半封闭活塞式制冷压缩机喷液的研究

文章分析了喷液对半封闭活塞式制冷压缩机性能的影响,并以三洋C-L150M82型号压缩机进行试验,试验分析了不同工况下喷液对压缩机的排气温度、制冷量、功耗和COP的影响,以及喷液量随蒸发温度与冷凝温度的变化趋势。试验表明制冷剂喷射可以有效的降低排气温度,但同时也降低了制冷量和COP,增加了功耗。喷液的质量流量主要由喷液管和喷液吸气腔的压差,喷液率的变化与制冷量以及温度的变化不是简单的线性比例关系,合理的选择喷液毛细管,就可以优化喷液量,既能有效的降低压缩机的排气温度,又能确保压缩机的性能。     

油循环率对汽车空调系统制冷性能的影响研究

本文阐述了油循环率对汽车空调系统制冷性能的影响,并且测试了不同的油循环率条件下汽车空调制冷量、空调出风口温度和车内温度。测试结果表明,通过降低系统油循环率,汽车空调制冷量可以提高约10%,空调出风口平均温度和车内平均温度可以降低2℃~4℃。本文也探讨了通过控制压缩机内润滑油加注量以及在压缩机内部设置油分离结构等措施来控制系统油循环率。     

电子膨胀阀开度及制冷剂充灌量对家用空调器性能影响的研究

对于家用变频空调系统,电子膨胀阀开度的改变会影响制冷系统的过冷度、过热度、蒸发压力等,从而影响系统的制冷量和COP。本文主要研究电子膨胀阀开度、压缩机运行频率以及制冷剂充灌量对空调系统性能的影响。研究结果表明:压缩机运行频率一定时,随电子膨胀阀开度的增大,系统的制冷量和COP均先增大后减小,存在最大值,且最大制冷量和最大COP对应的电子膨胀阀开度相同;压缩机在低频运行时,系统具有较高的COP,随制冷剂充灌量的增加,系统的制冷量和COP均先增大后减小,试验机型的最佳制冷剂充灌量为1 230g。     

制冷系统含油量对制冷压缩机工作性能影响的理论分析和实验研究

为研究制冷系统含油量对制冷压缩机工作性能的影响,建立了汽车空调用涡旋式压缩机工作过程数学模型,对压缩过程进行了计算模拟。并在汽车空调压缩机性能测试台上,进行了变含油量、变转速和变工况实验,得到了流入压缩腔内的润滑油量与压缩机容积效率、压缩功率损失、排气温度、制冷量和COP的关系曲线。研究结果表明：理论计算结果和实验结果符合较好;压缩腔内油气质量百分比为7％～9％时,压缩机工作性能较为理想。     

喷液冷却对空调压缩机性能影响研究

喷液冷却是压缩机运行过程对其电机冷却的一种方式,为考察喷液冷却对转子型空调压缩机性能的影响,本次采用GB/T 5773-2016《容积式制冷剂压缩机性能试验方法》标准中规定的试验设备和方法对喷液冷却转子压缩机性能进行检测,调节不同的喷液量考察压缩机的制冷量、耗电量、COP以及排气温度等参数的变化.研究发现压缩机制冷量、...     

R404A在涡旋式冷凝机组中替代R22的试验研究

在理论分析R404A和R22物性的基础上,对R404A在高温涡旋式冷凝机组中替代R22进行试验研究。研究结果表明,适用R22的机组更换高压压力开关、压缩机冷冻油、干燥过滤器和视液镜、热敏继电器后,充注R404A制冷剂,机组能够正常运转。同时发现蒸发温度和环境温度对R404A机组的制冷量、COP的影响比对R22的影响更大,对输入功率、电流、排气温度和排气压力的影响与对R22的影响相对接近;相同结构配置机组,R404A制冷剂的充注量比R22的大,制冷剂充注量的增加与理论质量流量增加的比例不同。     

