喷液冷却和喷气增焓低温热泵涡旋压缩机的对比分析

本文分析了目前低环境温度热泵用涡旋压缩机运行特性及技术要求,并对制冷剂喷液冷却和喷气增焓两种涡旋压缩机技术的特点进行了对比介绍。针对低环境温度热泵开发了两款R410A涡旋压缩机:PSH系列压缩机采用制冷剂喷液冷却技术控制压缩机排气温度,可以扩大低环境温度下的运行范围;PCH065压缩机采用制冷剂喷气增焓技术提高低环境温度工况制热量及制热性能,并通过中间排气技术提高部分负荷系统的制冷性能,内置温度保护器的应用提高了压缩机在高排气温度运行的可靠性。这些优点使得热泵系统可以在我国低环境温度区域推广使用。     

采用涡旋压缩机的电动汽车空调准双级压缩热泵性能实验研究

为了解决电动汽车空调系统冬季采暖问题和抑制冬季恶劣工况下压缩机排气温度过高状况,本文采用补气增焓技术,设计了电动汽车准双级压缩热泵空调系统,构建了电动汽车空调准双级涡旋式压缩机性能测试实验台。采用5种不同室外环境温度工况,分别测试了单级和准双级涡旋式压缩机。结果表明:压缩机的排气温度随环境温度的降低而升高。5种工况下,单级涡旋压缩机的排气温度均高于准双级涡旋压缩机的排气温度,尤其在环境温度为-7℃时,准双级涡旋压缩机的排气温度降低了10℃。与单级涡旋压缩机相比,在低温工况下,准双级涡旋压缩机的排气质量流量提高了12.9%~17.4%,系统制热量提高了7.3%~8.3%,制热性能系数COPh提高了7.6%~8.2%。     

基于制冷剂泄出的涡旋压缩机容量调节技术

具有固定内容积比的涡旋压缩机存在当外压缩比小于其内压缩比时内容积效率较快下降的问题,由于空调制冷(热泵)系统大部分时间运行在偏向小室内外温差工况即小压缩比工况下,此时压缩机处于过压缩工况,故制冷(热泵)系统的效率低下;同时,随着系统压缩比的减小,会出现建筑的供冷/供热负荷下降和系统的供冷/供热能力上升的矛盾,系统存在降容的需求。为解决小压缩比工况下压缩机效率降低和系统容量过大的问题,提出一种带制冷泄出功能的涡旋压缩机制冷系统,采用模拟分析和实验测量方法,对其技术可行性进行研究,结果显示:合理适度的制冷剂泄出能有效提高压缩机在过压缩工况下的内容积效率,提高系统的COP并减小制冷系统的制冷/制热能力,是一项极具潜力的制冷系统调节技术。     

喷气增焓与喷液冷却式空气源热泵在低温环境下实验数据对比及分析

对喷气增焓及喷液冷却式空气源热泵进行了热力学分析,并在低环境温度下对其制热性能进行了数据测试及对比研究,结果表明,随着室外环境温度在10℃～30℃之间下降时,两款热泵耗电量都在逐渐增加,制热量逐渐降低,喷气增焓空气源热泵机组相较喷液冷却式空气源热泵机组的COP下降有变缓趋势,当室外环境温度为-5℃时,喷气增焓热泵的COP为3.03,而喷液冷却式热泵降至2.66;在-20℃时,喷气增焓式热泵COP为2.15,喷液冷却式热泵COP已降至1.88;喷气增焓空气源热泵比喷液冷却式热泵性能提高大概13%左右。喷气增焓空气源热泵机组在低温环境下效率更高。     

电动汽车空调热泵型涡旋压缩机结构分析

为了解决电动汽车空调系统冬季采暖问题,针对冬季空调工况下压缩机单级压比增大的运行特性,以涡旋压缩机制热性能系数为热力学优化目标函数,确定了制冷剂循环系统中的最佳补气压力,优化了涡旋压缩机静涡旋盘上的中间补气口的几何位置和形状,使其具备了准双级压缩功能。将研发的热泵型电动涡旋压缩机安装于电动汽车空调系统,利用空气焓差法对系统进行了制热、制冷性能实验。实验结果表明,静涡旋盘结构优化后的热泵型电动涡旋压缩机,其制热和制冷能力可以满足5人座电动汽车司乘人员的冬季和夏季舒适性要求,并且具有较高的制热和制冷性能系数,从而提升了汽车空调系统热泵循环和制冷循环的热经济性,达到了节能的目的。     

