Evaporative cooler

Abstract

The invention relates to an evaporative cooler having two medium circuits which are thermally coupled to one another by a number of heat-conducting vertical walls. These walls and the heat-conducting fins arranged thereon are provided with a hydrophilic, water-buffering covering layer, for example made from Portland cement. A humidification unit for moistening the covering layer is added to the dew point cooler. According to the invention, the humidification unit comprises a releasable cover which forms part of the casing of the dew point cooler and bears at least one sprinkler or nozzle for distributing water over the covering layer.

1 . An evaporative cooler comprising a wettable heat exchange surface and an irrigation system, the irrigation system comprising:
 a spraying device for distributing the irrigation liquid over a distribution area; and   a drop forming device for forming a plurality of drops from the distributed liquid and supplying the drops to the wettable heat exchange surface.   
     
     
         2 . The evaporative cooler according to  claim 1 , wherein the drop forming device comprises a tray having a plurality of openings. 
     
     
         3 . The evaporative cooler according to  claim 2 , wherein the tray is provided with a plurality of recesses, the openings being located at the lowest points of the recesses. 
     
     
         4 . The evaporative cooler according to  claim 3 , wherein the distribution area is located over the tray. 
     
     
         5 . The evaporative cooler according to  claim 1 , wherein the distribution area is a substantially closed volume preventing egress of nebulized irrigation liquid. 
     
     
         6 . The evaporative cooler according to  claim 1 , wherein the spraying device comprises a rotary spray head. 
     
     
         7 . The evaporative cooler according to  claim 1 , wherein the irrigation system further comprises a source of pressurized liquid in communication with the spraying device. 
     
     
         8 . The evaporative cooler according to  claim 1 , comprising:
 a first medium circuit and a second medium circuit, which is thermally coupled to the first medium circuit via a number of at least partially heat-conducting, substantially vertical walls having top edges, through which two circuits two respective media can flow in countercurrent, at least the second medium containing a gas with a relative humidity of less than 100%;   which heat-conducting walls have break-up elements for breaking up at least the thermal boundary layer, the laminar boundary layer and the relative humidity boundary layer at the location of zones which are active for heat transfer in at least the primary medium, which break-up elements comprise heat-conducting projections which increase the size of the effective heat-conducting surface area of the said wall;   the heat-conducting surfaces of the said walls and the break-up elements, at least in the region of the secondary medium, being at least partially covered with a hydrophilic, covering layer, which covering layer can absorb an evaporable liquid through capillary action, 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 break-up elements are cooled;   which covering layer consists of a porous, technical-grade ceramic material, a fired layer, a cement such as a Portland cement, fibrous material, or a mineral wool;   primary drive means based on pressure difference for the primary medium;   a housing with primary and secondary medium inlets and outlets;   wherein the irrigation system is arranged for subjecting the secondary medium to humidification by the evaporable liquid by evaporation of liquid from the covering layer, in such a manner that the evaporated liquid entrained by the secondary medium extracts heat from the primary medium via the heat-conducting walls; and   wherein the irrigation system comprises a removable cover which forms part of the casing and bears the spraying device which is positioned at a distance above the top edges of the walls for distributing water onto the covering layer on the walls and the break-up elements, which spraying device receives pressurised water via at least one water feed line.   
     
     
         9 . The evaporative cooler according to  claim 8  wherein funnels are located in the regions between the top edges of adjacent walls, these funnels receiving the water received from the at least one spraying device and passing it on to the covering layer on the respective walls and the break-up elements. 
     
     
         10 . The evaporative cooler according to  claim 9 , wherein the funnels are formed as moulded strips, each having a number of funnels, which may be releasably connected to opposite top edges of the heat-conducting walls. 
     
     
         11 . The evaporative cooler according to  claim 10 , wherein each strip forms a monolithic unit with a wall or two adjacent walls. 
     
     
         12 . The evaporative cooler according to  claim 11 , wherein the strips, and if appropriate the associated wall or walls consist of plastic and are formed by thermoforming, vacuum-forming or injection-moulding. 
     
     
         13 . The evaporative cooler according to  claim 8 , comprising a number of spraying devices which are each connected to the at least one water feed line via an individual water feed line which is connected to each spraying device via a manifold. 
     
     
         14 . The evaporative cooler according to  claim 8 , wherein the cover comprises two molded plates which are placed on top of one another and are connected to one another, which plates delimit a passage which forms the water feed line. 
     
     
         15 . The evaporative cooler according to  claim 8 , wherein the housing comprises a base which has a discharge device for excess water. 
     
     
         16 . A method of wetting a heat exchange surface of an evaporative cooler with an evaporable liquid, comprising:
 supplying the liquid to a generally closed distribution area; and   delivering the liquid to the heat exchange surface in an intermittent manner substantially without nebulization.   
     
     
         17 . The method according to  claim 16 , wherein the liquid is sprayed into the distribution area. 
     
     
         18 . The method according to  claim 17 , wherein the liquid is delivered to the heat exchange surface from the distribution area from a plurality of recesses formed in the distribution area. 
     
     
         19 . The method according to  claim 17 , wherein the intermittent delivery comprises an actuation period in which the liquid delivery to the heat exchange surface is abruptly started and stopped. 
     
     
         20 . The method according to  claim 19 , wherein sufficient liquid is delivered in a single actuation period to substantially saturate the heat exchange surface. 
     
     
         21 . The method according to  claim 20 , wherein excess liquid is collected below the heat exchange surface for reuse.