Regenerative preheater for phase change cooling applications

Abstract

A method for cooling an information technology system, comprising: receiving a flow of at least a subcooled liquid phase change refrigerant; cooling the information technology system by sensible heat transfer in an evaporator, to produce at least gaseous refrigerant; and exchanging heat from the at least gaseous refrigerant from the evaporator to the subcooled liquid phase change refrigerant. The phase change refrigerant may be a hydrofluorocarbon ether having a boiling point of 30-65° C. at 1-12 bar.

What is claimed is: 
     
         1 . A manifold for a phase change refrigerant cooling system, comprising:
 an inlet port configured to receive a flow of phase change refrigerant comprising a liquid phase;   an outlet port configured to output a flow of the phase change refrigerant comprising a liquid phase and a gas phase, warmed with respect to the received flow of the phase change refrigerant;   a cold conduit configured to distribute the phase change refrigerant comprising the liquid phase from the inlet port to a plurality of cooling loops, each cooling loop warming the phase change refrigerant with at least one evaporator, such that the phase change refrigerant exiting the cooling loop comprises a liquid phase and a gas phase;   a hot conduit configured to receive the warmed phase change refrigerant from the plurality of cooling loops, and convey it to the outlet port;   a primary heat exchanger, comprising:
 a liquid phase change refrigerant inlet configured to receive a liquid phase change refrigerant having a first subcool from a pump; 
 a warm phase change refrigerant outlet configured to supply a mixed liquid phase and gas phase refrigerant to a condenser; 
 an inlet port interface configured to supply the flow of the phase change refrigerant comprising the liquid phase having a second subcool to the inlet port, the second subcool being less than the first subcool; and 
 an outlet port interface configured to interface with the outlet port, receive the flow of the phase change refrigerant comprising a liquid phase and a gas phase, 
 wherein the primary heat exchanger transfers heat from the received flow of the phase change refrigerant comprising the liquid phase and the gas phase to the liquid phase change refrigerant having the first subcool, to produce the liquid phase change refrigerant having the second subcool; 
   a plurality of secondary heat exchangers, each respective secondary heat exchanger being configured to transfer heat from the warmed phase change refrigerant from a respective cooling loop to a portion of the phase change refrigerant comprising a liquid phase from the cold conduit, whereby a subcooling of the phase change refrigerant comprising a liquid phase entering the respective cooling loop is reduced with respect to the phase change refrigerant comprising a liquid phase;   a controllable bypass valve, configured to control a bypass flow of a portion of the phase change refrigerant from the inlet port to the outlet port, without the bypass flow passing through the cold conduit or the hot conduit; and   a control configured to control the controllable bypass valve dependent on a subcool of the cold conduit.   
     
     
         2 . A phase change refrigerant cooling system, comprising:
 an inlet port configured to receive a flow of at least a liquid phase change refrigerant;   an outlet port configured to output a flow of heated phase change gaseous refrigerant comprising a liquid phase and a gas phase;   a cold conduit configured to distribute the at least liquid phase change refrigerant from the inlet port to at least two successive evaporators in a cooling loop;   a hot conduit configured to receive the heated phase change refrigerant comprising the liquid phase and the gas phase from the at least two successive evaporators in the cooling loop;   a heat exchanger, configured to transfer heat from the heated phase change refrigerant comprising the liquid phase and the gas phase to the at least liquid phase change refrigerant, whereby a subcooling of the at least liquid phase change refrigerant is reduced;   a controllable bypass valve, configured to control a bypass flow of liquid phase change refrigerant from the inlet port mixed with the heated phase change refrigerant from the hot conduit flowing to the outlet port that does not pass through the heat exchanger; and   an automated controller, configured to adjust a valve to control an amount of subcool of the cold conduit.   
     
     
         3 . A heat exchanger for a phase change refrigerant cooled electronic system, comprising:
 an inlet port configured to receive a flow of phase change refrigerant having a first subcool below a boiling point of the phase change refrigerant;   an outlet port configured to output a flow of heated phase change refrigerant comprising a gas phase;   an interface cold port configured to supply the phase change refrigerant having a second subcool below the boiling point of the phase change refrigerant to an evaporator;   an interface hot port configured to receive the heated phase change refrigerant comprising a gas phase from the evaporator;   a heat exchanger, configured to transfer heat from the heated phase change refrigerant from the evaporator to the liquid phase change refrigerant having the first subcool, to reduce the subcool and transform the liquid phase change refrigerant having the first subcool to the liquid phase change refrigerant having the second subcool;   a first valve, configured to control a mixing of a portion of the phase change refrigerant having the first subcool below the boiling point of the phase change refrigerant from the inlet port with the heated phase change refrigerant comprising the gas phase from the evaporator, for efflux through the outlet port as the heated phase change refrigerant comprising the gas phase, the mixed portion of the phase change refrigerant bypassing the heat exchanger; and   a controller, configured to adjust a level of the second subcool with a second valve.   
     
     
         4 . (canceled) 
     
     
         5 . The heat exchanger of  claim 3 , further comprising a pump configured to pressurize the subcooled phase change refrigerant to transport it up a height gradient from a reservoir to the heat exchanger, wherein a subcooling of the phase change refrigerant is greater at the reservoir than at the heat exchanger. 
     
     
         6 . The heat exchanger of  claim 3 , wherein the controller comprises a control system configured to maintain the phase change refrigerant entering the heat exchanger at a subcooled level. 
     
