Vapor compression AC system with evaporative cooler assisted evaporator

Abstract

A heating and ventilating and air conditioning system includes an evaporative cooler positioned upstream from an evaporator. The evaporative cooler defines a primary airstream and a secondary airstream flowing transversely to the primary airstream. The output temperature T o of the primary airstream is maintained by controlling the mass flow rate ratio of the secondary airstream to the primary airstream. By controlling the mass flow rate ratio, cooler air from the primary airstream is provided to the evaporator, thereby improving the efficiency of the overall system.

1 . A method of conditioning air comprising the steps of;
 providing intake air having a specific heat c pa  and an initial temperature T i  and an initial absolute humidity ω i ,   dividing the intake air into a primary airstream flowing at a primary mass flow rate {dot over (m)} p  and a secondary airstream,   flowing the secondary airstream transversely to the primary airstream at a secondary mass flow rate {dot over (m)} s ,   providing a liquid having a latent heat of evaporation h fg  to the secondary airstream,   extracting heat from the primary airstream,   transferring the extracted heat to the secondary airstream to evaporate the liquid into the secondary airstream having a secondary absolute humidity ω s , and   varying the ratio of the secondary airstream to the primary airstream from the intake air to maintain an output temperature T o  of the primary airstream according to the equation   
     
       
         
           
             
               T 
               o 
             
             = 
             
               
                 T 
                 i 
               
               - 
               
                 
                   [ 
                   
                     
                       ( 
                       
                         
                           h 
                           fg 
                         
                         
                           c 
                           pa 
                         
                       
                       ) 
                     
                      
                     
                         
                     
                      
                     
                       ( 
                       
                         
                           
                             m 
                             s 
                           
                           . 
                         
                         
                           
                             m 
                             . 
                           
                           p 
                         
                       
                       ) 
                     
                      
                     
                         
                     
                      
                     
                       ( 
                       
                         
                           ω 
                           s 
                         
                         - 
                         
                           ω 
                           i 
                         
                       
                       ) 
                     
                   
                   ] 
                 
                 . 
               
             
           
         
       
     
   
   
       2 . A method as set forth in  claim 1  wherein said varying the ratio is further defined as varying the airflow through a plurality of orifices fluidly connecting the primary and secondary airstreams. 
   
   
       3 . A method as set forth in  claim 2  wherein said varying the ratio is further defined as moving a cover to selectively diminish and increase the flow through said plurality of orifices. 
   
   
       4 . A heating and ventilating and air conditioning (HVAC) system comprising;
 an evaporative cooler for receiving a supply of intake air at a temperature T i  and a specific heat c pa  and an absolute humidity ω i ,   said evaporative cooler defining a plurality of dry channels for establishing a primary airstream having a primary mass flow rate {dot over (m)} p ,   said evaporative cooler defining a plurality of wet channels extending transversely to said dry channels for establishing a secondary airstream having an absolute humidity ω s  and a secondary mass flow rate {dot over (m)} s ,   a flow divider for dividing said intake air into said primary airstream and said secondary airstream,   a tank for providing a liquid having a latent heat of evaporation h fg  to said wet channels for evaporation into the secondary airstream, and   a controller for controlling said flow divider for varying the ratio of the secondary airstream to the primary airstream from the intake air to maintain an output temperature T o  of said primary airstream according to the equation   
     
       
         
           
             
               T 
               o 
             
             = 
             
               
                 T 
                 i 
               
               - 
               
                 
                   [ 
                   
                     
                       ( 
                       
                         
                           h 
                           fg 
                         
                         
                           c 
                           pa 
                         
                       
                       ) 
                     
                      
                     
                         
                     
                      
                     
                       ( 
                       
                         
                           
                             m 
                             s 
                           
                           . 
                         
                         
                           
                             m 
                             . 
                           
                           p 
                         
                       
                       ) 
                     
                      
                     
                         
                     
                      
                     
                       ( 
                       
                         
                           ω 
                           s 
                         
                         - 
                         
                           ω 
                           i 
                         
                       
                       ) 
                     
                   
                   ] 
                 
                 . 
               
