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• The structural model was constructed for a water evaporator operating in a low-pressure environment. • A multi-objective optimization method combining CFD simulations and the MO-SHERPA algorithm was proposed. • The offset strip fin structure and heat transfer performance of the water evaporator was optimized. The aim of this study was to investigate the optimal heat transfer performance and structure of airborne water evaporators in low-pressure environments. To achieve this, a multi-objective optimization design was performed on a plate-fin water evaporator with offset strip fins, operating in a low-pressure environment at an absolute pressure of 7 kPa. The multi-objective Simultaneous Hybrid Exploration that is Robust, Progressive and Adaptive (SHERPA) (MO-SHERPA) algorithm was used to optimize the structure of the plate–fin water evaporator under a low pressure of 7 kPa. There are three conflicting optimization objectives, including comprehensive performance factor (JF), entropy generation (S gen), and weight. The optimal Pareto frontier design points were compared and analyzed based on the three evaluation indicators. The optimization results showed that compared with the initial design point, the JF increased by 32.14% and the weight decreased by 48%, which indicated that the heat exchange performance has been significantly improved, and the weight of the heat exchanger was also reduced. The internal and external flow fields of the water evaporator, including temperature, pressure, and volume fraction of vapor, were qualitatively compared to prove the optimization effect. In addition, the influence of structural parameters on the heat transfer performance of the water evaporator were analyzed. The method proposed in this study can effectively optimize the fin structural design parameters, providing valuable guidance for the structural design of water evaporators operating in low-pressure environments. [ABSTRACT FROM AUTHOR]

• Experimental data for the thermodynamic properties of the nanofluids is presented. • Influence the fullerenes additives on thermodynamic properties is studied. • Fullerenes increase the specific isobaric heat capacity of mineral compressor oil. • Fullerenes affected the specific isobaric heat capacity, enthalpy, entropy of ROS. In present study a new experimental data for the saturated liquid density and saturated vapor pressure along the boiling line for the solutions of the "natural" refrigerant isobutane (R600a) with mineral compressor oil and solutions of R600a/compressor oil/fullerenes C 60 is presented. Moreover, a new experimental data on the specific isobaric heat capacity, enthalpy and entropy along the boiling line for the R600a/compressor oil solutions is reported. Experimental data of the two-phase isochoric heat capacity was obtained for different compressor oil fraction in the refrigerant in the temperature range from 260 to 330 K. Obtained information was used to calculate the caloric properties of the R600a/compressor oil solutions. In addition, an influence of fullerene C 60 on the specific isobaric heat capacity of mineral oil was examined. The measurements of the heat capacity for the R600a/compressor oil solutions, pure compressor oil and compressor oil containing fullerenes C 60 were performed using an experimental setup that implements a direct heating method in adiabatic calorimeter. In addition, the heat capacity of oil and oil containing fullerenes C 60 have been measured using differential scanning calorimetry. Finally, the heat capacity increase for the compressor oil with the additives of 0.0020 kg kg−1 of fullerenes C 60 was observed. [ABSTRACT FROM AUTHOR]

Highlights • The quality of experimental VLE data for ammonia–water mixture was evaluated. • Existing models for correlation of enthalpy and entropy were analyzed. • A new correlation was established for calculation of enthalpy and entropy. • New equations can be used for pressures up to 100 bar and temperatures up to 535 °C. Abstract In this paper we have reexamined the published correlations for liquid and vapor enthalpy and entropy data in order to obtain statistical proof that the correlations are in accordance with the databanks found in the open literature. In this process few new correlations were found to be with better accordance with data banks. After reconsiderations we have concluded that new correlations proposed hereby have to be given the preference rather than the previously published correlations. [ABSTRACT FROM AUTHOR]

Highlights • Conceptual and operating performances analysis of a solar absorption refrigeration cycle. • Quasi-real irreversible cycle operating in transient regime. • Application of the first and the second laws of thermodynamic. • Total entropy generation is acquired and the performances are examined at various operating conditions. • The stagnation temperature of the solar collector is needed to approach the real operations. Abstract The performances of a solar absorption refrigerator cycle are investigated. The cycle is considered as a real irreversible plant operating in transient regime. The total entropy generation is acquired applying the two laws of thermodynamic and the performances are examined at various operating conditions. The results show that high efficiency value is obtained at high control temperature. The increase of this temperature allows reaching the minimum time to reach a prescribed cooled-space temperature. Greatest and optimal values of the stagnation temperature of the solar collector are needed to approach the real operations. The minimum time and the dimensionless size of the solar collector are significantly affected by both the cold thermal load and the thermal conductance of the walls. [ABSTRACT FROM AUTHOR]

