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Les infirmières de pratique avancée sont actuellement formées et intégrées progressivement dans les équipes cliniques françaises. Dans certains pays comme le Royaume-Uni, elles sont déjà incluses depuis plusieurs années avec la délégation de gestes techniques comme l'ablation de sonde JJ en ambulatoire. L'expérience britannique montre qu'il existe une liberté quant aux gestes techniques autorisés avec une gestion locale par le coordinateur d'équipe, en accord avec les textes officiels. Il existe cependant des différences d'accès au titre d'infirmière de pratique avancée selon les pays, avec une difficulté plus importante dans le curriculum français. L'urologie doit intégrer ces nouveaux acteurs du soin pour améliorer la prise en charge des patients. Clinical Nurse Specialists (CNS) are currently being trained and progressively integrated into French clinical teams. In some countries, such as the UK, they have already been included for several years, with the delegation of technical procedures such as the removal of ureteral stents on an outpatient basis. The UK experience shows that a "grey zone" exists around the authorized technical procedures for CNS with local management by the team coordinator, in accordance with official texts. However, access to the title of CNS varies among countries, with greater difficulty in the French curriculum. French Urology needs to involve these new actors into the patient's care, as they are being integrated in other medical fields. [ABSTRACT FROM AUTHOR]

Les avancées technologiques en endo-urologie font désormais de l'urétéroscopie souple (URSS) une technique de choix pour traiter les calculs urinaires mais aussi un casse-tête lorsqu'il s'agit de choisir son équipement. La mise en place d'un guide de sécurité au sein des cavités rénales (nitinol, 0,035″, « stiff ») par cystoscopie rigide est non obligatoire mais constitue un critère de sécurité. Il en est de même concernant les gaines d'accès urétéral, celles avec aspiration étant en cours d'évaluation. Si leur utilisation réduit la pression et la température au sein des cavités rénales facilitant la vision, leur insertion peut occasionner des lésions urétérales. Les systèmes d'irrigation utilisant la gravité avec pompe manuelle sont à privilégier pour minimiser le risque de barotraumatisme. Le choix de l'urétéroscope est complexe : diamètre, capacité de déflexion, position du canal opérateur et qualité de vision sont à considérer. Aussi, il est difficilement envisageable de n'utiliser qu'un modèle endoscope pour l'intégralité des URSS. Les lasers Holmium:Yttrium-Aluminium-Grenat (Ho:YAG) et Thulium Fibré (TFL) sont aujourd'hui recommandés pour le traitement des calculs urinaires en URSS, avec un avantage potentiel du TFL pour la pulvérisation fine. Les paniers sont nombreux et divers, leur taille et forme devant également être considérées avant acquisition. En fin d'intervention, un drainage urétéral n'est pas systématique, mais les sondes JJ en silicone ont montré des risques d'incrustation et de gêne fonctionnelle plus faibles que les sondes faites de polyuréthane. Flexible ureteroscopy is now widely used as the preferred option to surgically treat a urinary stone, due to several technological advancements. Thus, choosing the adequate equipment is challenging, but respects safety concepts. Indeed, placing the safety wire (nitinol, 0,035″, "stiff") under rigid cystoscopy is not mandatory but improve safety. Regarding ureteral access sheath (UAS), considerations are similar: UAS facilitates vision, pressure and temperature control but can also be responsible of ureteral injuries at insertion. Suction devices are now under evaluation and could not be discussed. To limit the barotrauma risk, irrigation devices with manual pumps should be used (40 cmH 2 0). Choosing a flexible ureteroscope (fURS) is challenging; a special attention has to be given to size, deflexion, working channel position and vision. Thus, using a single fURS is hardly imaginable. Both Holmium:Yttrium-Aluminium-Garnet (Ho:YAG) and Thulium Fiber (TFL) lasers are recommended to treat urinary stones during fURS, with a potential advantage of TFL on thin pulverization. A wide variety of baskets exists and size and shape have to be considered before acquisition. Finally, if ureteral stenting is not mandatory in uncomplicated cases, silicone stents present a lower risk of encrustation and stent-related symptoms compared to polyurethane ones. [ABSTRACT FROM AUTHOR]

