Study of geometries of active magnetic regenerators for room temperature magnetocaloric refrigeration

Lei, Tian; Engelbrecht, Kurt; Nielsen, Kaspar Kirstein; Veje, Christian

doi:10.1016/j.applthermaleng.2015.11.113

Cited by 106 publications

(64 citation statements)

References 42 publications

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“…However, the amplitude of its decrease was lower for f = [0.1-0.6] Hz in their case. The results of Lei et al [16] confirmed this trend whatever the geometry considered (packed bed spheres, parallel plates or pack screen bed). However, they showed also that COP could also increase with the cycle frequency for large aspect ratios depending on the geometry and hydraulic parameter.…”

Section: Influence Of the Blowing Timesupporting

confidence: 77%

“…Numerical 1D or 2D models appeared also as valuable tools to design new active magnetic regenerative refrigeration (AMRR) systems [8][9][10][11][12][13][14][15][16]. Tagliafico et al [8] considered a reciprocating AMR with powder of gadolinium and investigated the influences of both the utilization factor UF (within the range [0.…”

Section: Introductionmentioning

confidence: 99%

“…The authors suggested to find a compromise between reducing the entropy generation by heat conduction, and increasing the magnetocaloric work when introducing insulator layers. Lei et al [16] published a parametric study about the influence of the cycle frequency, hydraulic diameter and mass flow rate on the COP and generated entropy of an AMR for five geometrical configurations using a 1D model. They recommended the use of the packed screen bed or of a similar matrix structure.…”

Section: Introductionmentioning

confidence: 99%

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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 Timesupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Mugica

Roy

Poncet

et al. 2017

Entropy

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“…These physical properties make freeze‐cast structures advantageous for, for example, biomedical applications or applications of limited thickness such as filters and ceramic support structure for, for example, membranes or fuel cells . However, for applications where the ceramic is a medium for oscillating flows of fluids or gasses in larger bodies, homogeneous channel sizes and consistent morphology are preferred …”

Section: Introductionmentioning

confidence: 99%

The effect of gelation on statically and dynamically freeze‐cast structures

et al. 2019

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Freeze‐casting is a technique used to produce structures with anisotropic porosity in the form of well‐defined microchannels throughout a sample. Here, this technique is used on the magnetocaloric ceramic La0.66Ca0.26Sr0.07 Mn1.05O3. We show that a dynamic freezing profile, where the temperature is decreased continuously at −10 K/min, results in homogeneous, lamellar channels with widths of ∼15 µm, while static freezing, where the temperature is kept constant at 177 K, results in channels of increasing size away from the initial ice crystal nucleation site. The effect of gelation before freeze‐casting is also investigated. Gelation inhibits ice crystal growth, which significantly changes the morphology by making channel cross sections less elongated, while additionally introducing more dendrites and ceramic bridges in the structure. The latter significantly dominates the flow path through the gelated structures, affecting the calculated tortuosity, which increases to τ ≈ 4 when compared to non‐gelated samples where calculated tortuosities are in the range of ∼1.3 to ∼3. Finally, we present a systematic and automatic approach for evaluating channel and wall sizes and calculating tortuosities. This is based on analysis of images obtained by scanning electron microscopy using a continuous particle size distribution method and the TauFactor application in MATLAB®.

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“…Recently, a study of regenerator geometries based on numerical AMR simulations has been carried out (Lei et al 2015). The analysis was based on conditions quite similar to those of the experiment considered here and the results may be used to roughly estimate potential improvements of the current experimental efficiency, disregarding parasitic losses due to pressure drop over external components and mechanical losses.…”

Section: Regenerator Designmentioning

confidence: 99%