Thermal management systems

Abstract

A thermal management system includes a closed-circuit refrigerant system to circulate a refrigerant fluid. The system includes a compressor to compress a flow of the refrigerant fluid. The system includes a condenser coupled to the compressor. The system includes a receiver to store at least a portion of the refrigerant fluid. The receiver is coupled to the condenser. The system includes a pump to circulate the refrigerant fluid through at least a portion of the system. The pump is coupled to the receiver. The system includes a flow control device to control the flow of the refrigerant fluid to an evaporator. The flow control device is coupled to the pump. The evaporator extracts heat from at least one heat load that is in thermal conductive or convective contact with the evaporator.

What is claimed is: 
     
         1 . A thermal management system comprising:
 a closed-circuit refrigerant system (CCRS) configured to circulate a refrigerant fluid, the CCRS comprising:
 a compressor having a compressor inlet and a compressor outlet and configured to compress a flow of the refrigerant fluid; 
 a condenser having a condenser inlet and a condenser outlet, with the compressor outlet coupled to the condenser inlet; 
 a receiver configured to store at least a portion of the refrigerant fluid, with the receiver having a receiver inlet and a receiver outlet, with the receiver inlet coupled to the condenser outlet; 
 a pump having a pump inlet coupled to the receiver outlet and having a pump outlet, the pump configured to circulate the refrigerant fluid through at least a portion of the CCRS; 
 a flow control device having an inlet and an outlet, with the inlet coupled to the pump outlet, the flow control device configured to control the flow of the refrigerant fluid to an evaporator; and 
 the evaporator having an evaporator inlet and an evaporator outlet, with the evaporator configured to extract heat from at least one heat load that is in thermal conductive or convective contact with the evaporator. 
   
     
     
         2 . The thermal management system of  claim 1 , further comprising:
 a control system configured to perform operations comprising adjusting operation of at least one of the pump or the compressor based on an ambient temperature of a condensing fluid circulated through the condenser to cool the refrigerant fluid.   
     
     
         3 . The thermal management system of  claim 2 , wherein the control system is configured to perform operation comprising:
 determining that the ambient temperature is less than a lower threshold; and   based on the determination, turning off the compressor and turning on the pump.   
     
     
         4 . The thermal management system of  claim 2 , wherein the control system is configured to perform operation comprising:
 determining that the ambient temperature is greater than an upper threshold; and   based on the determination, turning off the pump and turning on the compressor.   
     
     
         5 . The thermal management system of  claim 2 , wherein the flow control device is an expansion valve that comprises a valve inlet and a valve outlet, with the valve inlet coupled to the pump outlet, and the evaporator inlet is coupled to the valve outlet; and the system further comprises:
 a suction accumulator having an inlet and a vapor-side outlet, with the inlet coupled to the evaporator outlet and the vapor-side outlet coupled to the compressor inlet.   
     
     
         6 . The thermal management system of  claim 5 , further comprising a compressor bypass circuit that comprises a bypass conduit that fluidly couples the evaporator outlet to the condenser inlet external to the compressor, the control system configured to perform operations comprising:
 determining that the ambient temperature is less than a lower threshold; and   based on the determination, turning off the compressor and directing the flow of the refrigerant fluid from the evaporator outlet, through the bypass conduit, and to the condenser inlet.   
     
     
         7 . The thermal management system of  claim 6 , wherein the compressor bypass circuit further comprises:
 a solenoid control valve coupled between the vapor-side outlet of the suction accumulator and the compressor inlet; and   first and second check valves, with the first check valve coupled to the outlet of the compressor and the second check valve coupled to the vapor-side outlet of the suction accumulator.   
     
     
         8 . The thermal management system of  claim 1 , wherein the condenser comprises a subcooler, with the condenser configured to condense at least a portion of the refrigerant fluid to a saturated state or a subcooled state, and the subcooler is configured to subcool at least a portion of the refrigerant fluid and deliver the portion of the subcooled refrigerant fluid to the pump inlet. 
     
     
         9 . The thermal management system of  claim 8 , wherein the subcooler comprises a subcooler inlet fluidly coupled to the receiver outlet and a subcooler outlet fluidly coupled to the pump inlet. 
     
