Testing for Leaks in a Two-Phase Liquid Cooling System

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. A venting and refilling system may serve multiple cooling systems in a parallel arrangement. A return path of the cooling system can be tested for coolant leaks by increasing the pressure in the return path and placing a coolant detector near the path.

1 . A method for detecting leaks in a two-phase liquid cooling system, the method comprising:
 operating a two-phase cooling system in a normal mode, wherein a coolant is directed via a supply path to one or more cooling modules and collected via a return path in a thermal management unit for cooling and redeployment to the cooling modules, the return path having a pressure below atmospheric pressure;   changing to a diagnostic mode, wherein the pressure of the return path is raised to a pressure at or above atmospheric pressure;   in the diagnostic mode, using a coolant sensor to locate any leaks in the return path; and   returning the cooling system to the normal mode, wherein the pressure of the return path is below atmospheric pressure.   
   
   
       2 . The method of  claim 1 , wherein the pressure of the return path is increased by increasing the temperature of the coolant from the thermal management unit to the supply path. 
   
   
       3 . The method of  claim 2 , wherein the temperature of the coolant from the thermal management unit to the supply path is increased by restricting fluid supplied to a heat exchanger in the thermal management unit that is configured to cool the coolant therein. 
   
   
       4 . A method for detecting leaks in a two-phase liquid cooling system, the method comprising:
 circulating a coolant through a two-phase cooling system, wherein at least a portion of the cooling system has a low-pressure path through which coolant is directed at a pressure below atmospheric pressure;   a step for temporarily increasing the pressure of the low-pressure path of the cooling system above atmospheric pressure; and   testing for leaks in the low-pressure path by checking for coolant leaving the low-pressure path.   
   
   
       5 . The method of  claim 4 , further comprising:
 returning the low-pressure path to a pressure below atmospheric pressure.   
   
   
       6 . A system for detecting leaks in a two-phase liquid cooling system, the system comprising:
 a two-phase cooling system configured to direct a coolant via a supply path to one or more cooling modules and collect the coolant via a return path in a thermal management unit configured to cool and redeploy the coolant to the cooling modules, the return path having a pressure below atmospheric pressure during normal operation of the cooling system;   a control unit coupled to the cooling system, the control unit configured to increase the pressure of the return path to a pressure at or above atmospheric pressure for a diagnostic mode, the control unit further configured to return the cooling system to normal operation; and   a sensor configured to detect any coolant leaking from the return path of the cooling system during the diagnostic mode.   
   
   
       7 . The system of  claim 6 , wherein the control unit is configured to increase the pressure of the return path by increasing the temperature of the coolant from the thermal management unit to the supply path. 
   
   
       8 . The system of  claim 7 , wherein the thermal management unit comprises a heat exchanger configured to cool coolant received from the return path, and wherein the control unit is configured to increase the temperature of the coolant from the thermal management unit to the supply path by restricting fluid supplied to a heat exchanger to decrease the cooling of the coolant by the heat exchanger.