Event Details
Active Magnetic Refrigeration
Presenter: Andrew Rowe - Department of Mechanical Engineering, University of Victoria
Supervisor:
Date: Tue, March 26, 2002
Time: 11:00:00 - 12:00:00
Place: EOW 430
ABSTRACT
Abstract:
The reversible temperature change induced in materials by the application of a magnetic field is known as the magnetocaloric effect. The use of this phenomenon to produce cooling was suggested by Debye and Giauque in 1926, and was subsequently proven by the latter to produce a low temperature near 0.5 K. Although magnetic cooling was primarily used to produce temperatures below 1 K, a magnetic refrigerator near room temperature was developed in the mid 70's using the magnetocaloric effect of Gadolinium. With this demonstration, the idea of using magnetocaloric materials in refrigeration devices from room temperature to the cryogenic regime was born.
In contemporary materials, the magnetocaloric effect is a strong non-linear function of temperature. In addition, it is a function of the magnitude of the field change and the initial field strength. For most magnetic materials, the magnetocaloric effect is modest and producing a large temperature span using traditional cycles requires the use of superconducting magnets. Another way of increasing the temperature span is to create an Active Magnetic Regenerator (AMR). In this configuration, the refrigerant acts as a regenerator as well as the means of work input and can produce temperature spans many times larger than the adiabatic temperature change.
In this talk, a brief introduction of the magnetocaloric effect, active magnetic refrigeration, and reasons for the development of refrigerators based on this cycle will be presented. Design issues particular to this technology are related to various device geometries. Recent developments will be discussed, as will some of the issues of material research for AMRs. Finally, the development of a test apparatus used to study magnetocaloric materials and prove AMR design concepts will be described. The implications of experimental and numerical data gathered in the course of this research will be explained.