R32和R32/R1234yf混合工质黏度实验测量及模型

本文针对含HFOs类混合制冷剂黏度开展实验和模型研究。采用振动弦法黏度计对R32纯质和R32/R1234yf混合制冷剂黏度进行了实验测量,测量的温度范围分别为263~350 K、263~360 K,压力最高均为30 MPa,实验系统黏度测量的不确定度为2%。本文共获得了177组实验数据,利用得到的实验数据,基于硬球模型分别拟合了R32纯质和R32/R1234yf混合制冷剂黏度方程。R32纯质黏度实验数据与方程的平均绝对偏差为0.28%,最大绝对偏差为0.92%;R32/R1234yf混合工质黏度实验数据与方程的平均绝对偏差为0.69%,最大绝对偏差为2.09%。由此可见,实验数据和黏度模型吻合较好,为R32和R32/R1234yf混合制冷剂的应用研究提供了重要参考依据。     

非共沸混合制冷剂气液相平衡参数的计算

本文研究了改进的RKS方程在非共沸混合制冷剂气液相平衡参数计算中的应用，计算了非共沸混合物R14／R23的气液相平衡数据，结果表明：改进的RKS方程用于计算非共沸混合物的气液相平衡具有较好的准确性。     

混合制冷剂R1234yf/R32 PVTx性质的实验研究

为了获得混合制冷剂R1234yf/R32的热物性数据,本文以Burnett法为基础搭建了高精度PVTx实验台,在温度为253~313 K时,测定了质量分数为15%/85%和25%/75%混合制冷剂R1234yf/R32的PVT性质,拟合了两种不同配比的混合工质的气态维里方程,为进一步研究该工质的基础热物性提供了详实的数据。     

R1234yf/R290/R134a系气液相平衡的模拟

本文从理论方面研究了混合制冷剂的相平衡特性,基于Peng-Robinson(PR)状态方程与Wong-Sandler(WS)混合法则,结合Predictive Soave Redlich Kwong(PSRK)方程中使用的UNIFAC基团贡献法,构建了混合物气液相平衡预测模型(PRWS-UNIFAC-PSRK)。结果表明:二元混合物R32/R1234yf的压力及气相质量分数的模拟结果与实验值偏差分别在±2.5%和±0.02内;三元混合物R134a/R1234yf/R600a的压力及气相组分质量分数计算值与实验数据的偏差基本在±3%和±0.04内;建立了R1234yf/R290/R134a系的三元相平衡图,当质量分数在0.25/0.70/0.05左右时存在共沸点。通过采用多参数状态方程,改进活度系数模型,获取更为准确的二元相互作用系数,可进一步提高模型的预测精度。     

强非共沸工质R1234yf/R170/R14系气液相平衡的模拟

超额吉布斯自由能-状态方程法(G~E-EoS)是继传统的状态方程法和活度系数法之后预测气液相平衡的一个新思路。本文采用PRWS-UNIFAC-PSRK模型对R161/R1234yf、R32/R125/R134a及强非共沸工质R1234yf/R170/R14系的气液相平衡数据进行计算。结果表明:R161/R1234yf系压力和气相组分质量分数的计算值与实验值的偏差在±1.5%和±0.02以内,优于REFPROP9.0软件的计算结果,而R32/R125/R134a系的偏差分别在±4%和±0.02以内。根据计算结果及三维相平衡图发现,R1234yf/R170/R14在质量分数比为0.4/0.2/0.4附近时体系的温度滑移现象最为明显,最大的滑移温度达到72.5 K;且R1234yf组分的质量分数越大,泡点温度与露点温度越高。     

天然气和混合制冷剂的相平衡特性

就混合制冷剂液化天然气流程中相平衡计算智能识别三种状态,气态,气液平衡态和液态展开讨论,并给出了相平衡计算框图。     

制冷剂/润滑油汽液相平衡实验系统的研制与验证

针对制冷剂/润滑油相平衡测量,本文研制了一套基于循环法的高精度制冷剂/润滑油气液相平衡实验系统。该实验系统在循环系统上安装了可拆卸的样品罐,将循环法与称重分析法结合,避免了等体积饱和法由于理想假设而产生的系统误差,可适用于温度范围为263.15~373.15K的制冷剂/润滑油气液相平衡的测量。测量了温度为293.35?323.33K的R290的饱和蒸气压,与NIST数据库相比,最大相对误差为-0.18%。同时,测量了温度为303.35K的R290和角鲨烷的相平衡,并使用Aspen Plus中的PR方程结合单流体的van der Waals混合规则对实验结果及文献值进行了关联,本文和文献的最大相对误差分别为-0.37%和-0.76%。     

