Two-phase liquid cooling system with active venting

Abstract

A two-phase liquid cooling system includes an active venting system for regulating an amount of non-condensable gas within the cooling system. Various venting structures may be used to remove gases from the cooling system, some of which are designed to remove the non-condensable gases and avoid removing the vapor-phase coolant. A control system activates the venting system to achieve a desired pressure, which may be based on measured process conditions within the cooling system.

1 . A two-phase liquid cooling system with active venting, the system comprising: 
 a closed-loop flow path for circulating a coolant;    a two-phase liquid cooling module in the flow path for evaporative cooling of a device;    a venting system for exhausting gas outside the cooling system from a volume fluidly coupled to the flow path; and    a control system operatively coupled to the venting system, the control system configured to activate the venting system based on process conditions within the cooling system.    
   
   
       2 . The system of  claim 1 , wherein the venting system is designed to remove non-condensable gases and substantially no coolant from the system.  
   
   
       3 . The system of  claim 1 , wherein the venting system comprises a vacuum pump for removing gas from the volume fluidly coupled to the flow path.  
   
   
       4 . The system of  claim 1 , wherein the venting system comprises a valve for disallowing air from outside the cooling system to enter the venting system.  
   
   
       5 . The system of  claim 1 , wherein the volume to which the venting system is coupled is further coupled to a return line that has a membrane that is permeable to the coolant and not permeable to the non-condensable gases, thereby increasing the relative concentration of non-condensable gases in the volume for being removed from the cooling system.  
   
   
       6 . The system of  claim 1 , wherein the venting system comprises a condenser to condense the coolant and thereby separate the coolant from the non-condensable gases.  
   
   
       7 . The system of  claim 1 , wherein the venting system comprises a centrifugal separator to separate the coolant and the non-condensable gases based on density.  
   
   
       8 . The system of  claim 1 , wherein the venting system comprises: 
 a semi-permeable tubing coupled to the flow path, the semi-permeable tubing permeable to the non-condensable gases and not permeable to the coolant;    a vacuum chamber housing the semi-permeable tubing; and    a pump coupled to the housing to remove gases therefrom.    
   
   
       9 . The system of  claim 1 , wherein the venting system is coupled to a sealed chamber for storing gases vented from the cooling system.  
   
   
       10 . The system of  claim 9 , wherein the sealed chamber includes a condenser for condensing any coolant vapor therein and a valve for venting gas from the chamber when the pressure therein reaches a predetermined maximum.  
   
   
       11 . The system of  claim 1 , wherein the process conditions within the cooling system include temperature and pressure.  
   
   
       12 . The system of  claim 1 , wherein the control system is configured to activate the venting system to keep the coolant in the cooling system at a point near the coolant's saturation curve.  
   
   
       13 . The system of  claim 1 , wherein the control system is configured to activate the venting system to keep the coolant in the cooling system within a predetermined tolerance from the coolant's saturation curve.  
   
   
       14 . The system of  claim 1 , wherein the control system is configured to activate the venting system to maintain a desired temperature at a cooling module.  
   
   
       15 . The system of  claim 1 , wherein the control system is configured to perform a step for regulating the pressure within the cooling system.  
   
   
       16 . The system of  claim 1 , wherein the cooling system is a rack-mounting system.  
   
   
       17 . The system of  claim 1 , wherein the cooling module is a spray cooling module.  
   
   
       18 . The system of  claim 1 , wherein the volume from which the venting system exhausts gas is a reservoir in a heat exchanger of the cooling system.  
   
   
       19 . The system of  claim 1 , wherein the volume from which the venting system exhausts gas is a return manifold in the flow path.  
   
   
       20 . A cooling system comprising: 
 a closed-loop fluid path having an internal volume, the internal volume for holding: 
 a cooling fluid having a vapor portion occupying a partial amount of the internal volume and a liquid portion occupying a partial amount of the internal volume, and  
 a non-condensable gas occupying a partial amount of the internal volume;  
   one or more two-phase liquid cooling modules in the fluid path; and    a means for regulating an amount of the non-condensable gas within the internal volume.    
   
   
       21 . The system of  claim 20 , wherein the means for regulating is configured to remove substantially no coolant from the system.  
   
   
       22 . The system of  claim 20 , wherein the means for regulating is coupled to a sealed chamber for storing gases vented from the cooling system.  
   
   
       23 . The system of  claim 22 , wherein the sealed chamber includes a condenser for condensing any coolant vapor therein and a valve for venting gas from the chamber when the pressure therein reaches a predetermined maximum.  
   
