活塞式制冷压缩机技术现状及发展趋势

活塞式制冷压缩机在制冷空调行业有着广泛的应用,本文介绍现有活塞式制冷压缩机产品的应用及技术现状,对特殊型式的活塞式制冷压缩机产品性能等进行阐述,指出活塞式制冷压缩机技术发展趋势。     

A comprehensive model of a miniature-scale linear compressor for electronics cooling

A comprehensive model of a miniature-scale linear compressor for electronics cooling is presented. Linear compressors are appealing for refrigeration applications in electronics cooling. A small number of moving components translate to less theoretical frictional losses and the possibility that this technology could scale to smaller physical sizes better than conventional compressors. The model developed here incorporates all of the major components of the linear compressor including dynamics associated with the piston motion. The results of the compressor model were validated using experimental data from a prototype linear compressor. The prototype compressor has an overall displacement of approximately 3 cm³, an average stroke of 0.6 cm. The prototype compressor was custom built for this work and utilizes custom parts with the exception of the mechanical springs and the linear motor. The model results showed good agreement when validated against the experimental results. The piston stroke is predicted within 1.3% MAE. The volumetric and overall isentropic efficiencies are predicted within 24% and 31%, MAE respectively.     

Influence of the piston displacement profile on the performance of a refrigerating cycle equipped with an axial piston compressor

An extended analysis aiming to investigate the influence of the piston displacement in an axial compressor on the thermodynamic cycle of a refrigeration system was carried out. Axial piston compressors are commonly equipped with a rotating disk plate that guides the pistons along a sinusoidal displacement. A proper shape of the rotating disk can lead to a piston displacement that optimizes the power consumption and then the refrigeration cycle efficiency. In this paper, a sensitivity analysis on the compressor cycle characteristics by varying the piston displacement profile and the compressor operating conditions is presented. The mechanical analysis of the forces exerted by the piston on the rotating disk was also carried out to estimate the mechanical stresses acting on the rotating disk.     

容积式制冷压缩机电效率分析

对制冷压缩机的发展进行了简单的概述,统计计算了市场上几种主要容积式压缩机的电效率,并进行了对比和分析,结果表明： 涡旋压缩机的电效率基本上在0.5~0.75之间,主要集中于0.6~0.7之间;活塞压缩机的效率基本上在0.4~0.7之间,而主要集中于0.5~0.65之间;螺杆压缩机的电效率基本在0.5~0.75之间,主要集中于0.65~0.75之间;压比为2~4时压缩机电效率达到最大。为制冷压缩机的设计、校核和计算提供基础和依据,为制冷系统的性能改进提供方向。     

涡旋式制冷压缩机的输气量调节

本文介绍了涡式制冷压缩机常用的几种输气量调节方法,对每种调节方法的工作原理、优缺点和性能特性进行了分析讨论.同时也将涡旋式制冷压缩机与往复式压缩机、滚动转子式压缩机就一些性能参数进行了对比.     

Piston position sensing and control in a linear compressor using a search coil

Linear compressors with clearance seals are well established for cryocoolers using either a Stirling cycle or pulse tube. However, both piston stroke and piston offset require detection and control in valved compressors. In order to manufacture linear compressor in large scale, then a simple, robust, and cheap control system is required with a minimum of sensors and actuators. This work introduces an approach to sensing the position of the piston using a search coil. The piston stroke is detected by calculating the peak-to-peak flux linkage in relation to the measured drive voltage and current. The piston offset is proportional to an integrated modulus of the back electromotive force (emf) of the search coil. Two PID (proportional-integral-derivative) controllers were developed to control the piston stroke by adjusting the drive voltage and a solenoid valve and bleed flow to control the piston offset. Experimental results validate the proposed compressor control technique.     