Décrire la technologie du laser Thulium:Yttrium-Aluminium-Garnet pulsé (p-Tm:YAG) et ses résultats actuels pour lithotritie laser endocorporelle. Une revue de la littérature, interrogeant les bases Pubmed, Scopus, et Cochrane a été conduite en janvier 2024 utilisant les mots clés « laser », « pulsed Thulium:YAG », « stones » et « lithotripsy ». De par les faibles niveaux de preuve et nombre de publications, une revue narrative de la littérature a été réalisée. Le laser p-Tm:YAG est un laser à cavité avec un cristal YAG dopé aux ions thulium, pompé par des diodes laser. Avec une longueur d'onde du faisceau laser de 2013 nm, il présente un coefficient d'absorption dans l'eau intermédiaire entre le laser Ho:YAG et TFL. Le diamètre minimal utilisable des fibres laser est de 200 μm. Différentes modulations impulsionnelles sont proposées visant à minimiser la rétropulsion des calculs avec notamment une puissance crête (Peak Power) réglable (≥ 800 W). De multiples études comparatives in vitro suggèrent que la capacité du p-Tm:YAG à fragmenter les calculs serait similaire à celle de l'Ho:YAG ; au contraire, sa capacité à pulvériser (dusting) tous types de calculs serait similaire à celle du TFL, avec une faible rétropulsion. Une seule étude in vivo a confirmé la faisabilité de la lithotritie du p-Tm:YAG au cours d'une urétéroscopie souple avec des taux de sans fragment résiduel (< 3 mm) et zéro fragment résiduel de 95 % et 55 %, respectivement. Aucune étude comparative n'est disponible à ce jour. Le nouveau laser p-Tm:YAG pulsé pourrait représenter un compromis sûr et efficace entre le laser Ho:YAG et le TFL pour la lithotritie laser endocoporelle mais des études comparatives, notamment avec le TFL sont nécessaires pour définir sa place dans l'arsenal thérapeutique. To describe the pulsed-Thulium:Yttrium-Aluminum Garnet (p-Tm:YAG) laser technology and its current evidence for endoscopic laser lithotripsy. A literature review, querying PubMed, Scopus, and Cochrane databases, was conducted in January 2023 using keywords "laser", "pulsed Thulium:YAG", "stones" and "lithotripsy". Due to the limited level of evidence and the number of publications, a narrative literature review was undertaken. The p-Tm:YAG laser is a cavity laser with a thulium-doped YAG crystal, pumped by laser diodes. With a laser beam wavelength of 2013 nm, p-Tm:YAG presents an intermediate absorption coefficient in water between Ho:YAG and TFL lasers. The minimal usable diameter of laser fibers for this technology is 200 μm. Various pulse modulations are proposed to minimize stone retropulsion, including adjustable peak power (≥ 800 W). Multiple in vitro comparative studies suggest that p-Tm:YAG's ability to fragment stones is similar to that of Ho:YAG, while its ability to dust various types of stones is similar to TFL, with low retropulsion. A single in vivo study confirmed the feasibility of p-Tm:YAG lithotripsy during flexible ureteroscopy, with stone-free (< 3 mm) and zero-fragment rates of 95% and 55%, respectively. No comparative studies are available to date. The new pulsed p-Tm:YAG laser could represent a safe and effective compromise between Ho:YAG and TFL for endoscopic laser lithotripsy, but comparative studies, especially with TFL, are necessary to define its role in the therapeutic arsenal. [ABSTRACT FROM AUTHOR]

Les lasers sont aujourd'hui des outils incontournables en endourologie, aussi bien pour le traitement des calculs urinaires, que des tumeurs urothéliales (vésicales ou du haut appareil) ou de l'hypertrophie bénigne de prostate. Si pendant une trentaine d'années, le laser Holmium : Yttrium-Aluminium-Grenat (Ho:YAG) a été l'acteur prépondérant pour ces applications, les lasers thulium fibré (TFL) et Thulium : YAG (Tm:YAG) sont aujourd'hui des alternatives grandissantes. Les TFL et Ho:YAG sont désormais recommandés pour le traitement des calculs urinaires, un manque de données cliniques limite les recommandations concernant le Tm:YAG. Pour le traitement des lésions urothéliales (énucléation « en-bloc » vésicales ou vaporisation des lésions du haut appareil urinaire), Ho:YAG, TFL et Tm:YAG sont utilisables mais il n'est pas possible à ce jour de recommander une source laser en particulier. De la même manière, ces trois sources lasers semblent utilisables pour réaliser une énucléation endoscopique de prostate, bien que le recul soit plus important pour l'Ho:YAG. Les techniques chirurgicales et les courbes d'apprentissage vont dépendre de la source laser, responsables d'effets bien différents, qu'il faut donc prendre en considération avant d'acquérir un générateur laser. Nowadays, laser technology has become the gold standard for many endourological applications, encompassing the treatment of urinary calculi, urothelial tumors (bladder or upper tract), and benign prostatic hyperplasia. While the Holmium: Yttrium-Aluminum-Garnet (Ho:YAG) laser dominated these applications for about thirty years, thulium fiber laser (TFL) and Thulium: YAG (Tm:YAG) lasers are emerging as growing alternatives. TFL and Ho:YAG are now recommended for urinary calculi treatment, but a lack of clinical data limits recommendations for Tm:YAG. For urothelial lesion treatment ("en-bloc" enucleation of a bladder tumor or vaporization of upper urinary tract lesions), Ho:YAG, TFL, and Tm:YAG are usable, but it is not currently possible to recommend a specific laser source. Similarly, these three laser sources appear usable for endoscopic prostate enucleation, although there is more extensive experience with Ho:YAG. Surgical techniques and learning curves will depend on the laser source, which can produce different effects, requiring careful consideration before acquiring a laser generator. [ABSTRACT FROM AUTHOR]

La cystinurie est une maladie monogénique induisant une perte de fonction d'un transporteur d'acides aminés dibasiques impliqué dans la réabsorption de cystine au niveau des tubules rénaux proximaux. L'excrétion urinaire de cystine chez ces patients est augmentée d'un rapport 10 à 60 par rapport au sujet sain, responsable d'une sursaturation avec précipitation de cristaux de cystine dans les reins et de calculs dans les cavités excrétrices. La physiopathologie de la cystinurie est particulière : la concentration plasmatique de cystine est souvent normale alors que l'absorption intestinale est diminuée. Ce paradoxe est expliqué par une absorption intestinale préservée de cystéine et de méthionine qui sont deux acides aminés soufrés métabolisés notamment en cystine. Le principe du traitement consiste à empêcher la formation de cristaux de cystine dans les reins afin de prévenir la survenue d'une maladie lithiasique, mais aussi d'une authentique néphropathie cristalline responsable d'une insuffisance rénale chez plus de la moitié des patients. Le traitement médical des patients cystinuriques repose (1) sur une diminution de l'excrétion urinaire quotidienne de cystine qui est le reflet de l'absorption intestinale et donc des apports en méthionine ; (2) sur une augmentation du seuil de solubilité urinaire de la cystine afin de prévenir une précipitation cristalline intratubulaire et intracavitaire par une dilution et une alcalinisation des urines avec des valeurs cibles de 3 L et un pH urinaire aux alentour de 7,5. Le traitement par sulfhydryle dont le but est de dissocier les ponts disulfures des molécules de cystine avec un effet modeste sur la dissolution des calculs de cystine constitués ne devrait en toute logique être utilisé en dernier recours une fois les mesures diététiques et la cible de pH urinaire obtenue. Cystinuria is a dibasic amino acid transporter molecular defect preventing cystine reabsorption within renal proximal tubules. A 10 to 60 fold increase of urine cystine concentration compared to healthy subjects is responsible for pure cystine crystal onset within tubules and stones in the urinary tract leading to chronic renal failure in half cases. Plasma cystine concentration is usually reported in the normal range despite a decreased cystine intestinal absorption. This discrepancy is explained by a preserved intestinal absorption of cysteine and methionine, two sulphur amino acids which are partly metabolized into cystine. Monitoring and treatment is based on a pathophysiological approach aiming at decreasing both urine cystine excretion and concentration but also increasing urine cystine solubility (i.e. raising urine pH). Guidelines are thus based upon a methionine restricted diet, a water intake target of 3 liters/day and a urine pH target of 7.5. Sulfhydryl treatment (mainly tiopronin), frequently used in France in order to dissociate cystine disulfur bonds has a moderate effect on cystine stones solubilization and thus should be consider, to our view, only after diet and urine goal targets are reached. [ABSTRACT FROM AUTHOR]

