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An experimental study of passive regenerator geometries / K. Engelbrecht in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1817–1822 Titre : An experimental study of passive regenerator geometries Titre original : Etude expérimentale sur les géométries des régénérateurs passifs Type de document : texte imprimé Auteurs : K. Engelbrecht, Auteur ; K.K. Nielsen, Auteur ; N. Pryds, Auteur Année de publication : 2012 Article en page(s) : pp. 1817–1822 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Regenerator  Experimentation Résumé : Active magnetic regenerative (AMR) systems are being investigated because they represent a potentially attractive alternative to vapor compression technology. The performance of these systems is dependent on the heat transfer and pressure drop performance of the regenerator geometry. Therefore this article studies the effects of regenerator geometry on performance for flat plate regenerators. This paper investigates methods of improving the performance of flat plate regenerators for use in AMR systems and studies how manufacturing variation affects regenerator performance. In order to eliminate experimental uncertainty associated with magnetocaloric material properties, all regenerators are made of aluminum. The performance of corrugated plates and dimpled plates are compared to traditional flat plate regenerators for a range of cycle times and utilizations. Each regenerator is built using 18 aluminum plates with a 0.4 mm thickness, which allows their performance to be compared directly. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001897 [article] An experimental study of passive regenerator geometries = Etude expérimentale sur les géométries des régénérateurs passifs [texte imprimé] / K. Engelbrecht, Auteur ; K.K. Nielsen, Auteur ; N. Pryds, Auteur . - 2012 . - pp. 1817–1822. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1817–1822 Mots-clés : Magnetic  refrigerator  Regenerator  Experimentation Résumé : Active magnetic regenerative (AMR) systems are being investigated because they represent a potentially attractive alternative to vapor compression technology. The performance of these systems is dependent on the heat transfer and pressure drop performance of the regenerator geometry. Therefore this article studies the effects of regenerator geometry on performance for flat plate regenerators. This paper investigates methods of improving the performance of flat plate regenerators for use in AMR systems and studies how manufacturing variation affects regenerator performance. In order to eliminate experimental uncertainty associated with magnetocaloric material properties, all regenerators are made of aluminum. The performance of corrugated plates and dimpled plates are compared to traditional flat plate regenerators for a range of cycle times and utilizations. Each regenerator is built using 18 aluminum plates with a 0.4 mm thickness, which allows their performance to be compared directly. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001897

Design concepts for a continuously rotating active magnetic regenerator / C. R. H. Bahl in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1792–1796 Titre : Design concepts for a continuously rotating active magnetic regenerator Titre original : Concepts appliqués dans la conception d'un régénérateur actif magnétique en rotation continue Type de document : texte imprimé Auteurs : C. R. H. Bahl, Auteur ; K. Engelbrecht, Auteur ; R. Bjørk, Auteur Année de publication : 2012 Article en page(s) : pp. 1792–1796 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Magnet  Design  Optimization  Model Résumé : Design considerations for a prototype magnetic refrigeration device with a continuously rotating AMR are presented. Building the active magnetic regenerator (AMR) from stacks of elongated plates of the perovskite oxide material La0.67Ca0.33−xSrxMn1.05O3, gives both a low pressure drop and allows grading of the Curie temperature along the plates. This may be accomplished by a novel technique where a compositionally-graded material is tape cast in one piece. The magnet assembly is based on a novel design strategy, to create alternating high- and low magnetic field regions within a magnet assembly. Focus is on maximising the magnetic field in the high field regions but also, importantly, minimising the flux in the low field regions. The design is iteratively optimised through 3D finite element magnetostatic modelling. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001873 [article] Design concepts for a continuously rotating active magnetic regenerator = Concepts appliqués dans la conception d'un régénérateur actif magnétique en rotation continue [texte imprimé] / C. R. H. Bahl, Auteur ; K. Engelbrecht, Auteur ; R. Bjørk, Auteur . - 2012 . - pp. 1792–1796. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1792–1796 Mots-clés : Magnetic  refrigerator  Magnet  Design  Optimization  Model Résumé : Design considerations for a prototype magnetic refrigeration device with a continuously rotating AMR are presented. Building the active magnetic regenerator (AMR) from stacks of elongated plates of the perovskite oxide material La0.67Ca0.33−xSrxMn1.05O3, gives both a low pressure drop and allows grading of the Curie temperature along the plates. This may be accomplished by a novel technique where a compositionally-graded material is tape cast in one piece. The magnet assembly is based on a novel design strategy, to create alternating high- and low magnetic field regions within a magnet assembly. Focus is on maximising the magnetic field in the high field regions but also, importantly, minimising the flux in the low field regions. The design is iteratively optimised through 3D finite element magnetostatic modelling. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001873