     
         10 . The thermal management system of  claim 2 , wherein the flow control device is an ejector having a primary inlet, a secondary inlet, and an outlet, with the primary inlet fluidly coupled to the pump outlet; and the system further comprises:
 a liquid separator having an inlet, a vapor-side outlet, and a liquid-side outlet.   
     
     
         11 . The thermal management system of  claim 10 , wherein the evaporator is fluidly coupled between an outlet of the ejector and the inlet of the liquid separator. 
     
     
         12 . The thermal management system of  claim 10 , wherein the evaporator is fluidly coupled between the secondary inlet of the ejector and the liquid-side outlet of the liquid separator. 
     
     
         13 . The thermal management system of  claim 10 , further comprising a control valve fluidly coupled between the pump outlet and the primary inlet of the ejector. 
     
     
         14 . The thermal management system of  claim 10 , wherein the compressor inlet is fluidly coupled to the vapor-side outlet of the liquid separator. 
     
     
         15 . The thermal management system of  claim 10 , wherein the condenser comprises a subcooler, with the condenser configured to condense at least a portion of the refrigerant fluid to a saturated state or a subcooled state, and the subcooler is configured to subcool at least a portion of the refrigerant fluid and deliver the portion of the subcooled refrigerant fluid to the pump inlet. 
     
     
         16 . The thermal management system of  claim 15 , wherein the subcooler comprises a subcooler inlet fluidly coupled to the receiver outlet and a subcooler outlet fluidly coupled to the pump inlet. 
     
     
         17 . The thermal management system of  claim 10 , wherein the ejector, the liquid separator and the evaporator are a first ejector, a first liquid separator and a first evaporator, the CCRS further comprising:
 a second ejector having a primary inlet fluidly coupled to the pump outlet, the second ejector configured to receive the refrigerant fluid from the pump, and with the second ejector further having a secondary inlet and an outlet;   a second liquid separator having an inlet, a vapor-side outlet, and a liquid-side outlet; and   a second evaporator configured to extract heat from at least another heat load that is in thermal conductive or convective contact with the second evaporator, with the second evaporator fluidly coupled to the second ejector and the second liquid separator.   
     
     
         18 . The thermal management system of  claim 17 , wherein the first and second evaporators are fluidly coupled between outlets of the first and second ejectors and inlets of the first and second liquid separators. 
     
     
         19 . The thermal management system of  claim 17 , wherein the first and second evaporators are fluidly coupled between the respective secondary inlets of the first and second ejectors and the liquid-side outlets of the first and second liquid separators. 
     
     
         20 . The thermal management system of  claim 10 , further comprising a compressor bypass circuit that comprises a bypass conduit that fluidly couples the evaporator outlet to the condenser inlet external to the compressor, the control system configured to perform operations comprising:
 determining that the ambient temperature is less than a lower threshold; and   based on the determination, turning off the compressor and directing the flow of the refrigerant fluid from the evaporator outlet, through the bypass conduit, and to the condenser inlet.   
     
     
         21 . The thermal management system of  claim 20 , wherein the compressor bypass circuit further comprises:
 a solenoid control valve coupled between the vapor-side outlet of the liquid separator and the compressor inlet; and   first and second check valves, with the first check valve coupled to the outlet of the compressor and the second check valve coupled to the vapor-side outlet of the liquid separator.   
     
     
         22 . The thermal management system of  claim 1 , wherein the refrigerant fluid is ammonia. 
     
     
         23 . The thermal management system of  claim 10 , further comprising an open-circuit refrigeration system (OCRS) that includes the receiver, the evaporator, and the liquid separator, with the open-circuit refrigeration system configured to receive the refrigerant fluid from the receiver. 
     
     
         24 . The thermal management system of  claim 23 , wherein the OCRS further comprises:
 a back-pressure regulator having an inlet coupled to the vapor-side outlet of the liquid separator; and   an exhaust line coupled to the back-pressure regulator, with refrigerant vapor from the exhaust line not returning to the receiver.   
     
     
         25 . The thermal management system of  claim 23 , wherein the evaporator is configured to operate with a vapor quality of less than 1. 
     