In this work, the free-volume theory (FVT) was extended to modeling the viscosities of 24 hydrofluorocarbon refrigerants, and applied to predict the viscosities for the mixtures of hydrofluorocarbon refrigerants. It is the first time to apply the FVT to the viscosities of ternary mixtures of hydrofluorocarbon refrigerants. Hydrofluoro-olefins (HFOs) are a new class of refrigerants, which are identified as promising refrigerants because they have low global warming potential, were studied in this paper. For the viscosity of pure refrigerants, the average absolute relative deviations between the FVT calculation and experiment are less than 1.5%. When calculating the viscosities of the mixtures of hydrofluorocarbon refrigerants, three mixing rules without more parameters were tested and compared, the average absolute relative deviations between the FVT coupled with the best mixing rule and experiment are less than 6.5%. [ABSTRACT FROM AUTHOR]

Résumé Pathologie fréquente et récidivante, la lithiase urinaire peut évoluer de longues années de façon infraclinique, ou nécessiter un traitement en urgence et engager le pronostic vital. La connaissance de la composition chimique des différents types de calculs conditionne la thérapeutique à adopter. Cette affection nécessite une surveillance régulière et indéfinie pour éviter les récidives. Summary Urolithiasis, a condition requiring monitoring. A frequent and recurrent condition, urolithiasis can be subclinical, evolving over a number of years, or life-threatening and requiring urgent treatment. Knowledge of the chemical composition of the different types of calculi determines the treatment to adopt. This condition requires regular and long-term monitoring to avoid recurrences. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents the results of experimental research on up to 15% ice slurry made from 10.6% ethylene alcohol. It looks at the pressure loss coefficient during its laminar flow through sudden contractions and expansions. The experimental investigations dealing with pressure loss coefficients were preceded by considerations and calculations in the field of the rheological behaviour of the ice slurry. Similarly to what can be found in papers by some other authors, two different types of behaviour were observed, depending on the shear rate values: behaviour close to the Bingham model for the low shear rate region, and for high shear rate values, a power law with a shear thickening behaviour. To predict ice slurry behaviour in both the low and the high shear rate region, the modified Herschel–Bulkley rheological model was suggested. In this model, generalized correlations for the yield stress, the consistency coefficient and the flow index were proposed. [Copyright &y& Elsevier]

Abstract: When simulating refrigeration systems or equipment, knowledge of refrigerant thermodynamic properties is required. Even though the traditional equations of state have the ability to yield all of the thermodynamic properties, these formulations present the disadvantage of their low computational speed and that most of the thermodynamic properties equations are implicit and require iterations. In this paper a hybrid formulation for the calculation of thermodynamic properties of pure refrigerants and refrigerant mixtures is presented. Explicit formulations are obtained to model some properties that are used to predict other thermodynamic properties through differentiation, which assures a fast and stable calculation. As an example the equations for R1234yf and R407C are presented in the paper. The source data for regressing was obtained from REFPROP 9.0. The accuracy of the thermodynamic properties formulae is satisfactory for applications in which computation speed and stability are preferred rather than accuracy. [Copyright &y& Elsevier]

Abstract: The performance of the heat pump can be improved further when running under low temperature conditions when an ejector is used in a heat pump system coupled with economized vapor injection (EVI) scroll compressor. In this paper, the design method of the heat pump system with ejector (EVIe) is presented, and the process for designing the heat pump with ejector has been summarized. The optimal location of the vapor injection inlets is at the place where the vapor can inject into the working chambers when they just be closed. The reasonable value for the entrainment ratio u of the ejector is between 0.1 and 0.2. One prototype heat pump was designed under the condition of the evaporation temperature of −20 °C, and an experimental setup was established to test the prototype. The measured results demonstrated that the heating EER of the heat pump system with ejector could reach about 4% higher than that of the system without ejector when the heating capacity remained nearly constant. [Copyright &y& Elsevier]

Abstract: An analytical solution approach for the simultaneous heat and mass transfer problem in air washers operating as evaporative coolers is presented. A one-dimensional model using the coupled mass and energy balance equations in the air washer is presented. Then, starting from a linear approach for the experimental curve of the air saturation, an analytical solution for the model was derived. The solution showed an excellent agreement with the available results found in the literature. The influence of several important parameters for the cooling process such as temperature and ambient air humidity, air flow rate and feeding water temperature, in the air cooling rate was investigated. The efficacy of the process can be greatly increased by reducing the cooling water temperature and the applied air flow rate. The analytical solution can be easily included into the models used for simulating desiccant air-conditioning systems operating in conjunction with air washers. [ABSTRACT FROM AUTHOR]

