Patent ID: 7775064

Claim:
An evaporative cooler comprising; a heat exchanger having a number of heat conducting walls that separate i) a primary air flow circuit on a first side of the heat exchanger; and ii) a secondary air flow circuit on a second side of the heat exchanger, which is thermally coupled to the primary air flow circuit via the number of at least partially heat-conducting walls of the heat exchanger, through which two circuits the separated air flows can flow in countercurrent and in heat exchange, which heat-conducting walls have a plurality of zigzag-shaped strips forming fins, on both sides, each fin having a plurality of perforations in the form of slots, the slots having a shape such that in use an air flow is successively deflected from one side of the fin to another side of the fin improving heat exchange between the air flow and the fin; the heat-conducting surfaces of the said walls and the fins, at least in the region of the secondary medium forming a wettable heat exchange surface for evaporation of an irrigation liquid, and being at least partially covered with a hydrophilic, covering layer, which covering layer can absorb an evaporable liquid, can retain this liquid and then release it again through evaporation, in such a manner that the moistened covering layer and as a result also the heat-conducting surfaces and the fins are cooled; and iii) an irrigation system, the irrigation system comprising: a spraying device for spraying the irrigation liquid over a plurality of drop forming openings in a drop forming device that forms part of a distribution area; the drop forming openings forming a plurality of drops from the distributed irrigation liquid and supplying the drops from the distribution area to the wettable heat exchange surface, wherein the distribution area is a substantially closed volume for substantially preventing egress of nebulized irrigation liquid, and the slots in the fins are configured such that in use irrigation liquid can pass therethrough to wet the fins located at a lower level.