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。     

R1234ze(E)在R134a离心式制冷压缩机中的直接替代研究

随着全球对环保要求的日益提高,以R1234yf、R1234ze(E)、R1233zd(E)等为代表的ODP为0且GWP较低的制冷剂得到广泛关注并应用。针对R134a离心式冷水机组,采用CFD数值方法,对采用R1234ze(E)直接替代的离心制冷压缩机进行了模拟,对机组性能进行了比较分析。结果表明：在同一转速下,当冷凝温度较小时,R1234ze(E)机组的制冷量和COP都小于R134a机组的,当冷凝温度较大时,R1234ze(E)机组的制冷量和COP都大于R134a机组的。当R134a机组与R1234ze(E)机组的蒸发温度、冷凝温度和制冷量都相同时,R1234ze(E)机组的COP比R134a机组的COP平均降低了约5.14%。     

R1234ze/HCs非共沸混合工质热泵系统循环性能分析

在热泵热水器名义工况下,本文建立了热泵系统循环热力学模型,利用EES程序对混合工质R1234ze/HCs及对应的纯工质热泵系统循环性能进行了对比分析。结果表明:R1234ze/R600在质量分数(20/80)和R1234ze/R600a在质量分数(40/60)存在最优配比,对应的最大制热COP_h分别为3. 41和3. 32,而R1234ze/R290则呈现单调下降趋势。R1234ze/R600(20/80)系统的制热COP_h比R1234ze/R600a(40/60)、R1234ze、R290、R600、R600a系统分别高2. 7%、17%、0. 09%、16. 3%和17. 8%,排气温度为76. 9℃,冷凝压力为0. 711 MPa,压比为6. 32,有望成为新型替代工质。     

R1234ze(E)在水平圆管内流动沸腾换热过程中摩擦压降特性实验研究

新型制冷剂R1234ze(E)(trans-1,3,3,3-tetrafluoropropene)因较低的GWP而被广泛关注,有望在热泵中作为R134a的替代品。本文对R1234ze(E)在内径为8 mm水平管内流动沸腾过程中摩擦压降特性进行实验研究,并在相同实验工况下与R134a进行对比。实验研究的流动沸腾换热的饱和温度为10℃,热流密度为5.0 k W/m~2和10.0 k W/m~2,质流密度范围为300~500 kg/(m~2·s),并分析质流密度、热流密度对R1234ze(E)和R134a饱和流动沸腾过程中摩擦压降的影响。结果表明,在相同工况下R1234ze(E)的流动沸腾过程的摩擦压降略大于R134a,如质流密度为500 kg/(m~2·s)时,R1234ze(E)的平均摩擦压降值比R134a大8.4%左右。最后,将实验结果同四种摩擦压降经验关联式进行比较分析。     

R1234ze(E)在多元醇脂油中溶解度的实验研究

R1234ze(E)(1,1,1,3-四氟丙烯)是当下具有较强替代潜能的环保制冷剂之一。本文搭建了溶解度测试实验系统,对R1234ze(E)在两种多元醇脂油中的溶解度进行测试,测试的温度范围为40～80℃,压力范围为0.123～0.360 MPa。采用PR状态方程和MHV2混合规则及NRTL活度系数模型对实验结果进行关联计算,得到不同温度下的交互系数及计算值与实验值的平均相对误差。结果表明:R1234ze(E)在两种多元醇脂油中的溶解度均随着温度的升高而降低,且R1234ze(E)在两种多元醇脂油中的平衡压力与溶解度之间存在立方函数关系。在两种多元醇酯油中,计算值与实验值的平均相对误差分别为1.68%和1.11%,可较好的描述R1234ze(E)在两种多元醇酯油中的相平衡行为。     

微圆管内R1234ze(E)流动沸腾的环状流特性模拟研究

本文建立了制冷剂R1234ze(E)在微圆管内流动沸腾过程中的环状流模型,对传热和气液两相流动压降进行了模拟研究。综合考虑重力、表面张力及气液界面剪切力的影响,模拟分析了周向液膜不均匀分布特性及该特性对流动与换热的影响,经验证,计算结果与已有实验结果吻合较好。本文还研究了不同因素对环状流区域表面传热系数与压降的影响。模拟结果表明:在流动起始区域,截面液膜厚度的分布受重力作用影响,随着流动沸腾过程的进行,该影响作用开始减弱,且有重力作用时的环状流平均表面传热系数高于无重力作用时的环状流平均表面传热系数,随着重力加速度的增加,环状流的平均表面传热系数不断增大;随着质量流速的增大,表面传热系数与压降均随之增大;随着管径增大,表面传热系数与压降均随之减小。     