Abstract: Enhancement of heat transfer rate through porous fins is one of the common choices nowadays. As the energy equation is highly nonlinear, researchers never concentrated on analyzing porous fins analytically. In the present study, an effort has been devoted to develop an analytical model for determination of the performance and optimum dimensions of porous fins with consideration of different models of predictions. Every result has been presented in a comparative way so that the merit of the models adopting in the present work can easily be understood. The optimum design analysis of porous fins has also been carried out. The influences of all the dependent parameters on the performances and optimization conditions have been studied for the selection of a design criterion of porous fins in such applications where the requirement of heat dissipation is essentially high. [ABSTRACT FROM AUTHOR]

Abstract: The performance of an Internal Heat Exchanger (IHX) operating in a CO2 transcritical refrigeration plant is analysed, from an energetic point of view, in this work. The evaluation is based on experimental data by contrasting the performance of the plant working with (44 tests) and without the IHX (46 tests) at the same operating conditions. The experimental evaluation covers three evaporating levels (−5, −10 and −15 °C), at two different gas-cooler outlet temperatures each (31, 34 °C), for a wide range of gas-cooler operating pressures (74.5–105.9 bar). The thermal effectiveness of the IHX is empirically analysed for the different operating conditions in the first part of the paper. Moreover, the relation of its effectiveness with the operating parameters is presented. The second part is devoted to analyse the modification of the energetic performance of the plant caused by the IHX. The results show a maximum increment on cooling capacity of 12%, an increment of the efficiency of the plant up to 12% and a maximum increase on discharge temperature of 10 °C at −15 °C of evaporating temperature. [ABSTRACT FROM AUTHOR]

Abstract: In this work, M4 cubic equation of state (EOS) (proposed by ) is applied to calculate the saturated properties of refrigerants. A wide range of different types of refrigerants (CFCs, HCFCs, HFCS, etc.) is examined by calculating their saturated pressures, saturated liquid and vapor molar volumes. The comparison between the VLE calculation results and the experimental data, shows that the agreement of this EOS is better than two frequently-used (SRK and PR) EOSs for 42 refrigerants and some of their mixtures. [Copyright &y& Elsevier]

Abstract: In this paper, a general approach in evaluating and optimizing thermoelectric cooler (TEC) performance is presented. Analytical solutions for performance parameters such as cooling capacity and device temperature at both the TEC pellet level and module level are derived in simplified formulation based on the TEC thermal balance equations. The major advantage of the present solutions lies in the fact that the optimal TEC performances can be determined in a straightforward manner, as against the iterative procedure mostly reported in literature. In addition, the module level analysis facilitates the TEC optimization without prior knowledge of pellet details and dimensions. The validity of the present analysis approach is demonstrated by examining TECs of different cooling capacities. Furthermore, the optimization of device temperature for microprocessors under TEC enhanced air cooling and liquid cooling conditions is examined. The effect of hot side to cold side temperature difference is discussed and the thermal resistances at both hot and cold sides are also analyzed within given performance parameters. [Copyright &y& Elsevier]

Abstract: High-temperature heat pumps can be widely utilized for industrial heating as an energy-saving method due to their high condensing temperatures. This paper describes a cycle analysis and experimental study on the performance of a high-temperature heat pump (HTHP) system. The performance comparisons are conducted using performance calculations among the parallel cycles with serial heating on the water side, a two-stage compression cycle and a single-stage cycle. The results show that the performance of the heat pump using parallel cycles with serial heating is the best when the condensing temperature exceeds 75°C. Based on the cycle analysis, a prototype HTHP using parallel cycles with serial heating on the water side with a heating capacity of 700kW was built in this study. Also, a screw compressor was modified due to the high-temperature conditions. The measured performance shows that the HTHP can stably provide an outlet water temperature of up to 85°C with a high coefficient of performance (COP). The experimental results indicate that the average heating capacity and coefficient of performance of the HTHP could be improved significantly in high-temperature conditions due to the parallel cycles with serial heating on the water side and the modified compressor. All the results indicate that the HTHP using parallel cycles and modified compressor with serial heating on the water side is very competitive in industrial heating applications. [Copyright &y& Elsevier]

Abstract: For the analytical solution of a wet fin equation, a relationship between humidity ratio and temperature of the saturation air is necessary. A linearity of this relationship instead of the actual one was chosen by many researchers for the ease of analysis of fins for a specified geometric fin. This aforementioned linear relation does not satisfy in actual case and it can be correlated by humidity ratio as a polynomial function with temperature. In this work, an exercise is devoted to determine the optimum fin profile for both fully and partially wet longitudinal fins with a nonlinear saturation curve. For this establishment, temperature distribution in the fin can be expressed by a class of power law. From the optimization analysis, an optimality criterion is setup individually for the fully and partially wet surface conditions. The optimum fin profile and design variables have been determined as a function of thermo-psychrometric parameters. [Copyright &y& Elsevier]

Abstract: In this paper we represent the performance of an ejector used in the CO2 heat pump water heater system by means of experimental and theoretical studies. This work accounts for the effects of primary flow pressure, entrained flow pressure and back pressure on the entrainment ratio in off-design conditions. The performance of the ejector is experimentally investigated in a CO2-ejector test rig. Using ejector characteristic-curve equations, we provide predictions in good agreement with the experimental data. Furthermore, the model predictions will be utilized as a design tool for optimizing the performance of next generation ejector. [Copyright &y& Elsevier]

Abstract: Due to the negative impact of refrigerants containing Cl and Br on the ozone layer, these refrigerants are being replaced with refrigerants containing fluorine. The article describes the replacing of refrigerant R22 in a cooling system for preparing chilled water, used for cooling reactors producing phenol–formaldehyde resins. After analyzing the existing state and the capabilities of the cooling system, the refrigerant R22 was replaced with refrigerant R407C. For both refrigerants a calculation of the cooling system has been made, the results of which are given in the form of diagrams depending on the evaporation temperature of the refrigerant. Profitability evaluation of replacing a refrigerant was carried out using the method of the net present value (NPV), the coefficient of profitability and the period of time in which the investment is going to return itself. Also the calculations of the savings of electrical energy needed for the running of the compressors and the price of chilled water have been done, using the method of internal profitability level (IPL). [Copyright &y& Elsevier]

