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Copyright of Contemporary Accounting Research is the property of Canadian Academic Accounting Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Liquid density and viscosity of alternative refrigerants R513A were measured with a vibrating-wire viscosimeter in the temperature of 253 K to 363 K when pressure changes from 1 MPa to 12 MPa. The combined expended uncertainties with a confidence level of 0.95 (k = 2) of density and viscosity are 0.2 % and 2 %, respectively. In addition, a viscosity model of HFCs (fluorocarbons)/, HFOs (hydro-fluoroolefins) and their mixtures was provided by coupling the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state and a modified residual entropy scaling (RES) method. Obvious quasi-linear relation between the proposed entropy variable and the modified residual viscosity has been confirmed. The overall average absolute percentage deviations between the calculated results with the proposed RES model and the literature experimental data of pure and mixture refrigerants are 2.63 % and 2.05, respectively. [ABSTRACT FROM AUTHOR]

• The physical properties of work fluid-lubricant mixture systems were reviewed. • An overview of the classification and characteristics of existing lubricants was presented. • The experimental methods of the physical properties were summarized. • The efficiency and safety improvement studies were compared and summarized. As countries prioritize climate change concerns, promoting the use of new environmentally friendly working fluids has become a common goal for the industry. In thermal systems, lubricants come into contact with these working fluids and directly affect their utilization efficiency. Therefore, investigating the effect of lubricant mixing on the physical properties of process media is essential to promote the adoption of new environmentally friendly working fluids. This paper categorizes and organizes recent research literature on working fluids and lubricants. It was aimed to comprehend the effect of lubricants on the operating characteristics of working fluids. By comparing the research methods and experimental equipment utilized in previous studies, this work analyzes the variation of basic physical properties, including miscibility, solubility, viscosity, and gas-liquid phase equilibrium. In addition, the effects of lubricant mixing in terms of heat exchange characteristics, additives, and material compatibility are also summarized. These findings provide a reference for achieving optimal performance matching of new environmentally friendly working fluid-lubricant combinations. And it will be beneficial for future experimental studies investigating the physical properties associated with working fluid-lubricant mixing systems. [ABSTRACT FROM AUTHOR]

Copyright of Social Anthropology / Anthropologie Sociale is the property of Berghahn Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• The viscosities of POE32 and PVE32 oils saturated with R13I1 were measured. • The experimental viscosity data were correlated using three viscosity models. • The viscosities of R13I1/oil mixture decreased sharply with increasing solubility. Trifluoroiodomethane (R13I1) has attracted extensive attention because of its excellent environmental protection performance, and can be used as a component of environmentally friendly refrigerant blends. To better understand the cycle performance of R13I1 as a refrigerant, it is necessary to study the thermodynamic properties of the R13I1/lubricating oil mixture. In this work, the viscosities of polyol ester (POE) oil (RL 32H) and polyvinylether (PVE) oil (FVC 32D) saturated with R13I1 were measured at temperatures ranging from 293.15 to 353.15 K and pressures up to 0.6 MPa using a custom equilibrium viscosity system. The viscosities of R13I1/RL 32H and R13I1/FVC 32D showed similar trends with temperature, pressure, and solubility. With the increase of the solubility of R13I1 in the oil, the viscosity of the mixture decreased sharply at first and then tended to be flat. The dissolved R13I1 in oil greatly reduced the viscosity of lubricating oil, and the effect of R13I1 on the viscosity of RL 32H was greater than that of FVC 32D. The experimental viscosity data were correlated using the modified Setchenow-type equation, the Eyring-NRTL model, and the Eyring-MTSM model, and the calculated results of the models were in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

• Higher initial compressor temperature results in higher minimum viscosity. • Refrigerant concentration gradient went from present to absent during startup. • Poorer miscible lubricant results in higher mixture viscosity. • Oil discharge originates from excessive refrigerant condensation and oil supply. • PAG VG40 and MO VG100 showed good oil return performance. The low density, small adiabatic index, and restricted charge of R290 result in different startup characteristics for R290 air-source heat pumps (ASHP) from that for HFCs ASHP. The research on the startup process of R290 refrigeration systems in the past has focused on system and compressor pressures, temperatures, changes in the bottom viscosity of the oil sump, and control strategies. There is a lack of research on the effect of lubricant types on the startup process, especially for R290 air-source heat pump. This paper experimentally measured and analyzed the changes in system temperatures and pressures as well as the changes in refrigerant concentration, concentration gradient, and mixture viscosity in the compressor oil sump during the startup process of R290 ASHP under different conditions, different startup types and with different lubricants. In addition, the oil discharge time, oil discharge, refrigerant mass in the compressor, and oil return time during the cold startup of LTH using PAG VG40 and MO VG100 were observed and clarified by installing transparent tubes and dismantling and weighing method. The experimental results showed that during the startup process, the mixture viscosity in the oil sump decreased and then increased, the refrigerant concentration increased and then reduced, and the refrigerant concentration gradient went from present to absent. The minimum viscosity was greater, the maximum concentration was smaller, and the low-viscosity duration was shorter for higher initial compressor temperature and with poorer miscible lubricants. PAG VG40 and MO VG100 showed good oil return performance. [ABSTRACT FROM AUTHOR]

