吸收式制冷工质的发展

吸收式制冷机诞生至今已有一百多年的时间了，在这一百多年中，吸收式制冷技术获得了长足的进步和发展。与此同时，吸收式制冷机制冷工质的选择及改善作为吸收式制冷技术的核心组成部分也得到了不断的完善和发展。吸收制冷工质对选择的每一次突破，都对吸收式制冷技术的进步产生了巨大的推动作用。本文简要回顾了吸收式制冷工质的发展过程，分析比较了当今正在研究或使用的主要工质对，同时也介绍了我们浙江大学制冷与低温工程研究所正在研究的Ｒ２２／ＤＭＦ（二甲基甲酰胺）和Ｒ２２＋Ｒ１４２ｂ／ＤＭＦ工质对的有关情况。     

天然气液化流程中的汽液相平衡计算

在天然气液化流程中，不可避免地涉及到天然气和制冷工质的相平衡计算。利用ＳＲＫ方程计算了烃类混合物的相平衡特性。计算结果与国外实验数据作了比较，计算值与实验值吻合得很好，说明用ＳＲＫ方程计算烃类混合物的相平衡特性是合理的。还计算了不同压力和温度下烃类混合物的相平衡。本计算程序能智能判别某一状态是处于两相区还是单相区。     

用CSD方程计算R290、R600、R600a、戊烷的热力性质

本文用ＣＳＤ方程计算了Ｒ２９０、Ｒ６００、Ｒ６００ａ、戊烷的热力性质。这几种天然碳氢化合物的ＣＳＤ方程常数值可用于其混合工质的汽液相平衡计算     

混合制冷工质

混合制冷工质ＤＡＤｉｄｉｏｎＮＩＳＴ，ＧａｉｔｈｅｒｓｂｕｒｇＭＤ，ＵＳＡ工业上为了填补由于一些重要的ＣＦＣｓ（如Ｒ１１和Ｒ１２）被取消使用而导致的空白，初步的方法是发展对臭氧层破坏作用较小或没有破坏作用的其它单组分的工质（如ＨＣＦＣ１２３和ＨＦＣ１...     

法国泰康商用风冷冷凝机组用R404A替代R502的应用研究

Ｒ５０２曾广泛使用于商用低温制冷系统中，但因其中含有ＣＦＣ成分，它的使用受到限制。Ｒ４０４Ａ（由ＨＦＣ１２／ＨＦＣ１４３ａ／ＨＦＣ１３４ａ组成）是一种对大气臭氧层无破坏的，可长期替代Ｒ５０２的混合制冷剂。作者首先用ＣＳＤ状态方程对这两种工质的热力学与制冷循环特性进行了理论上的计算，然后，在一台可使用Ｒ４０４Ａ的风冷压缩冷凝机组上进行了一系列的试验。采用第二制冷剂量热器法来测量机组的制冷量。系统中加装了一个水过冷器来控制节流前液体温度。试验中，控制蒸发温度在－４０～－１０℃之间变化，环境温度为３２℃和４０℃。为了测定过冷的影响，在一定的环境温度和蒸发温度下进行了各种过冷温度的试验。在同一台机组上，相同工况下进行了Ｒ４０４Ａ和Ｒ５０２的对比试验。计算和试验结果表明，Ｒ４０４Ａ具有与Ｒ５０２相近的制冷性能，特别是在蒸发温度高和冷凝温度低的情况下。在低温范围，Ｒ４０４Ａ的性能比Ｒ５０２略有下降。在所测的温度范围内，Ｒ４０４Ａ的排气温度都比Ｒ５０２低，这有利于压缩机工作的可靠性。     

TFE／NMP,TFE／E181,NH3／H2O,H2O／LiBr等工质对（系）性能分析,比较评价

本文介绍新工质系ＴＦＥ／ＮＭＰ和ＴＦＥ／Ｅ１８１的性能特点并与ＮＨ３／Ｈ２Ｏ、Ｈ２Ｏ／ＬＩＢＲ工质系进行比较分析，指出应用前景和发展方向。     

TMD—高层钢结构系统风振舒适度控制设计方法

本文研究了ＴＭＤ－高层钢结构系统的风振舒适度控制设计方法,导出了ＴＭＤ－高层钢结构系统的传播函数和减振系统ＤＲＦ的表达式,同时对ＤＲＦ进行数值分析。最后给出了设计步骤,算例及结论。     