Abstract: The computation of the partial and total volume of pressure vessels with various type of head profiles requires detailed knowledge of the head profile geometry. Depending on the type of head profile the derivation of the equations can become very complex and the calculation process cumbersome. Certain head profiles require numerical methods to obtain the partial volume, which for most application is beyond the scope of practicability. This paper suggests a unique method that simplifies the calculation procedure for the various types of head profiles by using one common set of equations without the need for numerical or complex computation methods. For ease of use, all equations presented in this paper are summarized in a single table format for horizontal and vertical vessels. [Copyright &y& Elsevier]

Abstract: Small dimensions found in modern and novel heat exchanger (HX) designs encounter very challenging manufacturing issues. With current manufacturing techniques HXs in small dimensions will exhibit large tolerances relative to design variables. Hence, the anticipated variation in performance is a concern. Furthermore, small flow channel dimensions are very susceptible to severe fouling and even blockage. Therefore, flow distribution would be uncertain. These uncertainties in dimensions and flow distribution should be accounted for during the design and performance evaluation of new HX geometries with focus on ultra-compact designs. This paper outlines an effort to theoretically evaluate the performance of an air-to-water HX, assembled from tubes with non-conventional heat transfer surfaces. Vertical spacing within this HX is subject to a predefined statistical distribution compounded with uncertainty in water flow rate through each flow path (i.e., tube). A new implementation technique for ɛ-NTU is proposed in order to accommodate different air conditions on both tube sides. A Monte Carlo simulation approach is used to estimate the HX performance distribution. This approach is applied to three HX designs showing the performance degradation subject to geometrical and flow uncertainties. The simulation results under uncertainty provided useful insights into the reasons for the performance degradation and showed great impact to the uncertainty distribution. Overall, the proposed HX design with the smallest dimensions showed the least performance degradation due to manufacturing and operating conditions uncertainty. [Copyright &y& Elsevier]

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Abstract: Effects of solute included in a sample on the specific enthalpy of ice are investigated experimentally. In the experiments, ice including the solute was made from an aqueous solution, and the specific enthalpy was measured by melting the ice in the aqueous solution. Moreover, a physical model of the ice including the solute is proposed. As a result, when the concentration of the aqueous solution is set at a value equivalent to the concentration of the sample, the specific enthalpy of the sample increases with the concentration of the sample. The measurement results and the calculated values agree well, and it was found that the method for calculating the specific enthalpy of the sample is valid. Moreover, when the concentration of the aqueous solution is higher than that of the ice including the solute, it was found the calculation method for the specific enthalpy of the sample is appropriate. [Copyright &y& Elsevier]

Abstract: This paper presents a thermal analysis of a defrost cycle in order to design more efficient defrosting mechanisms in household refrigerators and freezers. A simple heat transfer model has been developed to determine energy flows from a defrost heater across various components of a refrigerator/freezer. The study measures power consumption and temperatures of a single temperature vertical empty freezer (in normal operation with and without defrosts) to determine the heat distribution from the radiant type electric defrost heater and its effect on power consumption. The surface temperature of the defrost heater was measured to be 520°C for minimal frost and 560°C for heavy frost. The efficiency of a defrost heater was measured to be 30.3%, while power consumption of the freezer was found to increase by 17.7% due to automatic defrost. [Copyright &y& Elsevier]

Abstract: The characteristics of double stage evaporator/absorber are studied to realize a large temperature difference absorption system. In the case of the double stage evaporator/absorber with the large temperature difference of the chilled water (15°C/7°C), the pressure of the lower stage in the evaporator/absorber is higher than that of the upper stage. And the concentration of the absorber for the double stage is lower than that for the single stage. If the solution flow ratio decreases with a constant concentration of strong solution of 63.7%, COP increases to 1.19 in the double stage system, which is 12.0% higher than that for the conventional system. When absorber and evaporator are divided by the same ratio, the optimum value of UAR for COP improvement is found to be 0.65.When absorber and evaporator are divided by different ratios, the optimum values of UARE and UARA are (0.6, 0.7). [Copyright &y& Elsevier]

Abstract: This paper deals with the performance evaluation of an innovative, waste heat driven dual evaporator type three-bed adsorption cycle for cooling application. The innovative adsorption chiller has two evaporators, three adsorbent beds, and a condenser, and the evaporators work at different pressure levels. The effects of hot water inlet temperature, chilled water inlet and outlet temperatures, and cycle time on the specific cooling capacity (SCC) and coefficient of performance (COP) were predicted by simulation. For the same operating condition, the SCC and COP of the dual evaporator type three-bed adsorption chiller were found to be 1.5 and 1.7 times higher than those of the two-bed single-stage adsorption chiller, respectively. [Copyright &y& Elsevier]

Abstract: A new type of compressor, called an orbiting compressor, is introduced in this paper. The orbiting compressor is characterized by an orbiting piston, and the piston or orbiter consists of a circular base plate and a ring type vane protruding vertically from the base plate. The orbiter is made to orbit in an annular space formed between two concentric circular walls via an Oldham-ring mechanism, producing two sealed gas pockets on both sides of the vane wrap with a 180° phase difference. This operating mechanism leads to alternating compression and discharge processes, which results in low torque variation. The orbiting compressor has been designed for an R410A residential air conditioner with a cooling capacity of 10.0 kW. The performance of the orbiting compressor model has been analytically investigated, where the volumetric, adiabatic and mechanical efficiencies were calculated to be 94.8%, 90.4% and 93.4%, respectively for the ARI condition. The EER was estimated to be about 10.86 with a motor efficiency of 89%. [Copyright &y& Elsevier]