Development and experimental results from a 1 kW prototype AMR / C. R. H. Bahl 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. 78-83 Titre : Development and experimental results from a 1 kW prototype AMR Titre original : Développement d'un prototype de régénérateur magnétique actif d'une puissance de 1 kW et résultats expérimentaux Type de document : texte imprimé Auteurs : C. R. H. Bahl, Auteur ; K. Engelbrecht, Auteur ; D. Eriksen, Auteur Année de publication : 2014 Article en page(s) : pp. 78-83 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Magnetic  refrigeration;  magnetocaloric  device;  active  magnetic  regenerator;  gadolinium Résumé : A novel rotary magnetic refrigeration device has been designed and constructed following the concepts recently outlined in Bahl et al. (2011). The magnet and flow system design allow for almost continuous usage of both the magnetic field and the magnetocaloric material in 24 cassettes, each containing an active magnetic regenerator (AMR) bed. The prototype design facilitates easy exchange of the 24 cassettes, allowing the testing of different material amounts and compositions. Operating with 2.8 kg of commercial grade Gd spheres a maximum no-span cooling power of 1010 W and a maximum zero load temperature span of 25.4 K have been achieved. For the purpose of actual operation, simultaneous high span and high performance is required. At a heat load of 200 W a high temperature span of 18.9 K has been obtained, dropping to a span of 13.8 K at the higher heat load value of 400 W. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300234X [article] Development and experimental results from a 1 kW prototype AMR = Développement d'un prototype de régénérateur magnétique actif d'une puissance de 1 kW et résultats expérimentaux [texte imprimé] / C. R. H. Bahl, Auteur ; K. Engelbrecht, Auteur ; D. Eriksen, Auteur . - 2014 . - pp. 78-83. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 78-83 Mots-clés : Magnetic  refrigeration;  magnetocaloric  device;  active  magnetic  regenerator;  gadolinium Résumé : A novel rotary magnetic refrigeration device has been designed and constructed following the concepts recently outlined in Bahl et al. (2011). The magnet and flow system design allow for almost continuous usage of both the magnetic field and the magnetocaloric material in 24 cassettes, each containing an active magnetic regenerator (AMR) bed. The prototype design facilitates easy exchange of the 24 cassettes, allowing the testing of different material amounts and compositions. Operating with 2.8 kg of commercial grade Gd spheres a maximum no-span cooling power of 1010 W and a maximum zero load temperature span of 25.4 K have been achieved. For the purpose of actual operation, simultaneous high span and high performance is required. At a heat load of 200 W a high temperature span of 18.9 K has been obtained, dropping to a span of 13.8 K at the higher heat load value of 400 W. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300234X

Experimental and numerical results of a high frequency rotating active magnetic refrigerator / J. A. Lozano 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. 92–98 Titre : Experimental and numerical results of a high frequency rotating active magnetic refrigerator Titre original : Réfrigérateur magnétique actif rotatif à haute fréquence: résultats expérimentaux et numériques Type de document : texte imprimé Auteurs : J. A. Lozano, Auteur ; K. Engelbrecht, Auteur ; C. R. H. Bahl, Auteur Année de publication : 2014 Article en page(s) : pp. 92–98 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Active  magnetic  regenerator;  magnetic  refrigeration;  experiment;  numerical  modelling;  parasitic  losses  analysis Résumé : Experimental results for a recently developed prototype magnetic refrigeration device at the Technical University of Denmark (DTU) were obtained and compared with numerical simulation results. A continuously rotating active magnetic regenerator (AMR) using 2.8 kg packed sphere regenerators of gadolinium (Gd) was employed. With operating frequencies up to 10 Hz and volumetric flow rates up to 600 L h−1, the prototype has shown high performance and the results are consistent with predictions from numerical modelling. Magnetocaloric properties of the Gd spheres were obtained experimentally and implemented in a one-dimensional numerical AMR model that includes also the parasitic losses from the prototype. The temperature span for a thermal load of 200 W as a function of frequency was measured and modelled. Moreover, the temperature span dependence on the cooling capacity as a function of cycle frequency was determined. A detailed study of these parasitic losses was carried out experimentally and numerically. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002351 [article] Experimental and numerical results of a high frequency rotating active magnetic refrigerator = Réfrigérateur magnétique actif rotatif à haute fréquence: résultats expérimentaux et numériques [texte imprimé] / J. A. Lozano, Auteur ; K. Engelbrecht, Auteur ; C. R. H. Bahl, Auteur . - 2014 . - pp. 92–98. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 92–98 Mots-clés : Active  magnetic  regenerator;  magnetic  refrigeration;  experiment;  numerical  modelling;  parasitic  losses  analysis Résumé : Experimental results for a recently developed prototype magnetic refrigeration device at the Technical University of Denmark (DTU) were obtained and compared with numerical simulation results. A continuously rotating active magnetic regenerator (AMR) using 2.8 kg packed sphere regenerators of gadolinium (Gd) was employed. With operating frequencies up to 10 Hz and volumetric flow rates up to 600 L h−1, the prototype has shown high performance and the results are consistent with predictions from numerical modelling. Magnetocaloric properties of the Gd spheres were obtained experimentally and implemented in a one-dimensional numerical AMR model that includes also the parasitic losses from the prototype. The temperature span for a thermal load of 200 W as a function of frequency was measured and modelled. Moreover, the temperature span dependence on the cooling capacity as a function of cycle frequency was determined. A detailed study of these parasitic losses was carried out experimentally and numerically. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002351

