超市展示柜中应用R404A/R744复叠制冷系统的理论分析

提出了一种可以应用于超市展示柜中的R404A/R744复叠制冷系统,该系统以R404A作为高温级制冷剂,以R744作为低温及制冷剂.并通过对该系统和R22制冷系统进行热力学性能和压缩机输气系数的计算和比较.研究表明:在蒸发温度和冷凝温度固定的情况下,存在一个最佳中间温度使系统的性能系数最大:R404A/R744复叠制冷系统的性能系数和R22制冷系统基本相当,而复叠系统的压缩机输气系数明显高于单级制冷系统.     

改进的R23/R134a自复叠制冷系统实验研究

为了研究R23/R134a混合工质自复叠制冷系统在变工况下的运行性能,更深入地了解系统各部件对自复叠循环的影响,在已建成的自复叠循环系统实验台上进行实验研究.在冷凝温度较高的夏季,测试该自复叠实验装置所能达到的最低蒸发温度,并研究冷凝温度、工质充注质量分数及蒸发冷凝压力对该系统的影响.     

R14／R22自动复叠制冷系统设计

针对以R14／R22为工质的两级自动复叠制冷系统的设计,讨论工质选择原则,系统各点的状态参数通过调用商业软件NIST进行计算。根据相关文献和经验估算毛细管长度和选取保温材料及其厚度,分析不合理的管路和部件布置对气液分离的影响,以及自动复叠制冷系统的优点。指出该系统在-80℃温区能提供50w的冷量,可应用于医学、生物学、食品、材料科学等领域。     

R134a／R23A动复叠制冷循环的试验研究

在分析自动复叠制冷循环特点和R134a／R23混合工质特性的基础上，搭建了试验台进行了循环特性的研究。在一系列合理简化的基础上对试验结果进行了分析，并给出了循环系统中各点参数的计算结果和制冷循环的空问压焓图。     

改进的R23/R134a自复叠制冷系统试验台设计

为了研究R23/R134a混合工质自复叠制冷系统在变工况下的运行性能,更深入地了解系统各部件对自复叠循环的影响,设计一套试验装置。该装置对现有循环流程进行改进,增加了电磁阀、膨胀容器等部件。对该系统的运行工况、参数范围以及系统的各部件进行设计或选型,并介绍所搭建的试验台。     

制冷剂R290的国内研究进展

对国内制冷剂R290作为R22替代工质的研究进展进行回顾,首先从热力学特性角度说明R290替代R22的可行性,并对R290在家用空调器等方面替代R22的理论分析和试验研究方面的进展进行陈述,进而对R290在复叠式制冷循环以及自行复叠制冷循环中的理论和试验研究进行论述。指出虽然R290在国内还未得到推广使用,但用来替代R22具有一定的可行性。     

采用R744/R290的自复叠制冷系统热力性质分析

对采用R744/R290混合自然工质的自复叠制冷循环的热力性质进行分析。经过计算,得出了冷凝器压力、蒸发器压力、冷凝器出口温度、蒸发器出口制冷剂的状态、混合工质中R744浓度对系统性能的影响。为今后R744/R290的实验研究和实际应用提供了理论依据,减少了实验的工作量。     

-60℃水冷自复叠制冷系统研究

提出一种新型水冷自复叠制冷循环方式,用冷凝分离器代替传统循环的冷凝器和相分离器,在冷凝分离器中同时完成了高沸点工质的冷凝及高沸点工质与低沸点工质的分离。对采用这种冷凝分离器的水冷自复叠制冷循环方式的R22/R23、R290/R170、R134a/R23、R134a/R170四种工质对进行了循环特性研究。在自行搭建的水冷自复叠制冷系统实验台上进行了R22/R23、R134a/R23两种工质对的实验研究。结果表明,在相同工况下,R22/R23自复叠制冷系统的COP要高于R134a/R23自复叠制冷系统;和传统的自复叠系统相比,采用冷凝分离器的水冷自复叠制冷循环COP明显提高,提升率达到60%~100%。     

R22/R23自动复叠制冷循环的特性研究

通过一个两级自动复叠制冷循环系统来研究R22/R23混合工质的循环特性,在一系列合理简化的基础上讨论了其组分的充注比例和循环比例的关系,分析了循环比例的计算方法,并给出了循环系统中各点参数的计算结果和空间压焓图.     

R134a/R23自动复叠制冷循环的试验研究

在分析自动复叠制冷循环特点和R134a/R23混合工质特性的基础上,搭建了试验台进行了循环特性的研究.在一系列合理简化的基础上对试验结果进行了分析,并给出了循环系统中各点参数的计算结果和制冷循环的空间压焓图.     

Viscosity of refrigerants R12, R113, and R114 and mixtures of R12 + R114 at high pressure

New viscosity measurements for the gaseous and supercritical state of the halogenated hydrocarbons R12, R113, and R114 and binary mixtures of R12 + R114 of different compositions are presented. The measurements were carried out at superheated and supercritical temperatures from 30 to 200° C and in the pressure range from 1 to 80 bar. Viscosity was measured with an oscillating-disk viscometer and the data obtained are relative to the viscosity of nitrogen. The estimated accuracy of the measured results is ±0.6%. The results obtained show that, at subcritical temperatures, the pressure effect on viscosity is negative. This anomalous behaviour is investigated in detail in this work. At atmospheric pressure the viscosity of gas mixtures is almost a linear function of their composition. At high pressure, the residual viscosities - ₀ of both the pure components and the mixtures were used to follow a single relationship versus the residual reduced density _r0.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

R32替代R22的可行性探讨

从理论热工性能分析、环保、安全以及性能测试试验对比等角度,讨论制冷剂 R32 替代 R22 的优势,认为R32替代R22是可行的.同时,分析R32替代R22时存在的高排气压力和高排气温度以及安全性问题.基于目前的制冷技术以及R32本身的热力特性,只要能够通过采取一系列技术手段和安全措施解决这些问题,R32可以作为R22良好的过渡或替代制冷剂.     