• Viscosities were measured for saturated solutions of R-290 with POE 75, PAG 68, and PVE 68 from 303.15 to 348.15 K. • The effect character of absorbed R-290 on oil viscosity was given. As a natural refrigerant, propane (R-290) with a similar cooling capacity of R-22 is being increasingly widely attention in refrigeration and air conditioning (RAC). In the refrigeration cycle, the working fluid is actually a mixture of refrigerant/oil. To gain insight into the performance of vapor-compression refrigeration using R-290 as a refrigerant, the thermophysical properties of R-290/oil mixtures should be well known, especially the viscosity behavior. A self-designed double-capillary apparatus was applied to measure the viscosities of saturated solution for R-290 with three synthetic oils (PAG 68, POE 75 and PVE 68) from 303.15 to 348.15 K. The results show that the viscosities of three blends have the similar trend as rising solubility. The absorbed R-290 has a great impact on the oil viscosity in the low temperature region. Viscosities of R-290/oil mixtures could be well represented by the Eyring-MTSM model. [ABSTRACT FROM AUTHOR]

Modeling the viscosity of potential replacements for refrigerants like hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs) is important because this information can be used to determine which refrigerants are suitable for use in different refrigeration systems and to guide decisions about system design, operation, and maintenance. In this work, the viscosities of four selected refrigerants, two HFCs and two HFOs, and their mixtures were calculated using two similar approaches, namely entropy scaling and Helmholtz scaling. In both cases, the polar perturbed-chain statistical associating fluid theory (PPC-SAFT) EoS provides the molecular parameters and the entropy or Helmholtz energy dependency required. Results indicate good predictive capabilities for both models, with comparable error to the available experimental data. Even so, the Helmholtz scaling exhibits superior overall robustness, given its extra adjustable parameter. However, predictive results tend to be the same or less quality than those given by the entropy scaling approach. • Viscosity models based on PPC-SAFT equation and scaling theories were developed. • Each model's capacity and limitations are revised depending on thermodynamic conditions and complexity. • Entropy scaling is more accurate in modeling certain kinds of data. [ABSTRACT FROM AUTHOR]

• There is no concentration gradient when the bottom viscosity reaches the minimum. • Viscosity of low oil charge is lower and duration of low viscosity is longer. • Lack of lubricant in the oil sump leads to low viscosity during startup. • Bearing cover modification efficiently enhances the viscosity of low oil charge. • Bearing cover modification allows R290 compressor to use low viscosity grade oil. As an A3 refrigerant, the charge of the natural refrigerant R290 in the refrigeration system is limited. The use of partially miscible lubricants and a reduction of the lubricant charge can effectively decrease the refrigerant charge. These two measures affect the startup dynamic characteristics of the compressor and the air conditioner. In this paper, variations in system temperature, pressure, and oil sump parameters during the cold startup process of a 1.5P R290 split inverter room air conditioner with different charges of PAG VG40 were experimentally measured under the rated cooling and low-temperature heating condition. The experimental results showed that the viscosity of the refrigerant/lubricant mixture of low lubricant charge (LLC) was lower than that of the normal lubricant charge (NLC), and the duration of low viscosity with LLC was longer. The low viscosity during startup is mainly due to the insufficient amount of lubricant in the oil sump. Three measures were proposed to alleviate the problem of low startup viscosity. Among them, the modification of the bearing cover effectively improved the viscosity of the LLC mixture, and the minimum viscosity of the bearing cover with LLC was even higher than that of the prototype with NLC. Furthermore, the bearing cover modification allows using a lower viscosity grade of lubricant for R290 rotary compressors. [ABSTRACT FROM AUTHOR]

• Viscosity, thermal conductivity, and interfacial tension of (CO 2 + R32) have been determined • Performance of existing models has been evaluated at industrial-relevant conditions • Accuracy of models implemented in REFPROP 10.0 has been improved Reliable understanding of viscosity (η), thermal conductivity (λ), and interfacial tension (γ) are demanded in the refrigeration process, especially in the heat, mass and momentum transfer calculations. In this work, measurements of these thermophysical properties for (CO 2 + R32) have been conducted by vibrating wire viscometry, transient hot-wire technique, and differential capillary rise approach. The experimental condition ranges from (208.4 to 344.4) K and pressures up to 7.58 MPa at x (CO 2) = 0.7, 0.8 and 0.9, including those in the single-phase and near the melting curves. The standard uncertainties (k = 1) are between (0.21 and 6.80) μPa·s, (0.00012 and 0.00290) W·m–1·K–1, and (0.13 and 0.67) mN·m–1 for viscosity, thermal conductivity, and interfacial tension, respectively. The achieved results and the literature data (if applicable) were utilised to regress the extended corresponding states correlation and Parachor approach implemented in REFPROP 10.0. With the regressed models, most viscosity and thermal conductivity results can be described within 4%. The determined data and improved model provided here should contribute significantly to the design margin minimisation in the refrigeration cycle. [ABSTRACT FROM AUTHOR]