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。     

基于喷气增焓技术的轻型商用变频空气源热泵的研究

针对寒冷区域的供热需求,结合喷气增焓技术,研发一款在低环境温度下高制热能力输出的轻型商用变频空气源热泵。测试该系统在低环境温度工况下的性能,并与传统制热循环进行比较。测试结果表明,制热时喷气增焓系统存在最佳中间压力并实现制热时最大能力输出;在室外环境温度为-25~7℃时,喷气增焓系统比原系统在制热能力上均有较大的提高,有效拓展了系统的低温运行范围;在室外干/湿球温度-15℃/-16℃条件下,喷气增焓系统制热能力可达到系统额定制热能力的100%,在压缩机运行频率为100 Hz时,喷气增焓系统的COP可达到2.07,较对应工况下无补气系统COP提升10.5%;在室外环境温度为-20℃且压缩机运行频率为100 Hz时,喷气增焓系统COP较原系统提升6.2%;喷气增焓系统排气温度比原系统低,系统低频运行时排气温度差值较大。     

滚动转子式补气压缩机在热泵系统中的实验研究

介绍了滚动转子式补气压缩机的设计,并将其在热泵系统中进行了实验研究。分析了不同制热工况下滚动转子式补气压缩机的性能,对比了带闪发器与过冷器的经济器热泵系统、滚动转子式与涡旋式补气压缩机的性能。结果表明:随着室外环境温度的下降,滚动转子式补气压缩机补气后制热量提升比例逐步增大;滚动转子式补气压缩机制热实验中,带闪发器系统的制热量较高;在超低温制热工况下滚动转子式补气压缩机制热量提升18%左右,与涡旋式补气压缩机相比制热量相当,性能略高。     

应用于高温烘干热泵领域涡旋压缩机的研究

本文介绍了高温烘干热泵原理,并根据应用特点及压缩机结构分析,提出普通涡旋压缩机应用于高温烘干热泵的结构优化,主要包括改进涡旋型线、电机和排气结构等方面。对比分析优化前后涡旋压缩机的制热能力、制热能效等试验结果,得出结论:两者在AHRI工况制热性能相近,但在高温烘干热泵工况下,高温烘干热泵专用涡旋机制热COP提升4. 5%。此外,笔者还对高温烘干热泵领域环保制冷剂替换加以研究,分析R134a与R513A在多个工况下的测试结果。综合分析结果显示两种制冷剂表现能力相当,R513A制冷剂GWP低于R134a 56%,有利于环保制冷剂替换。     

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;R32经济器热泵系统制热模式的最佳结构和运行参数为:系统的准一级压缩内容积比为1.1时,压缩机的相对喷气量值最大;当环境温度低于-10℃时,最佳相对喷气量宜取为0.22~0.33;当环境温度为-10~-5℃时,最佳相对喷气量宜取0.20~0.22;当环境温度高于-5℃时,则宜为0.18~0.20。相应的最佳相对喷气压力在0.85~1.31之间,处在最佳补气参数范围内,经济器热泵系统的优势越明显。     

Performance improvement of air source heat pump using gas-injected rotary compressor through port on blade

Gas injection has been a crucial technology to avoid the serious degradation of air source heat pumps in low ambient temperature. A novel injection structure on the blade for rotary compressors has been put forward in previous research to overcome the drawback of traditional injection structures. Based on a verified numerical model, the thermodynamic performance of an air source heat pump with the new gas-injected rotary compressor is investigated. The results indicate that, compared to the air source heat pump with the regular single-stage rotary compressor, the proposed injection structure can enhance heating capacity and COP of the air source heat pump by 23.1–28.2% and 4.5–8.1%, respectively.     

Scroll compressors using gas and liquid injection: experimental analysis and modelling

The first part of this paper presents an experimental analysis of different hermetic scroll compressors using different methods of injection: the first one is without injection, the second one uses vapor injection and the third one liquid injection. The analysis reveals the influence of these methods on the compressor behavior. A simplified model of the scroll compressor is then proposed that takes into account not only the different internal processes but also the refrigerant injection. It assumes that the refrigerant mass flow rate is affected by a heating-up due to a uniform wall temperature. This fictitious wall is supposed to gain heat from the electromechanical losses and from the discharged gas and to loose heat to the suction and to the ambient. The compression step is considered isentropic up to the adapted pressure and then at constant volume until the discharge pressure. The model is able to compute variables of first importance like the mass flow rate, the electric power and the discharge temperature, as well as secondary variables as suction heating-up, discharge cooling-down, and ambient losses. The validation based on 45 experimental results shows excellent results.     

Semi-empirical modeling and analysis of oil flooded R410A scroll compressors with liquid injection for use in vapor compression systems

Oil flooding is a technique that can be utilized in compression systems to achieve near-isothermal compression. This can lead to a boost in system efficiency and a reduction in compressor power consumption. In this paper a semi-empirical model for oil flooded compressors using liquid injection was developed. The model is validated with experimental data and integrated into a thermodynamic model of a vapor compression system with oil flooding and regeneration. The performance of the heat pump system is predicted and the semi-empirical model is used to identify and estimate the magnitude of the irreversibilities during the compression process. A method for generalizing the model for different working fluids is also presented. Using this model, design recommendations are made to improve the efficiency of the studied liquid flooded compressors for heat pump applications.     

