A Thermal Barrier With Adaptive Heat Transfer Characteristics

Abstract

A thermal barrier with adaptive heat transfer characteristics for applications in zero gravity environments is considered. The barrier consists of a mixture of fluid with a small volume fraction of arbitrarily oriented, randomly distributed particles of ellipsoidal shape. Heat flux control is obtained by changing the orientation of the particles. Heat flow may be increased up to several hundred times by rotating the particles from being parallel to the walls to being transverse to the walls and by increasing their aspect ratio, volume fraction, and relative thermal conductivity. An increase in the size of the particles results in the appearance of wall effects, which may substantially reduce heat flow as compared to the case of an infinite medium. Very large temperature variation is found to occur near the walls where an apparent “slip” of temperature occurs for barriers whose thickness is large compared to the particle size.