制冷压缩机机壳散热研究

许多机房专用空调的制冷压缩机置于室内机的机壳内,用回风冷却制冷压缩机,良好的冷却对于延长制冷压缩机的寿命非常有利,但是,会增大空调房间的冷负荷,制冷系统的能耗增大。本文研究了与制冷压缩机机壳散热有关的因素,计算了全封闭蜗旋压缩机机壳散热量,分析了机壳散热量与压缩机制冷量之间的关系和制冷压缩机置于室内与室外的利弊。     

小型制冷压缩机瞬态起动特性研究

在小型制冷系统中，转子式压缩机的制冷效果不及往复式压缩机，因而限制了转子式压缩机的推广应用。利用作者研制的起动电流测试装置，对不同结构的小型压缩机的瞬态起动特性进行了实验研究，提出了阻止工质在停机后的质量迁移来提高转子式压缩机制冷效果的观点．并进行了压差起动可靠性试验。本研究工作为转子式压缩机在小型制冷系统上的推广应用提供了理论依据。     

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。     

A capacity-controlled free piston electrodynamic compressor

A double acting free piston 50 Hz electrodynamic oscillating compressor has been designed and investigated. The power input of the compressor is about 200 W, its maximum stroke is 20 mm, and its cylinder diameter is 20 mm. The compressor includes a two coil linear motor with permanent magnet, optimized for the pressure ratio required. The compressor capacity can be controlled by means of control of the stroke, being in turn dependent of the applied voltage or the voltage waveform. Comparison of experimental results, ie regarding efficiency of the motor (up to 75%), stroke control and pV-diagram, with results of computer simulation shows a good agreement. The above compressor is intended for refrigeration purposes. A larger version, with a power input of about 2 kW will be used in a controllable heat pump system.     

转子压缩机与涡旋压缩机的对比与发展

空气源热泵压缩机的性能是适合不同气候条件的热泵的关键。本文回顾了转子与涡旋压缩机的发展历程,早期房间空调器用压缩机为活塞式,后期出现了转子压缩机和涡旋压缩机,压缩机效率得以提升。转子式压缩机和涡旋式压缩机均向适应低环境温度工况的方向发展。介绍了影响这两种压缩机发展的关键技术,改进电机与压缩机的结构来提升压缩机效率,通过变压比、喷气增焓、部分负荷下调节等技术,提升了压缩机系统性能系数COP与综合部分负荷性能系数IPLV(H)。采用直流电机替代交流电机,可提高两种压缩机的电机效率和频率调节范围。通过对涡旋压缩机进行不对称涡旋盘设计,可减小噪音与泄漏量;对转子压缩机的双转子进行对称布置,增大了压缩机的容量。带排气阀的涡旋压缩机可在一定程度上实现变压缩比,而转子式压缩机有排气阀,在变工况方面具有明显的优势。两种压缩机均可采用喷气增焓技术,实现热泵低环境温度较大的压缩比。     

The effect of clearance control on the performance of an oil-free linear refrigeration compressor and a comparison between using a bleed flow and a DC current bias

A moving magnet type oil-free linear compressor has been designed for applications such as electronics cooling. A control system using a solenoid operated valve was developed for DC offset and axial clearance control. Operation of the linear compressor with a fixed clearance of 0.8 mm was compared with a zero DC offset operation. The fixed clearance operation requires a higher power input.The mean piston position can be controlled by using a DC bias on the drive voltage or by using a bleed flow from the compressor body to the suction side of the compressor. Using a DC bias on the drive voltage induces a higher power loss than using a bleed flow when there is a small radial clearance between the piston and cylinder. This provides evidence that the piston control in a refrigeration system with capacity control should be for a zero DC offset using a bleed flow.     

A novel linear electromagnetic-drive oil-free refrigeration compressor using R134a

A new type of oil-free moving magnet linear compressor with clearance seals and flexure springs has been designed for incorporation into a vapour compression refrigeration system with compact heat exchangers for applications such as electronics cooling. A linear compressor prototype was built with a maximum stroke of 14 mm and a piston diameter of 19 mm. An experimental apparatus was built to measure the compressor efficiencies and coefficient of performance (COP) of a refrigeration system with the linear compressor, using R134a. The resonant frequency for each operating condition was predicted using the discharge pressure, suction pressure and stroke. Refrigeration measurements were conducted for different strokes under each pressure ratio with a fixed condenser outlet temperature of 50 °C and evaporator temperature ranging from 6 °C to 27 °C. The results show that the COPs are around 3.0 for tests with a pressure ratio of 2.5 (evaporator temperature of 20 °C).     

