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Various techniques are disclosed for improving airtight two-phase heat-transfer systems employing a fluid to transfer heat from a heat source to a heat sink while circulating around a fluid circuit, the maximum temperature of the heat sink not exceeding the maximum temperature of the heat source. Th

Various techniques are disclosed for improving airtight two-phase heat-transfer systems employing a fluid to transfer heat from a heat source to a heat sink while circulating around a fluid circuit, the maximum temperature of the heat sink not exceeding the maximum temperature of the heat source. The properties of those improved systems include (a) maintaining, while the systems are inactive, their internal pressure at a pressure above the saturated-vapor pressure of their heat-transfer fluid; and (b) cooling their internal evaporator surfaces with liquid jets. FIG. 43 illustrates the particular case where a heat-transfer system of the invention is used to cool a piston engine (500) by rejecting, with a condenser (508), heat to the ambient air; and where the system includes a heat-transfer fluid pump (10) and means (401-407) for achieving the former property.

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1. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources, and for transferring the absorbed heat to one or more heat sinks, wherein the system includes an airtight configuration, and wherein none of the one or more heat sources is an electrical apparatus

1. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources, and for transferring the absorbed heat to one or more heat sinks, wherein the system includes an airtight configuration, and wherein none of the one or more heat sources is an electrical apparatus having windings electrically insulated even in part by an inert gas inside the airtight configuration; the airtight configuration having(1) a refrigerant principal configuration comprising: (a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid, none o f the one or more heat sources including an electrical apparatus having windings electrically insulated even in part by an inert gas inside the airtight configuration; the refrigerant having one or more saturated-vapor pressures for a given refrigerant temperature; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; and (d) one or more refrigerant circuits containing refrigerant partly in the liquid phase and partly in the vapor phase under at least some operating conditions, the one or more refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the principal configuration is active the refrigerant principal circuit including (i) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (ii) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages, and (iii) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; and (2) supplementary-configuration means for ensuring the total pressure inside at least a part of the one or more refrigerant circuits of the principal configuration is maintained, for at least a part of the time during which the refrigerant principal configuration is inactive, at or above a preselected minimum pressure having a value higher than the lowest value of the refrigerant's one or more saturated-vapor pressures corresponding to the lowest temperature experienced by the refrigerant while the principal configuration is inactive; the supplementary-configuration means allowing said value to differ from the current value of the ambient atmospheric pressure, and the supplementary-configuration means comprising one or more controllable means. 2. A system, according to claim 1, wherein the one or more heat sources include a material substance remote from the one or more hot heat exchangers; and wherein the remote material substance emits thermal radiation intercepted by at least one of the system's one or more hot heat exchangers.3. A system, according to claim 1, wherein each of the one or more hot heat exchangers has one or more refrigerant passages; wherein the one or more heat sources include a material substance contiguous, at least in part, to the one or more refrigerant passages of at least one of the one or more hot heat exchangers; and wherein heat is transmitted by one or more of the three modes of heat transfer known in the art as conduction heat transfer, convection heat transfer, and radiation heat transfer, from the contiguous material substance to the refrigerant in the one or more refrigerant passages of said at least one of the one or more hot heat exchangers.4. A system, according to claim 3, wherein the contiguous material substance is a solid; and wherein the one or more refrigerant passages of said at least one of the one or more hot heat exchangers are embedded in the solid.5. A system, according to claim 3, wherein the contiguous material substance, not excluding a salt, releases?under at least some operating Conditions?primarily latent heat; and wherein the one or more refrigerant passages of said at least one of the one or more heat exchangers are embedded or immersed in the contiguous material substance.6. A system, according to claim 3, wherein the contiguous material substance, not excluding electrolytic cells, releases chemical energy.7. A system, according to claim 3, wherein the contiguous material substance releases nuclear energy.8. A system, according to claim 3, wherein the contiguous material substance includes the windings of an electric motor.9. A system, according to claim 3, wherein the contiguous material substance includes the windings of an electric generator.10. A system, according to claim 3, wherein the contiguous material substance includes the windings of an electric transformer.11. A system, according to claim 3, wherein the contiguous material substance includes electronic circuits, not excluding infrared and photovoltaic arrays.12. A system, according to claim 3, wherein the contiguous material substance is a hot fluid, not excluding a liquid metal such as lithium, and not excluding a non-azeotropic fluid; and wherein said at least one of the one or more hot heat exchangers has one or more fluid ways for absorbing heat from the hot fluid.13. A system, according to claim 12, wherein the hot fluid is a waste gas, not excluding a flue gas and the exhaust gas of a gas turbine.14. A system, according to claim 12, wherein the hot fluid is a gas generated by combustion of a fuel.15. A