As a novel low GWP working fluid 1,1,3,3,3-hexafluoro-2-methoxypropane (HFE-356mmz) is regarded as a promising candidate for high-temperature heat pumps and organic Rankine cycle. Recently, the experimental kinematic viscosity and thermal conductivity data of HFE-356mmz were published in the literature. However, at the time of that publication it was not possible to develop any mathematical model of the transport properties due to unavailability of an equation of state. In this work, we report dynamic viscosity data of HFE-356mmz together with mathematical models for dynamic viscosity and thermal conductivity using the extended corresponding states (ECS) and the residual entropy scaling (RES) technique. With R134a used as the reference fluid for ECS method, the transport shape factors and the other adjustable parameters were calculated by utilizing latest multi-parameter Helmholtz-energy-explicit-type equations of state for HFE-356mmz. Furthermore, slight modification of the original RES method has been adopted that removes the implicit dependency on the tuned ECS method. By using the adjustable parameters, the tuned ECS and RES transport equations can represent the experimental data within reported uncertainties. The average absolute deviations (AAD) for viscosity and thermal conductivity were found to be 0.85% and 0.76% using the tuned ECS and 0.83% and 0.44% using the modified RES method respectively. [ABSTRACT FROM AUTHOR]

L’utilisation des superplastifiants dans les bétons autoplaçants (BAP) est indispensable pour garantir la fluidité recherchée. A travers ce travail expérimental, nous visons à étudier l’effet du dosage en superplastifiant sur les caractéristiques des bétons autoplaçants (BAP). Les propriétés rhéologiques des mélanges sont étudiées au moyen d’un rhéomètre de forte capacité de couple muni d’une géométrie couette. En complément, les essais de la norme NF 206/CN ont été réalisés afin d’établir une comparaison avec les essais sur rhéomètre. Les résultats ont montré que les superplastifiants améliorent l’ouvrabilité des BAP en diminuant significativement les seuils de cisaillement statiques et dynamiques. Cependant, leur effet sur la viscosité plastique dépend fortement du dosage utilisé. Par ailleurs l’augmentation du dosage en superplastifiant s’accompagne toujours par une diminution de la stabilité du mélange, ce qui peut engendrer des pertes dans la résistance mécanique.

Copyright of Light Industry Machinery is the property of Light Industry Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Before any nanolubricant is being applied in a refrigeration system, its thermo-physical properties shall be investigated. In this paper, hybrid nanolubricant is prepared by dispersing SiO 2 -TiO 2 nanoparticles at 50:50 composition ratio into the polyvinyl ether (PVE) compressor lubricant using a two-step method. The investigation was done for volume concentrations from 0.01 to 0.10% under temperature range of 303 to 353 K. The Newtonian behaviour of the nanolubricant was obtained, and relative thermo-physical enhancement was determined by comparing its performance to the pure lubricant. It was observed that the maximum increment viscosity does not exceed 3% from the base fluid, while thermal conductivity for 0.1% concentration increases up to 1.6%. Overall observation also reveals that both rheological and thermal properties increase by increasing concentrations, but the same properties decrease with temperature. An interesting finding is the nanolubricant had viscosity decrement than the pure lubricant specifically at 303 K. New regression models were suggested for thermo-physical properties with high accuracy R-squared values of 0.9989 and 0.9920 for viscosity and thermal conductivity, respectively. As a conclusion, SiO 2 -TiO 2 /PVE nanolubricant is recommended in refrigeration systems with a volume concentration of less than 0.10%. [ABSTRACT FROM AUTHOR]

• Viscosity measurement of R1336mzz(E) was performed by the method of tandem capillary tubes. • The liquid, vapor, and supercritical viscosities were measured over a wide range of temperatures and pressures. • The measurement uncertainties are estimated using the law of propagation by the GUM guideline. • Simplified correlations for the saturated liquid and vapor viscosities are developed by the extrapolation method. As one of hydrofluoroolefins, trans-1,1,1,4,4,4-hexafluoro-2-butene (R1336mzz(E)) is treated as a novel working substance for organic Rankine cycles as well as heat pumps for its low GWP, non-flammability, and lower toxicity. The objectives of this study are the viscosity measurement for R1336mzz(E) in liquid, vapor, and supercritical regions by the method of tandem capillary tubes and the development of correlations for the saturated liquid and vapor viscosities. The viscosity measurements for R1336mzz(E) were conducted over the range of temperature from 314 to 394 K for the liquid, 391 to 453 K for the vapor, and 413 to 453 K for the supercritical region, respectively, at pressures from 1.0 to 4.0 MPa. The expanded uncertainties in the viscosity measurement are calculated as 2.26 % for liquid, 2.30 % for vapor, and 2.32 % for supercritical phase using k=2 and 95 % confidence level. The experimental data are correlated with the ECS model; the AAD is 5.04 % for the liquid, 22.19 % for the vapor, and 11.88 % for the supercritical phase, respectively. The saturated viscosities are also estimated by the extrapolation from the measurements to the liquid-vapor saturation conditions. For industrial design and simulation, simple correlations are developed in terms of the saturation temperature to predict the viscosities of the saturated liquid and vapor phases, respectively. [ABSTRACT FROM AUTHOR]

