Investigation On The Optimal Performance Of The Two Kinds Of Irreversible Magnetic Refrigeration Cycles

The technology of refrigeration has been applied popularly in many fields. Conventional refrigeration systems have many disadvantages such as serious concerns for the ozonosphere, complex apparatus and lower efficiency. Recently, more and more attentions have been paid to the environmental protection together with that magnetic refrigeration has had great development because its merits in refrigeration efficiency, reliability, saving energy and environmental friendliness. Magnetic refrigeration is an advanced and novel green refrigeration technology. So far most of research works involving magnetic refrigeration have been focused on exploring new magnetic refrigeration materials and designing novel magnetic refrigerators. However, study on the theory of magnetic refrigeration cycle has not been paid more attention to. Theoretical investigation on magnetic refrigeration cycle, which can reveal the influence of many irreversibilities on performance of magnetic refrigeration cycle, is beneficial to performance improvement of magnetic refrigerators and is becoming a significant and promising subject.At the beginning in Chapter 1, the theory of finite time thermodynamics and its development are introduced briefly. And, magnetocaloric effect, principle of magnetic refrigeration, technology of magnetic refrigeration and its development are presented in this Chapter. Afterward, the outline of this thesis is given.In Chapter 2, a new model of irreversible Ericsson refrigeration cycle employing paramagnetic materials as the working substance is established. By using finite time thermodynamic theory and the optimal control theory method, the influences of multi-irreversibilities, such as thermal resistance, heat leak, efficiency of regenerator and internal irreversibility resulting from magnetic working substances, on the performance of the refrigeration cycle are investigated. At the same time, by means of numerical value calculation, the effects of the irreversibilities on the cooling rate, coefficient of performance of the refrigeration cycle are analyzed in detail. The important performance bounds such as the cooling rate, coefficient of performance,...