一种节能型活塞式制冷压缩机耐久实验系统研究

提出了一种节能型活塞式制冷压缩机耐久实验系统,该系统基于“不完全冷凝,气液混合”原理,将压缩机排气后产生的高温高压工质的一部分冷凝成液体,其余不进行冷凝而直接节流变成气体,然后气、液进行混合形成饱和气体进入压缩机吸气.分析了不完全冷凝条件下,所需冷凝的工质与非冷凝工质的质量流量关系以及冷凝器的换热量,结果表明只需少量工质被冷凝,即可以满足耐久实验工况要求,因此,选用较小功率的冷凝器就可以完成较大功率压缩机耐久性测试.最后,以某型号压缩机对系统进行测试,验证了系统的有效性及可靠性.该系统结构简单,不仅节约能源消耗,而且可以降低实验系统成本,具有较高的经济性,可推广应用到其它压缩机类产品的耐久实验系统.     

小型全封闭式氦气压缩机的研究

小型全封闭式氦气压缩机是Ｇ－Ｍ制冷机的配套设备，广泛应用于空间环模设备、真空低温泵、真空镀膜等。目前，国内外小型全封闭式氦气压缩机几乎都是由全封闭式氟里昂制冷机改制而成。讨论了在不同工质、工况情况下，如何解决压缩的冷却、润滑以及气体纯化等问题，才能用氟里昂压缩机压缩氦工质，保证氦气压缩机安全、可靠、长寿命运行。     

气体冷却法压缩机测试装置的改进与应用

气体冷却法压缩机测试装置尺寸较大,易受试验室场地制约。本文在气体冷却法流程的基础上,对测试装置进行改进,提出近气环法流程,并阐述近气环法压缩机测试装置相关参数的控制方式。试验结果表明,被试压缩机在近气环法压缩机测试装置上运行稳定,工况参数在允许偏差范围内,达到测试要求。     

工业原料冷却工艺的节能新方法——螺杆双温冷源机组分级降温系统

一、引言在石油、化工、制药、啤酒制造以及其它类似的工业原料降温过程中,如采用螺杆双温冷源机组分级降温的形式进行冷却,利用螺杆压缩机的特点,即利用二次吸气,一方面利用了低品位的冷量,另一方面更加充分的利用了螺杆转子的容积,可使机组的总制冷量提高25～75%,而效率提高15～51%,因此,这是工业原料冷却工艺的一项重大进步。二、传统的冷却工艺以往通常使用的传统系统中,制冷工质从压缩机出来后进冷凝器冷凝,然后通过膨胀阀     

微型压缩机驱动的微型混合工质J-T制冷器实验研究

为研究微型混合工质节流制冷器的降温性能,搭建了微型压缩机驱动微型混合工质节流制冷器的制冷系统,并得到了初步实验研究结果。采用Aspen微型压缩机驱动微型J-T节流制冷器,应用混合制冷剂实现深度制冷。微型J-T节流制冷器采用微小通径的不锈钢毛细管制作,其通道特征尺寸为0.3mm。初步实验表明,微型J-T节流制冷器达到了180K温区。由于采用微型压缩机驱动,系统结构紧凑,可在便携生物储存设备、低温医疗以及电子器件冷却等领域应用。     

滚动转子式压缩机吸气压力脉动研究

滚动转子式压缩机吸气压力脉动对其制冷剂吸入量有着重要的影响。本文以某种型号的滚动转子式压缩机为研究对象,借助流体仿真软件Star-CD,模拟压缩机旋转压缩过程,得到汽缸吸气口的压力脉动规律,并同NI试验测试的压力脉动进行对比,发现两者结果较为吻合;并通过仿真对比吸气管路对压缩机吸气压力和吸气量的影响。     

1.27 K3He二级脉管制冷机性能研究

在一台具有独立气体回路的液氦温区G-M型二级脉管制冷机上,采用3He为第二级制冷工质,获得了1.27 K的最低无负荷制冷温度.研究表明,以3He为第二级工质,该系统在2 K,3 K和4.2 K,分别可以提供42 mW,205.5 mW和518.3 mW的制冷量,第一级和第二级压缩机相应的输入功率分别为4.3 kW(Leybold CP4000氦压缩机)和1.3 kW(Leybold RW2氦压缩机).与两级均采用4He工质的情况相比,在相同的条件下(相同的压缩机耗功:4.3 kW 1.3 kW),第二级采用3He为工质,使得该二级脉管制冷机在4.2 K的制冷量提高了40.5%.     