• The viscosity data of R1234ze(Z) is presented. • The expanded uncertainty of the experimental data is calculated. • The correlation of viscosity at saturation state is developed A Hydro-Fluro-Olefin (HFO) cis-1,3,3,3-tetrafluoropropene (R1234ze(Z)) can be assessed as a promising working fluid in the high-temperature heat pump as it has a low global warming potential (GWP). In this work, the viscosity of R1234ze(Z) is measured in liquid and vapor phases by the method of tandem capillary tubes. The viscosity measurements were performed from 0.5 to 4.08 MPa pressure over a temperature ranges from 313.74 to 414.31 K at liquid and 354.07 to 455.80 K at vapor phase. Total expanded uncertainties of the viscosity measurement with k = 2 and 95% confidence level in liquid and vapor phase are lower than ±2.19% and ±2.59%, respectively. Viscosities at saturation conditions are estimated from experimental measurement data by the extrapolation method. Simplified correlations are developed in terms of saturation temperature for the viscosity of liquid and vapor at saturation conditions. [ABSTRACT FROM AUTHOR]

• Viscosity of R32+R1234yf and R32+R1243zf were measured in liquid and gas phases. • Relative combined uncertainties (k = 2) in viscosity are generally from 3.2 to 5.0 %. • Parameters of the RES-CPA model for pure R1243zf and R32 + R1243zf were fitted. • Relative deviation of measured viscosities from the RES-CPA model is within 10%. Viscosity measurements of six binary mixtures of R32+R1234yf and R32+R1243zf at different compositions were conducted in the homogenous liquid and gas phases with a vibrating-wire viscometer in the temperature range from (254 to 383) K and pressures from (1 to 8) MPa. The measurement system was verified with the measurements of pure carbon dioxide and R32 in homogenous liquid and gas phases. The relative combined expanded uncertainties (k = 2) in the experimental viscosity of the mixtures are generally from 3.2% to 5.0%. The measured viscosities agree with the calculations of the extended corresponding state model implemented in the software package REFPROP 10.0 within 10% and mainly within 5%. The parameters of the residual entropy scaling model incorporating cubic-plus-association equation of state (RES-CPA model) for the viscosity of pure R1243zf and binary R32 + R1243zf mixture were determined. The relative deviation of the measured viscosities from values calculated with the RES-CPA model is mainly within 6% in the liquid phase and 10% in the gas phase. [Display omitted] [ABSTRACT FROM AUTHOR]

• The two refrigerants of R1243zf and R1233zd (E) could be used as the low-GWP working fluid. • Thermophysical properties of the selected R1243zf and R1233zd (E) were investigated. • Light scattering method was used for the determination of thermophysical properties. • Correlations were proposed for the investigated thermophysical properties. To facilitate the application of low-GWP refrigerants in the refrigeration and heat pump systems, it is highly necessary to obtain their thermophysical properties including the liquid surface tension, viscosity and thermal diffusivity. In the present study, these thermophysical properties of two low-GWP refrigerants 3,3,3-trifluoropropene (R1243zf) and trans-1-chloro-3,3,3-trifluoro-1-propene (R1233zd(E)) were investigated by using the light scattering method under saturation conditions. With the experimental data, a van der Waals type equation for surface tension and polynomial equation with an additional term to capture the trend close to the critical point for viscosity and thermal diffusivity were proposed for the future applications. [ABSTRACT FROM AUTHOR]

2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) as the promising refrigerants have attracted wide attention. To understand better of the refrigeration-cycle performance working with new refrigerants, the thermodynamic properties of refrigerant/oil mixtures should be well known, especially the viscosity of the refrigerant/oil mixture. Using a dual-capillary method, the viscosities were measured for POE75 saturated with R1234yf and R1234ze(E) from 303.15 to 348.15 K. The viscosity trends of R1234yf/POE75 and R1234ze(E)/POE75 mixtures are similar. As rising solubility, a sharp decrease of viscosity appeared firstly, and then it goes to be flat. Results show that the dissolved refrigerant in oil largely reduces the oil viscosity. Comparing to viscosity models including an empirical model (modified Setchenow-type equation) and Eyring's absolute rate theory coupled with three excess Gibbs energy models (Eyring-MTSM model, Eyring-NRTL model, and Eyring-wilson model), the Eyring-MTSM model give better results than the other studied models. [ABSTRACT FROM AUTHOR]

• ANN models of HFC/HFO Refrigerants' viscosity and thermal conductivity were proposed. • Inputs of ANN models were reduced pressure, reduced temperature, mole mass and acentric factor. • The correlation coefficient and the AAD of viscosity model were 0.9998 and 1.21%. • The correlation coefficient and the AAD of thermal conductivity model were 0.9992 and 1%. Accurate prediction models for the viscosity and thermal conductivity of refrigerants are of great importance and have drawn wide attention from scholars. Considering the great advantage of artificial neural network (ANN) models in solving non-linear problems, two fully connected feed-forward ANN models were proposed to predict the viscosity and thermal conductivity of the HFC/HFO refrigerants in this paper. The reduced pressure (p r), reduced temperature (T r), mole mass (M) and acentric factor (ω) of the refrigerants were selected as the input variables for both ANN models. Regarding the ANN model for viscosity, the neural number of the hidden layer was optimized to be 9 by trial-and-error method. The prediction results coincided with the experimental data very well. The correlation coefficient and the average absolute deviation (AAD) of regression were 0.9998 and 1.21%, respectively. The prediction of thermal conductivity also showed a good agreement with the experimental data, and the AAD of the model was 1.00%. The paper is expected to provide valuable methods to predict the viscosity and thermal conductivity of HFC/HFO refrigerants. [ABSTRACT FROM AUTHOR]