R1234ze(E)在冷藏车余热驱动型TORC-制冷循环系统运行性能分析

建立了冷藏车余热驱动型跨临界有机朗肯-制冷循环系统热力学计算模型,研究了R1234ze(E)在该循环系统中运行性能,系统地分析了冷凝温度为40℃、50℃、60℃时系统运行性能参数,得到冷凝温度为40℃时,对应发动机尾气温度约为140℃时,系统拥有最高的膨胀机做功量10.20 kW;对应发动机尾气温度约为165℃,系统拥有最优的TORC系统热效率9.49%和最大的TORC-制冷循环系统制冷量18.36kW以及最佳的热效率值19.12%。     

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。     

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。     

混合工质R32／R134a替代家用电冰箱工质R12的理论与实验研究

本文在Ｒ１３４ａ替代Ｒ１２的基础上提出用非共沸混合工质Ｒ３２／Ｒ１３４ａ替代Ｒ１２,理论分析和实验结果都证明Ｒ３２／Ｒ１３４ａ的主要制冷性能接近或优于Ｒ１２,而且与纯Ｒ１３４ａ替代方案相比,制冷量提高,能耗降低。     

Surface tension of low GWP refrigerants R1243zf,R1234ze(Z), and R1233zd(E)

The surface tension of R1243zf, R1234ze(Z), and R1233zd(E) were measured at temperatures from 270 K to 360 K by an experimental apparatus based on the differential capillary rise method. The deviation between the measured surface tension of R134a and R245fa and the calculated surface tension with REFPROP 9.1 (Lemmon et al., 2013) was ±0.13 mN m⁻¹, which is less than the estimated propagated uncertainty in surface tension of ±0.2 mN m⁻¹. Eleven points, thirteen points, and ten points of surface tension data were provided for R1243zf, R1234ze(Z), and R1233zd(E), respectively, in this paper. The measured data and the estimated surface tension using the methods of Miller, 1963, Miqueu et al., 2000, and Di Nicola et al. (2011) agree within the standard deviation of ±0.43 mN m⁻¹. The empirical correlations that represent the measured data within ±0.14 mN m⁻¹ were proposed for each refrigerant.     

Theoretical energy performance evaluation of different single stage vapour compression refrigeration configurations using R1234yf and R1234ze(E) as working fluids

R1234yf and R1234ze(E) have been proposed as alternatives for R134a in order to work with low GWP refrigerants, but this replacement results generally in a decrease of the performance. For this reason, it is interesting to explore ways to improve the system performance using these refrigerants. In this paper, a comparative study in terms of energy performance of different single stage vapour compression configurations using R1234yf and R1234ze(E) as working fluids has been carried out. The most efficient configuration is the one which uses an expander or an ejector as expansion device. On the other hand, using an internal heat exchanger in a cycle which replaces the expansion valve by an expander or an ejector could produce a detrimental effect on the COP. However, for all the configurations the introduction of an internal heat exchanger produces a significant increment on the cooling capacity.     

HFO-1234ze在空气源热泵热水器中 替代R417A、R22的研究

首先从热物性、ODP、GWP、工质毒性、可燃性方面对HFO-1234ze、R417A、R22三种制冷剂进行对比,并进行理论计算,初步分析HFO-1234ze制冷剂运用在空气源热泵热水器上的可行性。然后,在焓差法实验室内,对分别采用HFO-1234ze,R417A和R22作为制冷工质的空气源热泵热水器进行名义工况下的性能测试,对三种制冷剂的吸排气温度,吸排气压力,压缩机输入功率、制热量、性能系数进行对比分析。本文研究结果显示HFO-1234ze可以作为R417a与R22在热泵热水器中的替代制冷剂。此次研究为热泵热水器的工质选择提供参考。     

R1234ze(E) flow boiling inside a 3.4 mm ID microfin tube

R1234ze(E) has a GWP<1 and a normal boiling temperature approximately 7.3 °C lower than that of R134a; it represents an interesting candidate for its replacement as working fluid in refrigerating machines. The refrigerant charge minimization in refrigerating and air conditioning equipment is a key issue for the new environmental challenges. Mini microfin tubes represent an optimal solution for both heat transfer enhancement and charge minimization tasks. This paper presents an experimental study of R1234ze(E) flow boiling inside a mini microfin tube with internal diameter at the fin tip of 3.4 mm. The experimental measurements were carried out at constant saturation temperature of 30 °C, by varying the refrigerant mass velocity between 190 kg m⁻² s⁻¹ and 940 kg m⁻² s⁻¹, the vapour quality from 0.2 to 0.99 at three different heat fluxes: 10, 25, and 50 kW m⁻². The experimental results are then compared with those obtained for the more traditional R134a.