直线压缩机用多孔质气体轴承的仿真与实验

采用气体轴承的主动耗气技术可以实现直线压缩机的无油润滑和非接触运行,以保证运行可靠性。为研究多孔质轴承的结构参数和压缩机设计参数对耗气量的影响,本文以R600a为制冷工质,建立了多孔质气体轴承模型,利用Fluent对耗气量进行了仿真模拟计算,基于该模型模拟分析了多孔质材料厚度、间隙气膜厚度、排气压力、压缩机频率和排量占比对气体轴承耗气量和耗气率的影响,并通过实验测试验证了该模型的准确性。结果表明：气体轴承耗气量的仿真结果和实验测量的误差在±15%以内。根据耗气率给出了最佳的设计参数组合,为直线压缩机用多孔质气体轴承优化设计提供了参考。     

兰州空间技术物理研究所吸气式电推进技术进展

吸气式电推进技术是将超低轨空间的环境气体工质收集、增压、电离以及加速产生推力的技术,是一项具有里程碑意义的航天器动力技术.兰州空间技术物理研究所开展了近10年吸气式电推进技术研究.主要介绍了兰州空间技术物理研究所吸气式电推进技术的最新进展,包括吸气式电推进系统方案和应用分析;基于理论分析和数值计算进行的气体收集增压技术...     

基于CFD和声学FEM的旋转式双缸压缩机所配分液器单极子吸气噪声分析

旋转式压缩机广泛应用于家用空调器,是制冷系统的动力源,也是空调系统中主要噪声源。本文针对双缸压缩机吸气噪声,建立CFD模型,通过数值计算得到单、双吸气方式的质量流率。在此基础上,建立不同单、双吸气方式分液器声学FEM模型,分析不同分液器的单极子吸气噪声,并与测试结果进行对比。结果表明,单吸气方式在降低双缸压缩机单极子吸气噪声方面较双吸气方式具有一定优势,在本例中,分液器吸气噪声降低2 dB(A)以上。     

吸排气管管径变化对空调系统制冷性能的影响

采用系统仿真的方法研究吸排气管管径变化对空调系统性能的影响。研究结果表明：吸排气管管径变化直接影响吸排气管饱和温降或压降,且吸气管内制冷剂压降直接降低吸气压力,排气管内制冷剂压降直接增加排气压力。其中,吸气管压降变化主要影响低压侧热力参数、制冷剂质量流量、制冷量和EER,对系统耗功影响较小,而排气管压降变化主要影响高压侧热力参数、系统耗功和EER,对系统制冷量影响较小。对于本文研究的系统,吸气管和排气管饱和温降控制在1 K以内时,系统性能相对吸、排气管路制冷剂压降为零的系统降低幅度在2%以内,可作为吸排气管选型标准。     

R32热泵系统排气温度控制及理论预测

根据R32在空气源热泵中的研究和应用现状,介绍系统排气温度控制的3种途径,即中间压力补气（EVI）、中间压力喷液（ELI）和吸气干度控制（SX）;提出根据压缩机效率和制冷剂物性预测排气温度的模型,得到R32在EVI,ELI和SX热泵系统的排气温度预测矩阵表,以压缩机吸、排气饱和温度分别为-20℃和40℃为例,为使得排气温度控制在100℃左右,EVI系统补气干度应约为0.90,ELI系统喷液量比率应约为9%,SX系统吸气干度应约为0.96。     

Thermodynamic analysis on the performance of a variable speed scroll compressor with refrigerant injection

A thermodynamic model for a variable speed scroll compressor with refrigerant injection was developed using continuity, energy conservation and real gas equation. The model included energy balance in the low-pressure shell compressor, suction gas heating, motor efficiency, and volumetric efficiency considering gas leakages as a function of compressor frequency. The developed model was verified by comparing the predicted results for the no injection condition with the experimental data. The deviations of the predicted from the measured values were within 10% for approximately 90% of the experimental data. Based on the model, mass flow rate, suction gas heating, cooling capacity and power consumption of the compressor were estimated and analyzed as a function of frequency. The effects of refrigerant injection on the performance of the compressor were also discussed as a function of frequency, injection conditions, and injection geometry.

Résumé

A thermodynamic model for a variable speed scroll compressor with refrigerant injection was developed using continuity, energy conservation and real gas equation. The model included energy balance in the low-pressure shell compressor, suction gas heating, motor efficiency, and volumetric efficiency considering gas leakages as a function of compressor frequency. The developed model was verified by comparing the predicted results for the no injection condition with the experimental data. The deviations of the predicted from the measured values were within 10% for approximately 90% of the experimental data. Based on the model, mass flow rate, suction gas heating, cooling capacity and power consumption of the compressor were estimated and analyzed as a function of frequency. The effects of refrigerant injection on the performance of the compressor were also discussed as a function of frequency, injection conditions, and injection geometry.     

