螺杆式压缩机部分负荷性能计算方法探讨

根据螺杆式压缩机滑阀容量调节的特点,建立螺杆式压缩机部分负荷性能计算模型,并用螺杆式压缩机性能的实测数据对模型的预测精度进行验证。结果显示：模型预测的螺杆式压缩机部分负荷性能与实测数据吻合,在测试数据范围内,模型预测的最大误差小于2%。     

变频螺杆式压缩机性能计算的数学模型及试验验证

提出一套完整的针对变频螺杆式压缩机的性能计算非线性拟合数学模型,此数学模型可以计算压缩机全运行范围的制冷量、输入功率和效率。基于变频螺杆式压缩机的运行压比和螺杆转子齿顶圆速度的19系数和21系数非线性拟合数学模型分别计算容积效率和等熵效率,模型对于测试数据的拟合精度高,实用性好。     

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。     

螺杆式压缩机衍生机型的内容积比优化设计

介绍螺杆式压缩机内容积比的计算方法,分析螺杆转子有效长度的变化对螺杆式压缩机内容积比的影响。指出为了改善螺杆式压缩机衍生机型的性能,需合理调整主导机型的内容积比,这对衍生机型的内容积比优化、改善衍生压缩机的性能具有实际意义。     

螺杆式与活塞式制冷压缩机的比较

以萨布罗公司(SABROE)的产品为例,在容积效率、运行费用、绝热效率、COP值、部分载荷、电动机效率、冷量调节、制冷剂、维修检查及市场前景等方面对应用最为广泛的活塞式压缩机及螺杆式压缩机进行了评价,从而为压缩机的选择提供了一些参考依据。     

可变内容积比螺杆式压缩机的性能分析

随着冷水机组、单元式空调机和水源热泵机组等产品的能效指标从名义工况EER或COP发展到IPLV或ICOP,机组的变容量或变工况性能主要取决于压缩机的变容量或变工况性能。固定内容积比的螺杆式压缩机如果在偏离设计工况下工作,效率下降,进而导致整个机组的性能下降。本文研究变内容积比螺杆式压缩机,内容积比可变化,使得压缩机内压比与外压比与工况相适应,可提升压缩机效率及机组性能。应用于冷水机组、水源热泵机组时,水源热泵机组在制冷工况时能效比可提高14.1%～35%,冷水机组的IPLV可提高7.2%左右。     

螺杆压缩机专利现状及趋势分析

螺杆式压缩机通过使用阴阳转子互相啮合,高速选装使机组内部容积发生变化,进而获取压缩空气,螺杆式压缩机相比于传统活塞压缩机具有结构紧凑、压缩比大、输气量调节良好等优点,是大型压缩机中使用最广的压缩机。螺杆压缩机由于具有体积小、损件小、耐焦油等优点被广泛应用,该文主要借助数据收集与整理对螺杆压缩机专利现状及螺杆压缩机未来发展趋势进行探讨,以期为我国螺杆压缩机的发展提供参考。     

螺杆式制冷压缩机转子型线优化设计

前言六十年代以来,螺杆式压缩机以其可靠性高、结构简单、体积小、重量轻、易损件少、运转平稳以及可以带液压缩等明显的优点,在大冷量范围内逐步取代活塞式压缩机,然而就我国目前情况来看,螺杆式制冷压缩机还存在着效率偏低、噪音及振动偏大等缺点,急待作进一步的改进。     

国内螺杆式制冷压缩机行业现状与发展趋势

螺杆式制冷压缩机进入国内市场已有30多年,如今已逐步取代其他型式压缩机,成为中、高容量制冷空调系统的优势选择,市场份额逐年增加。本文从转子型线、转子加工、喷油及补气技术和控制调节技术等多个方面阐述我国螺杆式制冷压缩机行业所取得的技术进步,介绍螺杆式制冷压缩机在热泵及冷冻冷藏行业中的应用,指出目前国产螺杆式制冷压缩机在生产制造及控制系统方面存在的几点不足,预测螺杆式制冷压缩机的未来发展趋势,力求为我国螺杆式制冷压缩机的自主研发创新起到指导性作用。     

高效螺杆式CO2制冷压缩机的优化设计

在对螺杆式CO2制冷压缩机的转子进行优化的基础上,对相应的壳体强度、轴承选择、油路布置等进行优化设计,根据优化设计参数制造螺杆式CO2制冷压缩机样机并进行测试。试验结果表明,优化设计后的螺杆式CO2制冷压缩机具有很高的效率及可靠性。     

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.     

Thermodynamic model for reciprocating compressors with the focus on fluid dependent efficiencies

Fluids with high global warming potential, which are used in existing refrigeration cycles and heat pumps, will have to be replaced soon by less harmful fluids, but the fluid selection is difficult especially due to the unknown compressor performance. In this work a differential compressor model for reciprocating compressors is introduced which predicts volumetric and isentropic efficiencies quickly and can be easily fitted with measured data at only one operation point of an existing compressor. In order to characterise the influence of different fluids two semi-physical correlations for the valve flows are fitted here, and a procedure of transferring them to different compressors is shown. The model is validated on, in total, 63 measured points based on numerous fluids from one semi-hermetic reciprocating compressor which is part of a heat pump cycle. The calculations lead to mean prediction errors of 3.0% for the isentropic and 2.3% for the volumetric efficiency.     