     
         7 . The heat exchanger of  claim 3 , wherein the second valve is proximate to the evaporator and is configured to control a flow of the phase change refrigerant based on a temperature difference,
 further comprising a second heat exchanger configured to transfer heat from the heated phase change refrigerant comprising the gas phase from the evaporator, to the phase change refrigerant having the second subcool below the boiling point of the phase change refrigerant.   
     
     
         8 - 9 . (canceled) 
     
     
         10 . A method for cooling an information technology system, comprising:
 receiving a flow of at least a subcooled liquid phase change refrigerant through an inlet port and returning a warmed flow through an outlet port;   cooling the information technology system by sensible heat transfer in a plurality of evaporators in series, each respective evaporator being configured to produce a warmed at least gaseous phase change refrigerant from a received portion of the flow of at least subcooled liquid phase change refrigerant;   exchanging heat from the warmed at least gaseous phase change refrigerant from the plurality of evaporators in series to the received flow of that at least a subcooled liquid phase change refrigerant with at least one first heat exchanger;   controlling a flow of phase change refrigerant that bypasses the at least one first heat exchanger from the inlet port to the outlet port to form a mixture of the warmed at least gaseous phase change refrigerant with the at least the subcooled liquid phase change refrigerant using a controllable bypass valve controlled dependent on a subcool of mixture of the warmed at least gaseous phase change refrigerant with the at least the subcooled liquid phase change refrigerant; and   controlling a thermodynamic characteristic of the received flow of the at least a subcooled liquid phase change refrigerant with a second valve.   
     
     
         11 . The method of  claim 10 , wherein the heat is exchanged from the warmed at least gaseous phase change refrigerant from the evaporator to the subcooled phase change refrigerant with the first heat exchanger having a cold plate. 
     
     
         12 . The method of  claim 10 , further comprising normalizing the amount of subcooling to compensate for difference in height. 
     
     
         13 . The method of  claim 10 , further comprising:
 pumping the subcooled phase change refrigerant up a height gradient from a reservoir to a second heat exchanger, wherein a subcooling of the phase change refrigerant is greater at the reservoir than at the second heat exchanger;   heating the pumped subcooled phase change refrigerant with heat from the warmed at least gaseous phase change refrigerant in the second heat exchanger;   distributing the heated pumped phase change refrigerant through a cold channel in a manifold to the inlet port;   receiving the warmed at least gaseous phase change refrigerant from the outlet port into a warm channel in the manifold; and   supplying the collected warmed at least gaseous phase change refrigerant from the warm channel in the manifold to the second heat exchanger.   
     
     
         14 . The method of  claim 10 , wherein said controlling comprises controlling the heat exchanging to maintain the phase change refrigerant at a predetermined subcooled level. 
     
     
         15 . (canceled) 
     
     
         16 . The method of  claim 10 , wherein said controlling comprises controlling a flow of the phase change refrigerant with the second valve proximate to the plurality of evaporators in series operated based on a temperature difference. 
     
     
         17 . (canceled) 
     
     
         18 . The method of  claim 10 , wherein said controlling comprises controlling the exchanging of heat from the warmed at least gaseous phase change refrigerant from the evaporator to the subcooled phase change refrigerant dependent on a subcool condition of phase change refrigerant entering the evaporator. 
     
     
         19 . The method of  claim 10 , wherein said controlling comprises controlling the exchanging of heat from the warmed at least gaseous refrigerant from the evaporator to the subcooled phase change refrigerant dependent on sensing a cavitation of refrigerant. 
     
     
         20 . The method of  claim 10 , wherein said controlling comprises controlling the exchanging of heat from the warmed at least gaseous refrigerant from the evaporator to the subcooled phase change refrigerant to maintain at least a portion of liquid refrigerant in the at least gaseous refrigerant, wherein a terminal evaporator of the plurality of evaporators in series receives a flow of phase change refrigerant comprising a liquid phase and a gas phase. 
     
     
         21 . The method according to  claim 10 , wherein the information technology system has a plurality of cooling loops, each cooling loop comprising a respective plurality of evaporators in series, the plurality of cooling loops having different heights with respect to a common pump, each cooling loop being fed by a different respective first heat exchanger, further comprising separately controlling a subcool of the received portion of the flow of at least subcooled liquid phase change refrigerant from each respective heat exchanger. 
     
     
         22 . The manifold according to  claim 1 , further comprising a coolant distribution unit comprising the pump, the condenser, and a liquid phase change refrigerant reservoir. 
     
     
         23 . (canceled) 
     
     
         24 . The manifold according to  claim 1 , wherein each cooling loop comprises a plurality of evaporators in series, each evaporator being configured to cool a central processing unit of a server in a rack, wherein at least one cooling loop has a different height with respect to the pump. 
     
     
         25 . The phase change refrigerant cooling system according to  claim 2 , further comprising at least one additional heat exchanger, each additional heat exchanger being associated with an additional cold conduit configured to distribute the at least liquid phase change refrigerant from the inlet port to at least two successive evaporators in a respective additional cooling loop, and an additional hot conduit configured to receive the heated phase change refrigerant comprising the liquid phase and the gas phase from the at least two successive evaporators in the additional cooling loop, each additional heat exchanger being configured to transfer heat from the at least two successive evaporators to the at least liquid phase change refrigerant from the inlet port, whereby a subcooling of the at least liquid phase change refrigerant entering the additional cooling loop is reduced.