A heat transfer apparatus includes a heat source having a heat source
maximum operating temperature; and a heat sink comprising a closed
chamber having a chamber first end wall, a chamber second end wall and a
circumferential chamber side wall interconnecting said chamber first end
wall and said chamber second end wall, said walls defining a chamber
interior space, at least one of said chamber first end wall and said
chamber second end wall being a heat transfer wall, a heat transfer
material retained within said chamber, and at least one impeller having
an axis of impeller rotation and an impeller radius mounted within said
chamber adjacent to said heat source to rotate about the axis of impeller
rotation for moving the heat transfer material over said heat transfer
wall and propelling said heat transfer material to a location thermally
remote from said heat source for heat dissipation, wherein said chamber
interior space extends perpendicular to the axis of impeller rotation a
radial thermal spacing distance of at least two times the impeller
radius.