Optimization of the performance characteristics in an irreversible regeneration magnetic Brayton refrigeration cycle

Abstract

A model of the irreversible regenerative Brayton refrigeration cycle working with paramagnetic materials is established, in which the regeneration problem in two constant-magnetic field processes and the irreversibility in two adiabatic processes are considered synthetically. Expressions for the COP, cooling rate, power input, the minimum ratio of the two magnetic fields, etc., are derived. It is found that the influence of the irreversibility and the regeneration on the main performance parameters of the magnetic Brayton refrigerator is remarkable. It is important that we have obtained several optimal criteria, which may provide some theoretical basis for the optimal design and operation of the Brayton refrigerator. The results obtained in the paper can provide some new theoretical information for the optimal design and performance improvement of real Brayton refrigerators. paramagnetic salt, Brayton refrigeration, irreversibility, regeneration, performance characteristics, optimum criterion PACS number(s): 75.30.Sg, 07.20.Mc Citation:Wang H, Wu G X. Optimization of the performance characteristics in an irreversible regeneration magnetic Brayton refrigeration cycle.The conventional vapor compression refrigerator widely used in many fields has many disadvantages such as the energy efficiency being difficult to improve further, the gases used enhance the greenhouse effect or deplete the ozone layer, and so on. Magnetic refrigeration is an environment-safe refrigeration technology which has been studied for a long time [1][2][3][4][5] for its potential use in refrigeration cycles as an alternative to gases, especially at low temperatures. As more and more attention is paid to environmental protection and investigations on room-temperature magnetic refrigeration materials, magnetic refrigeration theory and technology have had a great development [6-11]. Optimal analysis and design of magnetic refrigeration cycles [12][13][14][15][16][17] have become one of the interesting research subjects for people working in thermodynamics and statistical physics. Moreover, most of the literature has only researched the optimal performance characteristics of a magnetic Stirling [18][19][20] or Ericsson refrigeration cycle [21][22][23][24].The magnetic Brayton refrigeration cycle is one of the important refrigeration cycles and has some distinct merits that are noteworthy in the research and manufacture of roomtemperature magnetic refrigerators. Although the analysis and design of some magnetic Brayton refrigeration cycles has been undertaken [25][26][27], research on the performance of the magnetic Brayton refrigeration cycle is relatively rare [28][29][30]. In fact, the magnetic Brayton refrigeration cycle is also a significant regenerative cycle. Therefore, it is necessary to consider both the regenerative and other irreversible effects on a magnetic Brayton refrigeration cycle.In the article, we investigate the main characteristics of an irreversible regenerative magnetic Brayton refrigeration cycle. The paper is organized as ...

Ecological optimization for an irreversible magnetic Ericsson refrigeration cycle

“…Using Eqs. ( 21)-( 25), ( 32), (34), and (36), by means of a numerical approach, one can reveal the general performance characteristics of the irreversible magnetic Ericsson refrigeration cycle and give the relation of some important parameters. It can be seen from Fig.…”

“…( 21)-( 25), Eqs. ( 32), (34), and (36), by means of a numerical approach we can also obtain the ratio of the cooling rate R * E /R * max , the COP ε E /ε max , and the entropy generation rate σ * E /σ * R versus the temperature ratio T C /T H , as shown in Fig. 10, respectively.…”

“…[29][30][31][32][33][34] In recent years, the performance optimization of magnetic cycles (magnetic engines, magnetic refrigerators, and magnetic heat pumps) has become one of the most interesting research subjects. However, most of the literature has only researched the optimal performance characteristics of magnetic Carnot, [35] Brayton, [36][37][38][39][40][41][42][43] Stirling, [44][45][46][47] and Ericsson [48][49][50][51][52] refrigeration cycles.…”