Numerical and experimental analyses of different magnetic thermodynamic cycles with an active magnetic regenerator

Plaznik, Uroš; Tušek, Jaka; Kitanovski, Andrej; Poredoš, Alojz

doi:10.1016/j.applthermaleng.2013.05.019

Cited by 78 publications

(43 citation statements)

References 13 publications

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“…This result was expected as the thermal conductivity of the fluid increased by adding the nanoparticles. This increase is regarded as a positive effect, as S conv can be lowered by shifting to a hybrid Brayton-Ericsson cycle by lowering F and increasing t blow at the same time (see for example the work of Plaznik et al [32]). Nonetheless, the increase of S Fcond points out that more heat is travelling in the longitudinal direction of the regenerator, destroying to some extent the temperature difference attained in the case with pure water.…”

Section: Influence Of the Blowing Timementioning

confidence: 99%

Exergy Analysis of a Parallel-Plate Active Magnetic Regenerator with Nanofluids

Mugica

Roy

Poncet

et al. 2017

Entropy

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This paper analyzes the energetic and exergy performance of an active magnetic regenerative refrigerator using water-based Al 2 O 3 nanofluids as heat transfer fluids. A 1D numerical model has been extensively used to quantify the exergy performance of a system composed of a parallel-plate regenerator, magnetic source, pump, heat exchangers and control valves. Al 2 O 3 -water based nanofluids are tested thanks to CoolProp library, accounting for temperature-dependent properties, and appropriate correlations. The results are discussed in terms of the coefficient of performance, the exergy efficiency, and the cooling power as a function of the nanoparticle volume fraction and blowing time for a given geometrical configuration. It is shown that while the heat transfer between the fluid and solid is enhanced, it is accompanied by smaller temperature gradients within the fluid and larger pressure drops when increasing the nanoparticle concentration. It leads in all configurations to lower performance compared to the base case with pure liquid water.

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Section: Influence Of the Blowing Timementioning

confidence: 99%

Exergy Analysis of a Parallel-Plate Active Magnetic Regenerator with Nanofluids

Mugica

Roy

Poncet

et al. 2017

Entropy

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“…4.2. It should be noted that these four steps can also overlap and can be performed simultaneously, which can lead to a number of different thermodynamic cycles [9,10]. However, the most basic, and by far the most widely applied, thermodynamic cycle of the AMR is the Brayton-like cycle, which is based on the following four operational phases (see Fig.…”

Section: Operation Of An Active Magnetic Regenerator (Different Thermmentioning

confidence: 99%

“…4.8) [9,10]. In this particular case, the thermodynamic cycle consists of six processes, as follows: adiabatic magnetization (a-b), isothermal magnetization (b-c), isofield fluid flow at a high magnetic field (c-d), adiabatic demagnetization (d-e), isothermal demagnetization (e-f), and isofield fluid flow at a low magnetic field (f-a).…”

Section: Characteristics Of a Hybrid Brayton-ericsson-like Amr Cyclementioning

confidence: 99%

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Active Magnetic Regeneration

Kitanovski

Tušek

Tomc

et al. 2014

Green Energy and Technology

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It is well known that the magnetocaloric effect of most magnetocaloric materials at moderate magnetic fields (up to 1.5 T) is limited to a maximum adiabatic temperature change of 5 K [1,2]. This value is not sufficient for such materials to be directly implemented into a practical cooling or heating device where temperature span over 30 K is required. Therefore, in order to increase the temperature span, one and so far the best option is for a heat regenerator to be included in the magnetic thermodynamic cycle.A heat regenerator is a type of indirect heat exchanger where the heat is periodically stored and transferred from/to a thermal storage medium (regenerative material) by a working (heat-transfer) fluid. The regenerative material usually has a porous structure, through which a working fluid is pumped in an oscillatory, counter-flow manner (which is more efficient than a parallel flow system). During the 'hot period', a warmer fluid flows through the regenerative material, which cools down, while the material heats up. As a result, heat is stored in the material. During the 'cold period', a cooler fluid flows through previously heated regenerative material, so the fluid heats up, while the material cools down. The heat is therefore transferred back to the fluid (the same fluid or a different one) at a different phase of the thermodynamic cycle. After a certain number of such steps, a periodic steady state is reached and, as a result, a temperature profile can be established along the length of the regenerator [3].The need to apply heat regenerators in a magnetic refrigerator was already realized by Brown [4] in the first prototype of a magnetic refrigerator, built in 1976. He applied a regenerative Stirling-like thermodynamic cycle (very similar to AMR), which significantly increased the temperature span of the device [4,5]. A few years later Steyert [6] and Barclay and Steyert [7] presented and explained the active magnetic regenerator, which remains the most applied method for the exploitation of the magnetocaloric effect at room temperature. Furthermore, all prototypes of magnetic refrigerators built since then have been based on the AMR process [5]. An AMR, unlike a passive (regular) heat regenerator, contains a magnetocaloric material as the regenerative material. It has a double function in a magnetic regenerator, i.e. it works as a regenerator and enables an increase in the temperature span as well as working as a coolant and generating/absorbing heat between the particular phases of the

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“…In this paper is presented a collection of test performed on MMs and EMs, with a 2D model of AMR/AER [15][16][17][18][19][20][21][22][23] regenerator, in the same operating conditions and room temperature range, to make a comparison between magnetic and electrocaloric refrigeration.…”

Section: Introductionmentioning

confidence: 99%

A comparison between electrocaloric and magnetocaloric materials for solid state refrigeration

Aprea¹,

Greco²,

Maiorino³

et al. 2017

IJHT

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Electrocaloric and magnetic refrigeration are two emerging, solid-state based technology, which could constitute a real chance to overcome vapor compression refrigeration limits. To underline the differences and the affinities concerning such solid-state techniques, in this paper electrocaloric and magnetic refrigeration are compared through some performance parameters. For this purpose, it has been introduced a two-dimensional model, capable to reproduce, in room temperature range, the behaviors of both AMR and AER parallel plates regenerator. AMR and AER are the acronyms of Active Magnetic/Electrocaloric Regenerative cycle, respectively, which are inverse Brayton based thermodynamical cycles. In the model have been tested as refrigerant the most promising magnetic and electrocaloric materials, like Gd, Gd5(SixGe1-x)4, LaFe11.384 Mn0.356Si1.26H1.52, LaFe11.05Co0.94Si1.10, as magnetocaloric, P(VDF-TrFE-CFE)/BSTs, 0.93PMN-0.07PT, PLZTs, as electrocaloric ones. Among them, the PLZT thin film class confers the best results, higher than every magnetocaloric material tested, conferring to electrocaloric refrigeration the real role of the environmental friendly technology of the future.

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Numerical and experimental analyses of different magnetic thermodynamic cycles with an active magnetic regenerator

Cited by 78 publications

References 13 publications

Exergy Analysis of a Parallel-Plate Active Magnetic Regenerator with Nanofluids

Exergy Analysis of a Parallel-Plate Active Magnetic Regenerator with Nanofluids

Active Magnetic Regeneration

A comparison between electrocaloric and magnetocaloric materials for solid state refrigeration

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