Abstract: Two different definitions of the vapor quality during a diabatic two-phase flow with and without the presence of oil are presented in this paper: the well-known vapor flow quality and the thermodynamic vapor quality. The vapor flow quality is based on the mass flow rates whereas the thermodynamic vapor quality is based on the mass. Two-phase thermodynamic diagrams for pure R-134a and R-134a/oil mixture are plotted for different slip ratios. It is shown that the iso-flow quality lines are moved to lower enthalpies for larger slip ratios. In addition, the maximum vapor flow quality of a fluid/oil mixture is shown to increase when increasing the slip ratio whereas the maximum thermodynamic vapor quality remains constant. In addition, the correct expression of the elementary derivative of the vapor quality is also proposed, highlighting the role of the heat capacity at constant vapor quality. [Copyright &y& Elsevier]

Abstract: This paper presents a theoretical evaluation of the influence of compressor oil admixtures on the thermodynamic performance of a vapor compression system using natural refrigerant R600a. The performance determination is based on the developed pressure–enthalpy diagrams (P–h) for the refrigerant oil solution (isobutane-mineral compressor oil Azmol). A method for calculating the enthalpy of refrigerant–oil solutions has been proposed and the influence of the compressor oil admixtures to isotherms the pressure–enthalpy diagrams has been analyzed. The change of enthalpy at the different oil concentrations in the working fluid in an evaporator has been investigated. An application of the developed refrigerant–oil P–h diagrams for the theoretical evaluation of the efficiency of the vapor compression systems is also demonstrated. [Copyright &y& Elsevier]

Abstract: The implicit curve-fitting method has been used for fast and stable calculations of thermodynamic properties of subcritical refrigerants, and it has to use the saturated liquid or vapor state as the reference state. In order to extend the application range of this method in supercritical region, an isothermal state in the supercritical region is used as the reference state, and the implicit equations for supercritical refrigerants in this state and out of this state are established, respectively. The new calculation method can be used in the entire supercritical region. With the new method, thermodynamic properties of supercritical CO2 and R410A are predicted and compared with REFPROP 8. It shows that the total mean relative deviations of the fast calculation formulae from REFPROP 8 are less than 1%, while the mean calculation speeds of the fast calculation formulae are more than 100 times faster than those of REFPROP 8. [Copyright &y& Elsevier]

Abstract: Different designs of flat-tube heat exchangers with plain fins have been evaluated theoretically in a parameter study in order to evaluate their performance potential in indirectly cooled display cabinets. Two different types of flat-tube heat exchangers were considered; one with serpentine fins and one with continuous plate fins. Both flat-tube heat exchanger types were adapted to the laminar flow regime on the liquid as well as on the air side. The performance of the two heat exchanger types had previously been verified experimentally under dehumidifying conditions. The results from this parameter study show that considerable savings in the required electric drive power to compressors, pumps and fans can be obtained in comparison with the traditional cooling coil. The savings may be up to 15%. In addition, the required temperature difference for the flat-tube heat exchangers is so small that frost-free operation is possible, which would result in even larger savings. [Copyright &y& Elsevier]

Abstract: The domestic transport of low volume perishable products is commonly conducted with the use of insulated boxes and non-refrigerated commercial courier networks. The temperature of the product during transport is governed by the balance of the environmental temperature and the protection provided by the box''s insulation and accompanying coolant (e.g. ice). While the box, product and coolant properties may be constant, the ability of that package to maintain appropriate product temperatures will be different due to the day-to-day variation in environmental conditions. This paper presents a method that uses historic climatic data to estimate environmental temperatures during transport and subsequently provides a quantitative estimate of the likelihood of package temperature control failure. Three packages travelling by road from Sydney to Melbourne are compared as an example of the use of the methodology. [Copyright &y& Elsevier]

Abstract: This article presents the general procedure for uncertainty calculation of net total cooling effect estimation for rating room air conditioners and packaged terminal air conditioners, by means of measurements carried out in a test bench specially designed for this purpose. The uncertainty analysis presented in this work looks for establishing a confidence degree or certainty of experimental results. It is particularly important considering that international standards related to this type of analysis are too ambiguous when treating this subject. The uncertainty analysis is on the other hand an indispensable requirement to international standard ISO 17025 [ISO, 2005. International Standard. 17025. General Requirement to Test and Calibration Laboratories Competences. International Organization for Standardization, Geneva.], which must be applied to obtain the required quality levels according to the Word Trade Organization WTO. [Copyright &y& Elsevier]

Abstract: Development of modern refrigeration systems is critical for the success of new global environmental protection efforts. The binary system of refrigerants: Hexafluoroethane (R116)+1,1,1-trifluoroethane (R143a), has been studied with the aim of providing PTxy data. Isothermal vapor–liquid equilibrium data have been generated using the “static–analytic” method from 258 to 328K at pressures from 0.39 to 3.89MPa. The model composed of the Peng–Robinson equation of state, the Mathias–Copeman alpha function, the Wong–Sandler mixing rules and the NRTL cell theory is applied herein to correlate the data and calculate the critical line. [Copyright &y& Elsevier]

Abstract: Ejector efficiencies for the primary nozzle, suction, mixing and diffuser were determined for the first time, according to their definitions, using an axi-symmetric CFD model. Water was considered as working fluid and the operating conditions were selected in a range that would be suitable for an air-conditioner powered by solar thermal energy. Ejector performance was estimated for different nozzle throat to constant section area ratios. The results indicated the existence of an optimal ratio, depending on operating conditions. Ejector efficiencies were calculated for different operating conditions. It was found that while nozzle efficiency can be considered as constant, the efficiencies related to the suction, mixing and diffuser sections of the ejector depend on operating conditions. [Copyright &y& Elsevier]

