R1234yf/R152a用作汽车空调制冷剂的配比范围研究

使用PR方程结合vdW法则建立了R1234yf/R152a的热物性模型,在此基础上结合余函数法编制了R1234yf/R152a的热力性质和制冷系统循环性能计算程序。在汽车空调制冷工况下,获得了R1234yf/R152a在不同摩尔组分比下的压力比、排气温度、COP、单位质量制冷量、单位体积制冷量和压缩机吸气口比容,并与R134a和R1234yf/R134a(0.89/0.11)进行了比较。之后,结合燃烧速度、GWP与循环性能获得了适宜的摩尔组分比范围。当R1234yf的液相摩尔分数在0.65～0.67时,R1234yf/R152a为近共沸混合物,具有较高的安全性,且制冷循环性能与R134a较为接近。     

新型制冷剂R1234yf/R134a可燃性实验研究

根据美国材料试验学会标准研制可燃性实验装置,对实验装置进行性能和误差分析,并进行校验。R1234yf环境性能好,臭氧消耗潜能值为零,其三元混合物R1234yf/DME/R134a可作为一种新型空调制冷剂。测试不同体积比时二元混合工质R1234yf/R134a的可燃性数据,得到其爆炸极限和临界抑爆比,并给出三元混合物R1234yf/DME/R134a的临界爆炸极限曲线图。结果表明:当R134a和R1234yf的体积比约为2时,二元混合物R1234yf/R134a达到临界抑爆点。     

R1234ze PVTx热物性模拟计算

寻找可靠高效的制冷剂已成为制冷行业中亟待解决的问题之一.通过使用基于量子化学的真实溶剂似导体屏蔽模型(COSMO-RS)来模拟计算混合制冷剂R1234ze的PVTx热物性,并将所得数据与美国国家标准研究所的Refprop 9.0数据相对比,结果表明:与以往的计算方法和实验方法相比,COSMO-RS所需参数少,耗时短,并...     

R1234yf有机朗肯循环系统热力学性能研究

为提高有机朗肯循环（Organic Rankine Cycle, ORC）在中低温地热发电领域的效率,本文以R1234yf为工质,依据热力学第一定律与第二定律分析了系统单位质量热水净发电功率和系统?效率,并与目前应用广泛的R245fa工质进行了性能对比。研究结果表明,存在最佳蒸发温度和最佳冷凝温度,使得ORC发电系统单位质量热水净发电功率、?效率最大。对于热源温度为110℃ ~ 150℃的ORC发电系统,R1234yf对应的最大系统单位质量热水净发电功率和最大?效率均大于R245fa     

R-1234yf在[HMIM][Tf2N]中的溶解度

基于等体积饱和法测量了温度在293.0~353.0K、压力在99.0~925.0kPa时R1234yf在离子液体1-己基-3-甲基咪唑双三氟甲磺酰亚胺盐([HMIM][Tf_2N])中的溶解度,温度、压力、溶解度的测量不确定度分别为0.02K、0.3kPa、3%。利用改进的Krichevsky-Kasarnovsky方程和NRTL方程对R1234yf在[HMIM][Tf_2N]中的溶解度进行了关联,计算值与实验值之间的相对偏差绝对平均值均为0.7%,最大相对偏差均小于1.9%。     

基于KULI的带回热器的R134a与R1234yf汽车空调系统仿真分析

使用KULI软件建立了带回热器的一维汽车空调仿真模型,通过试验数据验证了该模型的可靠性,并分别对R134a和R1234yf的系统性能进行了仿真分析。仿真结果表明:R1234yf系统的冷凝压力比R134a低,蒸发压力比R134a高;R134a系统的排气温度比R1234yf高10.5~17.9℃;R134a系统的制冷量比R1234yf高1.6%~3.4%;R134a系统的COP比R1234yf高0.2%~4.2%。     

不同制冷剂对喷射制冷系统性能的影响

选择R717、R290、R600a、R134a和R1234yf五种沸点相近的制冷工质,基于MATLAB软件,引入制冷剂物性参数的Cleland拟合模型,编写了喷射制冷系统的仿真模型,比较了五种制冷剂在不同冷冻水进口温度及不同冷却水进口温度下,喷射系数u和COP值的变化趋势。结果显示:冷冻水进口温度的改变,使制冷剂的制冷性能随之升高而增大;且制冷剂制冷性能随冷却水进口温度的升高而减小。R717在五种制冷剂中,喷射器喷射系数和系统性能COP都是最大的,R1234yf和R134a则具有相近的喷射系数。     