混合制冷剂R1234yf/R134a PVTx性质的实验研究

为了获得混合制冷剂R1234yf/R134a的热物性数据,本文利用Burnett法为基础搭建的高精度PVTx实验台,在温度为268~323 K时,测定了质量分数为55%/45%,50%/50%和45%/55%混合制冷剂R1234yf/R134a的PVT性质,最终拟合了三种不同配比的混合工质的气态维里方程,方程和实验数据具有较高的重合度。     

HFO-1234ze与HFC-32混合制冷剂用于热泵热水器的实验研究

本文选用了NIST发行的REFPRO9.0制冷剂计算程序及KW2模型参数对混合制冷剂HFO-1234ze与HFC-32在不同配比下的热物性进行了模拟计算,并依据热泵热水器测试的标准工况,计算了不同配比下混合制冷剂的理论循环特性,分析得出了HFO-1234ze/HFC-32较为合适的配比。通过一次加热(即热式)热泵热水器实验台,对多种环境工况及不同进水温度进行性能测试,分别对R410A和混合制冷剂(HFO-1234ze与HFC-32配比0.3/0.7)在实验系统中的压缩机功率、系统性能系数、压缩机吸、排气压力和温度、冷凝器出水温度等参数进行了对比分析。结果表明:混合制冷剂(HFO-1234ze与HFC-32配比0.3/0.7)的压缩机功率和排气压力都低于R410A系统,而COP高于R410A系统,在标准工况下,分别为4.03和3.56,且在高于标准工况的环境温度情况下,混合制冷剂系统COP下降速率低于R410A系统,有利于热水器机组的安全稳定运行,在替代R410A系统方面具有可行性。     

R32与R1234yf可燃性对比及燃烧抑制研究

卤代烷烃和卤代烯烃等氟为代表的工质是当前使用最广泛的人工合成制冷剂,随着环保要求不断提高,可选的氟代物多具有一定可燃性。制冷剂的可燃性限制了其在家用和商用等场景下的使用范围。根据可燃工质的燃烧特性寻找阻燃方法,其中重要的手段是从研究燃烧反应机理及反应路径出发对单一或混合制冷工质进行燃烧过程反应研究。本文研究了R1234yf为代表的低碳氟代烯烃燃烧点火延迟、温度压力变化、典型组元燃烧过程;并对比了R32和R1234yf燃烧机理与反应路径。研究结果表明：R32和R1234yf与烷烃和烯烃燃烧模型吻合,R1234yf点火延迟更高,加成和夺取反应更加复杂;通过反应路径的研究发现,两种可燃性工质中间稳定产物存在较多重合,在R32中仅添加体积分数为10%R1234yf时,当量比为1时的燃烧平衡温度可下降87.5 ℃;添加体积分数5%的R32混合物的燃烧平衡温度可下降21.0 ℃,混合物可燃性可低于两者任意组分;添加少量R32后点火时间提前,放热反应的自由基生成峰值明显降低。     

Correlations for the viscosity of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E))

Due to concerns about global warming, there is interest in 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) as potential replacements for refrigerants with high global warming potential (GWP). In this paper we survey available data and provide viscosity correlations that cover the entire fluid range including vapor, liquid, and supercritical regions. The correlation for R1234yf is valid from the triple point (220 K) to 410 K at pressures up to 30 MPa, and the correlation for R1234ze(E) is valid from the triple point (169 K) to 420 K at pressures up to 100 MPa. The estimated uncertainty for both correlations at a 95% confidence level is 2% for the liquid phase over the temperature range 243 K to 363 K at pressures to 30 MPa, and 3% for the gas phase at atmospheric pressure.     

Vapor–Liquid Equilibria For The Binary Difluoromethane (R-32) + Propane (R-290) Mixture

The vapor–liquid equilibrium of the mixture composed of difluoromethane (R-32) and propane (R-290) was studied in the temperature range between 273.15 and 313.15 K. The experimental uncertainties of temperature, pressure, and composition measurements were estimated to be within ±10 mK, ±3 kPa, and ±0.4mol%, respectively. Comparisons between the present data and available experimental data were made using the Helmholtz free energy mixture model (HMM) adopted in the thermophysical properties program package, REFPROP 6.0, as a baseline. In addition, the existence of an azeotrope and the determination of new adjustable parameters for HMM for the R-32 + R-290 mixture are discussed.     

Monte Carlo Simulation of Vapor–Liquid Equilibria for Perfluoropropane (R-218) and 2,3,3,3-Tetrafluoropropene (R-1234yf)

Thermophysical properties of two refrigerants (perfluoropropane and 2,3,3,3-tetrafluoropropene) were computed using Monte Carlo methods with the OPLS-AA (Optimized Potentials for Liquid Simulations-All Atoms) forcefield. Original OPLS-AA parameters were extended to include an F atom attached to a double bond in 2,3,3,3-tetrafluoropropene and modified to produce the correct stationary geometry for this compound. The results of the simulations for critical parameters, saturated densities, saturated pressures, liquid densities, and vaporization enthalpies are in good agreement with available experimental data and equation of state models. Systematic deviations between the experimental data and the predicted values were observed for liquid densities and saturated pressures, suggesting that further refinement of forcefield parameters that can lead to better accuracy may be possible.     