system, according to claim 12, wherein the hot fluid is a gas generated by combustion of a fuel inside an internal combustion engine attached to a platform, the platform not excluding a vehicle; and wherein the one or more evaporator refrigerant passages are an integral part of a quasi-stationary part of the engine with respect to the platform.16. A system, according to claim 15, wherein the engine is a rotary engine, not excluding a Wankel engine.17. A system, according to claim 1, wherein the one or more heat sinks include a material substance remote from the one or more cold heat exchangers; and wherein the remote material substance intercepts thermal radiation emitted by at least one of the system's one or more cold heat exchangers.18. A system, according to claim 1, wherein each of the one or more cold heat exchangers has one or more refrigerant passages; wherein the one or more heat sinks include a material substance contiguous, at least in part, to the one or more refrigerant passages of at least one of the one or more cold heat exchangers; and wherein heat is transmitted, by one or more of the three modes of heat transfer known in the art as conduction heat transfer, connection heat transfer, and radiation heat transfer, from the refrigerant in the one or more refrigerant passages of said at least one of the one or more cold heat exchangers to the contiguous material substance.19. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources and for transferring the absorbed heat to one or more heat sinks; the system including an airtight refrigerant configuration having(1) a refrigerant principal configuration comprising: (a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?charging at least in part from a vapor back into a liquid; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; and (d) one or more refrigerant circuits containing refrigerant partly in the liquid phase and partly in the vapor phase under at least some operating conditions, the one or more refrigerant circuits containing essentially no air while the principal configuration is active and while the principal configuration is inactive, said circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the principal configuration is active; the refrigerant principal circuit including (i) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (ii) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages, and (iii) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; and (2) a refrigerant ancillary configuration comprising (a) a liquid-refrigerant reservoir for storing liquid refrigerant outside the principal configuration's one or more refrigerant circuits; (b) liquid-refrigerant ancillary transfer means for transferring liquid refrigerant from the reservoir to the principal configuration's one or more refrigerant circuits, and for transferring liquid refrigerant from the principal configuration's one or more refrigerant circuits to the reservoir, thereby changing the amount of liquid refrigerant in the principal configuration's one or more refrigerant circuits; and (c) one or more controllable means for controlling collectively the transfer of liquid refrigerant between the reservoir and the principal configuration's one or more refrigerant circuits. 20. A system, according to claim 19, wherein the refrigerant principal configuration also comprises means for fluidly isolating, while the refrigerant principal configuration is inactive, a first part of the one or more refrigerant circuits of the refrigerant principal configuration from a second part of said one or more refrigerant circuits; wherein the liquid-refrigerant ancillary transfer means is fluidly connected to said first part; wherein the liquid-refrigerant reservoir is a variable-volume reservoir; wherein said one or more controllable means fluidly connect said variable-volume reservoir to said first part for at least some of the time during which the refrigerant principal configuration is inactive, and fluidly isolate said variable-volume reservoir from said first part under at least some operating conditions; and wherein said isolating means fluidly isolates said first part from said second part for at least some of the time during which the refrigerant principal configuration is inactive, and fluidly connects said first part to said second part under at least some operating conditions.21. A system, according to claim 20, wherein the one of more controllable means is a refrigerant valve.22. A system, according to claim 20, wherein said first part is completely filled with liquid refrigerant immediately prior to the instant in time at which the refrigerant principal configuration becomes inactive.23. A system, according to claim 20, wherein the refrigerant has one or more saturated-vapor pressures at a given refrigerant temperature; and wherein the total pressure inside said first part is maintained, for at least some of the time during which the refrigerant principal configuration is inactive, at or above a preselected minimum pressure having a value higher than the lowest value of the refrigerant's one or more saturated-vapor pressures corresponding to the lowest temperature experienced by the refrigerant while the refrigerant principal configuration is inactive.24. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources, and for transferring the absorbed heat to one or more heat sinks, wherein the system includes an airtight refrigerant and inert-gas configuration, and wherein none of the one or more heat sources is an electrical apparatus having windings electrically insulated even in part by an inert gas inside the airtight refrigerant and inert-gas configuration; the airtight refrigerant and inert-gas configuration having(1) a refrigerant principal configuration comprising: (a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid, none of the one or more scat sources including an electrical apparatus having windings electrically insulated even in part by an inert gas inside the airtight configuration; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; and (d) one or more refrigerant circuits containing refrigerant partly in the liquid phase and partly in the vapor phase under at least some operating conditions, the one or more refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the principal configuration is active; the refrigerant principal circuit including (i) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (ii) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages, and (iii) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; and (2) an inert-gas configuration comprising (a) an inert gas; (b) an inert-gas reservoir for storing inert gas outside the principal configuration's one or more refrigerant circuits; (c) inert-gas transfer means for transferring the inert gas from the reservoir to the principal configuration's one or more refrigerant circuits, and for transferring the inert gas from the principal configuration's one or more refrigerant circuits to tho reservoir, thereby changing the mass of inert gas in the principal configuration's one, or more refrigerant circuits; and (d) one or more controllable means for controlling collectively the transfer of the inert gas between the reservoir and the principal configuration's one or more refrigerant circuits. 