R22,R407C和R410A热泵专用涡旋式压缩机研究

分析多种热泵制冷剂物理性质,并对热泵用涡旋式压缩机运行特性进行分析。采用新设计的热泵专用涡旋式压缩机进行R22,R407C与R410A性能测试,结果表明:R410A和R407C制冷剂均可以替代R22制冷剂在热泵系统中使用;R410A与R22在制热能力、排气温度及运行范围方面相近;R407C的制热能力高于R22和R410A,运行范围相对较宽。     

冷冻冷藏用制冷剂R404A的替代品对比分析

基于现有的R404A涡旋式压缩机,模拟分别采用R404A,R407A,R407F,R134a和R1234ze制冷剂时的压缩机性能,计算5种制冷剂系统的理论循环COP,并对各典型工况进行对比分析。计算结果表明,R407A和R407F可直接应用于R404A压缩机,而R134a和R1234ze替代R404A时压缩机设计变更较大,4种制冷剂系统能效均较R404A系统有较大提高。     

R22、R404A与R407F制冷剂压缩机性能对比

分析R22、R404A与R407F制冷剂的物理性质,并采用涡旋压缩机进行试验测试。结果表明:在高温应用上,R22、R404A和R407F制冷能力数值相近,R407F制冷系数比R22、R404A稍低;而在低温应用上,R407F制冷能力、制冷系数比R22、R404A都低。     

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。     

R410A与R22制冷压缩机性能试验装置的对比

对制冷剂R410A与R22的热物性进行比较,并对分别以R410A和R22为工质的制冷压缩机性能试验装置进行对比分析,为建立以R410A为工质的制冷压缩机性能试验装置提供技术支持。     

R507A与R404A循环特性的理论与试验研究

在理论和试验上对R507A与R404A两种制冷剂的循环特性进行对比分析.在冷凝温度40.5℃,吸气温度18.3℃,过冷度0℃,压缩机等熵效率0.8的条件下,理论分析表明：R507A的制冷量较R404A高6％左右,COP高2％左右;相同条件下的性能测试结果表明：R507A的制冷量较R404A高2％～4％,COP高1％～2％,排气温度高0～4℃.     

R32涡旋式压缩机开发

R32是一种具有巨大应用潜力的制冷剂,但其适用的涡旋式压缩机的开发尚不成熟,尤其是排气温度过高的问题严重影响R32制冷剂的应用。本文指出R32涡旋式压缩机开发的重点与难点,并探讨R32涡旋式压缩机未来的开发方向。     

一种R410A替代制冷剂的特性及应用前景分析

目前家用空调器R22的替代制冷剂，主要是R407C和R410A。由于这些制冷剂的专利权都在国外，且价格高昂，为此，国内浙江化工研究院开发出一种可替代R410A，且部分性能优于R410A的新型环保制冷剂。受该单位委托，笔者所在公司对该制冷剂进行了实机测试分析。     

R407C制冷压缩机使用指南

本文从开发R407C新制冷剂压缩机的角度，并结合R407C制冷剂的特点，对空调器厂家如何正确使用R407C压缩机及空调系统匹配提出了一些注意事项，希望对用户更好、更快地使用R407C新制冷剂提供一些帮助。     

采用R410A为制冷剂的小型风冷式冷水机组设计

以R410A为制冷剂设计的一套小型家用风冷冷水机组。标准工况下,该机组的设计制冷量和制热量分别为16.5kW和18.0kW。在系统热力计算的基础上,介绍了以R410A为制冷剂的小型家用风冷冷水机组设备选型过程,选用了制冷量和制热量分别为16.89kW和19kW的全封闭涡旋式压缩机、实际总管长144m和实际传热面积70.24m2的翅片管式换热器作风侧换热器,板间距为0.0032m、单片传热面积为0.12m2的板式换热器作水侧换热器,毛细管作节流装置等。     

R404A和R407C在水平强化管外的凝结换热实验研究

实验研究了近共沸制冷工质R404A与非共沸制冷工质R407C在水平强化换热管管外的凝结换热性能。采用"Wilson图解法"对实验数据进行处理。结果表明:对于R404A和R407C,强化管外的凝结换热系数随着壁面过冷度的增加而增大,呈现出与纯工质冷凝时不同的变化趋势,这主要是近共沸或非共沸工质凝结过程中,某些组分的凝结会遇到其它组分的凝结气膜热阻所造成的;随着过冷度增加,易挥发组分开始凝结,气膜变薄,冷凝传热系数增大。R407C在强化换热管管外的凝结换热系数比R404A要小70%左右,这是由于R407C的温度滑移较R404A要大,管外形成的凝结扩散气膜造成的影响更大。R407C在高热流密度工况下的换热效果提升明显,故应尽量工作在高热流密度区域。     