             
           
         
       
     
   
   
       5 . A system as set forth in  claim 4  wherein said wet channels are lined with a wicking material for drawing liquid from said tank into said wet channels. 
   
   
       6 . A system as set forth in  claim 5  wherein said flow divider includes a plurality of orifices fluidly connecting said dry and wet channels. 
   
   
       7 . A system as set forth in  claim 6  wherein said flow divider includes a cover movable by said controller for selectively diminishing and increasing the flow through said orifices. 
   
   
       8 . A system as set forth in  claim 7  wherein said controller includes an actuator engaged with said cover for moving said cover. 
   
   
       9 . A system as set forth in  claim 6  wherein said flow divider includes a slide cover movable by said controller for selectively obstructing and opening said orifices. 
   
   
       10 . A system as set forth in  claim 6  wherein said flow divider includes a hinge cover pivotably connected to said evaporative cooler vertically above said wet channels for selectively diminishing or increasing the flow through said wet channels. 
   
   
       11 . A heating and ventilating and air conditioning (HVAC) system comprising:
 an evaporative cooler for receiving a supply of intake air having an initial temperature of T i  and an absolute humidity ω i and a specific heat c pa ,   said evaporative cooler defining a plurality of horizontal dry channels for establishing a primary airstream at a primary mass flow rate {dot over (m)} p ,   said evaporative cooler defining a plurality of wet channels extending transversely to said dry channels for establishing a secondary airstream having an absolute humidity of ω s  at a secondary mass flow rate {dot over (m)} s ,   a flow divider for dividing said intake air into said primary airstream and said secondary airstream,   an evaporator core downstream of said evaporative cooler for receiving the primary airstream at an output temperature T o  from said dry channels, a tank disposed under said wet channels for containing liquid having a latent heat of evaporation h fg ,   a wicking material disposed in said wet channels for distributing liquid from said tank into said wet channels,   a reservoir for collecting liquid condensate from said evaporator core, and   a controller for controlling said flow divider for varying the ratio of the secondary airstream to the primary airstream from the intake air to maintain the temperature T o  according to the equation   
     
       
         
           
             
               T 
               o 
             
             = 
             
               
                 T 
                 i 
               
               - 
               
                 
                   [ 
                   
                     
                       ( 
                       
                         
                           h 
                           fg 
                         
                         
                           c 
                           pa 
                         
                       
                       ) 
                     
                      
                     
                         
                     
                      
                     
                       ( 
                       
                         
                           
                             m 
                             s 
                           
                           . 
                         
                         
                           
                             m 
                             . 
                           
                           p 
                         
                       
                       ) 
                     
                      
                     
                         
                     
                      
                     
                       ( 
                       
                         
                           ω 
                           s 
                         
                         - 
                         
                           ω 
                           i 
                         
                       
                       ) 
                     
                   
                   ] 
                 
                 . 
               
             
           
         
       
     
   
   
       12 . A system as set forth in  claim 11  wherein said flow divider comprises a plurality of orifices fluidly connecting said dry and wet channels . 
   
   
       13 . A system as set forth in  claim 12  wherein said flow divider includes a cover movable by said controller for selectively diminishing and increasing the flow through said orifices. 
   
   
       14 . A system as set forth in  claim 13  wherein said controller includes an actuator engaged with said cover for moving said cover. 
   
   
       15 . A system as set forth in  claim 12  wherein said flow divider includes a slide cover movable by said controller for selectively obstructing and opening said orifices. 
   
   
       16 . A system as set forth in  claim 12  wherein said flow divider includes a hinge cover pivotably connected to said evaporative cooler above said wet channels for selectively diminishing and increasing the flow through said wet channels. 
   
   
       17 . A system as set forth in  claim 16  wherein said flow divider includes at least one hinge disposed along an upper surface of said evaporative cooler and connected to said hinge cover.