     
         26 . The thermal management system of  claim 23 , wherein the evaporator is configured to operate with a value of vapor quality in a range of 0.5 to less than 1 and with the value of the vapor quality avoiding dryout and mist regions of a phase diagram of the refrigerant fluid. 
     
     
         27 . The thermal management system of  claim 23 , wherein the evaporator is configured to operate with a vapor quality of 0.6 to 0.95. 
     
     
         28 . The thermal management system of  claim 23 , wherein the evaporator is configured to operate with a vapor quality of 0.8 to 0.9. 
     
     
         29 . The thermal management system of  claim 23 , wherein the evaporator is configured to operate with a vapor quality of 0.8 to 0.85. 
     
     
         30 . The thermal management system of  claim 23 , wherein the at least one heat load comprises:
 a first heat load in thermal conductive or convective contact with the evaporator from which heat is removed by the CCRS; and   a second heat load in thermal conductive or convective contact with the evaporator from which heat is removed by the OCRS.   
     
     
         31 . The thermal management system of  claim 30 , wherein the second heat load is a high heat load, relative to the first heat load, the high heat load having one or more characteristics of being at least one of a highly temperature sensitive load or operative for short periods of time, relative to one or more corresponding characteristics of the first heat load. 
     
     
         32 . A thermal management method, comprising:
 transporting refrigerant fluid from a receiver through a closed-circuit refrigeration system (CCRS) having a closed-circuit path;   pumping, with a pump, the refrigerant fluid from the receiver to a flow control device disposed in the closed-circuit path;   controlling, by the flow control device, a thermodynamic property of the refrigerant fluid;   extracting heat from at least one heat load that is in thermal conductive or convective contact with an evaporator disposed in the closed-circuit path, with the extracted heat being transferred to the refrigerant fluid having the controlled thermodynamic property to convert at least a portion of the refrigerant fluid into refrigerant vapor;   compressing, by a compressor disposed in the closed-circuit path, the refrigerant fluid including the refrigerant vapor received from the evaporator to provide compressed refrigerant fluid including compressed refrigerant vapor;   condensing the compressed refrigerant fluid including compressed refrigerant vapor received from the compressor, with a condenser disposed in the closed-circuit path to provide condensed refrigerant fluid; and   transporting the condensed compressed refrigerant fluid to the receiver.   
     
     
         33 . The method of  claim 32 , further comprising adjusting operation of at least one of the pump or the compressor based on an ambient temperature of a condensing fluid circulated through the condenser to condense the refrigerant fluid. 
     
     
         34 . The method of  claim 32 , wherein the flow control device is an expansion valve that comprises a valve inlet and a valve outlet, with the valve inlet fluidly coupled to a pump outlet of the pump. 
     
     
         35 . The method of  claim 34 , wherein the evaporator is fluidly coupled between the valve outlet and a compressor inlet of the compressor. 
     
     
         36 . The method of  claim 35 , wherein an evaporator inlet is fluidly coupled to the flow control device outlet, the method further comprising:
 accumulating, with a suction accumulator disposed in the closed-circuit path, refrigerant vapor received from an evaporator outlet of the evaporator; and   transporting the accumulated vapor to the compressor inlet.   
     
     
         37 . The method of  claim 34 , further comprising bypassing the compressor with a compressor bypass circuit. 
     
     
         38 . The method of  claim 34 , wherein the condenser comprises a subcooler, the method further comprising:
 condensing, with the condenser, the compressed refrigerant fluid to a saturated state or subcooled state;   subcooling the condensed refrigerant fluid with the subcooler; and   circulating the subcooled, condensed refrigerant fluid to a pump inlet of the pump.   
     
     
         39 . The thermal management method of  claim 32 , wherein the flow control device is an ejector having a primary inlet, a secondary inlet, and an outlet, with the primary inlet coupled to a pump outlet of the pump, the method further comprising:
 separating refrigerant fluid received at an inlet of a liquid separator into refrigerant vapor at a vapor-side outlet of the liquid separator and refrigerant liquid at a liquid-side outlet of the liquid separator.   
     
     
         40 . The thermal management method of  claim 39 , further comprising:
 mixing refrigerant fluid from the pump with refrigerant fluid received from the liquid-side outlet; and   circulating the mixed refrigerant fluid to the inlet of the liquid separator.   
     