Efficiency analysis of power consumption in small hermetic refrigerant rotary compressorsAnalyse,du point de vue du rendement,de la consommation d'énergie dans les petits compresseurs frigorifiques rotatifs hermétiques

Theoretical and experimental studies of small hermetic rotary compressors for room air conditioners are reported. Comparing rotary and reciprocating compressors from the viewpoint of efficiency, the rotary compressor has a disadvantage of higher friction loss because the sliding surfaces in the compression chamber increase in number, however it has the following three significant features: volumetric efficiency is high; valve loss is low; since suction, compression and discharge are performed simultaneously, suction velocity and discharge velocity become approximately one half. Therefore the efficiency of the rotary compressor is higher than that of the reciprocating compressor.     

Efficiency analysis of power consumption in small hermetic refrigerant rotary compressors

Theoretical and experimental studies of small hermetic rotary compressors for room air conditioners are reported. Comparing rotary and reciprocating compressors from the viewpoint of efficiency, the rotary compressor has a disadvantage of higher friction loss because the sliding surfaces in the compression chamber increase in number, however it has the following three significant features: volumetric efficiency is high; valve loss is low; since suction, compression and discharge are performed simultaneously, suction velocity and discharge velocity become approximately one half. Therefore the efficiency of the rotary compressor is higher than that of the reciprocating compressor.     

Development of capacity modulation compressor based on a two stage rotary compressor – part I: Modeling and simulation of compressor performance

Two-stage rotary compressors are gaining popularity because of their ability to reduce operating and energy costs over the entire compressor life cycle. In this work, a capacity modulation compressor based on a two-stage rotary compressor (CMCTR) is developed to improve the performance of the rotary compressor system. The working principle of the CMCTR is presented and the cycle efficiency of the compressor through two-stage compression is numerically investigated. The CMCTR model considers mass and energy balance for a control volume, the internal leakage condition for all leakage paths, the discharge valve motion, and the force and moment balance. For simulation results, the motor efficiency is estimated with respect to shaft power and the pressure during an entire cycle is obtained with respect to the compression volume for saving mode and power mode. The optimum efficiency of the CMCTR is obtained for the modulation for these modes.     

A lumped-parameter thermal model for scroll compressors including the solution for the temperature distribution along the scroll wraps

A lumped-parameter thermal model is presented to predict the temperature in different chambers and components inside scroll compressors with particular attention to gas superheating in the suction process. Thermal resistances between the components are based on global heat transfer conductances, whereas conduction heat transfer through the scroll wraps is solved via a one-dimensional finite volume method. The thermal model was coupled to a thermodynamic model of the compression cycle and then applied to simulate the compressor performance under different conditions of speed and pressure ratio. The model was able to correctly predict the compressor temperature for operating conditions within the range of those adopted for its calibration. The results showed a strong coupling between the compressor thermal profile and the temperatures of the motor and lubricating oil. It has also been found that heat conduction through the scroll wraps reduces slightly the discharge temperature.     

Mathematical modeling of scroll compressors — part II: overall scroll compressor modeling

This paper presents the development of a comprehensive simulation model of a horizontal scroll compressor, which combines a detailed compression process model (Chen Y., Halm N., Groll E., Braun J. Mathematical modelling of scroll compressors — part I: compression process modeling, International Journal of Refrigeration 2002;25(6):731–750) and an overall compressor model. In the overall model, compressor components are analyzed in terms of nine different elements. Steady state energy balance equations are established applying the lumped capacitance method. In combination with the detailed compression process model, these equations were implemented into computer code and solved recursively. In this way, the temperature and pressure of the refrigerant in different compressor chambers, the temperature distributions in the scroll wraps, and the temperatures of the other compressor elements can be obtained. Thereafter, power consumption and efficiency of the compressor can be calculated. Tests were used to verify the overall model on a macroscopic basis. Using the simulation program based on the overall compressor model, a parametric study of the scroll compressor was performed, and the effects of internal leakage and heat transfer losses were investigated and some preliminary results were obtained. These results indicate that the comprehensive scroll compressor model is capable of predicting real compressor behavior and useful to the design and optimization of scroll compressors.     

涡旋压缩机涡旋型线的研究现状及展望

涡旋压缩机作为第三代容积式压缩机,具有效率高、能耗低、噪声低、结构紧凑等诸多优点,被广泛应用于制冷空调与气体压缩等方面。由于涡旋压缩机的寿命、加工性能、效率和功耗等都受到涡旋型线的制约,所以涡旋型线的研究是开展涡旋压缩机其他研究的基础和关键。本文总结了国内外相关的研究成果,从型线类型和型线修正两个方面出发,对现有涡旋型线的研究现状进行综述分析,并对未来涡旋型线发展方向和趋势进行预测和展望,对于今后涡旋压缩机型线的研究与工程应用具有指导和借鉴作用。