基于HFO的混合制冷剂R514A在离心式冷水机组中直接替代R123制冷剂的试验研究

R514A是一种低GWP,不可燃、基于HFO-1336mzz(Z)的新一代制冷剂,其物性参数与R123接近。因此,本文选择R514A作为原R123离心式冷水机组的替代制冷剂开展试验研究。依据GB/T18430.1—2007规定的试验工况,针对直接充注R514A和原制冷剂R123的机组性能进行测试,对比研究R123和R514A在离心式冷水机组中的机组输入功率、制冷量、性能系数(COP)、压缩机吸/排气压力、压缩机排气温度,并计算综合部分负荷性能系数(IPLV)值。结果表明:在对原机组结构不做任何改动,仅更换机组润滑油的情况下,R514A机组与原R123机组相比压缩机吸/排气压力和排气温度较为接近,COP和IPLV性能略有提升。     

基于吸气喷液的制冷系统热力性能理论研究

吸气喷液是降低压缩机排气温度的有效手段,通过建立制冷系统热力循环计算模型,研究基于吸气喷液的制冷系统热力学状态,以制冷剂R410A为工质,分析在不同工况下热力性能随喷液流量比例的变化趋势。计算结果表明,当喷液流量比例增加到5%时,排气温度平均降低幅度为9℃,功率、制冷量和COP值分别平均下降0.4%、0.6%和0.3%;若蒸发温度增加,功率呈先上升后下降的趋势,蒸发温度每增加5℃,排气温度平均降低幅度为4.5℃,制冷量、COP值分别平均增加17.6%、16.9%;冷凝温度每降低5℃,排气温度平均降低幅度为8℃,功率平均下降11.3%,制冷量、COP值分别平均增加6%、17.9%。     

电动汽车二次回路热泵空调系统性能试验研究

为了研究制冷剂充注量和环境温度对电动汽车二次回路热泵空调系统的影响规律,笔者设计并搭建了带有二次回路的热泵空调系统试验台。针对不同转速下,制冷量/制热量、COP和压缩机排气温度等参数随充注量及环境温度的变化趋势进行了试验研究,并确定标准制冷和制热工况的最佳充注量。结果表明：随着充注量的增加,蒸发器出口过热度和排气温度逐渐降低,而排气压力逐渐升高;制冷量/制热量和COP随充注量的增加而增大,并在最佳充注量处达到峰值,之后保持小幅变化。综合考虑,制热和制冷模式下系统最佳充注量分别为650 g和1 100 g。基于最佳充注量、压缩机转速为2 000 r/min时,制热模式环境温度由0℃升至12℃,制热量增加48.4%,COP_h升高8.3%;制冷环境温度由27℃升高至43℃时,制冷量和COP分别降低12.3%和44.4%。     

美国谷轮公司压缩机应用技术讲座：第16讲压缩机故障分析（4）——过热

排气温度过高和电机高温表明压缩机存在过热问题.电机高温源于冷却不足、负载过大和电源问题;而排气温度过高的原因在于制冷剂的性质、回气温度、冷却方式、冷凝压力、压缩比等.此外COP对排汽温度有明显影响.过热对压缩机具有很大危害,它不仅会缩短电机寿命、降低润滑油的润滑性能、加速润滑油变质,还会增加能耗,最终会损坏压缩机.     

降低卧式冷冻压缩机油循环率的方案探讨

油循环率在卧式冷冻压缩机的开发中是个重点关注的问题。过高的油循环率会影响换热性能,降低系统的性能。同时,随冷媒排出压缩机的冷冻机油如果不能及时地返回到压缩机中,可能会造成压缩机缺油,影响压缩机泵体的可靠性。本文针对卧式冷冻压缩机油循环率过高的问题提出了改善方案,并对改善方案进行优化,通过试验验证,油循环率大幅降低,同时提高了压缩机的可靠性。     

Effects of liquid refrigerant injection on the performance of a refrigeration system with an accumulator heat exchanger

