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。     

三元混合制冷剂R32+R161+R1234yf气液相平衡实验研究

本文研究了含R1234yf的三元混合制冷剂的气液相平衡性质和模型,利用基于液相单相循环法搭建的气液相平衡实验装置,对温度范围为283.15～323.15 K的三元混合制冷工质R32+R161+R1234yf进行了实验研究,共得到45组实验数据。同时采用Peng-Robinson-Stryjek-Vera(PRSV)状态方程结合Wong-Sandler(WS)混合法则和Non-Random Two-Liquid(NRTL)活度系数模型,在前期工作得到的二元混合工质的模型参数的基础上,对三元混合工质气液相平衡性质进行推算。最后将模型推算结果与实验数据进行对比,结果表明系统压力平均绝对偏差AAD_p为0.34%,系统组分R32和R161的气相摩尔分数平均绝对偏差AAD_y_1和AAD_y_2分别为0.002和0.001。     

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。     

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。     

新一代制冷剂HFO-1234yf的热物性模型

基于Peng-Robinson通用状态方程,采用基团贡献原理以及多项式拟合方法,建立了符合精度要求的新型LGWP制冷剂HFO-1234yf的热物性模型,并对模型进行了验证,利用数学软件对模型进行编程求解,得到了较为全面的HFO-1234yf制冷剂的热物性数据.将HFO-1234yf制冷剂与R134a及R417A制冷剂的热物性能进行了对比,结果显示HFO-1234yf的饱和蒸汽压力与定压比热容和R134a的表现相似,二者的饱和蒸气压均低于R417A,HFO-1234yf制冷剂与R134a和R417A相比,其饱和状态焓值较低,这将导致HFO-1234y系统运行时的性能系数不高.该模型能为HFO-1234yf制冷剂在汽车空调以及固定式空调制冷设备上的应用提供理论依据.     

新一代制冷剂HFO-1234yf的热物性模型

基于Peng-Robinson通用状态方程,采用基团贡献原理以及多项式拟合方法,建立了符合精度要求的新型LGWP制冷剂HFO-1234yf的热物性模型,并对模型进行了验证,利用数学软件对模型进行编程求解,得到了较为全面的HFO-1234yf制冷剂的热物性数据。将HFO-1234yf制冷剂与R134a及R417A制冷剂的热物性能进行了对比,结果显示HFO-1234yf的饱和蒸汽压力与定压比热容和R134a的表现相似,二者的饱和蒸气压均低于R417A,HFO-1234yf制冷剂与R134a和R417A相比,其饱和状态焓值较低,这将导致HFO-1234y系统运行时的性能系数不高。该模型能为HFO-1234yf制冷剂在汽车空调以及固定式空调制冷设备上的应用提供理论依据。     

R32/R1234yf混合工质热泵循环性能分析

在热泵热水器的名义工况下,对R32/R1234yf混合工质热泵循环性能进行计算分析。结果表明:R32/R1234yf的最优质量配比为60/40,使制热性能系数达到最大值4.727,较R22系统增大8.64%;在最优质量配比下,R32/R1234yf系统的单位容积制热量、单位质量制热量和冷凝压力均比R22系统大,但其压比和排气温度均低于R22系统。     

新型制冷剂HFO-1234yf/R134a/DME的理论与试验研究

提出一种在汽车空调应用中替代R134a的新型制冷剂HFO-1234yf/R134a/DME。利用数据库REFPROP 9.0,通过自行编制的软件对该制冷剂的热力学性能和循环性能进行理论分析,并在电量热器制冷剂循环性能测试装置上,对R134a和HFO-234yf/R134a/DME进行试验研究。理论与试验研究发现,新型制冷剂的制冷量比R134a略小,循环性能系数(COP)也略低,而排气温度比R134a低12℃左右。该新型制冷剂具有替代R134a的潜在可行性。     