A new structure and theoretical analysis on leakage and performance of an oil-free R290 rolling piston compressor

Lubricating oil improves the reliability of compressors and systems, whereas increases the system complexity. Compared with other types of compressors that have oil-free models, a rolling piston compressor has more leakage paths and bigger leakage loss. Therefore, the leakage is an important problem to be solved in order to develop an oil-free rolling piston compressor. The paper put forward a new structure of rotary compressor adopting a low pressure shell, connecting the cavities within piston and behind vane to the cavity at suction pressure and using radial compliance mechanisms. Then the leakage models were developed to calculate the mass flow rates within both the present rolling piston compressor without any oil as sealant and the new structure of oil free compressor. Results showed that by the new structure, the influences of leakage on the performance of a R290 oil free rolling piston compressor can be largely decreased.     

An experimental and numerical study on an inherent capacity modulated linear compressor for home refrigerators

Linear compressors are built based on a free piston system and usually require stroke controllers, since the piston movement is sensitive to the ambient temperature. This paper presents a novel design method for an inherent capacity modulated linear compressor that uses R600a for application in household refrigerators. The compressor is capable of modulating its capacity independently, and this feature secures stable and efficient operation without requiring stroke controllers. Electrical parameters are designed to deliver inherent capacity modulation in accordance with cooling demand variation. Mechanical parameters are tuned to establish an efficient resonance system. A numerical model was developed and a prototype compressor was constructed. The prototype compressor was evaluated over a condensing temperature range of 15-50 °C, which corresponds to an ambient temperature range of 5-43 °C. The simulation results show that the cooling capacity was inherently modulated from 55 to 90% over the ambient temperature range, and the inherent modulation is confirmed 70-90% by the experiment.     

并联螺杆压缩机制冷系统的研究

在制冷系统中两台并联压缩机中只能运行任一台压缩机,交替运行并相互备用,均衡磨损,保证机组系统的可靠性。     

New non-dimensional performance parameters for the characterization of refrigeration compressors

Pierre (1982) developed general correlations of compressor performance for a wide range of open piston compressors based on a vast amount of data provided by the most important open compressors manufacturers at that time. Based on a wide experimental test campaign with 6 different hermetic and semihermetic compressors, this paper assesses the potential of Pierre's correlations to describe the performance of modern compressors. A full review of the functionals proposed by Pierre in order to improve their accuracy was then performed and as a result the authors found that it is possible to improve the characterization by employing a nondimensional definition of the compressor performance instead of using the efficiencies. These new parameters provide a much more consistent estimation at the borders of the correlation range than the usual correlation obtained following the ARI standard, and could be even employed to extrapolate the performance of the compressor to non-tested conditions with reasonable accuracy.     

Theoretical study of a novel refrigeration compressor – Part II: Performance of a rotating discharge valve in the revolving vane (RV) compressor

A new refrigeration compressor, named ‘Revolving Vane (RV) compressor’, has been introduced in Part I of this paper series. For a first time in refrigeration compressors, a rotating discharge valve is employed in the RV compressor mainly due to the rotation of the entire cylinder. This paper presents a theoretical investigation on the dynamic behavior of a reed-type discharge valve undergoing rotatory motion, with the primary objective of elucidating the applicability of such valves in refrigeration compressors. Under the application of the Euler–Bernoulli beam theory, a mathematical model of the rotating valve is formulated and the transient response of the valve under centrifugal loads in addition to pressure forces is analyzed. Results have shown that under careful design considerations, the performance as well as the reliability of the rotating discharge valve can be enhanced as compared to a non-rotating valve that has been used in all refrigeration compressors currently.     

Optimization of electrostatically actuated miniature compressors for electronics cooling

This paper explores the feasibility of using electrostatically actuated diaphragm compressors in a miniature-scale refrigeration system for electronics cooling. A previously developed experimentally validated analytical model for the diaphragm compressor is used in conjunction with an optimization approach to determine the required dimensions for the compressor. The analysis reveals that the pressure rise and volume flow rate required for the electronics cooling application are not achieved using a single compressor because of material property limitations. A three-dimensional array of compressors is proposed instead with which the cooling requirements and the size restrictions for electronics cooling applications may be simultaneously satisfied.