• Load on crank part doubles when ambient temperatures rises to 50°C. • Bottom viscosity drops to 1.59 mPa⋅s with increased temperature. • Proportion of squeeze and wedge effect changes at different rotation angle. • Contact force accounts for 35% supporting force in extreme condition. Propane has been suggested as one of the alternative working fluids for room air conditioners in hot climate areas because of its excellent environmental properties and lower discharge temperature though there still is concern about its flammability. The lubricating condition of rotor bearings system should also be emphasized because a heavier load and lower viscosity in the oil sump could impair the reliability of rotary compressor under high ambient temperature. In this study, in order to obtain the input of simulation, the dynamic pressures and viscosity of a R290 air conditioner are experimentally measured under several conditions. On these bases, lubricating characteristics are numerically simulated by coupling the dynamics equation of crank shaft and the modified Reynolds equation of oil film using finite element method. The results show that the load on crank under 50 °C is twice as large as that of 30 °C while the viscosity of bottom oil sump decreases from 1.89 to 1.59 mPa⋅s. Simulation results imply that the minimum oil film thickness decreased to 0.44 µm under 50 °C, in which asperity contact force peaks at 3 N when arithmetic mean roughness is 0.2 µm. Asperity contact force would significantly increase to 174 N if surface roughness is 0.6 µm and boundary lubrication regime is reached. Strategies to increase oil sump viscosity is recommended to avoid adhesive wear in this case. [ABSTRACT FROM AUTHOR]

• The liquid viscosities of [Hmim][Tf 2 N] saturated with R1234ze(E) and R1234yf were reported. • The viscosity was measured based on the dual-capillary method. • The viscosities of the mixtures decreases sharply with increasing the mole fraction of refrigerant. The working pairs of refrigerant/ionic liquids have been proposed and considered as good candidates to substitute the traditional H 2 O/LiBr and NH 3 /H 2 O in the absorption refrigeration cycle. The viscosities of refrigerant/ionic liquid mixtures have greatly influence on the heat transfer and the flow behavior of the fluids and the performance of the absorption refrigeration system. In this work, the liquid viscosity of the mixtures of 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide ([Hmim][Tf 2 N]) saturated with trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) and 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) were reported at the temperatures from 283.15 K to 343.15 K and pressures up to 1.4 MPa. The viscosity was measured based on the dual-capillary method, and the experimental system was developed in our laboratory. Results showed that the viscosities of the mixtures decrease sharply with increasing the mole fraction of refrigerant. The viscosity data obtained in this work were correlated using the modified Setchenow-type equation, Eyring-MTSM model, Eyring-NRTL model, and improved Eyring-NRTL model, and the calculated results of the models were compared. [ABSTRACT FROM AUTHOR]

• New experimental data for solubility and viscosity of R-290/POE ISO 22. • Phase equilibrium was correlated with Peng-Robinson and PC-SAFT equations of state. • Viscosity was correlated with the generalized friction theory (f -theory) • Absolute average deviations of 8.4% (Peng-Robinson), 6.6% (PC-SAFT) and 24.8% (f -theory). Novel experimental data and theoretical calculations of bubble point pressure and liquid-phase viscosity for a propane (R-290)/POE ISO 22 binary system are presented. The experimental setup consisted of an oscillating-piston viscometer connected in series with a synthetic variable-volume PVT cell. Experimental data were acquired for R-290 with mole fractions ranging from 0.2 to 0.8, temperatures between 283 and 353 K and pressures up to 22.5 bar. The phase equilibrium (bubble point pressure) was modelled using the Peng and Robinson (1976) and PC-SAFT (Gross and Sadowski, 2001) equations of state, while the liquid mixture viscosity data were predicted with the generalized friction theory (f -theory) of Quiñones-Cisneros and Deiters (2006). The absolute average deviations associated with the phase equilibrium and liquid viscosity calculations were 8.39% and 6.56% (Peng-Robinson and PC-SAFT), and 24.77% (generalized f -theory). [ABSTRACT FROM AUTHOR]

• A soft-SAFT molecular model is used to describe HFOs for refrigeration. • Density, surface tension, derivative properties and viscosity are perfectly reproduced. • Binary mixtures of HFOs and HFO-HFC are described in agreement with data. • Thermodynamics of ternary mixtures are predicted without any fitting parameter. • The CoP of several new mixtures is evaluated with process simulation. This work presents a thermodynamic model that characterizes 4th-generation hydrofluoroolefins (HFOs)-based refrigerants with the molecular-based soft-SAFT equation of state (Blas and Vega, 1998) as well as its application in process simulations for a selected refrigeration application. The evaluation of the HFOs has been done building on a molecular model transferred from the equivalent hydrofluorocarbons (HFCs), taking advantage of the similarities between the two chemical families. The model has been used to calculate all thermophysical properties of the selected HFOs relevant for their application as refrigerants, including the saturated density, vapor pressure, heat capacity, speed of sound, surface tension and viscosity, providing good agreement with experimental available data. In addition, phase equilibria, interfacial behavior and viscosity calculations have been performed for blends between HFCs and the two most common HFOs, R1234yf and R1234ze(E). The obtained thermodynamic properties have been used for a process simulation of a vapor compression refrigeration system, comparing the 3rd generation refrigerant R410A with these 4th generation blends, including the Coefficient of Performance for different cases, in order to establish the best alternative to R410A. Overall, this work shows how molecular modeling tools can be used now a day, as a complementary tool to generate reliable data for process simulation, in this case related to the search for alternative refrigerants. [ABSTRACT FROM AUTHOR]