采用不同工质时吸气消声器性能研究

以单连通直接吸气消声器为研究对象,采用Fluent软件和Sysnoise软件分别对工质为R600a和R134a时的流场和声场进行数值模拟,并对采用不同工质时的消声器流动特性和声学性能进行对比分析.结果表明,R600a的压力损失比R134a的低,R600a的最大消声量比R134a大,但消声频率的范围比R134a窄.研究成果可用于预测消声器的综合性能,为消声器的设计、选型及结构优化提供理论依据.     

Flow visualization applied to a small refrigeration compressor

This paper describes a flow visualization technique that was used to evaluate qualitatively the gas flow pattern inside a small, hermetically sealed, reciprocating refrigeration compressor. The applicable compressor designs are those in which the suction gas from the evaporator is dumped into the compressor shell, and is then drawn through a muffler into the suction plenum of the compressor. The physical separation of the muffler inlet from the suction gas inlet serves to reduce compressor noise and also provides an easy and convenient means of separating any liquid (compressor oil or liquid refrigerant) from the refrigerant gas. For the flow visualization studies the compressor housing was replaced by a clear plastic shell. Atmospheric air seeded with white smoke was the working fluid. The suction inlet and muffler were parts from a commercial compressor. The flow pulsations were modelled by connecting the muffler outlet to the input plenum of an auxiliary compressor. The flow patterns near the muffler inlet were recorded with a video camera. The mixing of the inlet gas with the gas circulating inside the muffler was studied. The effect of alignment and offset of the muffler inlet relative to the suction inlet, the effect of muffler size, and the effect of a shroud around the muffler were studied. The results were used to guide a companion study of detailed temperature and pressure measurements inside a working compressor.     

滑板喷射型准二级滚动转子压缩机性能

本文提出一种将补气结构设置于滑板上的新型滚动转子压缩机结构,该结构能保证吸气结束后补气口才向压缩腔打开,避免了补气回流至吸气管导致的容积效率降低。通过建立数值模型,对该新型结构进行了模拟研究。结果显示:该新型结构可完全避免喷射过程中喷射制冷剂回流至吸气腔;与传统结构补气单缸滚动转子压缩机相比,带有新型喷射结构的单缸滚动转子压缩机的容积效率提升2.6%~3.7%。     

分体式空调器长连接管制冷剂追加量的试验研究

基于制冷量为12 kW的风管送风式空调(热泵)机组进行试验研究,分析节流位置、工况等因素对长连接管制冷剂追加量的影响,得出9.52 mm液管和15.88 mm气管条件下R410A制冷剂追加量的参考值。研究发现,对于单冷型空调器,节流位置会对长连接管的制冷剂追加量产生较大影响,室内机节流时的追加量大于室外机节流;而对于热泵型空调器,节流位置对长连接管制冷剂追加量的影响较小。     

Thermal modeling for the motor in semi-hermetic screw refrigeration compressors under part-load conditions

In the semi-hermetic screw refrigeration compressor, the motor is mostly cooled down by suction refrigerant before it flows into the compressor suction port. To investigate cooling effects of the motor and performance of the compressor under part-load conditions, a lumped parameter model describing heat-transfer characteristics inside the motor and a part-load model of screw refrigeration compressor are developed and validated. Heating effects at compressor suction end and heat conduction from the male rotor screw to the motor shaft are taken into account. Nodes representing refrigerant inside the motor cooling passages are modeled separately. Temperature rise of refrigerant through the motor increases when the compressor load drops by either suction volume variation or speed variation. With drop of the compressor load, stator winding temperature goes up in the case of suction volume variation by slide valve motion, but it lows in the case of speed variation by frequency conversion.     

Effects of flash gas generation at the expansion device inlet on the dynamic characteristics of a refrigeration system

The flash gas generation at the expansion device inlet in multi-air-conditioners causes rapid reduction of refrigerant mass flow rate and irregular distribution of refrigerant into multi-indoor units. The objective of this study is to evaluate the influence of the flash gas generation on the dynamic characteristics of a refrigeration system. The dynamic characteristics of a refrigeration system with an electronic expansion valve (EEV) were measured with time at various levels of flash gas generation, which were expressed as flash gas ratio. In addition, the averaged operating parameters and system COP were investigated with the variation of flash gas ratio. As the EEV inlet condition changed from the subcooled to the two-phase state, the refrigerant flow rate decreased rapidly due to the flash gas generation at the EEV inlet. At two-phase inlet conditions, the system operating parameters, such as mass flow rate, suction and discharge pressures, fluctuated periodically with time. As the flash gas ratio increased, the average COP decreased and the discharge temperature increased, degrading the system performance and reliability more severely.