空调系统压缩机在多变的环境中能够平稳运行,其工作功率能够根据光伏发电功率做出迅速、准确的调节,实现太阳能利用率最大化。     

空气压缩站集中控制系统设计

本文介绍了将单机运行空压机进行改造，通过可编程控制器实现与空压机通讯，在上位机画面对设备的运行状态进行监控及控制，大大减轻了操作人员的点检强度，同时避免了因设备故障导致管网压力不足延误生产现象发生。     

A DDC-based capacity controller of a direct expansion (DX) air conditioning (A/C) unit for simultaneous indoor air temperature and humidity control – Part I: Control algorithms and preliminary controllability tests

For residential buildings located in the subtropics, direct expansion (DX) air conditioning (A/C) units are commonly used. Most DX A/C units are currently equipped with single-speed compressors and supply fans, relying on on–off cycling compressors as a low-cost approach to maintain only indoor air dry-bulb temperature, resulting in either space overcooling or an uncontrolled equilibrium indoor relative humidity (RH) level. With the rapid development of A/C industry, the use of variable-speed compressor and supply fan has become more and more prevalent and practical. This paper, the first part of a two-part series, reports on the development of a novel direct digital control (DDC)-based capacity controller for a DX A/C unit having variable-speed compressor and supply fan to simultaneously control indoor air temperature and RH in a conditioned space served by the DX A/C unit. The controller is the first of its kind as a composite parameter, sensible heat ratio (SHR), is used as a controlled parameter. The core element of the capacity controller, a numerical calculation algorithm (NCA) is firstly presented. This is followed by reporting the results of preliminary controllability tests of the DDC-based capacity controller, which suggested that the controller developed could achieve a reasonable control accuracy, but with room for improvement with respect to control sensitivity. Part II of the two-part series reports on the further development of the controller to improve its control sensitivity, and the results of associated controllability tests.     

Saving energy using fuzzy control applied to a chiller: an experimental study

In this study the energy consumption of a chiller system, under different configurations and control strategies, was investigated. Two control strategies (Proportional integral—PI and fuzzy-PI) were applied to regulate the temperature of propylene glycol solution and the evaporating temperature using compressor motor supply frequency and pump rotation frequency as manipulated variables. The experiments were initiated with the system in open loop. When the steady-state condition was reached the system was submitted to a positive disturbance in its heat load and the feedback control was activated. Hence, the results were analyzed by means of integral of the time-weighted absolute error (ITAE) criterion and total energy consumption. The analysis of experimental results showed that both controllers were able to regulate the controlled variables appropriately. Also, it was verified that the use of the compressor motor supply frequency as manipulated variable can smooth out process variable oscillations. Besides, comparing the energy demands of both controllers, it was observed that the fuzzy-PI controller required 3.4% less electric energy (0.81?kWh). Considering the propylene glycol solution temperature (secondary fluid) as controlled variable and compressor motor supply frequency as manipulated variable, fuzzy-PI control achieves smaller ITAE index value, and energy consumption than the PI counterpart, consuming 0.25?kWh less energy. Thus, energy savings could be attained for control configurations that exhibit higher ITAE values. It was demonstrated that is desirable to include the energy consumption as a control performance parameter in order to increase the energetic efficiency of process.     

Optimization of refrigeration system with gas-injected scroll compressor

Gas refrigerant injection has been proven as an effective method to improve the performance of the scroll compressor and its refrigeration system under high compression ratio working conditions. Much research on the injected scroll compressor and its system has been conducted, but the universal control and design method is still lacking. A model of the refrigeration system with a gas-injected scroll compressor is developed in this paper. With this model, the effects of gas injection on the system and component parameters are investigated. Based on the identified evaporator characteristics and thermodynamic analysis, a set of general principles for the design and operation of the refrigeration or heat pump system with a gas-injected scroll compressor is proposed.