La régénération des huiles lubrifiantes peut être considérée comme une option privilégiée à la conservation des ressources énergétiques et à la réduction des dommages causés à l'environnement. Dans ce contexte, le présent travail a été élaboré en vue de démontrer la faisabilité de régénérer l’huile usagée Repsol32 utilisé comme lubrifiant dans le compresseur de synthèse d’ammoniac du complexe Fertial, Annaba. Le traitement à l’acide sulfurique a montré que pour un ratio VAcide/VHuile égal à 1/20 et une température de 40 °C, la viscosité cinématique et la teneur en eau de l’huile usagée sont nettement améliorées. Les valeurs des différents paramètres physicochimiques entrant dans la caractérisation de l’huile traitée (viscosité, humidité, indice de réfraction et densité) répondent bien aux normes d’utilisation des huiles minérales dans les processus de lubrification.

The cis-1-chloro-2,3,3,3-tetrafluoropropene (R-1224yd(Z)) is a new low global warming potential promising working fluid in high temperature heat pumps and organic Rankine cycle. In this study, the thermal conductivity was measured in the temperatures from 317 to 416 K with pressures from 1.0 to 4.0 MPa at liquid phase and from 376 to 453 K with pressures from 0.2 to 1.5 MPa at vapor phase. The combined standard uncertainties of thermal conductivity measurements were estimated to be less than ±2.1% at liquid and ±2.3% at vapor phases. On the other hand, the viscosity was measured over the temperature range of 303–424 K at liquid and from 394 to 475 K at vapor phase up to 4.0 MPa. The combined standard uncertainties were estimated to be less than ±2.95% at liquid and ±3.0% at vapor phases. Moreover, correlations were developed at saturation condition. [ABSTRACT FROM AUTHOR]

• Experimental study on rheological behavior of MWCNT-CuO/SAE50 nanolubricant. • Measuring viscosity at several concentrations, temperatures and the shear rates. • The highest viscosity reduction (−15%) occurred in a volume fraction of 0.0625%. • A comparison was performed between the viscosities of different nanofluids. • The viscosity sensitivity analysis for temperature and volume fraction has been performed. This study discussed the rheological behavior of MWCNT-CuO(30–70%)/SAE50 nanofluid experimentally at the volume fractions of 0–1 percent in the temperature range of 25–50 °C and the shear rate of 666–7998 s-1. Due to a nonlinear relationship between the shear rate and shear stress, nanofluid behavior can be considered close to the non-Newtonian fluids. Nanofluid viscosity reduces by adding nanoparticles at the volume fractions of 0.0625%, 0.125%, and 0.25% (maximum reduction of 15%). Nanofluid viscosity increases at the volume fractions higher than 0.5%, as the maximum viscosity increase, i.e. 14%, occurs at the volume fraction of 1%. Reduction of viscosity at low volume fractions and a small increase of viscosity at higher volume fractions show that this nanofluid can be used in the applications other than lubrication. This study presents for the first time a new mathematical relation for the relative viscosity of MWCNT-CuO(3–70%)/SAE50. In the relation provided to predict the relative viscosity of nanofluid, R2= 0.9453, which indicates its accuracy. This study also discussed the sensitivity of the relative viscosity of nanofluid to temperature and volume fraction. [ABSTRACT FROM AUTHOR]

Highlights • For automotive use, LiBr-based aqueous absorbents are proposed. • Thermophysical properties, such as vapor pressure, of the absorbents were measured. • Thermophysical properties were correlated with proper regression equations. Abstract Absorption refrigerators are expected for automotive use due to their advantage of utilizing waste heat from exhaust gas. The compactness and efficiency of the refrigeration system required for such use indicates a pair of water/lithium bromide (LiBr) as a promising working fluid. However, operation of absorption refrigerators for automotive use would be hampered by the crystallization of LiBr solution, because relatively high concentration of LiBr solution is necessary for automotive use in which the absorber should be air-cooled. Therefore, the crystallization temperature of LiBr solution needs to be reduced. In this study, we focused on LiBr + lithium iodide (LiI) + ethylene glycol (C 2 H 4 (OH) 2) aqueous solution as an absorbent, due to its lower crystallization temperature compared with LiBr solution. We measured the crystallization temperature, saturated vapor pressure, density and viscosity of these solutions with different composition ratios. The measured saturated vapor pressure, density and viscosity were then correlated using proper regression equations. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