     
         41 . The thermal management method of  claim 40  wherein the refrigerant fluid received from the liquid-side outlet is received at the secondary inlet, the method further comprising:
 transporting the mixed refrigerant fluid to the inlet of the evaporator from the outlet of the ejector. 
 
     
     
         42 . The thermal management method of  claim 40 , wherein the refrigerant fluid received from the liquid-side outlet is received at the secondary inlet through the evaporator, the method further comprising:
 transporting the mixed refrigerant fluid to the inlet of the liquid separator.   
     
     
         43 . The method of  claim 39 , wherein the condenser comprises a subcooler, the method further comprising:
 condensing with the condenser the compressed refrigerant fluid to a saturated state or subcooled state;   subcooling the condensed refrigerant fluid with the subcooler; and   circulating the subcooled refrigerant fluid to the pump inlet.   
     
     
         44 . The thermal management method of  claim 39 , wherein the ejector, the liquid separator, and the evaporator are a first ejector, a first liquid separator and a first evaporator, the method further comprising:
 transporting the pumped refrigerant fluid through a second ejector having a primary inlet coupled to a pump outlet and a second liquid separator having an inlet, a vapor-side outlet, and a liquid-side outlet; and   extracting heat from at least another heat load that is in thermal conductive or convective contact with a second evaporator.   
     
     
         45 . The thermal management method of  claim 39 , further comprising turning off the compressor during operation at a low ambient temperature. 
     
     
         46 . The thermal management method of  claim 45 , further comprising by-passing the compressor during operation at the low ambient temperature. 
     
     
         47 . The thermal management method of  claim 46 , wherein by-passing comprises:
 closing a solenoid control valve coupled between the vapor-side outlet of the liquid separator and a compressor inlet to divert refrigerant vapor from the vapor-side outlet through first and second check valves, with the first check valve coupled to the outlet of the compressor and the second check valve coupled to the vapor-side outlet of the liquid separator.   
     
     
         48 . The thermal management method of  claim 39 , further comprising discharging the refrigerant vapor through an exhaust line so that the discharged refrigerant vapor is not returned to the receiver. 
     
     
         49 . The thermal management method of  claim 39 , further comprising transporting the refrigerant fluid from the receiver through an open-circuit refrigeration system (OCRS) that comprises an open-circuit refrigeration fluid path including the receiver, the ejector, the evaporator, and the liquid separator, and to an exhaust line. 
     
     
         50 . The thermal management method of  claim 49 , further comprising discharging refrigerant vapor through a back-pressure regulator having an inlet coupled to the vapor-side outlet of the liquid separator and into an exhaust line with the discharged refrigerant vapor not returning to the receiver. 
     
     
         51 . The thermal management method of  claim 49 , wherein the evaporator is configured to operate with a value of vapor quality of less than 1, and with the value of the vapor quality avoiding dryout and mist regions of a phase diagram of the refrigerant fluid. 
     
     
         52 . The thermal management method of  claim 49 , wherein the evaporator is configured to operate with a vapor quality of in a range of 0.5 to less than 1. 
     
     
         53 . The thermal management method of  claim 49 , wherein the evaporator is configured to operate with a vapor quality of 0.6 to 0.95. 
     
     
         54 . The thermal management method of  claim 49 , wherein the evaporator is configured to operate with a vapor quality of 0.8 to 0.9. 
     
     
         55 . The thermal management method of  claim 49 , wherein the evaporator is configured to operate with a vapor quality of 0.8 to 0.85. 
     
     
         56 . The thermal management method of  claim 49 , further comprising:
 removing heat from a first heat load of the at least one heat load that is in thermal conductive or convective contact with the evaporator; and   removing heat from a second heat load of the at least one heat load that is in thermal conductive or convective contact with the evaporator.   
     
     
         57 . The thermal management method of  claim 56 , wherein the second heat load is a high heat load, relative to the first heat load, the high heat load having one or more characteristics of being at least one of a highly temperature sensitive load or operative for short periods of time, relative to one or more corresponding characteristics of the first heat load. 
     
     
         58 . The thermal management method of  claim 32 , wherein the refrigerant fluid is ammonia.