Abstract: A diffusion absorption refrigeration (DAR) cycle is driven by heat and utilizes a binary solution of refrigerant and absorbent as working fluid, together with an auxiliary inert gas. Commercial DAR systems operate with ammonia–water solution and hydrogen or helium as the inert gas. In this work, the performance of a simplified DAR system working with an organic absorbent (DMAC – dimethylacetamide) and five different refrigerants and helium as inert gas was examined numerically, with the aim of lowering the generator temperature and system pressure along with a non-toxic refrigerant The refrigerants were: chlorodifluoromethane (R22), difluoromethane (R32), 2-chloro-1,1,1,2-tetrafluoroethane (R124), pentafluoroethane (R125) and 1,1,1,2-tetrafluoroethane (R134a). The results were compared with the performance of the same system working with ammonia–water and helium. Similar behavior was found for all systems, regarding the coefficient of performance (COP) and rich and poor solution concentrations as functions of generator temperature. It was found that typical generator temperature with the new substances was 150°C, yet lower COPs, higher evaporator temperatures and lower condensation temperature of about 40°C governed these systems. [Copyright &y& Elsevier]

Abstract: This paper presents a new rotary type compressor, named ‘Revolving Vane (RV) compressor’, in which frictional losses are effectively reduced through the radical use of a rotating cylinder. The friction at various contact regions are formulated and analyzed, after which a parametric study is conducted to reveal configurations of the compressor that achieves high mechanical efficiencies. Inadvertently, the rotating cylinder is also found to enhance the smoothness of the compressor''s operation by reducing its torque fluctuations. Besides good mechanical performance, the RV compressor is also found to possess a high volumetric efficiency, as shown in Part III of this paper series (). In further consideration of the small number of parts and simple geometries of its components, it is believed that the RV compressor is well suited and can be readily adopted for refrigeration and air-conditioning applications. [Copyright &y& Elsevier]

Abstract: The aim of this paper is the thermodynamic evaluation and optimisation of different two-stage transcritical carbon dioxide cycles. Five different cycles are studied: basic single-stage cycle, single-throttling with two-stage compression cycle, split cycle, phase separation cycle and single-stage cycle coupled with a gas cooling circuit. Each basic cycle is analysed for the effect of internal heat transfer between different streams of refrigerants. In the case of two-stage compression, intermediate cooling between the compressor stages is present. An analysis on the Plank cycle for intermediate pressure higher than critical one is performed. Each cycle is optimised with regards to energy performance, calculating the optimal values of both the upper and the intermediate pressures. In the case of split cycle, the ratio of the mass flow rate in the main stream to the one in the auxiliary stream is also optimised. [Copyright &y& Elsevier]

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

Abstract: The rheological behaviour of the ice slurry made from 9% NaCl brine has been experimentally studied in this work. Starting from the dimensional analysis of pressure drop and heat transfer processes, the minimum numbers of non-dimensional parameters present in these processes have been determined. Rheological behaviour has been adjusted to the experimental data on ice slurry pressure drop. Two different behaviours were observed depending on the shear rate values, with a clear yield stress recognizable in the low shear rate region and a shear thickening behaviour for high shear rate values. A modified Herschel–Bulkley rheological model has been proposed, which is able to predict ice slurry behaviour in both, low and high shear rate region. The influence of the parameters involved has been determined and an analytical equation for the Darcy friction factor has been obtained from the model proposed and compared to experimental results. The comparison showed a very good agreement between these data. [Copyright &y& Elsevier]

Abstract: The transient model of thermal components usually consists of three basic governing equations: continuity equation, energy equation, and momentum equation. For different reasons, the momentum equation is used in three different forms: transient, steady-state, and zero pressure drop. In this paper, the three forms of momentum equation are numerically studied and compared at both component level and system level, particularly in the residential applications. It is found that the results with transient and steady-state momentum equation are pretty close at both levels. Therefore, the steady-state momentum equation is recommended in refrigeration system and component transient modeling because of the robustness and the computation speed. To consider only the system-level cases, it is also found that the transient results without pressure drop give very close estimation of control parameters in comparison with the results taking account into the transient or steady-state pressure drop. [Copyright &y& Elsevier]

Abstract: This paper deals with the scroll compressor, which is a machine used for compressing air or refrigerant. By using a novel reference frame, it proposes an original way of describing the geometry of the scroll wraps (represented as circle involutes) in which the symmetries are exploited in order to establish a thermodynamic model of the scroll compressor. This approach allows the chamber volumes to be analytically described without any special assumption and takes into account the discharge as a non-symmetrical process. The proposed geometric model is aimed to be coupled with the thermodynamic model by using the standardized VHDL-AMS language and should be then considered as preliminary to the scroll overall simulation and design of a functional virtual prototype. Simulations and experiments have shown good agreement. [Copyright &y& Elsevier]

Abstract: An approximate analytical method has been suggested for solving the governing equation for horizontal pin fins subject to condensation while saturated steam flowing over its under laminar forced convection. Adomian decomposition method is used for determination of the temperature distribution, performance and optimum dimensions of pin fins with temperature dependent thermal conductivity under the condensation of steam on the fin surface. From the results, a significant effect on the temperature distribution in the fin and its performances are noticed with the variation in fin-geometric parameters and thermo-physical properties of saturated vapor. Next, a generalized scheme for optimization has been demonstrated in such a way that either heat-transfer duty or fin volume can be taken as a constraint. Finally, the curves for the optimum design have been generated for the variation of different thermo-physical and geometric parameters, which may be helpful to a designer for selecting an appropriate design condition. [Copyright &y& Elsevier]