R32/R134a和R407C用于变浓度热泵系统的实验

为了解决R32/R134a应用于变浓度热泵系统存在的排气温度过高问题,提出使用三元混合工质R407C用于该系统中.以R32/R134a和R407C作为工质在变浓度容量调节热泵系统中进行了吸气压力不变时的变浓度实验.实验结果表明,R407C在本系统中变浓度范围低于R32/R134a,但R407C的排气温度和耗功均低于R32/R134a,具有良好的变浓度调节潜力.     

Viscosity of Gaseous R404A, R407C, R410A, and R507

This paper presents new measurements of the viscosity of gaseous R404A (52 wt% R143a, 44 wt% R125, 4 wt% R134a), R407C (23 wt% R32, 25 wt% R125, 52 wt% R143a), R410A (50 wt% R32, 50 wt% R125), and R507 (50 wt% R143a, 50 wt% R125). These mixtures are recommended as substitutes for the refrigerants R22, R502, and R13B1. Measurements were carried out in an oscillating-disk viscometer. The obtained values of the viscosity are relative to the viscosity of nitrogen. The experiments were performed at atmospheric pressure over the temperature range 297 to 403 K. and near the saturation line up to pressures of 0.6 P _crit. The estimated uncertainty of the reported viscosities are ±0.5% for the viscosities at atmospheric pressure and ± 1% along the saturation line, being limited by the accuracy of the available vapor pressure and density data. The experimental viscosities at atmospheric pressure are employed to determine the intermolecular potential parameters, and , which provide the optimum representation of the data with the aid of the extended law of corresponding states developed by Kestin et al. A comparison of the experimental viscosity data with the values calculated by REFPROP, both at atmospheric pressure and along the saturation line, is presented.     

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。     

Viscosity of R134a, R32, And R125 at Saturation

This paper reports the results of the measurement of the viscosity of R134a close to the saturation line in the vapor phase. The new measurements were carried out in a vibrating-wire viscometer specially constructed for the purpose, and the results have an accuracy of ±2%. In addition, the opportunity is taken to present a reevaluation of earlier measurements along the saturation line of the viscosity of R32 and R125. Improved equations of state for these fluids are now available and can be employed to generate improved values for the viscosity.     

Measurements of the thermal conductivity of liquid R32, R124, R125, and R141b

This paper reports measurements of the thermal conductivity of refrigerants R32, R124, R125, and R141b in the liquid phase. The measurements, covering a temperature range from 253 to 334 K and pressure up to 20 MPa, have been performed in a transient hotwire instrument employing two anodized tantalum wires. The uncertainty of the present thermal-conductivity data is estimated to be ±0.5%. The experimental data have been represented by polynomial functions of temperature and pressure for the purposes of interpolation. A comparison with other recent measurements is also included.     

在家用／商用空调中用R32替代R22的探索

在R22的替代工作进入实质性阶段,但国内外成熟替代品又尚不明朗之际,本文在分析国内外R22替代物的现状、存在的问题以及国际上对环保工质要求的新趋向的前提下,探索提出在家用／商用空凋中使用R32替代R22的设想,并从其热物理性质、环保特性、安全性、热工性能、市场可获得性等几个方面,与现有的R22替代物R410A,R290和R1234yf等进行比较,认为R32是一种兼顾减排、安全、节能和市场诸方面要求的、很有前景的R22替代制冷剂。     

冷藏车层叠式蒸发器应用R404A与R22和R134a的比较

采用分布参数法对层叠式蒸发器建立数学模型，并对蒸发器采用R404A，R22和R134a时的换热和流动性能进行模拟比较。结果表明，在空调工况范围内，新型中低温混合制冷剂R404A具有R134a换热性能好和R22压降小的特点，能够很好地适用于冷藏车系统空调侧层叠式蒸发器。     

Measurement of vapor viscosity of R1234yf and its binary mixtures with R32, R125

The vapor viscosities of the new refrigerant R1234yf and its binary mixtures, R32+R1234yf, R125+R1234yf, were measured at atmospheric pressure with a falling-ball-type viscometer. The combined expanded uncertainty of the measurement apparatus was less than 1.5%. The binary mixtures consisted of 20.0, 30.0, 40.0, and 50.0 wt% R32 for R32+R1234yf and of 20.0, 35.0, 50.0, and 70.0 wt% R125 for R125+R1234yf. The viscosities of R1234yf were correlated with the Chapman–Enskog gas kinetic theory and those of binary mixtures were correlated with the Wilke mixture rule. The average absolute deviation (AAD) is 0.189% for R32+R1234yf and 1.169% for R125+R1234yf. The deviations of experimental viscosities of the binary mixtures from data calculated using RefProp v9.1 were also obtained. The AAD is 0.555% for R32+R1234yf and 1.479% for R125+R1234yf.