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.     

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。     

R407C组分质量误差对压缩机性能测试——流量计法的影响

对于混合工质R407C,在生产过程中其组分HFC32/HFC125/HFC1348浓度难以严格达到23%/25%/52%,并且由于试验装置的泄露,其组分的浓度也会有所偏差.针对上述问题,讨论了R407C各组分浓度误差小于5%时对压缩机性能实验-流量计法的影响,从而提高测试结果的精度.     

基于小型空调系统的R410a和R407C性能比较

小型空调系统在低温工况下存在无法正常运行或运行效率较低等缺点,为寻找低温工况下制冷工质,本文在焓差实验室对R410a和R407C两种制冷剂在小型空调系统中的不同工况进行了实验测试。通过实验结果分析发现,冬季供热时,R410a的平均COP比R407C高4.1%,夏季制冷时,R407C的平均COP比R410a高7.2%。因此,相对于R407C制冷剂,R410a更适合于热泵低温工况。     

汽车空调系统采用工质R407C的性能结构探讨

提出了汽车空调制冷剂对环境的污染问题,并对此具体论述了制冷系统采用混合工质R407C替代氟利昂-22的必要性和可行性,从而根据新工质特性,研究探讨出满足公交车空调冷量要求的空调系统.     

空调用替代R22工质的试验研究

对空调系统用R22和替代工质R407C，R410A的性能进行试验研究，并在对比分析基础上对未来几年的空调用替代工质选用提供建议。     

R407C、R410A系统热力性能研究综述

本文介绍了R22制冷剂最有希望的替代物R407C和R410A的基本物性，以及国外学者对使用这两种工质的制冷系统有关换热、压降特性及对COP影响的研究成果，以帮助国内制冷、空调企业了解R22替代工质研究的新动向、加快制冷工质替代的步伐。     

无油压缩机驱动的混合工质节流制冷机工质浓度变化特征的实验研究

建立了一套由无油压缩机驱动的多元非共沸混合工质节流制冷机系统，用以实验研究其中多元混合工质组分浓度变化特征。针对一种典型混合工质进行多次系统的测量，实验结果得出了不同气量时制冷系统内混合工质组分浓度的变化和分布情况，以及组分浓度随制冷温度的变化特征等一般性规律，将为进一步研究多元混合工质J—T节流制冷机的动态工作特性和优化设计提供重要的依据。     

碳氢工质R600a/R1150在低温冰箱中的应用研究

采用碳氢制冷工质R600a/R1150进行实验研究,以低温冰箱为研究对象,对比分析了R600a/R1150与R600a/R23/R14两种混合工质在两级自复叠制冷循环系统中的特性。在不同工况下,对混合工质的几种质量配比进行了对比实验,结果表明,混合工质R600a/R1150在62/38的配比下系统性能最优,此配比下,系统在25℃环境温度下,箱内温度可以达到-80℃,在32℃环境温度下,箱内温度可以达到-77℃。在相同工况下,混合工质R600a/R1150的系统性能优于R600a/R23/R14,前者的箱内温度较后者低约2℃,系统充注量比后者少了36.4%。     

环保制冷剂R1270/RE170/R13I1的热力学性能分析

针对制冷剂R22的替代问题,提出一种适用于空调等制冷设备的环保型混合制冷剂R1270/RE170/R13I1。基于Refprop8.0,对R1270/RE170/R13I1的基本热物理性质和制冷系统循环性能进行分析,研究表明:在标准工况下,R1270/RE170/R13I1混合制冷剂的COP和单位容积制冷量均与R22相当,非常有利于直接充注式替代;在变工况下,R1270/RE170/R13I1的滑移温度较小,性能优于R407C,单位容积制冷量与R407C和R22基本相当,排气温度和压比均低于R22和R407C,是一种优良的R22和R407C制冷设备的替代物,具有充注式替代的潜力。     

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。     

R404A单机双级与R404A/R23复叠式制冷系统对比分析

通过建立双级压缩制冷系统和复叠式压缩制冷系统热力学模型,在冷凝温度40℃,蒸发温度为-65℃条件下,分析不同的中间温度对两种制冷系统压缩机轴功率,制冷剂流量以及制冷系数等性能参数的影响,并对两种制冷系统的实际运行费用进行了比较。结果表明:在相同的工况下,双级压缩式压缩机轴功率、R404A制冷剂质量流量低于复叠式;而双级压缩制冷系统COP(制冷性能系数)高于复叠式。在冷凝温度为40℃,蒸发温度为-65℃,中间温度为-14℃时,与复叠式制冷系统相比双级压缩式制冷系统全年运行节能可达13%。理论研究表明在-65℃的超低温工况下,双级压缩式制冷系统更具有优势。     

Performance of mixture refrigerant R152a/R125/R32 in domestic air-conditioner

This work reports a ternary blend R152a/R125/R32 with a mass ratio of 48/18/34 as a potential alternative to R22. A computer code has been developed with NIST REFPROP 7.0 for the comparative analysis of thermophysical properties and refrigerant performance of this new mixture and of R22. A drop-in test of this new mixture was performed in a domestic air-conditioner originally designed for R22. Both the calculation and experimental results showed that this new mixture could be regarded as a most likely drop-in substitute for R22 in many applications. The flammability of this ternary blend was also studied with an explosion apparatus to prove that it could be used safely. Besides, simulation of the refrigerant cycle leakage showed that the variation of composition due to leakage was so little that there is no much performance degradation.     

