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Concentric Halbach cylinder magnetic refrigerator cost optimization / A. Tura in International journal of refrigeration, Vol. 37 N° 1 (Janvier 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 106–116 Titre : Concentric Halbach cylinder magnetic refrigerator cost optimization Titre original : Optimisation du coût d'un réfrigérateur magnétique à deux cylindres d'Halbach Type de document : texte imprimé Auteurs : A. Tura, Auteur ; A. Rowe, Auteur Année de publication : 2014 Article en page(s) : pp. 106–116 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Gadolinium;  magnetocaloric  effect;  active  magnetic  regenerator;  efficiency;  magnetic  refrigerator;  optimization Résumé : Commercial magnetic refrigeration near room temperature faces technological challenges and high costs. Although several laboratory devices have been developed, no design is realistically close to the performance, reliability, and financial proposition of a vapor compression refrigerator. This study examines the total cost of cooling provided by an idealized dual-regenerator concentric Halbach design. An optimization process, based on a simplified analytical model rather than a computationally intensive finite element model, is applied to geometrical and operational parameters, with the objective function minimizing capital and operating cost. Additionally, the model utilizes a refrigerant with ideal magnetocaloric (MCE) properties and constant specific heat. The model is first validated against extrapolated experimental data from an existing device, and then the optimization routine is applied to a range of cooling demand and MCE values. Results help in identifying target refrigerant properties, and refrigerator geometrical/operational parameters. Moreover, a sensitivity analysis demonstrates how the design variables affect the system performance. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002387 [article] Concentric Halbach cylinder magnetic refrigerator cost optimization = Optimisation du coût d'un réfrigérateur magnétique à deux cylindres d'Halbach [texte imprimé] / A. Tura, Auteur ; A. Rowe, Auteur . - 2014 . - pp. 106–116. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 106–116 Mots-clés : Gadolinium;  magnetocaloric  effect;  active  magnetic  regenerator;  efficiency;  magnetic  refrigerator;  optimization Résumé : Commercial magnetic refrigeration near room temperature faces technological challenges and high costs. Although several laboratory devices have been developed, no design is realistically close to the performance, reliability, and financial proposition of a vapor compression refrigerator. This study examines the total cost of cooling provided by an idealized dual-regenerator concentric Halbach design. An optimization process, based on a simplified analytical model rather than a computationally intensive finite element model, is applied to geometrical and operational parameters, with the objective function minimizing capital and operating cost. Additionally, the model utilizes a refrigerant with ideal magnetocaloric (MCE) properties and constant specific heat. The model is first validated against extrapolated experimental data from an existing device, and then the optimization routine is applied to a range of cooling demand and MCE values. Results help in identifying target refrigerant properties, and refrigerator geometrical/operational parameters. Moreover, a sensitivity analysis demonstrates how the design variables affect the system performance. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002387

Design improvements of a permanent magnet active magnetic refrigerator / D.S. Arnold in International journal of refrigeration, Vol. 37 N° 1 (Janvier 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 99-105 Titre : Design improvements of a permanent magnet active magnetic refrigerator Titre original : Amélioration de la conception d'un réfrigérateur magnétique actif permanent Type de document : texte imprimé Auteurs : D.S. Arnold, Auteur ; A. Tura, Auteur ; Alex Ruebsaat-Trott, Auteur Année de publication : 2014 Article en page(s) : pp. 99-105 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Permanent  magnet  magnetic  refrigerator;  AMR  cycle Résumé : A second-generation room-temperature permanent magnet active magnetic regenerator test apparatus using Halbach arrays is described. The magnet arrays consist of three concentric cylinders. Each cylinder is constructed using 12 permanent magnet segments. The inner magnet array is stationary while the intermediate and outer arrays are designed to rotate in opposite directions so as to create a sinusoidal magnetic field waveform with a stationary field direction. The fluid flow system utilizes a novel check valve configuration so that fluid dead volumes are minimized. The system construction is modular to allow for quick replacement of material or system components. Fringing fields near the outer and inner diameters of the arrays are found to create large forces between arrays leading to large torques. Test results using 650 g of gadolinium spheres produce a no-load temperature span of 33 K at 0.8 Hz. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002582 [article] Design improvements of a permanent magnet active magnetic refrigerator = Amélioration de la conception d'un réfrigérateur magnétique actif permanent [texte imprimé] / D.S. Arnold, Auteur ; A. Tura, Auteur ; Alex Ruebsaat-Trott, Auteur . - 2014 . - pp. 99-105. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 99-105 Mots-clés : Permanent  magnet  magnetic  refrigerator;  AMR  cycle Résumé : A second-generation room-temperature permanent magnet active magnetic regenerator test apparatus using Halbach arrays is described. The magnet arrays consist of three concentric cylinders. Each cylinder is constructed using 12 permanent magnet segments. The inner magnet array is stationary while the intermediate and outer arrays are designed to rotate in opposite directions so as to create a sinusoidal magnetic field waveform with a stationary field direction. The fluid flow system utilizes a novel check valve configuration so that fluid dead volumes are minimized. The system construction is modular to allow for quick replacement of material or system components. Fringing fields near the outer and inner diameters of the arrays are found to create large forces between arrays leading to large torques. Test results using 650 g of gadolinium spheres produce a no-load temperature span of 33 K at 0.8 Hz. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002582