MxLa1—xFeO3气敏材料的制备及表征

采用液相化学共沉淀法制备出ＭｘＬａ１－ｘ ＦｅＯ３气敏材料。利用ＸＲＤ、ＳＥＭ、ＴＥＭ、ＩＲ、ＤＴＡＴＧ等分析技术，对材料的物相组成，结构，形貌等方面进行了表征。研究了各种因素对材料导电特性的影响情况。     

涡旋压缩机HFC替代工质的研究

根据涡旋压缩机的热力过程，村６种ＨＦＣ纯工质和相应两组混合工质进行了制冷循环计算，指出适当比例混合的二元混合工质Ｒ３２／Ｒｌ３４ａ是替代Ｒ２２工质较理想的选择。     

用于坐标测量机上测量与评定形位误差的软件包

为强化坐标测量机的功能，本文建立了评定直线、平面、圆、圆柱、圆锥、球等六项基本要素形状误差的、符合国家标准的数学模型，并用ＴＵＲＢＯＣ语言编制了计算程序．它不仅可直接用于评定位置时确定基准的理想要素，而且稍加扩展又可用来评定位置误差．本软件包可ＣＡＤ／ＣＡＭ系统联网，从而也极大地提高了ＣＡＤ／ＣＡＭ系统的效率．     

Experimental research on the performance of the diffusion absorption refrigerator with mixed fluoride refrigerants

A diffusion absorption refrigerator (DAR) operating with mixed fluoride refrigerants was built to obtain low refrigerating temperature at low generating temperature. Two groups of mixed fluoride refrigerants, R23/R134a and R23/R32/R134a, were tested experimentally. The N,N-dimethylformamide (DMF) and helium were used as the absorbent and inert gas, respectively. For the DAR with R23/R134a, the refrigerating temperature was not obviously influenced by the concentration of R23 in the mixed refrigerant vapor or the amounts of helium. For the DAR with R23/R32/R134a, an optimal concentration of R32 in the mixed refrigerant vapor and an optimal pressure were both found to achieve the lowest refrigerating temperature which was −28.8 °C at a generating temperature of 106.9 °C, and a refrigerating temperature of −23.7 °C was obtained at an extraordinarily low generating temperature of 83.3 °C. It showed the promising potentials of DAR operating with mixed fluoride refrigerants in applications of low temperature refrigeration and efficient utilization of the low-grade thermal energy.     

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。     

Investigation of the heat pump water heater using economizer vapor injection system and mixture of R22/R600a

This paper presents the experimental study of a heat pump water heater (HPWH) using economizer vapor injection system and mixture of R22/R600a. Performances of HPWH using economizer vapor injection system are compared with that at different mixed mass ratios of R22/R600a. Study demonstrates that the heating capacity and energy efficiency ratio (EER) of the unit increased, and the discharge temperature of compressor decreased when using vapor injection and mixing refrigerant of R22/R600a. It is also found that the HPWH unit with economizer vapor injection system has a better performance for the high outlet water temperature under lower temperature conditions at 15% mass ratio of R600a for the mixing refrigerant. In addition, fundamental and practical influence of vapor injection pressure on the HPWH performance has been investigated experimentally. The simplified model is proposed for predicting the optimal vapor injection pressure of compressor using the mixing refrigerant R22/R600a.     

The use of an MHV-2 equation of state for modeling the thermodynamic properties of refrigerant mixtures

This paper reports on the development and application of a thermodynamic model based on the second-order Modified Huron Vidal equation of state (MHV-2) to predict the properties of ternary mixtures of the refrigerants R32, R125, and R134a. The mixing rules of this equation of state have been used to incorporate directly an activity-coefficient model for the excess Gibbs free energy. The parameters for the activity-coefficient model have been derived from experimental VLE data for binary mixtures. This methodology has enabled the production of a thermodynamically consistent model which can be used to predict the phase equilibria of R32/R125/R134a mixtures. The input data used in the model are presented in the paper and the predictions of the model are compared with available experimental data. The model has been used to predict the behavior of ternary refrigerant blends of R32/R125/R134a in fractionation scenarios, such as liquid charging and vapor leakage, which are of direct interest to the refrigeration industry. Details of these applications and comparisons with experimental data are discussed, along with other general uses of the thermodynamic model.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, USA.     