新型混合制冷剂R1270/R152a/R13I1的理论研究

针对制冷剂R22的替代问题,提出了一种适用于空调等制冷设备的环保型混合制冷剂R1270/R152a/R13I1。基于Refprop8.0,对R1270/R152a/R13I1的基本热物理性质和制冷系统循环性能进行了分析,研究表明:在标准工况下,R1270/R152a/R13I1混合制冷剂的COP和单位容积制冷量均与R22相当,非常有利于直接灌注式替代;在变工况下,R1270/R152a/R13I1的滑移温度较小,性能优于R407C,单位容积制冷量与R407C和R22相当,是一种优良的R22替代物。     

R1234yf整车汽车空调泄漏扩散研究

新能源电动汽车热管理系统与传统乘用车不同,对采用热泵空调系统并利用液冷冷却电池的新能源电动汽车,制冷剂充注量比传统汽车空调增加了400～800 g.若使用可燃制冷剂,泄漏扩散至乘员舱,燃烧风险将增大.本文通过数值模拟对R1234yf制冷剂在蒸发器破损泄漏随送风进入乘员舱后的浓度变化过程和最高浓度进行了动态监测.结果表明...     

Experimental assessment of R134a and its lower GWP alternative R513A

Lower GWP refrigerants are essential to mitigate the impact of refrigeration systems on climate change. HFO/HFC mixtures are currently considered to replace HFCs in refrigeration and air conditioning systems. The aim of this paper is to present the main operating and performance differences between R513A (GWP of 573) and R134a (GWP of 1300), the most used refrigerants for medium evaporation temperature refrigeration systems and mobile air conditioners. To perform the experimental comparison, 36 tests are carried out with each refrigerant at evaporating temperatures between −15 and 12.5°C and condensing temperatures between 25 and 35°C. The conclusion of the experimental comparison is that R513A can substitute R134a with only a thermostatic expansion valve adjustment, achieving better performance and higher cooling capacity. The discharge temperature of R513A is always lower than that of R134a.     

Performance characteristics of a small-capacity directly cooled refrigerator using R290/R600a (55/45)

In this study, the performance of a small-capacity directly cooled refrigerator was evaluated by using the mixture of R290 and R600a with mass fraction of 55:45 as an alternative to R134a. The compressor displacement volume of the alternative system with R290/R600a (55/45) was modified from that of the original system with R134a to match the refrigeration capacity. Both systems with R290/R600a (55/45) and R134a were tested, and then optimized by varying the refrigerant charge and capillary tube length under experimental conditions for both the pull-down test and the power consumption test. The refrigerant charge of the optimized R290/R600a system was approximately 50% of that of the optimized R134a system. The capillary tube lengths for each evaporator in the optimized R290/R600a system were 500 mm longer than those in the optimized R134a system. The power consumption of the optimized R134a system was 12.3% higher than that of the optimized R290/R600a system. The cooling speed of the optimized R290/R600a (55/45) system at the in-case setting temperature of −15 °C was improved by 28.8% over that of the optimized R134a system.     

Numerical research on R32/R1234ze(E) air source heat pump under variable mass concentration

R32/R1234ze(E) mixtures are potentially low-GWP alternative refrigerants for air conditioning and heat pumps while the rare pure refrigerants can totally meet the requirements of new international protocols on environmental conservation, thermodynamic performance, and safety. The system performance under different concentrations is important for selection of working concentration for the new R32/R1234ze(E) refrigeration or heat pump. In this paper, the thermodynamic model of an ASHP with R32/R1234ze(E) mixtures is built and used to investigate the influence of the refrigerant composition on the performance of the system. The results show that when the mass fraction of R1234ze(E) changes from 0% to 100%, the heating capacity of the ASHP decreases by 67.2%, while the COP continuously increases by 70.3%, which means the changing tendency of system COP is quite different from previous research under fixed evaporating and condensing temperature. Adjusting the refrigerant concentration will be a good system modulation method for ASHPs with R32/R1234ze(E) to meet both the heating capacity and energy efficiency requirements. Furthermore, temperature matching degree is an important factor that affects the energy efficiency of ASHPs with non-azeotropes, which can guide the circuitry optimization of evaporator and condenser in ASHPs with non-azeotropes.     

Real-time measurement of mixing ratio of refrigerant/refrigeration oil mixture

The mixing of refrigeration oil with refrigerant in a refrigeration cycle has great influence on cycle performance. A sampling method is the most general way to measure the mixing ratio of refrigerant and refrigeration oil. Since the sampling method is time-consuming and reduces the amount of refrigerant and oil in the cycle, a real-time measurement is desirable. In this study, a refractive index measurement was applied to measure the mixing ratio of refrigerant/oil mixture. A laser displacement sensor was used to detect any change in optical path which results from changes of the refractive index of refrigerant/oil mixture. For the practical application of real-time measurement of the oil circulation ratio (OCR) in the refrigeration cycle, a correlation between the refractive index and the mixing ratio was developed. In addition, the changes of the refractive index in a range of a few percentages of the oil concentration and under subcooled conditions were measured. Finally, a transient measurement of the OCR in a practically operating refrigeration cycle was carried out successfully.