Influence of the flow rate waveform and mass imbalance on the performance of active magnetic regenerators. Part I: Experimental analysis

Nakashima, Alan T.D.; Dutra, Sergio Luiz; Trevizoli, Paulo V.; Barbosa, Jader R.

doi:10.1016/j.ijrefrig.2018.07.004

Cited by 29 publications

(20 citation statements)

References 33 publications

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“…Extensive reviews of the developed machines are given in Kitanovski et al (2015) and Balli et al (2017). Recently it was demonstrated numerically and experimentally that maldistribution of heat transfer fluid through regenerator beds leads to severe reduction of the machine performance (Eriksen et al, 2016;Nakashima et al, 2018;Trevizoli et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Nature—Inspired Flow Patterns for Active Magnetic Regenerators Assessed Using a 1D AMR Model

Navickaitė

Bahl

2019

Front. Energy Res.

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A novel flow structure of a solid active magnetic regenerator is proposed in this paper. The numerical performances of two nature-inspired flow geometries, based on double corrugated tubes with an elliptical cross-section, are compared to the performance of conventional flow structures for Active Magnetic Regeneration (AMR) applications, namely, packed spheres and a cylindrical micro-channel matrix. The numerical performance of all the geometries is analyzed in terms of cooling power and coefficient of performance. Regenerators with various porosities and two different hydraulic diameters of the flow channels are evaluated varying utilization at fixed temperature spans between the hot and cold reservoirs. The selection of the regenerator geometry is based on two actual AMR machines. The numerical results demonstrate that a suitably optimized AMR geometry with a double corrugated flow pattern provides the same or higher efficiency at higher porosity compared to conventional AMR flow geometries. These findings suggest that the magnetocaloric material used to construct AMR beds can be exploited more efficiently and at a lower investment cost of an AMR device when suitable double corrugated flow pattern is used.

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Section: Introductionmentioning

confidence: 99%

Nature—Inspired Flow Patterns for Active Magnetic Regenerators Assessed Using a 1D AMR Model

Navickaitė

Bahl

2019

Front. Energy Res.

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“…Some of the more significant problems of active magnetic regenerators are the mass imbalance related to the duration of the fluid flow and the need to synchronize the magnetic field and fluid flow. This was further investigated by Nakashima et al, who examined the effects of the flow rate waveform and mass imbalance on the performance of an active magnetic regenerator with a Gd packed bed. Flow maldistribution in the regenerator was found to substantially affect the performance and could cause large irreversible losses.…”

Section: Magnetocaloric Refrigeration and Heat Pumpingmentioning

confidence: 99%

“…A static active magnetic regenerator also enables the use of a unidirectional pump. However, such a system requires a rotary valve or valve assembly such as of solenoid valves for continuous operation of the pump while maintaining the oscillation of the fluid flow. Cam valves may also be used.…”

Section: Magnetocaloric Refrigeration and Heat Pumpingmentioning

confidence: 99%

Energy Applications of Magnetocaloric Materials

Kitanovski

2020

Advanced Energy Materials

377

156

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The need for energy‐efficient and environmentally friendly refrigeration, heat pumping, air conditioning, and thermal energy harvesting systems is currently more urgent than ever. Magnetocaloric energy conversion is among the best available alternatives for achieving these technological goals and has been the subject of substantial basic and applied research over the last two decades. The subject is strongly interdisciplinary, requiring proper understanding and efficient integration of knowledge in different specialized fields. This review article presents a historical and up‐to‐date account of the energy‐related applications of magnetocaloric materials and information about their processing and magnetic fields, thermodynamics, heat transfer, and other relevant characteristics. The article also discusses the conceptual design of magnetocaloric refrigeration and power generation systems and some guidelines for future research in the field.

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“…When the blows have different time durations, the AMR cycle is considered unbalanced, and that is known to have a negative effect on performance [11,34]. In this work, the blows are always balanced; hence, the blow fraction, i.e., the ratio of blow durations to cycle period [11], can be evaluated as:…”

Section: Fluid Flow Profile Modelingmentioning

confidence: 99%

“…Fluid flow profiles can be more easily investigated experimentally, as no changes in the fluid flow hardware are generally required, provided that a reliable and flexible valving system is in place. In particular, the effect of the duration of the fluid blows has been extensively investigated [10][11][12]. There appears to be a consensus in the literature that the cooling capacity of magnetic refrigerators can be increased by displacing the fluid during periods where the magnetic field is at its extreme values.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of the influence of magnetic field waveforms on the performance of active magnetic regenerators

Fortkamp

Lang

Lozano

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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Magnetic cooling is an alternative to vapor compression that does not rely on the use of hazardous substances. The refrigerant is a solid material which reacts to oscillations in magnetic field by changing its temperature (the magnetocaloric effect). In active magnetic regenerators, the magnetocaloric material arranged as a porous medium is subjected to an oscillating fluid flow to allow heat transfer from a cold source to a hot sink in a thermodynamic cooling cycle. Although the literature is abundant with studies on the influence of the fluid flow waveform on magnetic refrigeration devices, the influence of the magnetic field waveform has been much less investigated. In this work, we make use of an active magnetic regenerator numerical model with different mathematically defined waveforms to determine which operating parameters yield the highest values of cooling capacity and coefficient of performance for a specific set of operating conditions. The results show that the best performance is achieved when the magnetic field is kept constant for the same time duration of the fluid flow through the magnetized material, and the transition times between the high and low levels of the magnetic field should be as short as possible.

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Influence of the flow rate waveform and mass imbalance on the performance of active magnetic regenerators. Part I: Experimental analysis

Cited by 29 publications

References 33 publications

Nature—Inspired Flow Patterns for Active Magnetic Regenerators Assessed Using a 1D AMR Model

Nature—Inspired Flow Patterns for Active Magnetic Regenerators Assessed Using a 1D AMR Model

Energy Applications of Magnetocaloric Materials

Numerical analysis of the influence of magnetic field waveforms on the performance of active magnetic regenerators

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