Dépouillements

Several motivations, improved procedures, and different contexts: The first liquefactions of helium around the world in Revue internationale du froid, vol 32, issue 5 (2009)

Public ISBD [article]  inRevue internationale du froid > vol 32, issue 5 (2009) . - pp. 738–762 Titre : Several motivations, improved procedures, and different contexts: The first liquefactions of helium around the world Titre original : Les premiers liquéfacteurs d'hélium à travers le monde : motivations, procédures améliorées et contextes différents Type de document : texte imprimé Année de publication : 2012 Article en page(s) : pp. 738–762 Langues : Anglais (eng) Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Cryogénie; Liquéfaction; Hélium; Historique; Technologie Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : Helium was the last member of the list of the so-called permanent gases to be liquefied. The main reasons for that were the very late discovery of the element on the earth's surface and its boiling point, the lowest of all substances. This account of the earliest and different methods for its liquefaction reveals, both chronologically and geographically, the technical developments involved. An effort is made to show how the availability of the natural resource, together with political circumstances and economic limitations, had different roles in specific moments of the entire history. [article] Several motivations, improved procedures, and different contexts: The first liquefactions of helium around the world = Les premiers liquéfacteurs d'hélium à travers le monde : motivations, procédures améliorées et contextes différents [texte imprimé] . - 2012 . - pp. 738–762. Langues : Anglais (eng) in Revue internationale du froid > vol 32, issue 5 (2009) . - pp. 738–762 Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Cryogénie; Liquéfaction; Hélium; Historique; Technologie Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : Helium was the last member of the list of the so-called permanent gases to be liquefied. The main reasons for that were the very late discovery of the element on the earth's surface and its boiling point, the lowest of all substances. This account of the earliest and different methods for its liquefaction reveals, both chronologically and geographically, the technical developments involved. An effort is made to show how the availability of the natural resource, together with political circumstances and economic limitations, had different roles in specific moments of the entire history.

A review on polymer heat exchangers for HVAC&R applications in Revue internationale du froid, vol 32, issue 5 (2009)

Public ISBD [article]  inRevue internationale du froid > vol 32, issue 5 (2009) . - pp. 763-779 Titre : A review on polymer heat exchangers for HVAC&R applications Titre original : Echangeurs de chaleur en polymère pour les applications dans le chauffage, la ventilation, le conditionnement d'air et le froid : état de l'art Type de document : texte imprimé Année de publication : 2012 Article en page(s) : pp. 763-779 Langues : Anglais (eng) Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Échangeur de chaleur; Conditionnement d'air; Froid; Enquête; Matériau; Polymère; Additif; Exemple; Technologie Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : Because of their low thermal conductivity, polymers are not commonly considered as a material to construct heat exchangers, except for specific applications, e.g. heat recovery from solvent laden streams, where exotic alloys are required to prevent corrosion. In this review the material properties of polymers are examined, as well as the current state of the art of polymer matrix composites. It is shown that these materials do hold promise for use in the construction of heat exchangers in HVAC&R applications, but that a considerable amount of research is still required into material properties and life-time behavior. A successful application of polymers or polymer matrix composites is based on careful material selection and modification of the design to fully exploit the material properties, as is demonstrated through a series of examples. [article] A review on polymer heat exchangers for HVAC&R applications = Echangeurs de chaleur en polymère pour les applications dans le chauffage, la ventilation, le conditionnement d'air et le froid : état de l'art [texte imprimé] . - 2012 . - pp. 763-779. Langues : Anglais (eng) in Revue internationale du froid > vol 32, issue 5 (2009) . - pp. 763-779 Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Échangeur de chaleur; Conditionnement d'air; Froid; Enquête; Matériau; Polymère; Additif; Exemple; Technologie Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : Because of their low thermal conductivity, polymers are not commonly considered as a material to construct heat exchangers, except for specific applications, e.g. heat recovery from solvent laden streams, where exotic alloys are required to prevent corrosion. In this review the material properties of polymers are examined, as well as the current state of the art of polymer matrix composites. It is shown that these materials do hold promise for use in the construction of heat exchangers in HVAC&R applications, but that a considerable amount of research is still required into material properties and life-time behavior. A successful application of polymers or polymer matrix composites is based on careful material selection and modification of the design to fully exploit the material properties, as is demonstrated through a series of examples.