Thermal Conductivity of the Refrigerant Mixtures R404A, R407C, R410A, and R507A

New thermal conductivity data of the refrigerant mixtures R404A, R407C, R410A, and R507C are presented. For all these refrigerants, the thermal conductivity was measured in the vapor phase at atmospheric pressure over a temperature range from 250 to 400 K and also at moderate pressures. A modified steady-state hot-wire method was used for these measurements. The cumulative correction for end effects, eccentricity of the wire, and radiation heat transfer did not exceed 2%. Calculated uncertainties in experimental thermal conductivity are, in general, less than ±1.5%. All available literature thermal conductivity data for R404A, R407C, R410A, and R507C were evaluated to identify the most accurate data on which to base the thermal conductivity model. The thermal conductivity is modeled with the residual concept. In this representation, the thermal conductivity was composed of two contributions: a dilute gas term which is a function only of temperature and a residual term which is a function only of density. The models cover a wide range of conditions except for the region of the thermal conductivity critical enhancement. The resulting correlations are applicable for the thermal conductivity of dilute gas, superheated vapor, and saturated liquid and vapor far away from the critical point. Comparisons are made for all available literature data.     

Theoretical comparison of low GWP alternatives for different refrigeration configurations taking R404A as baseline

Six refrigerants are evaluated as low GWP replacements for R404A using different configurations, including two-stage system architectures. These refrigerants are selected according to similar characteristics to R404A, and they are the mid-term alternatives R407A and R407F, and the long-term alternatives: L40 and DR-7 (with very low GWP and low flammability), N40 and DR-33 (with low GWP and no flammability). In order to have a complete comparison range, various operating conditions are considered, covering low and medium evaporator temperatures and two levels of condensation temperatures. Configurations selected are presented and the equations used to simulate the expected performance are shown. From a given cooling capacity, volumetric flow rate and COP are compared, taking R404A as baseline. The most efficient alternatives are the low-flammable refrigerants, L40 and DR-7, and when no flammability is acceptable, N40 and DR-33 are also very good options.     

吸气过热对R404A涡旋式压缩机性能影响的研究

针对在不同蒸发温度下,不同吸气过热度对R404A涡旋式压缩机的能力、功率、排气温度及COP的影响进行试验研究,并进行比较和分析.     

R404A和R410A应用于平行流冷凝器的模拟分析比较

采用分布参数法对平行流冷凝器建立数学模型，对目前广泛使用的制冷剂R134a和低温制冷剂R404A和R410A在平行流冷凝器中的换热和流动性能进行模拟计算和分析比较。分别在相同和不同工况下。比较3种制冷剂的换热系数及压降等换热和流动性能参数。结果表明，在采用平行流冷凝器的汽车空调工况范围内，R410AR404A的流动和传热性能均优于R134a，更适宜用于汽车空调用平行流冷凝器。     

R290与R404A在水平管内沸腾换热的压降研究

将R22的两种新型替代工质R290和R404A在光管和内螺纹管中的沸腾换热压降实验结果与Lockhart ＆ Martinelli压降计算关联式预测结果进行了比较，并依据工质R290和R404A在内螺纹管中的实验压降值对Lockhart ＆ Marlinelli压降计算关联式进行了修正。结果表明Lockhart ＆ Martinelli关联式对R404A在光管和内螺纹管的沸腾换热摩擦压降，均有良好的预测精度，平均偏差分别为-11．52％和-17．86％。Lockhart ＆ Martinelli关联式可以较好的预测R290在光管内的沸腾换热摩擦压降，平均偏差为-21．68％；经修正后的Lockhart ＆ Martinelli关联式可以较好的预测R290在在内螺纹管中的沸腾换热摩擦压降，Lockhart ＆ Martinelli关联式乘上修正系数2．06后的修正值与实验值偏差较小，平均偏差为2．37％。研究结果对R290和R404A蒸发器的工程设计及优化具有一定参考意义。     

Modelling of reciprocating and scroll compressors

This paper presents simple and thermodynamically realistic models of two types of compressors widely used in domestic heat pumps (reciprocating and scroll compressors). These models calculate the mass flow rate of refrigerant and the power consumption from the knowledge of operating conditions and parameters. Some of these parameters may be found in the technical datasheets of compressors whereas others are determined in such a way that the calculated mass flow rate and electrical power match those given in these datasheets.The two models have been tested on five reciprocating compressors and five scroll compressors. This study has been limited to compressors with a maximum electrical power of 10 kW and for the following operating conditions: evaporating temperatures ranging from −20 to 15 °C and condensing temperatures ranging from 15 to 60 °C.The average discrepancies on mass flow rate and power for reciprocating compressors are 1.10 and 1.69% (for different refrigerants: R134a, R404A, R22, R12 and R407C). For scroll compressors, the average discrepancies on mass flow rate and power are 2.42 and 1.04% (for different refrigerants: R134a, R404A, R407C and R22).