Machine 2R is necessary in order to avoid the release of refrigerant during the repair of an air conditioning machine. The main goals of this paper are to determine the rate of exergy transfer, the rate of exergy destruction and the rate of exergy change in the compressor, condenser, oil separator and 2R machine. This study also determines the performance of the 2R machine. Pressure, temperature and mass of the refrigerant were measured every 0.5 minutes for 10 minutes. In conclusion, the results of this analysis show that the rate of destruction exergy in the compressor is 59.98%, and 25.37% in the condenser. The value of the Residual Trapped Refrigerant (RTR) of recycling and recovery machine meets the AHRI standard, that is, 34 grams, and the value of the Refrigerant Loss (RL) complies with the AHRI standard, which is 10 grams, while its performance is 91.2%. [ABSTRACT FROM AUTHOR]

The purpose of this investigation is to study the efficiency of a R134a ejector operating with three different mixing chambers by means of a CFD based entropy generation analysis. With the aid of the differential equation for entropy, the local entropy generation is pursued. Using this method, the areas where the irreversibilities occur are identified and geometry improvements suggested. The novelty of the numerical procedure presented herein is that the bulk entropy generation is analysed by means of four sources related with viscous dissipation and heat transfer, divided in mean and fluctuating terms. Entropy generation within the boundary layer has also been considered. The latter has proved to be small, as well as the heat transfer contribution. The fluctuating viscous dissipation accounts for more than 75% of the added entropy, being its main sources the shear layer after the nozzle exit and the shock wave trains, independently of their position. [ABSTRACT FROM AUTHOR]

Abstract: Ammonia/LiNO3 and ammonia/NaSCN absorption refrigeration cycles are alternatives to ammonia/water cycles for refrigeration applications at temperatures below 0 °C. They exhibit higher coefficient of performance (COP) values and do not require purification of the refrigerant vapor. Entropy data for such solutions calculated using their most recently published thermophysical property data; we study and compare the cycles thermodynamically. The simulation results are used to examine the influence of various operating parameters on performance and the possibility of crystallization in these cycles. It is shown that, for low generator temperatures, ammonia/LiNO3 cycles have better performance. For high generator temperatures, ammonia/NaSCN cycles have better performance, but the range of allowable generator temperatures is quite limited for this mixture. [Copyright &y& Elsevier]

Abstract: This study presents a numerical model that is applicable to fin-and-tube condensers with complex refrigerant circuitry, and can be used to describe the exergy loss on the refrigerant side. The model was validated by comparing numerical results with experimental data for an R410A multi-pass condenser. The modeled and measured heat transfer rates were observed to agree with an error of less than 10%. Refrigerant-side performance was analyzed according to the design parameters using the numerical model, and appropriate performance evaluation criteria (PEC) were established for the refrigerant side of the condenser. A methodology was developed for refrigerant circuitry design based on entropy generation minimization (EGM). The resulting refrigerant circuit design enhanced heat transfer performance and lowered entropy generation in comparison to simple refrigerant circuitries. [Copyright &y& Elsevier]

Abstract: With refrigerant charge reduction concern we introduce a new criterion, the so-called Ecological Cost (EC), and establish its relevance for HEXs design optimization. EC takes into account both entropy generation in the HEX and its refrigerant charge by the special environment cost values c and c’. EC minimization is conducted with given heat flux rate or given temperature difference. Results show that optimal design value depends on device life duration and on c/c’ Leakage effect can also be included in EC. We establish a link between EC and TEWI and show that optimal EC leads to optimal TEWI. We deal in the second part of this paper with volumes optimal allocation of cold and hot heat exchangers under given total volume or total refrigerant fluid mass constraint when assuming reversible cycle. [Copyright &y& Elsevier]

Abstract: Optimization of evaporators in refrigeration systems, for instance, can be conducted using entropy generation as a criterion. The latter can be used for choosing a technology (smooth tubes, enhanced tubes, tube diameter, etc) or selecting a fluid. Once this optimization is performed, the refrigerant charge can be evaluated. In this paper, different entropy generation expressions are presented for a diabatic two-phase flow of a pure refrigerant and a refrigerant–oil mixture. These expressions are developed based on the separated flow model. Depending on the boundary conditions, the equations are different and the conclusions differ from one to the other. It is shown that for a heat flux condition at the tube wall, the use of enhanced tubes is recommended at low mass velocities whereas, the use of smooth tubes is better at higher mass velocities. On the contrary, for a constant wall temperature, the use of enhanced tubes is always better than smooth tubes. The role of oil is also emphasized. The higher the oil concentration in the refrigerant, the higher the entropy generation. [Copyright &y& Elsevier]