Experimental validation of void fraction models for R410A air conditioners in Revue internationale du froid, vol 32, issue 5 (2009)

Public ISBD [article]  inRevue internationale du froid > vol 32, issue 5 (2009) . - pp. 770-780 Titre : Experimental validation of void fraction models for R410A air conditioners Titre original : Validation expérimentale des modèles de taux de vide pour les systèmes de conditionnement d'air au R410A Type de document : texte imprimé Année de publication : 2012 Article en page(s) : pp. 770-780 Langues : Anglais (eng) Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Conditionnement d'air; R410A; Charge en frigorigène; Modélisation; Vide Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : This paper presents the combined void fraction models on the basis of flow pattern to choose suitable models for calculating the two-phase refrigerant mass of R410A air conditioners, and the model is validated experimentally. The existing single void fraction models are also evaluated experimentally. The Taitel–Dukler flow pattern map is recommended to use in the combined void fraction models. The results presented herein show that the calculated refrigerant mass using the combined void fraction models agrees relatively better with the measured refrigerant mass than that of the single void fraction models. T–B model (for intermittent flow) and Premoli model (for annular flow) are recommended for calculating the two-phase refrigerant mass in evaporator, and T–B model (for intermittent flow) and Harms model (for annular flow) are also indicated for calculating the two-phase refrigerant mass in condenser. [article] Experimental validation of void fraction models for R410A air conditioners = Validation expérimentale des modèles de taux de vide pour les systèmes de conditionnement d'air au R410A [texte imprimé] . - 2012 . - pp. 770-780. Langues : Anglais (eng) in Revue internationale du froid > vol 32, issue 5 (2009) . - pp. 770-780 Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Conditionnement d'air; R410A; Charge en frigorigène; Modélisation; Vide Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : This paper presents the combined void fraction models on the basis of flow pattern to choose suitable models for calculating the two-phase refrigerant mass of R410A air conditioners, and the model is validated experimentally. The existing single void fraction models are also evaluated experimentally. The Taitel–Dukler flow pattern map is recommended to use in the combined void fraction models. The results presented herein show that the calculated refrigerant mass using the combined void fraction models agrees relatively better with the measured refrigerant mass than that of the single void fraction models. T–B model (for intermittent flow) and Premoli model (for annular flow) are recommended for calculating the two-phase refrigerant mass in evaporator, and T–B model (for intermittent flow) and Harms model (for annular flow) are also indicated for calculating the two-phase refrigerant mass in condenser.

Effect of CuO nanolubricant on R134a pool boiling heat transfer in Revue internationale du froid, vol 32, issue 5 (2009)

Public ISBD [article]  inRevue internationale du froid > vol 32, issue 5 (2009) . - pp. 791-799 Titre : Effect of CuO nanolubricant on R134a pool boiling heat transfer Titre original : Effet de l’oxyde de cuivre utilisé comme nanolubrifiant sur l’échange de chaleur lors de l’ébullition libre du R134a Type de document : texte imprimé Année de publication : 2012 Article en page(s) : pp. 791-799 Langues : Anglais (eng) Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Échangeur de chaleur; Ébullition libre; Expérimentation; Transfert de chaleur; Mélange binaire; Polyolester; R134a; Additif; Particule; Oxyde de cuivre Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : This paper quantifies the influence of CuO nanoparticles on the boiling performance of R134a/polyolester mixtures on a roughened, horizontal, flat surface. A lubricant based nanofluid (nanolubricant) was made with a synthetic ester and CuO particles. For the 0.5% nanolubricant mass fraction, the nanoparticles caused a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) of between 50% and 275%. A smaller enhancement was observed for the R134a/nanolubricant (99/1) mixture, which had a heat flux that was on average 19% larger than that of the R134a/polyolester (99/1) mixture. Further increase in the nanolubricant mass fraction to 2% resulted in a still smaller boiling heat transfer improvement of approximately 12% on average. Thermal conductivity measurements and a refrigerant/lubricant mixture pool-boiling model were used to suggest that increased thermal conductivity is responsible for only a small portion of the heat transfer enhancement due to nanoparticles. [article] Effect of CuO nanolubricant on R134a pool boiling heat transfer = Effet de l’oxyde de cuivre utilisé comme nanolubrifiant sur l’échange de chaleur lors de l’ébullition libre du R134a [texte imprimé] . - 2012 . - pp. 791-799. Langues : Anglais (eng) in Revue internationale du froid > vol 32, issue 5 (2009) . - pp. 791-799 Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Échangeur de chaleur; Ébullition libre; Expérimentation; Transfert de chaleur; Mélange binaire; Polyolester; R134a; Additif; Particule; Oxyde de cuivre Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : This paper quantifies the influence of CuO nanoparticles on the boiling performance of R134a/polyolester mixtures on a roughened, horizontal, flat surface. A lubricant based nanofluid (nanolubricant) was made with a synthetic ester and CuO particles. For the 0.5% nanolubricant mass fraction, the nanoparticles caused a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) of between 50% and 275%. A smaller enhancement was observed for the R134a/nanolubricant (99/1) mixture, which had a heat flux that was on average 19% larger than that of the R134a/polyolester (99/1) mixture. Further increase in the nanolubricant mass fraction to 2% resulted in a still smaller boiling heat transfer improvement of approximately 12% on average. Thermal conductivity measurements and a refrigerant/lubricant mixture pool-boiling model were used to suggest that increased thermal conductivity is responsible for only a small portion of the heat transfer enhancement due to nanoparticles.

