Efficiency indirect evaporative cooler

Abstract

An indirect evaporative cooler wherein the exhaust air from the wet passages is drawn directly from the wet passages by a first fan ( 66 ) while a second fan ( 64 or 42 ) powers the movement of air to be cooled through dry passages of the cooler.

1 . An indirect evaporative cooler comprising:
 a heat exchanger having alternating wet and dry air flow passages such that, in use, a first air flow passes in a first direction through the dry air flow passages and a secondary air flow, being a portion of the first air flow emerging from the dry passages, travels in counter flow to the first direction and through the wet passages to an exhaust;   a plenum adapted to receive air emerging from the dry passages and from which a portion of the emerging air is, in use, said secondary air and the remainder is supply air;   means of wetting said wet passages;   a first fan adapted to move air into and through the dry passages;   characterised in that a second fan is located downstream of the exhaust of the wet passages to draw said secondary air through the wet passages.   
     
     
         2 . A cooler as claimed in  claim 1 , wherein the first fan is located upstream of the dry passages. 
     
     
         3 . A cooler as claimed in  claim 1 , wherein the first fan is located downstream of the dry passages. 
     
     
         4 . A cooler as claimed in  claim 1  wherein at least one of the fans is speed controlled. 
     
     
         5 . A cooler as claimed in  claim 4  wherein both fans are speed controlled. 
     
     
         6 . A method of indirect evaporative cooling wherein a lower than ambient pressure is applied to exhaust outlets of wet passages of a heat exchanger having alternating wet and dry air flow passages and comprising passing a first air flow through the dry passages before drawing off a portion thereof as secondary air through the wet passages by said lower than ambient pressure. 
     
     
         7 . A method as claimed in  claim 6  wherein the lower than ambient pressure is variable. 
     
     
         8 . A method as claimed in  claim 6 , wherein the first air flow rate is variable. 
     
     
         9 . A cooler as claimed in  claim 2  wherein at least one of the fans is speed controlled. 
     
     
         10 . A cooler as claimed in  claim 3  wherein at least one of the fans is speed controlled. 
     
     
         11 . A cooler as claimed in  claim 9  wherein both fans are speed controlled. 
     
     
         12 . A cooler as claimed in  claim 10  wherein both fans are speed controlled. 
     
     
         13 . A method as claimed in  claim 7 , wherein the first air flow rate is variable.