Patent ID: 9644899
Date: 2017-05-09
CPC Classifications: F28D,F28F

Claim:
1. A heat transfer sheet for a rotary regenerative heat exchanger that receives a hot flue gas stream and an air stream and transfers heat from the hot flue gas stream to the air stream, the heat transfer sheet comprising: a rectangular metallic body having a central plane, the rectangular body being defined by and the central plane extending between a first longitudinal end and a second longitudinal end and lateral sides extending therebetween, the first longitudinal end defining a first exposed edge surface entirely along the first longitudinal end and the second longitudinal end defining a second exposed edge surface entirely along the second longitudinal end; a plurality of sheet spacing features extending along the rectangular metallic body in a longitudinal direction parallel to a direction of flow of the hot flue gas stream between the first longitudinal end and the second longitudinal end, the sheet spacing features extending away from opposing sides of the central plane, and the sheet spacing features defining a portion of a flow passage between an adjacent heat transfer sheet; and a plurality of sections of undulations disposed between each pair of adjacent sheet spacing features, the plurality of sections of undulations having a cross-section defined by ridges and valleys that extend normal to the rectangular metallic body into the flow passage, the plurality of sections of undulations undulate laterally between the lateral sides, in the longitudinal direction and parallel to the central plane said plurality of sections of undulations are shaped in an at least partial sinusoidal pattern, said at least partial sinusoidal pattern extending in the longitudinal direction from said first longitudinal end to said second longitudinal end of the sheet so that at least one of the ridges trace a continuous first line, parallel to the central plane, from said first longitudinal end to said second longitudinal end and so that at least one of the valleys trace a continuous second line, parallel to the central plane, from said first longitudinal end to said second longitudinal end, said first longitudinal end and said second longitudinal end being exposed across the entire sheet in a direction transverse to the longitudinal direction to allow a fluid to flow therethrough, said at least partial sinusoidal pattern being oriented such that the first line and the second line are at least partially and continuously redirected laterally in an alternating manner, such that there are no straight through flow paths in the longitudinal direction, in the valleys, that extend continuously from said first longitudinal end to said second longitudinal end.