Magnetic Refrigeration Technology at Room Temperature

Bouchekara, Houssem R. E. H.; Nahas, Mouaaz

doi:10.5772/33789

Cited by 10 publications

(4 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…B2, the variations of the magnetic entropy and change in magnetic entropy are compared with the one that is obtained from the literature (Bouchekara and Nahas, 2012). Here the solid lines represent the evaluated values using the procedure that is described in Appendix B1 and the symbols denote the numerical data from the reference work (Bouchekara and Nahas, 2012) magnetic field intensity values, B = 0.0, 2.0, 5.0 and 10.0 Tesla. Under zero magnetic field, there is a sharp change near the Curie temperature of the material.…”

Section: B2 Algorithm Of the User Defined Functionmentioning

confidence: 99%

Numerical analysis of a near-room-temperature magnetic cooling system

Ezan

Ekren

Metin

et al. 2017

International Journal of Refrigeration

View full text Add to dashboard Cite

In this study, for a near-room-temperature magnetic cooling system, a decoupled multiphysics numerical approach (Magnetism, Fluid Flow, and Heat Transfer) is developed using a commercial CFD solver, ANSYS-FLUENT, as a design tool. User defined functions are incorporated into the software in order to take into account the magnetocaloric effect. Magnetic flux density is assumed to be linear during the magnetization and demagnetization processes. Furthermore, the minimum and maximum magnetic flux densities (Bmin and Bmax) are defined as 0.27 and 0.98, respectively. Two different sets of analyses are conducted by assuming an insulated cold heat exchanger (CHEX) and by defining an artificial cooling load in the CHEX. As a validation case, experimental work from the literature is reproduced numerically, and the results show that the current methodology is fairly accurate. Moreover, parametric analyses are conducted to investigate the effect of the velocity of heat transfer fluid (HTF) and types of HTF on the performance of the magnetic cooling system. Also, the performance metrics of the magnetic cooling system are investigated with regards to the temperature span of the magnetic cooling unit, and the cooling load. It is concluded that reducing the cycle duration ensures reaching lower temperature values. Similarly, reducing the velocity of the HTF allows reducing the outlet temperature of the HTF. In the current system, the highest temperature spans are obtained numerically as around 6 K, 5.2 K and 4.1 K for the cycle durations of 4.

show abstract

Section: B2 Algorithm Of the User Defined Functionmentioning

confidence: 99%

Numerical analysis of a near-room-temperature magnetic cooling system

Ezan

Ekren

Metin

et al. 2017

International Journal of Refrigeration

View full text Add to dashboard Cite

show abstract

“…This was actually done by Tura and Rowe [49,50], who applied a double Halbach as the 1.34 T magnetic field source for a magnetic refrigerator. This kind of approach was also studied by Bjørk et al [51] as well as by Bouchekara and Nahas [52].…”

Section: Rotary Halbach (2d) and Simple (2d) Magnet Assembliesmentioning

confidence: 91%

Magnetic Field Sources

Kitanovski

Tušek

Tomc

et al. 2014

Magnetocaloric Energy Conversion

View full text Add to dashboard Cite

In this chapter we describe some of the most important issues that relate to the sources for magnetic fields. We will try to provide information for engineers about the different possible magnetic field sources with respect to their application in magnetocaloric energy conversion. However, the main emphasis will be on permanent magnets and their assemblies. This is due to the fact that other kinds of magnetic field sources, for instance, electric resistive coils (electromagnets) operate with a rather low efficiency. The efficiency in electromagnets in terms of thermodynamics must be considered as the ratio of the energy output (magnetization energy) and the energy input to the coil. The current passing through the coiled wires in an electromagnet will induce Joule heating, due to the electric resistance. Not only will a loss of valuable energy occur, but the magnetic field source will, in most cases, also require cooling, especially in cases where a high magnetic flux density is required. In superconducting magnets, which can be treated as a special class of electromagnets, the current may be kept circulating through the wires of a coil without electrical resistance losses. However, in order to keep the superconducting magnet operating, a cryogenic system is required to provide cooling for the superconducting electrical coils. Namely, there is no practical application of a room-temperature superconducting material. There are, however, some indicators that this could be possible [1][2][3][4][5]. And if this happens in future, this chapter will unfortunately (or fortunately) not be of much use, but the application will open up an unbelievable range of applications, which will certainly change our way of life, including magnetocaloric energy conversion.The reader should note that the magnetic field source is the most expensive part of a magnetic refrigerator or a heat pump, especially if those are based on permanent or superconducting magnets. Therefore, the optimal design of a magnetic field source is crucial for obtaining a cost-effective and energy-efficient device.

show abstract

“…Based on the law of energy conservation, the main equations describing the heat transfer between the solid material and the carrier fluid in a 1D model (Bouchekara and Nahas, 2012) are given by the following partial differential equations (PDEs),…”

Section: Governing Equationsmentioning

confidence: 99%