Experimental analysis of a two-material active magnetic regenerator / D.S. Arnold in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 178-191 Titre : Experimental analysis of a two-material active magnetic regenerator Titre original : Analyse expérimentale d'un régénérateur magnétique actif faisant appel à deux matériaux Type de document : texte imprimé Auteurs : D.S. Arnold, Auteur ; A. Tura, Auteur ; A. Rowe, Auteur Année de publication : 2011 Article en page(s) : pp. 178-191 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigeration  COP-exergy  Performance  Gadolinium-cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Experimental results of an active magnetic regenerator (AMR) composed of two equal volumes of gadolinium and Gd0.85Er0.15 using 2 T and 5 T are reported. Drive forces and system losses are measured as a function of thermal load and magnetic field. Metrics for coefficient of performance and efficiency are defined and used to distinguish between regenerator and device performance. Results suggest the largest temperature spans are expected to occur when each material is operating with its average temperature near their Curie temperatures. Force measurements indicate that mechanical losses and pumping power are the most significant contributions to network while the net magnetic work is too small to be resolved. COP values for the magnetic cycle are as high as 2.4 while efficiencies are all less than 0.15. A maximum exergetic cooling of 1.94 W is estimated with a corresponding specific exergetic cooling power of 23 W T−1L−1. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002008 [article] Experimental analysis of a two-material active magnetic regenerator = Analyse expérimentale d'un régénérateur magnétique actif faisant appel à deux matériaux [texte imprimé] / D.S. Arnold, Auteur ; A. Tura, Auteur ; A. Rowe, Auteur . - 2011 . - pp. 178-191. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 178-191 Mots-clés : Magnetic  refrigeration  COP-exergy  Performance  Gadolinium-cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Experimental results of an active magnetic regenerator (AMR) composed of two equal volumes of gadolinium and Gd0.85Er0.15 using 2 T and 5 T are reported. Drive forces and system losses are measured as a function of thermal load and magnetic field. Metrics for coefficient of performance and efficiency are defined and used to distinguish between regenerator and device performance. Results suggest the largest temperature spans are expected to occur when each material is operating with its average temperature near their Curie temperatures. Force measurements indicate that mechanical losses and pumping power are the most significant contributions to network while the net magnetic work is too small to be resolved. COP values for the magnetic cycle are as high as 2.4 while efficiencies are all less than 0.15. A maximum exergetic cooling of 1.94 W is estimated with a corresponding specific exergetic cooling power of 23 W T−1L−1. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002008

Permanent magnet magnetic refrigerator design and experimental characterization / A. Tura in International journal of refrigeration, Vol. 34 N° 3 (Mai 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 628-639 Titre : Permanent magnet magnetic refrigerator design and experimental characterization Titre original : Conception d'un réfrigérateur magnétique à aimant permanent et caractérisation expérimentale Type de document : texte imprimé Auteurs : A. Tura, Auteur ; A. Rowe, Auteur Année de publication : 2011 Article en page(s) : pp. 628-639 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Magnet  Magnetic  field  Gadolinium  Regenerator  Curie  Cop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Magnetic refrigeration (MR) using permanent magnets is being investigated for near-room temperature applications. An MR prototype is described and results using gadolinium as refrigerant are presented. Important design features are simple sealing, compactness, high operating frequencies, and ease of use. Using a total of 110 g of refrigerant, the device produces a maximum temperature span under no thermal load of 29 °C, and 10 °C under 50 W. The overall COP determined by using the power to the drive motor is between 0.3 and 0.8 under most operating conditions and temperature spans. The maximum COP measured is 1.6 with a span of 2.5 °C when operating at 1.4 Hz and utilization of 1.28. If the inefficiency of the motor is removed the maximum COP is 2.2, and, when the magnet drive losses are excluded, the maximum COP becomes 10. The peak specific exergetic cooling power is 0.085 W T−1 cm−3. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002847 [article] Permanent magnet magnetic refrigerator design and experimental characterization = Conception d'un réfrigérateur magnétique à aimant permanent et caractérisation expérimentale [texte imprimé] / A. Tura, Auteur ; A. Rowe, Auteur . - 2011 . - pp. 628-639. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 628-639 Mots-clés : Magnetic  refrigerator  Magnet  Magnetic  field  Gadolinium  Regenerator  Curie  Cop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Magnetic refrigeration (MR) using permanent magnets is being investigated for near-room temperature applications. An MR prototype is described and results using gadolinium as refrigerant are presented. Important design features are simple sealing, compactness, high operating frequencies, and ease of use. Using a total of 110 g of refrigerant, the device produces a maximum temperature span under no thermal load of 29 °C, and 10 °C under 50 W. The overall COP determined by using the power to the drive motor is between 0.3 and 0.8 under most operating conditions and temperature spans. The maximum COP measured is 1.6 with a span of 2.5 °C when operating at 1.4 Hz and utilization of 1.28. If the inefficiency of the motor is removed the maximum COP is 2.2, and, when the magnet drive losses are excluded, the maximum COP becomes 10. The peak specific exergetic cooling power is 0.085 W T−1 cm−3. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002847