Measurements and Correlations of cis-1,3,3,3-Tetrafluoroprop-1-ene (R1234ze(Z)) Subcooled Liquid Density and Vapor-Phase PvT

22 182 compressed liquid density data and 98 vapor-phase PvT data for cis-1,3,3,3-tetrafluoroprop-1-ene (R1234ze(Z)) are presented. The compressed liquid density data are for nine isotherms evenly spaced approximately from 283 K to 363 K for pressures from close to saturation to 35 MPa, and the vapor-phase PvT data are for seven isochores for temperatures approximately from 303 K to 375 K for pressures approximately from 82 kPa to 436 kPa. In addition, a saturated liquid density correlation, a Tait correlation for the compressed liquid density data, and a Martin–Hou equation of state for the vapor-phase PvT data are presented.     

Compressed Liquid Densities and Helmholtz Energy Equation of State for Fluoroethane (R161)

In this study, compressed liquid densities of Fluoroethane (R161, CAS No. 353-36-6) were measured using a high-pressure vibrating-tube densimeter over the temperature range from (283 to 363) K with pressures up to 100 MPa. A Helmholtz energy equation of state for R161 was developed from these density measurements and other experimental thermodynamic property data from the literature. The formulation is valid for temperatures from the triple point temperature of 130 K to 420 K with pressures up to 100 MPa. The approximate uncertainties of properties calculated with the new equation of state are estimated to be 0.25 % in density, 0.2 % in saturated liquid density between 230 K and 320 K, and 0.2 % in vapor pressure below 350 K. Deviations in the critical region are higher for all properties. The extrapolation behavior of the new formulation at high temperatures and high pressures is reasonable.     

R1234ze(E)与R32混合工质在热泵系统中替代R410A的实验研究

新型制冷剂R1234ze(E)因较低的GWP备受制冷行业关注,其与R32的混合工质作为热泵系统制冷剂的研究也在逐步展开,本文以R1234ze(E)/R32(质量配比:27%/73%,命名为L-41b,GWP=493)混合工质为研究对象,在人工环境室中设计并搭建了空气源热泵测试系统,对比研究了L-41b与R410A在热泵系统中的性能系数COP、压缩机功耗、制热量、排气温度和循环压比。结果表明:当恒定冷凝温度,蒸发温度从5℃增加到13℃时,R410A和L-41b的COP偏差从8.6%缩小到2.8%。当恒定蒸发温度,冷凝温度从30℃提高到42℃时,L-41b的运行性能系数COP的降幅小于R410A,变工况实验表明在相对高温区L-41b替代R410A具有较好的替代性能。     

New Equation for Vapor Pressures of Difluoromethane (HFC-32)

Critically evaluated experimental vapor-pressure data sets supplemented with calculated data for low-temperature region were used in the development of vapor-pressure equations. The optimum number of terms, coefficients, and exponents of the Wagner-type equation were derived by means of the Setzmann–Wagner program OPTIM based on the combination of the stepwise regression analysis and evolutionary optimization method. Equations were checked by the reduced enthalpy of vaporization criterion derived from the Clausius–Clapeyron equation and specific volume of ideal gas. An equation developed using 261 experimental data points and low-temperature data calculated by Lüddecke and Magee gives an RMS deviation of 0.102%; a second equation based on the same experimental data and low-temperature data calculated by Tillner-Roth gives an RMS deviation of 0.101% from experimental points. The triple-point pressure extrapolated to the measured temperature T _tp = 136.34 K is discussed. Comparisons with vapor pressure equations by Outcalt and McLinden, Duarte-Garza and Magee. and Kubota et al. are also given.     

Liquid Thermal Conductivity of Ternary Mixtures of Difluoromethane (R32), Pentafluoroethane (R125), and 1,1,1,2-Tetrafluoroethane (R134a)1

The thermal conductivities of ternary refrigerant mixtures of difluoromethane (R32), pentafluoroethane (R125), and 1,1,1,2-tetrafluoroethane (R134a) in the liquid phase have been measured by the transient hot-wire method with one bare platinum wire. The experiments were performed in the temperature range of 233 to 323 K and in the pressure range of 2 to 20 MPa at various compositions. The measured data are correlated as a function of temperature, pressure, and composition. From the correlation, we can calculate the thermal conductivity of pure refrigerants and their binary or ternary refrigerant mixtures. The uncertainty of the measurements is estimated to be ±2%.