R1234yf热泵技术综述与潜力分析

为了满足逐步严苛的环保法规要求,R1234yf成为车用热泵制冷剂R134a的热门替代制冷剂之一。本文对R1234yf热泵技术的研究进行了综述与分析,其GWP<1,各方面性质均符合车用热泵系统的工作需求。在传热效果上,R1234yf的沸腾传热性能略优于R134a,且冷凝过程压降比R134a低5%~10%,优于R134a系统。在诸多R1234yf和R134a系统的仿真和实验研究中,R1234yf热泵性能略低于R134a,但可以通过优化零部件、强化补气、改善工况等方式使其与R134a十分接近甚至超越。R1234yf低压饱和压力比R134a高约15%,可以适配更高的压缩机转速,低温下制热性能比R134a更好,且较低的压缩机排气温度使系统工作更为稳定,强化补气的效果也优于R134a。因此,R1234yf在车用热泵中具有较好的工作性能和发展前景,可以作为R134a的替代制冷剂。     

R1234yf和R134a制冷及制热性能实验研究

通过搭建实验台,对R1234yf的制冷及制热性能进行测试,并与R134a进行比较。测试结果表明,相同工况下,采用同一压缩机,R1234yf的排气温度更低,能在更大的工况范围内运行;R1234yf功耗比R134a高0.76%~5.18%;R1234yf的制冷量和制冷COPc与R134a相比因工况的不同而大小不同;R1234yf的制热量和制热COPh与R134a相比分别小0.75%~27.08%和1.50%~29.96%。     

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。     

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.     

Experimental study of R1234yf as a drop-in replacement for R134a in a domestic refrigerator

This paper presents an experimental study for three identical domestic refrigerators using R1234yf as a drop-in replacement for R134a. An alternative methodology was proposed to estimate the optimal mass charge for R1234yf; with the use of such methodology, new evidences were sought on the thermal behavior of the refrigerator compartments as well as at the heat exchangers. Additionally, energy performance for both refrigerants was measured, and, finally, a TEWI analysis was conducted. For the type of refrigerator evaluated, results showed that R1234yf presented an average (for the 3 refrigerators) of 0.4 °C for the fresh food compartment, and 1.2 °C for the freezer, among different charges with respect to R134a. The optimal charge for R1234yf was 92.2 g, which is about 7.8% lower than the one for R134a, which represents a small increase of 4% in energy consumption in comparison to R134a. Finally, the TEWI analysis for the R1234yf was 1.07% higher than the R134a.     

Condensation heat transfer coefficients of R1234yf on plain, low fin, and Turbo-C tubes

In this study, external condensation heat transfer coefficients (HTCs) of HFC134a and R1234yf are measured on a plain, low fin, and Turbo-C tubes at the saturated vapor temperature of 39 °C with the wall subcooling of 3-8 °C. R1234yf is a new alternative refrigerant of low greenhouse warming potential for replacing HFC134a, one of the greenhouse gases in Kyoto protocol, used extensively in automobile air conditioners and other refrigeration systems. Test results show that the condensation HTCs of R1234yf are very similar to those of HFC134a for all three surfaces tested. For the development of heat transfer correlations, thorough property measurements are needed for R1234yf in the near future.     

Experimental investigation on heating performance of gas-injected scroll compressor using R32, R1234yf and their 20wt%/80wt% mixture under low ambient temperature

In this paper, an integrated gas-injected scroll compressor heat pump system using R1234yf, R32 and its binary mixtures as working fluid was developed and their heating performances under low ambient temperature were quantitatively evaluated. A composite test system consisting of second-refrigerant calorimeter and water-cooled condenser was used to test the system working performance. The condensing temperature, evaporating temperature, compressor power input and other variables were analyzed to evaluate the system heating capability and energy efficiency. Test results showed that the R1234yf system can run at an evaporating temperature of −25 °C. R1234yf/R32 mixture can run at an evaporating temperature of −20 °C and it has the highest heating COP value among other refrigerants; R1234yf/R32 gas injection system provided very significant performance improvements for heating performance, compared with no gas injection, the heating capacity and heating COP can improve 16%~20% and 13%~16%, respectively.