   
       24 . The system of  claim 20 , wherein the means for regulating is configured to control an amount of the non-condensable gas within the internal volume based on at least one of a temperature and a pressure at a location in the internal volume.  
   
   
       25 . The system of  claim 20 , wherein the means for regulating is configured to keep the cooling fluid at a point near the cooling fluid's saturation curve.  
   
   
       26 . The system of  claim 20 , wherein the means for regulating is configured to keep the cooling fluid within a predetermined tolerance from the cooling fluid's saturation curve.  
   
   
       27 . The system of  claim 20 , wherein the means for regulating is configured to maintain a desired temperature at the cooling modules.  
   
   
       28 . The system of  claim 20 , wherein the cooling system is a rack-mounting system.  
   
   
       29 . The system of  claim 20 , wherein the cooling module is a spray cooling module.  
   
   
       30 . A closed-loop liquid cooling system having an internal volume, the system comprising: 
 a cooling fluid having a vapor portion occupying a partial amount of the internal volume and a liquid portion occupying a partial amount of the internal volume;    a non-condensable gas occupying a partial amount of the internal volume; and    a means for regulating the amount of the non-condensable gas within the internal volume.    
   
   
       31 . The system of  claim 30 , wherein the means for regulating is configured to remove substantially no coolant from the system.  
   
   
       32 . The system of  claim 30 , wherein the means for regulating is configured to control an amount of the non-condensable gas within the internal volume based on at least one of a temperature and a pressure at a location in the internal volume.  
   
   
       33 . The system of  claim 30 , wherein the means for regulating is configured to keep the cooling fluid at a point near the cooling fluid's saturation curve.  
   
   
       34 . The system of  claim 30 , wherein the means for regulating is configured to keep the cooling fluid within a predetermined tolerance from the cooling fluid's saturation curve.  
   
   
       35 . The system of  claim 30 , wherein the cooling system is a rack-mounting system.  
   
   
       36 . The system of  claim 30 , wherein the cooling system further comprises one or more spray cooling modules.  
   
   
       37 . A method for venting a non-condensable gas from a two-phase liquid cooling system, the method comprising: 
 passing a coolant through a closed-loop flow path, the flow path including one or more cooling modules;    cooling a heat producing device using the cooling modules, the cooling resulting in the formation of coolant vapor;    collecting the coolant vapor and a non-condensable gas in a volume fluidly coupled to the flow path; and    venting an amount of the non-condensable gas from the volume to outside the cooling system, the venting based on measured process conditions within the cooling system.    
   
   
       38 . The method of  claim 37 , wherein the venting removes non-condensable gases and substantially no coolant from the system.  
   
   
       39 . The method of  claim 37 , wherein the volume from which the non-condensable gas is vented is coupled to a return line that has a membrane that is permeable to the coolant and not permeable to the non-condensable gas, thereby increasing the relative concentration of non-condensable gases in the volume for being removed from the cooling system.  
   
   
       40 . The method of  claim 37 , further comprising: 
 condensing coolant in the volume to separate the coolant from the non-condensable gas being vented.    
   
   
       41 . The method of  claim 37 , further comprising: 
 separating the coolant from the non-condensable gas being vented using a centrifugal separator.    
   
   
       42 . The method of  claim 37 , wherein the venting system comprises: 
 directing a flow of the coolant and non-condensable gas through a semi-permeable tubing in a vacuum chamber, the semi-permeable tubing permeable to the non-condensable gases and not permeable to the coolant;    reducing the pressure in the vacuum chamber to collect non-condensable gas from the tubing to the vacuum chamber; and    pumping the non-condensable gas from the vacuum chamber.    
   
   
       43 . The method of  claim 37 , wherein the vented non-condensable gas is directed to a sealed chamber.  
   
   
       44 . The method of  claim 38 , further comprising: 
 condensing coolant vapor in the sealed chamber; and    venting gas from the sealed chamber through a valve when the pressure in the sealed chamber reaches a predetermined maximum.    
   
   
       45 . The method of  claim 37 , wherein the process conditions within the cooling system include temperature and pressure.  
   
   
       46 . The method of  claim 37 , wherein the venting is controlled to keep the coolant in the cooling system at a point near the coolant's saturation curve.  
   
   
       47 . The method of  claim 37 , wherein the venting is controlled to keep the coolant in the cooling system within a predetermined tolerance from the coolant's saturation curve.  
   
   
       48 . The method of  claim 37 , wherein the venting is controlled to maintain a desired temperature at a cooling module.  
   
   
       49 . The method of  claim 37 , wherein the cooling modules are spray cooling modules.