Thermosiphon having improved efficiency

Abstract

The invention relates to an improved thermosiphon and to a method for transferring heat. The thermosiphon has a higher efficiency than existing thermosiphons because it does not rely on a pool-boiling evaporator but rather uses a forced-convection boiling evaporator. The inlet of the evaporator is located in its upper portion and is in fluid communication with a condenser. The fluid in its liquid phase enters the evaporator from its inlet in its upper portion and, by gravity, flows down the piping network of the evaporator, clinging on the inner surface of the tubes of the piping network. As the liquid flows down, it evaporates such that the fluid at the bottom of the evaporator is predominantly in a gaseous phase. The fluid in gaseous phase is then returned to the condenser.

1 . A method for transferring heat comprising the steps of: 
 providing a condenser having a condenser lower portion;    providing an evaporator having a downwardly extending piping network, said piping network having an upper end and a lower end;    providing a fluid in said evaporator;    providing a temperature difference between said condenser and said evaporator;    circulating said fluid in gaseous phase from said evaporator to said condenser;    circulating said fluid in liquid phase from said condenser lower portion to said evaporator upper end;    allowing said fluid in liquid phase to flow by gravity inside said piping network from said upper end of said piping network towards said lower end of said piping network, while causing said fluid in a liquid phase to cling to at least a portion of an inside surface along said piping network, said fluid co-existing in both liquid phase and gaseous phase at a cross-section of said piping network;    along said evaporator piping network, transferring heat from an outside of said evaporator piping network to said inside surface to evaporate said fluid clinging to said inside surface; and    condensing said fluid in gaseous phase in said condenser.    
   
   
       2 . A method as defined in  claim 1  further comprising the step of: 
 placing said condenser lower portion at a higher position than said upper end of said piping network.    
   
   
       3 . A method as defined in  claim 2  further comprising the step of: 
 routing said conduit such that said fluid in a liquid phase flows by gravity from said condenser lower portion to said upper end of said piping network.    
   
   
       4 . A method as defined in  claim 3  wherein said lower end of said piping network is closed.  
   
   
       5 . A method as defined in  claim 1  further comprising the step of: 
 distributing said fluid in liquid phase on said inside surface of said piping network by providing a wick adjacent said inside surface of said piping network.    
   
   
       6 . A method as defined in claim.  1  wherein said fluid in gaseous phase circulates from said evaporator to said condenser inside said conduit.  
   
   
       7 . A method as defined in  claim 1  wherein said fluid in gaseous phase circulates from said lower end of said piping network to an upper portion of said condenser.  
   
   
       8 . A method as defined in  claim 1  further comprising the step of: 
 pumping said fluid in liquid phase from said condenser lower portion to said upper end of said piping network.    
   
   
       9 . A thermosiphon comprising:  
   
   
       10 . a condenser having an upper portion and a lower portion, said lower portion being provided with a condenser outlet;  
   
   
       11 . an evaporator having a downwardly extending piping network, said piping network having an upper end, a lower end and at least one pipe, said upper end of said piping network being connected to said condenser outlet by a conduit, said evaporator being adapted to receive a fluid in liquid phase and have it flow downwardly by gravity in contact with an inner surface of said at least one pipe of said piping network.  
   
   
       12 . A thermosiphon as defined in  claim 9  wherein an inner surface of said at least one pipe is textured to increase its surface roughness.  
   
   
       13 . A thermosiphon as defined in  claim 9  wherein said piping network further comprises a wick located in contact with an inner surface of said at least one pipe.  
   
   
       14 . A thermosiphon as defined in  claim 9  wherein said at least one pipe is formed in the shape of a coil.  
   
   
       15 . A thermosiphon as defined in  claim 9 , further comprising a condenser inlet located at said upper portion, said inlet being connected to said lower end of said piping network.  
   
   
       16 . A thermosiphon as defined in  claim 9 , further comprising a condenser inlet located at said upper portion, said inlet being connected to said upper end of said piping network.  
   
   
       17 . A thermosiphon as defined in  claim 9  wherein said lower end of said piping network is closed.  
   
   
       18 . A thermosiphon as defined in  claim 9  further comprising a sight glass located at said lower end of said piping network.  
   
   
       19 . A thermosiphon as defined in  claim 9  further comprising a fluid in both a gaseous phase and a liquid phase, said fluid in a liquid phase being operative to flow from said condenser outlet to said upper end of said piping network.  
   
   
       20 . A thermosiphon as defined in  claim 17  wherein said fluid in liquid phase is further operative to flow downwardly by gravity from said upper end of said piping network to said lower end of said piping network.  
   
   
       21 . A thermosiphon as defined in  claim 18 , wherein said fluid is further operative to cling on said inner surface of said at least one pipe of said piping network.  
   
   
       22 . A thermosiphon as defined in  claim 19  wherein said fluid in gaseous phase circulates in said conduit from said upper end of said piping network towards said condenser outlet and into said lower portion of said condenser.  
   
   
       23 . A thermosiphon as defined in  claim 20  wherein said lower end of said piping network is closed.  
   
   
       24 . A thermosiphon as defined in  claim 19  wherein said fluid in gaseous phase circulates from said lower end of said piping network to said upper portion of said condenser.  
   
   
       25 . A thermosiphon as defined in  claim 19  wherein said fluid in gaseous phase circulates from said upper end of said piping network to said upper portion of said condenser.  
   
   
       26 . A thermosiphon as defined in  claim 19  further comprising a pump operative to circulate said fluid in liquid phase from said lower portion of said condenser to said upper end of said piping network.  
   
   
       27 . A thermosiphon as defined in claims  19  wherein said fluid is predominantly in a gaseous phase at said lower end of said piping network.