Abstract: The present work addresses a simplified procedure for the calculation of certain parameters in the Tao-Mason (TM) equation of state needed to estimate thermodynamic properties of 12 ozone–friendly refrigerants fluids. The calculations cover wide ranges extending from the dilute vapor or gas to highly compressed liquid and supercritical region. The theoretical equation of state (EOS) is that of Tao and Mason which is based on statistical mechanical perturbation theory. The novelty of the present work is that we use two scaling constants, the enthalpy of vaporization and the molar density, both evaluated at the normal boiling temperature. This approach contrasts with the original procedure that employs five scaling constants including the critical temperature, the critical pressure, the Boyle temperature, the Boyle pressure and the acentric factor for calculating three parameters second virial coefficient and temperature-dependent parameters. The modified TM EOS predicts thermodynamic properties with equal or better accuracy than those emerging from the original TM EOS. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this work is to investigate the entropy generation in ice slurry pipe flow. Fully developed laminar flow is considered with uniform heat flux at the walls. The fluid behaves as a non-Newtonian fluid following the power-law model. Expressions for velocity, entropy generation number and average entropy generation number are obtained as function of mass fraction of ice and the dimensionless group parameter. [Copyright &y& Elsevier]

Abstract: Objective: Comparison between BIS (Bispectral Index) and state (SE) and response (RE) entropy during laparotomy for inflammatory bowel disease patients (IBD) and evaluation of the variations of RE and SE during nociceptive stimulation. Study design: Prospective, observational study. Patients and methods: Fourteen IBD''s patients undergoing laparotomy were included. Anaesthesia aimed to maintain BIS between 40 and 60 by isoflurane and nitrous oxide. Analgesia was performed by sufentanil bolus administrated according to an increase of 20% of systolic blood pressure (SBP) and heart rate compared with the baseline values. BIS, RE and SE were measured at each nociceptive stimulation. A variance analysis (Anova) was used to assess BIS, RE and SE variations throughout surgery (p <0.05 as significant). Relationship between BIS, RE and SE was assessed by Pearson correlation (p <0.01 as significant). The ability for SE and RE to predict depth of anaesthesia and intraoperative analgesia was performed by calculating aera under the receiver operated curves (AUC). Results: BIS and entropy parameters had strictly the same evolution during anaesthesia. SBP increased significantly during nociceptive stimulation while no variation of RE was observed. A significant correlation was shown between BIS, RE and SE. The evaluation of anaesthesia depth was good for RE (AUC: 0.932±0.26) and SE (AUC: 0.926±0.27). There was however no difference between RE and SE to predict analgesic requirement. Conclusion: Because RE includes muscular frequency analysis, it does not allow analgesic requirement evaluation in paralyzed patients. [Copyright &y& Elsevier]

Abstract: Replacing and selecting materials for different engineering applications is relatively common. It must be noted that in some cases, there is more than a single definite criterion for selecting the right kind of material. The designers and engineers have to take into account a large number of material selection criteria. Experts usually apply trial and error methods or build on previous experimentation. In this paper, a new approach has been carried out for the use of the ELECTRE: ELimination Et Choix Traduisant la REalité (ELimination and Choice Expressing the REality) model in material selection. By producing a material selection decision matrix and criteria sensitivity analysis, ELECTRE has been applied to obtain a more precise material selection for a particular application, including logical ranking of considered materials. A list of all possible choices from the best to the worst suitable materials can be obtained taking into account all the material selection criteria, including the cost of production. This work shows that ELECTRE can be used successfully in selecting a suitable material for the particular application of a loaded thermal conductor. There is good agreement between the results of the methods being used and available data in Cambridge Engineering Selector (CES) databases. A computer program, Mathematica has been developed to facilitate the application of the method to other types of material selection problems. [Copyright &y& Elsevier]

Abstract: LiBr aqueous solution has been the most popular choice in absorption cooling industry. As increasing interest is paid to the exploitation of its unconventional working range for various new applications, the need of a wide-ranging thermodynamic description of the solution has been growing. In order to meet the observed need, this paper presents a Gibbs energy equation valid for the solutions in the concentration range from 0 to 70 LiBr wt% and the temperatures from 0 to 210°C with the equilibrium pressures ranging from 74 to 1MPa. The osmotic coefficients were determined for 405 experimental density and 487 vapor pressure data collected from the literature. A function for the partial molar enthalpy of infinitely dilute solution has been developed and the resulting enthalpy and entropy values are evaluated. [Copyright &y& Elsevier]