Modeling and experimental investigation of accumulators for automotive air conditioning systems

A stream analysis model was developed to simulate the behavior of accumulators and their influence on the automotive air conditioning (A/C) systems. It allows a comprehensive steady state simulation with a set of input conditions such as refrigerant vapor mass flow rate and pressure at the inlet of an accumulator. In this study, the refrigerant/oil mixture is R134a/PAG oil which are totally miscible, but could be any air conditioning refrigerant/oil, including carbon dioxide (CO₂)/oil. The model accounts for all major effects inside the accumulator, such as friction, bends, sudden expansion, sudden contraction and heat exchange. The outputs are vapor quality, pressure and temperature at various positions of accumulator. In order to verify the mathematical model, experiments are performed in an experimental setup made up of real size automotive air conditioning components. The simulated results agree well with the experimental data. The simulation and experimental results show an important function of accumulators that is to determine the vapor quality into compressor, and thus has influence on the performance of whole automotive A/C systems.     

Modeling absorption of pure refrigerants and refrigerant mixtures in lubricant oil

This paper addresses the problem of absorption of refrigerant vapor in a stagnant layer of lubricant oil. The bulk motion of the solute is described in terms of apparent diffusion coefficients that encompass both molecular diffusion and possible macroscopic motion induced by liquid density instability and surface tension. In absorption of refrigerant mixtures, diffusion in the vapor and liquid phases are coupled with a thermodynamic model for interfacial equilibrium. Results are compared with experimental data available in the literature for absorption of several refrigerants in polyol ester oil (POE68). The adequacy of the formulation is assessed in the light of its basic assumptions and performance of the model.     

HFCs混合制冷剂热力性质的研究

为了利用PR方程和Huron-Vidal混合规则对三元混合制冷剂的热力性质进行精确计算，通过对10组二元HFCs混合制冷剂的汽液相平衡实验数据进行热力学关联，得出了相应的NRTL模型参数，由优选得到的过量Gibbs自由能NRTL模型的相互作用系数预测了构成R407C和R404A的三元混合制冷剂R32／R125／R134a以及R125／R143a／R134a的汽液相平衡，结果表明，泡点压力实验值和计算值的算术平均相对偏差小于0．42％，各组分的汽相组成实验值和计算值基本吻合。最后还应用相关热力性质分别对R32／R125和R407C进行了理论制冷循环分析计算并和其他模型的计算结果进行了比较。     

Prediction of in-tube condensation heat transfer characteristics of binary refrigerant mixtures

This study presents a prediction model for the condensation heat transfer characteristics of binary zeotropic refrigerant mixtures inside horizontal smooth tubes. In this model, both the vapor-side and liquid-side mass transfers are considered, and the high flux mass transfer correction factor is used to evaluate mass transfer coefficients. The model was applied to the binary zeotropic refrigerant mixture R134a/R123, which has a large temperature glide. Calculation results showed that the heat transfer degradation of R134a/R123 due to gradients in the mass fraction and temperature is considerable, and depends on the mass fraction of the more volatile component and the vapor mass quality of the refrigerant mixture. By comparison with experimental data, incorporating the present finite mass transfer model for the liquid film side into the calculation algorithm was shown to reasonably well predict the condensation heat transfer coefficients of binary refrigerant mixtures with the mean deviation of about 10.3%. In the present calculations, however, it was also found that the high flux mass transfer correction factor had only a slight effect on the condensation heat transfer.     

Solubility characteristics of R22-DMF refrigerant-absorbent combinationCaractéristiques de solubilité du mélange frigorigéne-absorbant R22-diméthylformamide

This Paper presents the solubility data of Refrigerant 22 (R22) - dimethyl formamide (DMF) measured over a wide range of temperature (?25°C to 120°C) and over a complete range of composition. The mixtures show large negative deviation from Raoult's law and there is large difference in normal boiling point its components. Thus this combination is suited for vapour absorption refrigerant systems. The In P-1/T diagram and temperature-composition diagram for the mixtures of R22-DMF have also been plotted for use in the analysis of vapour absorption systems.     

Solubility characteristics of R22-DMF refrigerant-absorbent combination

This Paper presents the solubility data of Refrigerant 22 (R22) - dimethyl formamide (DMF) measured over a wide range of temperature (−25°C to 120°C) and over a complete range of composition. The mixtures show large negative deviation from Raoult's law and there is large difference in normal boiling point its components. Thus this combination is suited for vapour absorption refrigerant systems. The In P-1/T diagram and temperature-composition diagram for the mixtures of R22-DMF have also been plotted for use in the analysis of vapour absorption systems.