Optimal Temperature -Entropy Curves for Magnetic Refrigeration

Cross, Charles R.; Barclay, J. A.; DeGregoria, A. J.; Jaeger, S. R.; Johnson, J.W.

doi:10.1007/978-1-4613-9874-5_93

Cited by 39 publications

(7 citation statements)

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“…The AMR, in fact, is more than a single HR process between two solids as because it utilizes a combination of serially connected internal HR and cascade heat pumping processes by enhancing HTF in reciprocating manner or circulating periodically. Despite the variation in how the cycles are cascaded locally (Cross et al, 1988, Hall et al 1996, the heat regeneration process was achieved by cycling fluid internally back and forth between the heat sink and heat source. Recently, Gu et al (2013) demonstrated an oscillatory refrigerator prototype based on electrocaloric principle while using solid-to-solid contact heat transfer design to regenerate cooling and heating between the high and low temperature solid-state materials by the solid regenerator.…”

Section: Introductionmentioning

confidence: 99%

Study on high efficient heat recovery cycle for solid-state cooling

Qian

Ling

Muehlbauer

et al. 2015

International Journal of Refrigeration

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Traditional vapor compression cycles (VCCs) use mainly halogenated refrigerants such as hydrochloroflurocarbons and hydrofluorocarbons that are considered as greenhouse gases. Therefore, their regulations are imposed on a global scale. As an alternative cooling technology other than VCCs, solid-state cooling technologies, such as magnetic cooling, thermoelastic cooling and electrocaloric cooling, demonstrate its advantage of not using greenhouse gases as working fluids. However, one of the most challenging issues of these solid-state cooling technologies is the relative high parasitic internal latent heat loss, which could significantly deteriorate the system performance. In order to improve the system performance of solid-state cooling, the authors propose a novel and high-efficient heat recovery (HR) cycle for solid-state materials with high thermal conductivity. The novel heat recovery process was first compared as an analog of spatial scale counter-flow heat transfer process. A simplified ideal model was developed to quantitatively investigate the heat recovery process performance limit and the physics behind the analogy of the spatial scale counter-flow heat transfer process. Experiment was conducted and 60% HR efficiency was achieved. In addition, a detailed dynamic model validated by the experiment results was developed and used to further investigate the limiting factors together with the theoretical analysis.

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Section: Introductionmentioning

confidence: 99%

Study on high efficient heat recovery cycle for solid-state cooling

Qian

Ling

Muehlbauer

et al. 2015

International Journal of Refrigeration

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“…This requirement arises from the fact that the refrigeration cycle must satisfy the second law and should be as efficient as possible. An early analysis of an AMR by Cross et al 1 based upon entropy balance determined that the ideal MCE should vary linearly with temperature throughout the bed according to…”

Section: Introductionmentioning

confidence: 99%

Ideal magnetocaloric effect for active magnetic regenerators

Rowe

Barclay²

2003

Journal of Applied Physics

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The active magnetic regenerator ͑AMR͒ uses a magnetic solid as a thermal storage medium and as a working material in a refrigeration cycle. Thermodynamically coupled to a heat transfer fluid, the regenerator produces a cooling effect and generates a temperature gradient across the AMR. The coupling between the heat transfer fluid and the magnetic refrigerant is a key aspect governing the operating characteristics of an AMR. To increase our understanding of AMR thermodynamics, we examine the entropy balance in an idealized active magnetic regenerator. A relation for the entropy generation in an AMR with varying fluid capacity ratios is derived. Subsequently, an expression describing the ideal magnetocaloric effect ͑MCE͒ as a function of temperature is developed for the case of zero entropy generation. Finally, the link between ideal MCE and refrigerant symmetry is discussed showing that an ideal reverse Brayton-type magnetic cycle cannot be achieved using materials undergoing a second-order magnetic phase transition.

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“…the more heat can be extracted per cycle. If the volumetric heat capacity of the heat transfer fluid is constant and small compared to that of the bed material, it has been suggested [7] that optimum refrigeration performance requires a magnetic regenerator bed material with the property that the adiabatic temperature change. ~Tad' with change in magnetic field should be proportional to the absolute temperature T. However, recent work indicates that there may be no specific ideal adiabatic temperature change profile for a material [8] because AMRR constitutes a unique thermodynamic process that cannot be equated to a cascade of thermodynamic cycles each of infinitesimal active element.…”

Section: ~ ~mentioning

confidence: 99%

Simulation of magnetic refrigeration systems

Agrawal

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Optimal Temperature -Entropy Curves for Magnetic Refrigeration

Cited by 39 publications

References 1 publication

Study on high efficient heat recovery cycle for solid-state cooling

Study on high efficient heat recovery cycle for solid-state cooling

Ideal magnetocaloric effect for active magnetic regenerators

Simulation of magnetic refrigeration systems

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