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Highlights • Saturated solution temperature of oil sump mixture was proposed and calculated. • Impact of R290 solubility and mixture viscosity in the oil sump were investigated. • Viscosity of R290/NM100 MO mixture was enough to lubricate the journal bearings. • Suggestions about the optimization of suction superheat degree were made. Abstract The solubility of R290 in the oil and the R290/oil mixture viscosity in the oil sump of rotary compressors used in air conditioner are important parameters affecting the compressor reliability, system performance and R290 charged mass in system. In the study, a set of experiments were carried out in both compressor performance test platform and system psychrometric chambers for an R290 rotary compressor with mineral oil having high viscosity. The dynamic viscosity and temperature of R290/oil mixture at some points within the oil sump of compressor, besides the temperature on shell outside corresponding oil sump and the performance parameters of compressor or air conditioner were measured under different cooling and heating conditions. The variation ranges of oil sump mixture viscosity and R290 solubility were given. The saturated solution temperature and superheat degree of oil sump mixture were proposed and calculated. The effect of compressor suction superheat on the oil sump superheat and its effect on solubility and viscosity was analyzed. A greater suction superheat degree was suggested for an R290 air conditioner with mineral oil in terms of compressor reliability because of the low discharge temperature of R290 compressor. [ABSTRACT FROM AUTHOR]

Highlights • Viscosity measurements of R-1233zd(E) are presented. • Correlations were assessed using experimental data by extrapolation method. • Validation of experimental data using Nusselt theory has performed. Abstract Measurements of viscosity of trans -1‑chloro‑3,3,3-trifluoropropene (R-1233zd(E)) in liquid and vapor phases are the key attention of the present study and we developed correlations to predict viscosities of saturated liquid and vapor by extrapolating the data to saturation condition, which are useful in industrial design and simulation. R-1233zd(E) is being introduced as a potential candidate to be an alternative working fluid for high temperature heat pumps and organic Rankine cycles (ORCs). In this work, the viscosity of R-1233zd(E) was measured by a tandem capillary tubes method up to 4.07 MPa pressure over a temperature ranges from 314 K (40.85°C) to 434 K (160.85°C) and 394 K (120.85°C) to 474 K (200.85°C) for liquid and vapor phases, respectively. Total standard combined uncertainties in liquid and gas viscosity measurements are lower than ± 3.0% and ± 3.1%, respectively. On the other hand, there were large deviations between experimental data and REFPROP version 9.1 for the liquid viscosity in a range of -25 to -37% and those of vapor phase are −7 to −16%. Experimental data of condensation heat transfer which cannot be correlated well with Nusselt's theory by REFPROP version 9.1 viscosity give a good agreement by using the present viscosity data. [ABSTRACT FROM AUTHOR]

The viscosities of six environmentally friendly pure refrigerants with low GWP are predicted based on three artificial neural network (ANN) models: back propagation neural network (BPNN), radial biased function neural network (RBFNN) and adaptive neuro fuzzy interface system (ANFIS). A total of 1089 experimental data are used to train and test the models. Temperature, pressure and density are considered as input variables of networks. The optimal parameters are obtained through the stepwise searching method. The predicted values using the three optimized ANN models with values of experimental data are compared. Moreover, the viscosity of the six refrigerants in saturated liquid state are predicted using all three models in a wide temperature range. The results show that the deviations of almost all data are less than 5.0% and the ANFIS has the best performance. [ABSTRACT FROM AUTHOR]

A viscosity model based on the Patel–Teja equation of state has been applied to pure refrigerants and their liquid mixtures. 7490 data points, containing 6481 points for pure refrigerants and 1009 points for binary, ternary and quaternary mixtures, have been used. First, 29 pure refrigerants are selected and the pure-component parameters of the model are then fitted. Subsequently, seven binary mixtures have been used to regress the binary interaction parameters of the model. The resulting binary interaction parameters and pure-component parameters are then used to predict the viscosity of two ternary and one quaternary mixtures. The results show that deviations are generally low for all analyzed compounds and mixtures. (Overall AADs% are 7.44 for pure compounds, 3.37 for binary mixtures, 3.77 for ternary mixtures and 3.36 for a quaternary mixture). This model does not require the property of density, which is one of its main advantages. [ABSTRACT FROM AUTHOR]

The use of superplasticizers in self-consolidating concretes (SCC) is essential to ensure the desired fluidity. Through this experimental work, we aim to study the effect of the superplasticizer dosage on the characteristics of SCC. The rheological properties of the mixtures are studied by means of a high torque rheometer with couette geometry. In addition, tests of EN NF 206 / CN standard were achieved to make a comparison with rheometer tests. The results showed that superplasticizers improve the workability of SCC by significantly decreasing the static and dynamic shear thresholds. However, their effect on the plastic viscosity depends strongly on the dosage used. Moreover, the increase in the superplasticizer dosage is always accompanied by a decrease in the stability of the mixture, which can lead to losses in mechanical strength. [ABSTRACT FROM AUTHOR]

This paper is devoted to investigating the cylindrical collapse of an anisotropic fluid in f( R) gravity. For this purpose, the viscous charged anisotropic fluid dissipating energy with heat flow and shear is assumed. We use the perturbation scheme to develop the dynamical equations for the variables that ultimately lead to the disturbance of the physical variables and the Starobinksy-like f( R) model chosen. The evolution of the matter variables is discussed with the help of these equations. It can be concluded that the range of dynamic instabilities depends on the field strength, density distribution, pressure, and the curvature term of the f( R) model. We find that our results of Newtonian and post-Newtonian regimes reduce asymptotically to general relativity solutions in the limiting case. [ABSTRACT FROM AUTHOR]