Abstract: A conceptual trigeneration system is proposed based on the conventional gas turbine cycle for the high temperature heat addition while adopting the heat recovery steam generator for process heat and vapor absorption refrigeration for the cold production. Combined first and second law approach is applied and computational analysis is performed to investigate the effects of overall pressure ratio, turbine inlet temperature, pressure drop in combustor and heat recovery steam generator, and evaporator temperature on the exergy destruction in each component, first law efficiency, electrical to thermal energy ratio, and second law efficiency of the system. Thermodynamic analysis indicates that exergy destruction in combustion chamber and HRSG is significantly affected by the pressure ratio and turbine inlet temperature, and not at all affected by pressure drop and evaporator temperature. The process heat pressure and evaporator temperature causes significant exergy destruction in various components of vapor absorption refrigeration cycle and HRSG. It also indicates that maximum exergy is destroyed during the combustion and steam generation process; which represents over 80% of the total exergy destruction in the overall system. The first law efficiency, electrical to thermal energy ratio and second law efficiency of the trigeneration, cogeneration, and gas turbine cycle significantly varies with the change in overall pressure ratio and turbine inlet temperature, but the change in pressure drop, process heat pressure, and evaporator temperature shows small variations in these parameters. Decision makers should find the methodology contained in this paper useful in the comparison and selection of advanced heat recovery systems. [Copyright &y& Elsevier]

Abstract: A model has been developed analytically to carry out the performance and optimum design analysis of four fin arrays, namely, longitudinal rectangular fin array (LRFA), annular rectangular fin array (ARFA), longitudinal trapezoidal fin array (LTRA) and annular trapezoidal fin array (ATFA) under convective cooling conditions. The performance parameters such as fin efficiency, fin effectiveness and augmentation factor are evaluated for a wide range of design variables. It has been observed that the conduction through the supporting structure and the convection from the interfin spacing have a pronounced effect on the performance of a fin array. The optimum fin dimensions in a fin assembly have been determined by consideration of the constant total height of the fin assembly and interfin spacing. From the results, it can be highlighted that the optimum fin dimensions in fin arrays differ from that of the individual fins. [Copyright &y& Elsevier]

Abstract: The aim of the investigation was to evaluate the content of amino acids and the quality of protein in Brussels sprouts. The investigation included the raw material, cooked sample and two types of frozen product stored at −20°C for 12 months and then prepared for consumption. The frozen products investigated were obtained using the traditional method (blanching before freezing) and the modified method (cooking before freezing, then defrosting and heating in microwave oven after refrigerated storage) of the ready-to-eat type. Brussels sprouts, both fresh and prepared for consumption, were a good source of protein and amino acids. Proline and glutamic acid were dominating; leucine and tyrosine with phenylalanine were limiting amino acids. The product obtained by modified method contained 16% less amino acids in 16gN than the raw material and 14% less than the raw material after cooking, and also 10% lower than that of the traditionally obtained product. [Copyright &y& Elsevier]

Abstract: Freeze concentration is one of the methods to concentrate solution by making pure ice in the solution. In general, the ratio of condensation is focused on, and so the research on the concentration captured in ice is very limited. However, quality improvement of eliminating impurities from wastewater is a very important task. In this study, the difference of initial morphology of ice was focused on and the influence on the freeze concentration was studied. It was found that the concentration of solute captured in ice was in the following order, from bigger value, multi-crystal ice, a single crystal ice with growth direction in a-axis and a single crystal ice with growth direction in c-axis. It was clarified that the ratio of concentration between the solute captured in ice and the solute in the mother solution varied from 1/10 to 1/250, depending on the crystal orientation of the ice. [Copyright &y& Elsevier]

Abstract: A calculation method to define the latent heat of fusion of ice in aqueous solution in the situation of the variation in the ice packing factor being infinitesimal is proposed. The calculation of the latent heat considers the effects of dilution and freezing-point depression, and the latent heat was calculated for five actual solutions, ethanol, ethylene glycol, propylene glycol, NaCl and NaNO3 solutions. Additionally, experiments in which ice was added to the five solutions were conducted to compare with the results of the calculations. Differential scanning calorimetry analysis was performed and the measurements and calculated values compared with respect to the specific enthalpy of the ice/solution mixture. Finally, since the values obtained by the measurements and calculations are in good agreement, the calculating method proposed in this study has proven to be adequate. [Copyright &y& Elsevier]

Abstract: Microfin tubes are widely used in air cooled and water cooled heat exchangers for heat pump and refrigeration applications during condensation or evaporation of refrigerants. In order to design heat exchangers and to optimize heat transfer surfaces, accurate procedures for computing pressure drops and heat transfer coefficients are necessary. This paper presents a new simple model for the prediction of the heat transfer coefficient to be applied to condensation in horizontal microfin tubes of halogenated and natural refrigerants, pure fluids or nearly azeotropic mixtures. The updated model accounts for refrigerant physical properties, two-phase flow patterns in microfin tubes and geometrical characteristics of the tubes. It is validated against a data bank of 3115 experimental heat transfer coefficients measured in different independent laboratories all over the world including diverse inside tube geometries and different condensing refrigerants among which R22, R134a, R123, R410A and CO2. [Copyright &y& Elsevier]

Abstract: The optimum design of a high capacity double inlet pulse tube refrigerator based on second law of thermodynamics has been presented in this paper. Second law is applied to calculate the work loss in the regenerator and to optimize the cryocooler performance. To investigate the behavior of the pulse tube refrigerator, mass and energy balance equations are applied to several control volumes of the cryocooler cycle. A complete system of conservation equations is employed to solve the regenerator analytically. The proposed model reports the cooling capacity of 110W at 80K cold end temperature at frequency of 50Hz, orifice conductance of 0.4 and double inlet coefficient of 0.6, with 2.4kW net power delivered to the gas. In this case, the entropy generation in the gas phase is dominant which is contributing more than 85% of the total lost work in the regenerator. The optimum thermal efficiency of 99.1% was achieved at a proper mesh number. However, the second law efficiency is reported to have an inverse behavior at this mesh number. [Copyright &y& Elsevier]