Performance optimization of a hybrid cooler combining vapor compression and natural circulation cycles in Revue internationale du froid, vol 32, issue 5 (2009)

Public ISBD [article]  inRevue internationale du froid > vol 32, issue 5 (2009) . - pp. 800-808 Titre : Performance optimization of a hybrid cooler combining vapor compression and natural circulation cycles Titre original : Optimisation de la performance d’un refroidisseur hybride alliant les cycles à compression de vapeur et les cycles à circulation naturelle Type de document : texte imprimé Année de publication : 2012 Article en page(s) : pp. 800-808 Langues : Anglais (eng) Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Refroidissement; Composant; Électronique; Télécommunication; Système frigorifique; Système à compression; Thermosiphon; Expérimentation Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : A hybrid cooler combining vapor compression and natural circulation cycles was developed for the cooling of telecommunication equipment in the cabinet-type base station of mobile communication. This hybrid cooler normally operates in the vapor compression mode at high ambient temperatures, but works in the natural circulation mode at low ambient temperatures by the thermosiphon principle. The performance of the hybrid cooler was measured according to the refrigerant charge, outdoor temperature, heat exchanger geometry, and the vertical distance between the condenser and the evaporator. The optimum design conditions for these variables are discussed with respect to the performance of the hybrid cooler in both operating modes. The difference in the optimum refrigerant charge between the two operating modes was solved by installing a liquid receiver. The temperature difference between the indoor and ambient air was introduced as a control parameter for use when changing the operating mode. [article] Performance optimization of a hybrid cooler combining vapor compression and natural circulation cycles = Optimisation de la performance d’un refroidisseur hybride alliant les cycles à compression de vapeur et les cycles à circulation naturelle [texte imprimé] . - 2012 . - pp. 800-808. Langues : Anglais (eng) in Revue internationale du froid > vol 32, issue 5 (2009) . - pp. 800-808 Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Refroidissement; Composant; Électronique; Télécommunication; Système frigorifique; Système à compression; Thermosiphon; Expérimentation Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : A hybrid cooler combining vapor compression and natural circulation cycles was developed for the cooling of telecommunication equipment in the cabinet-type base station of mobile communication. This hybrid cooler normally operates in the vapor compression mode at high ambient temperatures, but works in the natural circulation mode at low ambient temperatures by the thermosiphon principle. The performance of the hybrid cooler was measured according to the refrigerant charge, outdoor temperature, heat exchanger geometry, and the vertical distance between the condenser and the evaporator. The optimum design conditions for these variables are discussed with respect to the performance of the hybrid cooler in both operating modes. The difference in the optimum refrigerant charge between the two operating modes was solved by installing a liquid receiver. The temperature difference between the indoor and ambient air was introduced as a control parameter for use when changing the operating mode.

An approximate analytical prediction about thermal performance and optimum design of pin fins subject to condensation of saturated steam flowing under forced convection in Revue internationale du froid, vol 32, issue 5 (2009)

Public ISBD [article]  inRevue internationale du froid > vol 32, issue 5 (2009) . - pp. 809-825 Titre : An approximate analytical prediction about thermal performance and optimum design of pin fins subject to condensation of saturated steam flowing under forced convection Titre original : Prévision analytique approximative de la performance thermique et de la conception optimale des picots cylindriques assujettis à la condensation de vapeur d'eau saturée en écoulement en convection forcée Type de document : texte imprimé Année de publication : 2012 Article en page(s) : pp. 809-825 Langues : Anglais (eng) Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Échangeur de chaleur; Surface augmentée; Ailette; Géométrie; Système à absorption; Condensation; Vapeur; Eau; Calcul; Transfert de chaleur; Optimisation; performance Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : 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. [article] An approximate analytical prediction about thermal performance and optimum design of pin fins subject to condensation of saturated steam flowing under forced convection = Prévision analytique approximative de la performance thermique et de la conception optimale des picots cylindriques assujettis à la condensation de vapeur d'eau saturée en écoulement en convection forcée [texte imprimé] . - 2012 . - pp. 809-825. Langues : Anglais (eng) in Revue internationale du froid > vol 32, issue 5 (2009) . - pp. 809-825 Catégories : 621.5 : Technique pneumatique, du vide, des basses températures Mots-clés : Échangeur de chaleur; Surface augmentée; Ailette; Géométrie; Système à absorption; Condensation; Vapeur; Eau; Calcul; Transfert de chaleur; Optimisation; performance Index. décimale : 621.56 Technique des basses températures : réfrigération, pompe à chaleur Résumé : 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.