Experimental investigation of the effect of thermal hysteresis in first order material MnFe(P,As) applied in an AMR device / L. von Moos 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. 303-306 Titre : Experimental investigation of the effect of thermal hysteresis in first order material MnFe(P,As) applied in an AMR device Titre original : Étude expérimentale sur l'effet de l'hystérésis thermique sur un matériau MnFe(P,As) de premier ordre, appliqués à un dispositif à régénération active magnétique Type de document : texte imprimé Auteurs : L. von Moos, Auteur ; K.K. Nielsen, Auteur ; K. Engelbrecht, Auteur Année de publication : 2014 Article en page(s) : pp. 303-306 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Magnetocaloric  effect;  first-order  material;  hysteresis;  magnetic  refrigeration;  MnFe(P,As) Résumé : The magnetocaloric first order material MnFe(P,As) is a candidate for room temperature magnetic refrigeration. However, these materials have intrinsic hysteresis and the impact on the refrigeration performance has not yet been thoroughly investigated in the literature. Here, the magnetocaloric effect (MCE) and the thermal hysteresis are studied using vibrating sample magnetometry. The influence on actual refrigeration performance is investigated with an established active magnetic regenerator (AMR) test device (Bahl et al., 2008), utilizing a flat plate regenerator of a single Curie temperature material. We find that the MCE curves are shifted 1.5 K when comparing heating and cooling the material, while the maximum MCE remains constant. The width of the MCE curve peak is seen to increase 0.3 K when cooling compared to heating. These results are confirmed by experiments on the AMR test device. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001163 [article] Experimental investigation of the effect of thermal hysteresis in first order material MnFe(P,As) applied in an AMR device = Étude expérimentale sur l'effet de l'hystérésis thermique sur un matériau MnFe(P,As) de premier ordre, appliqués à un dispositif à régénération active magnétique [texte imprimé] / L. von Moos, Auteur ; K.K. Nielsen, Auteur ; K. Engelbrecht, Auteur . - 2014 . - pp. 303-306. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 303-306 Mots-clés : Magnetocaloric  effect;  first-order  material;  hysteresis;  magnetic  refrigeration;  MnFe(P,As) Résumé : The magnetocaloric first order material MnFe(P,As) is a candidate for room temperature magnetic refrigeration. However, these materials have intrinsic hysteresis and the impact on the refrigeration performance has not yet been thoroughly investigated in the literature. Here, the magnetocaloric effect (MCE) and the thermal hysteresis are studied using vibrating sample magnetometry. The influence on actual refrigeration performance is investigated with an established active magnetic regenerator (AMR) test device (Bahl et al., 2008), utilizing a flat plate regenerator of a single Curie temperature material. We find that the MCE curves are shifted 1.5 K when comparing heating and cooling the material, while the maximum MCE remains constant. The width of the MCE curve peak is seen to increase 0.3 K when cooling compared to heating. These results are confirmed by experiments on the AMR test device. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001163

Experimental results for a magnetic refrigerator using three different types of magnetocaloric material regenerators / K. Engelbrecht in International journal of refrigeration, Vol. 34 N° 4 (Juin 2011) 

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Modeling of in-vehicle magnetic refrigeration / U. L. Olsen in International journal of refrigeration, Vol. 37 N° 1 (Janvier 2014) 

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Review on numerical modeling of active magnetic regenerators for room temperature applications / K.K. Nielsen in International journal of refrigeration, Vol. 34 N° 3 (Mai 2011) 

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The influence of the magnetic field on the performance of an active magnetic regenerator (AMR) / R. Bjørk in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

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