Liquid refrigerant injection technique can be a very effective method for controlling subcooling and the compressor discharge temperature of a refrigeration system at high ambient temperatures. In this study, the effects of liquid refrigerant injection on the performance of a refrigeration system with an accumulator heat exchanger were investigated by varying the liquid injection rate at the conditions of constant expansion valve opening in the evaporator and constant total flow rate. During the tests, the ambient temperature was maintained at 43 °C. With the increase of the liquid injection rate, the subcooling at the inner heat exchanger outlet increased and the superheat at the accumulator outlet decreased. However, unacceptable results such as the increase of the compressor discharge pressure and decrease of the system performance were also observed depending on the control method applied. To obtain high system performance and reliability, optimum control methods for liquid injection in the accumulator heat exchanger are suggested. The liquid injection technique for the refrigeration system with an accumulator heat exchanger was found to be an effective method for controlling adequate subcooling and the compressor discharge temperature of the refrigeration system at high ambient temperatures.     

An investigation of the performance of a scroll compressor under liquid refrigerant injection

In this study, fundamental and practical influence of liquid refrigerant injection on the performance of a refrigerant scroll compressor has been investigated experimentally and theoretically. In the theoretical analysis, a compression model of vapor/liquid mixture is developed by taking account of heat transfer from the cylinder wall to suction, compression and injection refrigerant. An experiment has been done under the condition of keeping the oil temperature constant in order to investigate the fundamental influence of the liquid refrigerant injection on the compressor performance, and the results were compared with the theoretical ones. It was found that the injection basically increases the compression power and decreases the compressor efficiency, though the situation depends on the condition of the heat transfer to the injection refrigerant. And furthermore, the performance of the liquid refrigerant injection compressor under practical operating condition without controlling the oil temperature has been investigated. Under this condition, the compressor showed recovery and slight improvement of performance due to the decrease of the oil and cylinder temperatures by the injection. In addition, influence of the refrigerant injection on the oil viscosity and refrigerant solubility in the oil, which relate mechanical loss and reliability of the compressor, have been discussed.     

R32制冷系统降低排气温度的方法研究

从理论与实验两方面分析了R32替代R410A后,制冷系统运行参数的变化,提出了采用补气方法降低R32系统排气温度的方法。并以某厂家5HP空调器进行实验,对比了同一系统采用两种不同的制冷剂后,系统充注量、换热量、功率、COP、排气温度等参数的变化;分析了不同工况下补气对系统排气温度、换热量、COP的影响。结果表明:R32替代R410A后,系统能力及能效均有所提升,同时排气温度也上升;采用补气方法后,能够有效降低排气温度,同时在一定程度上增加换热量及COP。R32是一种具有潜力的替代制冷剂,采用补气系统,将打破排气温度过高对其应用的限制。     

Modeling of rotary vane compressor applying artificial neural network

The thermal modeling of rotary vane compressor (RVC) was performed in this paper by applying Artificial Neural Network (ANN) method. In the first step, appropriate tests were designed and experimental data were collected during steady state operating condition of RVC in the experimental setup. Then parameters including refrigerant suction temperature and pressure, compressor rotating speed as well as refrigerant discharge pressure were adjusted.With these input values, the operating output parameters such as refrigerant mass flow rate and refrigerant discharge temperature were measured. In the second step, the experimental results were used to train ANN model for predicting RVC operating parameters such as refrigerant mass flow rate and compressor power consumption. These predicted operating parameters by ANN model agreed well with the experimental values with correlation coefficient in the range of 0.962-0.998, mean relative errors in the range of 2.79-7.36% as well as root mean square error (RMSE) 10.59 kg h⁻¹ and 12 K for refrigerant mass flow rate and refrigerant discharge temperature, respectively. Results showed closer predictions with experimental results for ANN model in comparison with nolinear regression model.     