R290/R744新型混合工质汽-液相平衡研究

为了适应节能与环境保护的需求,研究了一种适用于自复叠制冷系统的新型绿色混合制冷工质(R290/R744)的汽液相平衡特性。根据相平衡条件采用PT状态方程结合Van der Waals混合规则推导出该混合制冷工质的相平衡计算式,通过软件编程计算了两种有工程实用意义的相平衡问题,一种是已知混合物压力和液相摩尔分数,计算泡点温度和气相摩尔分数;另一种是已知混合物压力和气相摩尔分数,计算露点温度和液相摩尔分数,并根据计算数据绘制了汽液平衡曲线。数据显示最大相对误差为4.840%,最小相对误差为0.005%。计算结果表明,采用给出的R290/R744混合制冷剂相平衡计算式具有较高的计算精度,从而为采用该混合制冷剂的自复叠制冷循环研究奠定基础。     

采用混合自然工质的自复叠制冷系统热力性质分析

对R744／R290、R744／R600a混合自然工质的热力性质进行分析比较，并将它们用于自复叠制冷循环，对系统的循环特性进行分析。经过计算，得出了两种混合工质制冷性质的不同点及环境温度、制冷温度、混合工质中R744浓度对系统性能的影响。为今后R744／R290、R744／R600a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。     

R125/R290混合工质热泵制冷剂变流量特性研究

对混合工质R125/R290(25/75,质量配比)热泵变制冷剂流量特性进行了实验研究,并以55℃热汇出口温度为例,与被替代工质R134a和R22进行了对比分析。研究结果表明:随着制冷剂流量增大,排气温度线性下降,单位质量制热量则先上升后下降,系统COP随着制冷剂流量的增加表现为先线性增加后缓慢下降的趋势;在混合工质流量为1.12kg/min时,系统出现最大COP值3.040;系统火用效率则随着制冷剂质量流量的增大而增大。整个实验工况范围内,传热温差窄点一直保持在换热器中间部位。实验结果表明,在实验工况范围内,R125/R290(25/75)有望成为R134a及R22的替代工质。     

PVTx Study of Binary System R22／R152a with Burnett Method

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Flow boiling characteristics of refrigerant mixture R22/R114 in the annulus of enhanced surface tubing

The paper presents an experimental study of flow boiling heat transfer characteristics of refrigerant mixture R22/R114 in the annuli of a horizontal enhanced surface tubing evaporator. The test section had an inner tube bore diameter of 17.3 mm, an envelope diameter of 28.6 mm and an outer smooth tube of 32.3 mm internal diameter. The ranges of heat flux and mass velocity covered in the tests were 5–25 kW/m² and 180–290 kg/m²/s, respectively, at a pressure of 570 kPa. The enhanced surface tubing data shows a significant enhancement of the heat transfer compared with an equivalent smooth tube depending on the mixture components and their concentrations. Correlations are proposed to predict such heat transfer characteristics as the average heat transfer coefficients as well as pressure drops of R22/R114 nonazeotropic refrigerant mixture flow boiling inside enhanced surface tubing. In addition, it was found that the refrigerant mixture's pressure drop is a weak function of the mixture composition.     

Shell-and-tube evaporator model performance with different two-phase flow heat transfer correlations. Experimental analysis using R134a and R1234yf

This work presents a model of a shell-and-tube evaporator using R1234yf and R134a as working fluids. The model uses the effectiveness-NTU method to predict the evaporation pressure and the refrigerant and secondary fluid temperatures at the evaporator outlet, using as inputs the geometry of the evaporator, the refrigerant mass flow rate and evaporator inlet enthalpy, and the secondary fluid volumetric flow rate and evaporator inlet temperature. The model performance is evaluated using different two-phase flow heat transfer correlations through model outputs, comparing predicted and experimental data. The output parameter with maximum deviations between the predicted and experimental data is the evaporating pressure, being the deviations in outlet temperatures less than 3%. The evaporator model using Kandlikar's correlation obtains the highest precision and the lowest absolute mean error, with 4.87% in the evaporating pressure, 0.45% in the refrigerant outlet temperature and 0.03% in the secondary fluid outlet temperature.     

Experimental study of R152a and R32 to replace R134a in a domestic refrigerator

This paper presents an experimental study of R152a and R32, environment-friendly refrigerants with zero ozone depletion potential (ODP) and low global warming potential (GWP), to replace R134a in domestic refrigerator. A refrigerator designed and developed to work with R134a was tested, and its performance using R152a and R32 was evaluated and compared with its performance when R134a was used. The results obtained showed that the design temperature and pull-down time set by International Standard Organisation (ISO) for small refrigerator were achieved earlier using refrigerant R152a and R134a than using R32. The average coefficient of performance (COP) obtained using R152a is 4.7% higher than that of R134a while average COP of R32 is 8.5% lower than that of R134a. The system consumed less energy when R152a was used. The performance of R152a in the domestic refrigerator was constantly better than those of R134a and R32 throughout all the operating conditions, which shows that R152a can be used as replacement for R134a in domestic refrigerator.     

