Thermodynamic and exergy efficiencies of magnetocaloric energy conversion utilising industrial waste heat

Vuarnoz, Didier; Kitanovski, Andrej; Gonin, Cyrill; Egolf, Peter W.

doi:10.1504/ijex.2012.047508

Cited by 8 publications

(5 citation statements)

References 9 publications

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“…[3,4,7,10,11] This cycle consists of two isothermal curves and two isofield curves. Graphically, this can be represented in two ways-either with a T-s diagram [7,12] or via a M-B diagram [3,13] (see Figure 1), where M is specific magnetization in Am 2 /kg, B is the external field in T, s is the specific entropy in J/Kkg, T is in K (°C), and w is the work done per kg material per cycle.…”

Section: The Working Principlementioning

confidence: 99%

Proof-of-Concept Static Thermomagnetic Generator Experimental Device

Christiaanse

Brück

2014

Metallurgical and Materials Transactions E

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A thermomagnetic power conversion device is constructed using water flows with very low caloric energy. The device has two active regenerators built from (Mn,Fe) 2 (P,As) materials suspended in a magnetic circuit as proposed by Brillouin and Iskenderian. The final magnetic circuit design was further optimized with finite-element simulations. The permanent magnet acting as field source was 1.4 kg of NdFeB alloy. The active part of the generator consists of 48 disks of (Mn,Fe) 2 (P,As) material with four different Curie temperatures of 300 K, 304 K, 307 K, and 310 K (27°C, 31°C, 34°C, and 37°C) measured in 1 T. Into each plate, microchannels are laser cut. By stacking these plates in series, two regenerators with a gradient temperature span are built. Both generators have an exact weight of 26.9 g. The material was cycled at different speeds to find the maximum power output at the optimum frequency. Critical to a better design is a more tapered design and different materials. The tapered design ensures a greater external field and a larger external field change across the material. The materials for devices that use water as heat-transfer fluid in combination with this type of regenerator design should have a lower latent heat while maintaining their magnetic properties. This will increase the cycling speed and improve the power output of this type of device.

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Section: The Working Principlementioning

confidence: 99%

Proof-of-Concept Static Thermomagnetic Generator Experimental Device

Christiaanse

Brück

2014

Metallurgical and Materials Transactions E

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“…the internal energy of the ambient) is called the "anergy". There have been just a few publications on exergy analyses for magnetocaloric energy conversion [21,[51][52][53][54].…”

Section: The Coefficient Of Performance (Cop) and Exergy Efficiencymentioning

confidence: 99%

The Thermodynamics of Magnetocaloric Energy Conversion

Kitanovski

Tušek

Tomc

et al. 2014

Magnetocaloric Energy Conversion

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Magnetocaloric energy conversion is a technology based on the exploitation of the magnetocaloric effect (MCE). The MCE is a physical phenomenon that occurs in magnetic materials under the influence of a varying magnetic field. Is it usually expressed as the adiabatic temperature change or isothermal total entropy change of a material. In a ferromagnetic material the entropy can be, for instance, related to the magnetic part and the part related to the temperature of the system (e.g. the lattice entropy). In the absence of a magnetic field, the magnetic moments in the material are disordered. If a magnetic field is applied to the material, the magnetic moments will be forced to align in a higher order. As a consequence, the magnetic entropy will decrease. In isentropic (adiabatic) conditions, the total entropy will remain constant. Therefore, the decreased magnetic entropy will manifest itself in an increased lattice entropy. The atoms in the material will start to vibrate more intensively, and as the consequence, the temperature of the magnetic material will increase. The opposite occurs when the magnetic field is removed: the magnetic entropy is increased and the temperature decreases. On this basis, it is possible to create energy conversion cycles by applying different thermodynamic processes.In this chapter, the basic magnetocaloric thermodynamic potentials are presented and described. The state of the art gives an overview of the existing theoretical and experimental approaches to magnetocaloric thermodynamic cycles. Different magnetic thermodynamic cycles are described. Besides thermodynamic cycles with conventional simple cycles, an important emphasis is placed on thermodynamic cycles that apply active magnetic regeneration (AMR). Since most of the existing devices apply the AMR principle, a whole chapter (Chap. 4) is dedicated to this topic.

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“…As a result, a comprehensive study was performed for the Swiss Federal Office of Energy in 2008 [15]. Later, a number of publications were produced by the same group (see Diebold et al [16], Egolf et al [17], Vuarnoz et al [18][19][20]). …”

Section: Review Of Magnetocaloric Power Generationmentioning

confidence: 99%

Design Issues and Future Perspectives for Magnetocaloric Energy Conversion

Kitanovski

Tušek

Tomc

et al. 2014

Magnetocaloric Energy Conversion

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This chapter provides information about the design characteristics for particular types of magnetic refrigerators and heat pumps. The sections therefore indicate the different categories to which a particular magnetocaloric device can belong. For these we show the different design configurations. These are related to linear devices that are based on the linear movement of a magnetic field source or magnetocaloric material; rotary devices, which are based on the rotation of the magnetic field source or the rotation of the magnetocaloric material; and static magnetocaloric devices. Some of the configurations were already applied in research. However, we also present a few new solutions, which are based on our research experiences and which might be applied in future studies and related devices. We again address the importance of the thermal diode mechanism in combination with the active magnetic regeneration (AMR) principle. In addition, a note on power generation is added, with a brief review of the existing work in this particular domain. By pointing out the most successful design approaches, this chapter also serves as a future guideline on the magnetic refrigeration and heat pumping.Since the magnetocaloric devices will, in the following decade, most probably start to penetrate some market niches, it is important, before starting, to address the standardization (or classification) issue relating to magnetocaloric energy conversion. Only a few studies have been performed in this particular and very important domain. However, the research community in the field of magnetocaloric energy conversion decided to enter such a standardization process.For instance, for devices, Scarpa et al. in 2012 [1] proposed a classification method for room-temperature magnetic refrigerators. They proposed a classification of magnetic refrigerators using 12 different criteria, marked by the numbers 1-12. Here, we denote these; however, we marked in bold a slight addition and changes that we think should be included or modified in such a classification.(1) Device type (0 for single-stage cycle without regeneration, 1 for passive regeneration, 2 for active regeneration), (2) magnet type (0 for permanent, 1 for electromagnet), (3) type of permanent magnets (0 for simple magnets, 1 for 2D magnets with Halbach principle, 2 for 3D magnets with Halbach principle),

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Thermodynamic and exergy efficiencies of magnetocaloric energy conversion utilising industrial waste heat

Cited by 8 publications

References 9 publications

Proof-of-Concept Static Thermomagnetic Generator Experimental Device

Proof-of-Concept Static Thermomagnetic Generator Experimental Device

The Thermodynamics of Magnetocaloric Energy Conversion

Design Issues and Future Perspectives for Magnetocaloric Energy Conversion

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