Experimental testing of an oil-flooded hermetic scroll compressor

In this work, a residential air conditioning compressor designed for vapor injection has been modified in order to inject large quantities of oil into the working chamber in order to approach an isothermal compression process. The compressor was tested with oil injection mass flow fractions of up to 45%. At an evaporating temperature of ?10 °C and condensing temperature of 30 °C, the overall isentropic efficiency was up to 70% at the highest oil injection rate. Overall, over the testing envelope investigated, there are no significantly negative effects experienced for the compressor and the compressor isentropic efficiency and refrigerant mass flow rate improve monotonically as the oil injection rate is increased.     

Characterization of lubricating oil effects on the performance of reciprocating compressors in air–water heat pumps

Lubricating oils play several key roles in compressors, such as lubrication of the parts exposed to friction, prevention of gas leakage at the compression chamber, and cooling of the pieces heated by friction. Oil viscosity and possibility of mixing with refrigerant are the significant factors that should be considered in choosing compatible lubricants. Generally, high viscosity lubricants reduce the efficiency and lubricants with low viscosity cause to direct contact between the metal parts in the compressor. In this study, an experimental procedure has been carried out to investigate the influences of oil circulation in the compressor working with R-404a refrigerant. Although this study has been devoted to a detailed attempt to identify the effects of oil viscosity on energy consumption, an innovative way to analyze this critical parameter has been carried out in parallel with other parameters including refrigerant charge amount, condenser water flow rate and air temperature in the evaporator. The sample oils selected for experiments are SL22, SL68 and SL220. The basic nature of the lubricants and their mixtures with refrigerant, COP value, compressor efficiency and exergetic efficiency of the system has been analyzed under different working conditions.     

制冷系统湿压缩时吸气干度控制方法的实验研究

不完全湿压缩能大幅度降低压缩机排气温度,然而该应用的最大难点是如何控制实时压缩机吸气干度在合适的范围内。本文提出了假拟饱和等熵压缩排气温度控制压缩机吸气该干度的方法,理论分析了在AHRI(空调供暖制冷协会)空调和低温制冷两种典型工况下,R22、R32、R134a和R410A四种制冷剂作为冷媒时,应用该方法控制压缩机吸气带液时系统性能的变化,并通过R32实验验证该结论的正确性。结果表明:利用假拟饱和等熵压缩排气温度可以将压缩机吸气状态控制在少量湿蒸气的状态;在T-s图上具有钟型饱和线形状的R32制冷剂,利用假拟饱和等熵压缩所控制的制冷系统,当吸气干度在0.96~1时,制冷量和COP均能达到最大值。     

An experimental study on oil discharge ratio at inverter-driven high shell pressure scroll compressor using R410A/PVE

In this study, the oil discharge characteristics of a high shell pressure scroll compressor, which uses R410A as the refrigerant and PVE as the oil, were measured according to the conditions for oil management. The measurement of oil discharge ratio (ODR) in the system is very important to secure the operational reliability. It was made in real time through the refractive index sensor. ODR was greatly influenced by the mass flow rate and the dynamic viscosity of the refrigerant. As the rotation frequency of the compressor became higher, ODR increased rapidly. ODR at 120 Hz was 4.22 times higher than that at 60 Hz. At the same rotation frequency of the compressor, the increase of the suction pressure also played a role in increasing the ODR. In addition, in the zone where the ODR increased rapidly, the compressing efficiency of the compressor decreased significantly.     

制冷剂-润滑油互溶混合物系流动沸腾特性测试装置的研制

在对已有相关测试装置设计技术的利弊分析基础上,提出了一种测试制冷剂-润滑油互溶混合流体管内流动沸腾特性的装置,其特征是通过与制冷剂流动沸腾换热测量回路并联接入一开式的润滑油回路,从而实现灵活控制和调节实验段内润滑油量的目的.通过在压缩机出口串连接入3个油分离器进行三级油分,从而实现压缩机出口的润滑油零排放.该装置具有连续在线注油、达到稳态时间短、操作灵活、控制简单等优点.