Abstract: Temperature–entropy (T–s) diagrams have the unique capability of being able to quantify processes in terms of both the first and second laws of thermodynamics. Although use of generalised T–s diagrams has been made to indicate or represent generalised absorption cycles, with the exception for NH3/water systems, these diagrams have not been specifically tailored to scale to quantify LiBr/water systems. The main barrier for this is that the diagram needs to represent the necessary properties of both the refrigerant (water) and of the solution (LiBr/water). This paper describes the use of the T–s diagram of water extended with additional curves to represent real and ideal LiBr/water absorption cycles. An explanation is provided on several methods available, including details of the thermodynamic justification of the method that was used, to construct the extended diagrams. Finally, the extended T–s diagram is provided with the representation of a real single-effect LiBr/water absorption refrigeration cycle. This should prove to be a valuable tool for design and research engineers to study and optimise LiBr/water chillers. [Copyright &y& Elsevier]

In this work an original improvement of the Corresponding States technique is developed and a new model, based on a three parameters CS format, is proposed to predict the enthalpy and the entropy of the new generation halogenated alkanes fluids together with some alkanes. Limiting the analysis of the selected fluids to a specific thermodynamic property behaviour, an appropriate conformality approach can be deduced, which allows to set up a predictive model of high accuracy level on a wide range of the enthalpy and entropy surfaces. The fundamentals of the model are innovative scaling parameters deduced from the enthalpy of vaporization and from two dedicated equations, belonging to the selected family of fluids. This allows to set up innovative models following a CS format. Through the introduction of advanced mixing rules, the models can be simply extended to calculate the corresponding properties for mixtures. The proposed models allow also the calculation of VLE for systems of rather regular behaviour. The required inputs for a pure target fluid are an ideal gas isobaric heat capacity correlation, a single value of saturated liquid density and of vaporization enthalpy; if the last one is lacking, a single value of vapor pressure can be alternatively supplied. For non azeotropic mixtures the enthalpy and entropy models are predictive, whereas in case of azeotropy VLE calculations are possibly only applying regressed interaction coefficients. Due to the lack of accurate experimental enthalpy data and to the particular nature of the entropy function, the validation of the models is proposed against fundamental dedicated EoS available, both for pure and mixtures, for a significant number of the studied family of fluids. The predictive character of the proposed approach as well as the high performances reached, make these models particularly suitable for the new families of fluids regarding advanced technological applications. [Copyright &y& Elsevier]

In this paper, we find optimal constants of a special class of Gagliardo–Nirenberg type inequalities which turns out to interpolate between the classical Sobolev inequality and the Gross logarithmic Sobolev inequality. These inequalities provide an optimal decay rate (measured by entropy methods) of the intermediate asymptotics of solutions to nonlinear diffusion equations. [Copyright &y& Elsevier]

Abstract: Objective: Evaluate the supply of entropy monitoring on anaesthetic drugs consumption, haemodynamic stability, and recovery time in patients undergoing embolisation of cerebral artery aneurysm (asymptomatic or low Hunt and Hess grades). Methods: Two groups, G1 without entropy monitoring (Datex-Ohmeda S/5™), G2 with entropy monitoring (16 patients in each group). Each group had similar anaesthetic protocol (propofol target control infusion and continuous intravenous infusion remifentanil). For G2, the state entropy (SE) values were kept between 35 and 45. We studied anaesthetic drug consumption, arterial pressure parameters, extubation delay and feasibility. Statistical analysis used Mann and Whitney test, Fisher test. Significativity was p <0.05. Results: No intraoperative incident. Propofol consumption was lower in G2 (7.49±2.28mg/kg per hour versus 9.46±2.50mg/kg per hour; p <0.05). A tendency to reduction was observed for remifentanil consumption (6.65±2.04μg/kg per hour versus 7.94±2.92μg/kg per hour; p =0.056), and extubation delay (14.1±8.6min versus 26.5±22.0min; p =0.056), in G2. The entropy monitoring had no repercussion on haemodynamic stability, but the arterial pressure values were significantly higher in G2 (73.60±8.49mmHg versus 67.10±5.58mmHg). Entropy captor does not disrupt embolisation procedure. Coils liberation alter temporarily RE and SE values. [Copyright &y& Elsevier]