Viscosity measurements were performed with a falling cylinder viscometer on difluoromethane (R32) and the refrigerant blend R410A (R32 + R125 with 50% by mass) at the temperatures 313.15 K, 348.15 K, and 393.15 K with pressures of 350 MPa. The measurement results are compared with literature data and with data calculated using an extended corresponding states (ECS) model. The agreement with literature data is closer for R410A than for R32 while the deviations from the ECS model are higher for R410A than for R32. Correlations that represent the new results as functions of temperature and pressure within their uncertainty are also reported. [ABSTRACT FROM AUTHOR]

To select the optimal ammonia–water nanofluids and apply to ammonia–water absorption refrigeration systems (AARS), this paper investigated the influence of heating on viscosity, thermal conductivity and absorbance of binary nanofluids. The hysteresis phenomenon was observed after heating at high temperature which is rarely reported in the literature. Experimental results show that most of nanofluids' thermal conductivity increased by about 3–12% after heating. However, their viscosities increased by as much as 15% to 25% except the γ-TiO 2 ammonia–water nanofluid, which was reduced by 2% to 7%. This study also shows that the trend of viscosity is consistent with the absorbance. Due to fact that the thermal conductivity of γ-TiO 2 /NH 3 –H 2 O mixture increased after heating, while the viscosity decreased, even if the concentration of the base liquid is 12.5% or 25%, therefore it is the optimal choice for practical research in AARS at present. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical and experimental study on the rheological behaviours of a grade of paraffin that is intended for use in environmental control systems for the purpose of thermal storage. This research concentrates on the paraffin flow properties in a laminar flow. In the experiments, when the paraffin temperature is greater than 291.15 K, the rheological behaviours of the paraffin obey the power-law principles. However, as the paraffin temperature reduces to 291.15 K or lower, the behaviour index tends to decrease with the shear rate, and thus, the rheological behaviours of the paraffin cannot be defined by the power-law model effectively. In the non-power-law phase, the solid properties of the material become increasingly apparent as the temperature gradually reduces. Simultaneously, the paraffin fluidity decreases. Therefore, a new phenomenological model of binary-series viscosity is proposed. The binary model provides an effective definition of the rheological properties of the paraffin in the non-power-law phase (the corresponding material temperatures range from 291.15 K to 288.15 K). In general, the paraffin-specific pressure drop in a horizontal pipe is approximately 1.4–6.0 times that of water at the same temperatures. [ABSTRACT FROM AUTHOR]

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Lubricating oils play several key roles in compressors, such as lubrication of the parts exposed to friction, prevention of gas leakage at the compression chamber, and cooling of the pieces heated by friction. Oil viscosity and possibility of mixing with refrigerant are the significant factors that should be considered in choosing compatible lubricants. Generally, high viscosity lubricants reduce the efficiency and lubricants with low viscosity cause to direct contact between the metal parts in the compressor. In this study, an experimental procedure has been carried out to investigate the influences of oil circulation in the compressor working with R-404a refrigerant. Although this study has been devoted to a detailed attempt to identify the effects of oil viscosity on energy consumption, an innovative way to analyze this critical parameter has been carried out in parallel with other parameters including refrigerant charge amount, condenser water flow rate and air temperature in the evaporator. The sample oils selected for experiments are SL22, SL68 and SL220. The basic nature of the lubricants and their mixtures with refrigerant, COP value, compressor efficiency and exergetic efficiency of the system has been analyzed under different working conditions. [ABSTRACT FROM AUTHOR]

This paper presents liquid kinematic viscosity, density, and thermal conductivity measurements of eleven different synthetic polyolester-based nanoparticle nanolubricants (dispersions) at atmospheric pressure over the temperature range 288 K to 318 K. Aluminum oxide (Al 2 O 3 ) and zinc oxide (ZnO) nanoparticles with nominal diameters of 127 nm and 135 nm, respectively, were investigated. A good dispersion of the spherical and non-spherical nanoparticles in the lubricant was maintained with a surfactant. Viscosity, density, and thermal conductivity measurements were made for the neat lubricant along with eleven nanolubricants with differing nanoparticle and surfactant mass fractions. Existing models were used to predict kinematic viscosity (±20%), thermal conductivity (±1%), and specific volume (±6%) of the nanolubricant as a function of temperature, nanoparticle mass fraction, surfactant mass fraction, and nanoparticle diameter. The liquid viscosity, density and thermal conductivity were shown to increase with respect to increasing nanoparticle mass fraction. [ABSTRACT FROM AUTHOR]

This paper presents experimental data for the density, solubility, viscosity and capillary constant for solutions of the natural refrigerant isobutane (R600a) with mineral compressor oil and nanoparticles Al 2 O 3 and TiO 2 over a wide range of temperatures and concentrations. Based on obtained information for the capillary constant, the surface tension of the solutions isobutane/mineral oil/Al 2 O 3 nanoparticles and isobutane/mineral oil/TiO 2 nanoparticles is determined. SP-QSPR (Scaling Principles–Quantitative Structure Property Relationship) model has been successfully applied for fitting the experimental data obtained for solutions of isobutane with mineral compressor oil and nanoparticles Al 2 O 3 and TiO 2 . It was shown that the nanoparticle additives lead to increase of the viscosity and reduce surface tension of the refrigerant/oil solutions. [ABSTRACT FROM AUTHOR]