An air fluidized bed, contained in the wall cavity of an exterior building wall, forms the basis of a new solar collector design which is simpler than a water-cooled collector and has a thermal performance superior to that of an air-cooled collector. The fluidized bed serves as an intermediate heat transfer medium between a solar flux absorbed on the external building surface and a liquid thermal transfer loop. Fluidized beds yield heat-transfer coefficients an order of magnitude higher than single phase air flow. Low density particles are used in the bed to minimize power consumption. When defluidized, the bed acts as a good thermal insulator. Recent experimental results are presented for the heat-transfer coefficients of the immersed tubes, bounding walls, the effective conductivity of the bed, and the overall full-scale thermal design efficiency for various low density materials. Structural and power consumption performance is examined as well. An integrated fluidized bed solar collector design is proposed and compared with representative water and air collector designs.
Heat transfer in fluidized and fixed beds of adsorption chillers
