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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

Configuration and performance analysis of magnetic refrigerators / A. Rowe 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. 168-177 Titre : Configuration and performance analysis of magnetic refrigerators Titre original : Configuration et analyse de la performance des réfrigérateurs magnétiques Type de document : texte imprimé Auteurs : A. Rowe, Auteur Année de publication : 2011 Article en page(s) : pp. 168-177 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Exergy  Performance  Gadolinium  Cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The commercialization of magnetic refrigerators depends upon the ability to meet performance targets while having acceptable equipment costs. This paper links device design parameters and performance of magnetic refrigerators to the cost of cooling delivered. A device configuration parameter, D, is defined that links the field volume to the volume of magnetocaloric material. Combined with the magnet performance parameter, efficiency, and specific exergetic cooling, the cost structure of a magnetic refrigerator is determined. Some magnetic refrigerators reported in the literature are classified using their configuration parameters, and are then compared in terms of demonstrated performance using results available in the literature. The required improvement in performance is calculated such that the cost of a magnetic refrigerator would be equivalent to a conventional compressor-based device. Finally, some of the reasons for different performance are discussed with a focus on opportunities for improvements. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001957 [article] Configuration and performance analysis of magnetic refrigerators = Configuration et analyse de la performance des réfrigérateurs magnétiques [texte imprimé] / A. Rowe, Auteur . - 2011 . - pp. 168-177. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 168-177 Mots-clés : Magnetic  refrigerator  Exergy  Performance  Gadolinium  Cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The commercialization of magnetic refrigerators depends upon the ability to meet performance targets while having acceptable equipment costs. This paper links device design parameters and performance of magnetic refrigerators to the cost of cooling delivered. A device configuration parameter, D, is defined that links the field volume to the volume of magnetocaloric material. Combined with the magnet performance parameter, efficiency, and specific exergetic cooling, the cost structure of a magnetic refrigerator is determined. Some magnetic refrigerators reported in the literature are classified using their configuration parameters, and are then compared in terms of demonstrated performance using results available in the literature. The required improvement in performance is calculated such that the cost of a magnetic refrigerator would be equivalent to a conventional compressor-based device. Finally, some of the reasons for different performance are discussed with a focus on opportunities for improvements. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001957

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

Validation of an active magnetic regenerator test apparatus model / J. Dikeos in International journal of refrigeration, Vol. 36 N° 3 (Mai 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 921–931 Titre : Validation of an active magnetic regenerator test apparatus model Titre original : Validation d'un modèle de banc d'essai utilisé pour tester les régénérateurs actifs magnétiques Type de document : texte imprimé Auteurs : J. Dikeos, Auteur ; A. Rowe, Auteur Année de publication : 2013 Article en page(s) : pp. 921–931 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Magnetic  refrigeration;  Simulation;  Magnetocaloric  effect;  Active  magnetic  regenerator;  Gadolinium Résumé : This work focuses on the development and validation of a transient one-dimensional numerical model of an active magnetic regenerator (AMR) test apparatus. Simulation results are validated by comparison to room temperature experiments for varying hot heat sink temperature, system pressure, and applied heat load. Three different second-order magnetocaloric materials are used. In addition to external heat leaks, parameters such as thermal conductivity, Curie temperature, and peak magnetocaloric effect are adjusted to obtain better fits to experimental results. In the case of gadolinium, where material properties are well-characterized, the inclusion of parasitic heat leaks as well as an increase in diffusivity resulted in good fits across a broad range of operating conditions. Adjustments to Curie temperature and peak magnetocaloric effect produced good matches with experimental data for Gd0.85Er0.15. Predictive simulations of a Gd – Gd0.85Er0.15 two-layer regenerator are briefly discussed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003465 [article] Validation of an active magnetic regenerator test apparatus model = Validation d'un modèle de banc d'essai utilisé pour tester les régénérateurs actifs magnétiques [texte imprimé] / J. Dikeos, Auteur ; A. Rowe, Auteur . - 2013 . - pp. 921–931. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 921–931 Mots-clés : Magnetic  refrigeration;  Simulation;  Magnetocaloric  effect;  Active  magnetic  regenerator;  Gadolinium Résumé : This work focuses on the development and validation of a transient one-dimensional numerical model of an active magnetic regenerator (AMR) test apparatus. Simulation results are validated by comparison to room temperature experiments for varying hot heat sink temperature, system pressure, and applied heat load. Three different second-order magnetocaloric materials are used. In addition to external heat leaks, parameters such as thermal conductivity, Curie temperature, and peak magnetocaloric effect are adjusted to obtain better fits to experimental results. In the case of gadolinium, where material properties are well-characterized, the inclusion of parasitic heat leaks as well as an increase in diffusivity resulted in good fits across a broad range of operating conditions. Adjustments to Curie temperature and peak magnetocaloric effect produced good matches with experimental data for Gd0.85Er0.15. Predictive simulations of a Gd – Gd0.85Er0.15 two-layer regenerator are briefly discussed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003465