滚动转子式压缩机性能参数通用计算模型

探讨了滚动转子式压缩机容积效率、功率因子、制冷量、运行电流等几个主要性能参数的通用计算模型.依据压缩机厂商提供的大量不同系列压缩机的实验数据,运用麦夸特算法拟合求解各性能参数相关系数,总结出精度高、通用性好的性能关联式.对不同性能参数,以及单一性能参数的不同公式形式进行分析对比,结果表明,由该方法所建立的模型能够准确地描述变工况下滚动转子式压缩机性能参数,可作为滚动转子式压缩机性能参数计算的理想关联式.     

罗茨水蒸气压缩机性能实验研究

压缩机是蒸气压缩蒸发系统的核心设备,会显著影响系统的能耗和运行稳定性.本文搭建了基于罗茨压缩机驱动的蒸气压缩蒸发实验台,蒸发温度为80～100℃,蒸发压力为46.60～101.64 kPa,压缩机压升为17.86～36.03 kPa,蒸发量为125.72～424.85 kg/h,实验研究了吸气流量、压缩比功、容积效率和...     

半封闭活塞式制冷压缩机容积效率的研究

通过对一台半封闭活塞式制冷压缩机分别采用R22、R134a和R404A时的容积效率的实验研究,数据拟合出不同工质容积效率的计算公式,为半封闭活塞式制冷压缩机的设计提供依据。     

Detailed thermodynamic characterization of hermetic reciprocating compressors

The aim of this paper is the detailed analysis of different well-known thermodynamic efficiencies usually used to characterize hermetic compressors. Attention is focussed on the volumetric efficiency, the isentropic efficiency, and the combined mechanical–electrical efficiency. A procedure is presented to detach these efficiencies into their main components (physical sub-processes) to get deeper insight on the overall behavior.The volumetric efficiency is split into partial efficiencies related to pressure drop and heat transfer effects, supercharging effects, superdischarging effects, leakages, etc. The isentropic efficiency is detached using two different points of view: the work associated to the individual sub-processes (compression, discharge, expansion, suction), and the work associated to the underpressures, overpressures, and between the inlet and outlet mean compressor pressures. Finally, the combined mechanical–electrical efficiency is related to the heat transfer losses/gains, and to the exergy transfers and exergy destroyed.Even though some of the concepts introduced in the paper can be applied to different kinds of compressors, the discussion is specially focussed on hermetic reciprocating compressors. An advanced simulation model developed by the authors has been used to generate data to illustrate the possibilities of the detailed thermodynamic characterization proposed. The criteria developed are useful tools for comparison purposes, to characterize compressors, and to assist designers during the optimization process.     

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%。     

Loss-efficiency model of single and variable-speed compressors using neural networks

Compressor is the critical component to the performance of a vapor-compression refrigeration system. The loss-efficiency model including the volumetric efficiency and the isentropic efficiency is widely used for representing the compressor performance. A neural network loss-efficiency model is developed to simulate the performance of positive displacement compressors like the reciprocating, screw and scroll compressors. With one more input, frequency, it can be easily extended to the variable speed compressors. The three-layer polynomial perceptron network is developed because the polynomial transfer function is found very effective in training and free of over-learning. The selection of input parameters of neural networks is also found critical to the network prediction accuracy. The proposed neural networks give less than 0.4% standard deviations and ±1.3% maximum deviations against the manufacturer data.     

A phenomenological model for analyzing reciprocating compressors

A new model for hermetic reciprocating compressors is presented. This model is able to predict compressor efficiency and volumetric efficiency in terms of a certain number of parameters (10) representing the main sources of losses inside the compressor. The model provides users with helpful information about the way in which the compressor is designed and working.A statistical fitting procedure based on the Monte Carlo method was developed for its adjustment. The model can predict compressor performance at most points with a maximum deviation of 3%.A possible gas condensation on cold spots inside the cylinder during the last part of the compression stroke was also evaluated.     

Scaled boundary finite element method for compressible and nearly incompressible elasticity over arbitrary polytopes

In this paper, a purely displacement-based formulation is presented within the framework of the scaled boundary finite element method to model compressible and nearly incompressible materials. A selective reduced integration technique combined with an analytical treatment in the nearly incompressible limit is employed to alleviate volumetric locking. The stiffness matrix is computed by solving the scaled boundary finite element equation. The salient feature of the proposed technique is that it neither requires a stabilization parameter nor adds additional degrees of freedom to handle volumetric locking. The efficiency and the robustness of the proposed approach is demonstrated by solving various numerical examples in two and three dimensions.