混合工质R134a/R23替代R22的可行性研究

叙述了基于新型环保型混合制冷剂R134a/R23替代制冷剂R22的问题,以及通过REFPROP7.5,对混合工质R134a/R23从物性和热力学特性进行的理论计算分析,指出,由质量分数为70%的R134a和质量分数为30%的R23组成的混合制冷剂与R22性能最为接近,在变工况运行条件下,其COP值比R22高8%左右,其冷凝压力比同条件下用R22作为循环工质低21%～36%,理论上完全具有替代R22的可能性。     

Performance simulation of refrigerated display cabinets operating with refrigerants R22 and R404A

This paper describes the analysis and performance comparison of a display cabinet system using refrigerant R404A and its substitute refrigerant R22. The model of the display cabinet is developed at steady state and integrated from three main component sub-models, air-cooling finned-tube evaporator, air curtain and display cabinet body. The evaporator model is built up based on the distributed method, which can simulate the heat exchangers with different circuit structures. The frost effect on the performance of the evaporator is included in the model. The correlations for the heat transfer and pressure drop calculations of both air and refrigerant sides are purposely selected in the evaporator model. In addition, the evaporator model has been validated with experimental results at steady states from published literature. Several correlated functions from the detailed numerical solution are used for the model of the air curtain. Some simplifications are also utilized for the model of display cabinet body. The performance simulation and comparison of the display cabinet using refrigerants R404A and R22 are carried out at different indoor ambient conditions especially at varied ambient air humidity to mimic the actual indoor space conditions in super stores. Some significant results such as the comparison of cooling load requirement for different refrigerant display cases have been obtained from the simulation, which can significantly contribute to the optimal cabinet design and operating analysis.     

HCFC22替代物吸收制冷特性的实验研究

报道了吸收制冷系统中R22／DMF、R134a／DMF和R134a＋R32／DMF（R134a和R32分别以1∶1和3∶7摩尔比混合)等四种工质对的实验结果,并进行了比较和分析。结果表明,混合制冷工质对R134a＋R32（3∶7)／DMF在工作压力比R22高出20%的条件下,其系统性能与工质对R22／DMF相当。     

R744/R600a热泵热水器系统性能实验研究

为了研究环保混合制冷剂R744/R600a应用于热泵系统的可行性,在直热式水源热泵系统实验台上对R744充注质量分数在3%～11%的五种工况进行了实验研究。实验结果表明:R744充注质量分数的变化对热泵系统的COP_h、制热量和排气温度等性能参数均产生显著的影响;在热泵名义工况下,混合工质的最优R744充注质量分数为7%,其对应的系统COP_h和制热量相比R600a系统均明显提高,而其排气温度则明显降低。     

An experimental investigation of the global environmental impact of the R22 retrofit with R422D

In recent years a new refrigerant, R422D, has been introduced as substitute of R22 for refrigeration systems. This new fluid is an easy-to-use, non-ozone-depleting HFC refrigerant and, differently from its predecessor (R407C), it is compatible with mineral oil. However, R422D has a very high GWP, and it tends to worsen the efficiency of retrofitted R22 systems. Consequently, even if R422D respects the limits of Montreal Protocol, its global environmental impact could be high. In this paper, we report an experimental analysis in terms of TEWI aimed to identify the global environmental impact of R22 systems retrofitted with R422D. For this purpose, we considered a direct expansion refrigerator for commercial applications and we investigated energy consumption with the temperature of the cold reservoir set to −5, 0, 5, 10 °C. The experimental investigation confirmed that the system, when retrofitted with R422D, leads to an increase of TEWI. Therefore an optimization analysis aimed to eco-friendly scenarios was performed.     

Calculation of NARM''''s Equilibrium with Peng-Robinson Equation of State

IntroductionThere are mainly tWo well-known methods for thecalculation of fluid Phase equilibriUm, the method ofusing equation of state (EOS) or achvity coeffident.The later needs a plenty Of vapor-liquid equilibriumexperimental data in Order tO regress the calculatingmodel's parameters (such as non-random tWo liquidequation, (NRTL) etc). All means to describethermodynndc prOPelties are theoretically fonddedwith the equation Of state. If the EOS is suitable for theentire thermodyntalc …