25. A system, according to claim 24, wherein the system also includes a refrigerant ancillary configuration comprising(a) a liquid-refrigerant reservoir for storing liquid refrigerant outside the principal configuration's one or more refrigerant circuits; and (b) liquid-refrigerant ancillary transfer means for transferring liquid refrigerant from the reservoir to the principal configuration's one or more refrigerant circuits, and for transferring liquid refrigerant from the principal configuration's one or more refrigerant circuits to the reservoir. 26. A system, according to claim 24 wherein the refrigerant principal configuration also comprises means for fluidly isolating, while the principal configuration is inactive, a first part of the one or more refrigerant circuits of the refrigerant principal configuration from a second part of said one or more refrigerant circuits; wherein the inert-gas transfer means is fluidly connected to said first part; and wherein said isolating means fluidly isolates said first part from said second part for at least some of the time during which the refrigerant principal configuration is inactive, and fluidly connects said first part to said second part under at least some operating conditions.27. A system, according to claim 26, wherein the refrigerant has one or more saturated-vapor pressures at a given refrigerant temperature; and wherein the total pressure inside said first part is maintained, for at least some of the time during which the refrigerant principal configuration is inactive, at or above a preselected minimum pressure having a value higher than the lowest value of the refrigerant's one or more saturated-vapor pressures corresponding to the lowest temperature experienced by the refrigerant while the refrigerant principal configuration is inactive.28. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources, and for transferring the absorbed heat to one or more heat sinks, wherein the system includes an airtight configuration, and wherein none of the one or more heat sources being either an electrical apparatus having windings electrically insulated even in part by an inert gas inside the airtight configuration; the system having(1) a refrigerant principal configuration comprising: (a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid, none of the one or more heat sources including an electrical apparatus having windings electrically insulated even in part by an inert gas inside the airtight configuration; the refrigerant having one or more saturated-vapor pressures for a given refrigerant temperature; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; and (d) one or more refrigerant circuits containing refrigerant partly in the liquid phase and partly in the vapor phase under at least some operating conditions, the one or more refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the principal configuration is active; the refrigerant principal circuit including (i) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (ii) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages, and (iii) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; (2) an inert-gas passive configuration comprising (a) an inert-gas; (b) an inert-gas reservoir for storing inert gas outside the principal configuration; and (c) inert-gas passive transfer means for transferring the inert gas from the reservoir to the principal configuration, and for transferring the inert gas from the principal configuration to the reservoir; the airtight configuration having an airtight refrigerant and inert-gas enclosure from which essentially all air is removed before the refrigerant and inert-gas enclosure is charged with refrigerant, and the inert gas with which the refrigerant and inert-gas enclosure is initially charged containing essentially no oxygen.29. A system, according to claim 28, wherein the refrigerant principal configuration also comprises means for fluidly isolating, while the refrigerant principal configuration is inactive, a first part of the one or more refrigerant circuits of the refrigerant principal configuration from a second part of the one or more refrigerant circuits; wherein said first part is completely filled with liquid refrigerant immediately prior to the instant in time at which the principal configuration becomes inactive; and wherein said isolating means fluidly isolates said first part from said second part for at least some of the time during which the refrigerant principal configuration is inactive, and fluidly connects said first part to said second part under at least some operating conditions.30. A system, according to claim 29, wherein the refrigerant has one or more saturated-vapor pressures at a given refrigerant temperature; and wherein the total pressure inside said first part is maintained, for at least some of the time during which the refrigerant principal configuration is inactive, at or above a preselected minimum pressure having a value higher than the lowest value of the refrigerant's one or more saturated-vapor pressures corresponding to the lowest temperature experienced by the refrigerant while the refrigerant principal configuration is inactive.31. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources, and for transferring the absorbed heat to one or more heat sinks, wherein none of the one or more heat sources is an electrical apparatus having windings insulated at least in part by an inert gas inside the system; the system including an airtight configuration having a refrigerant principal configuration comprising:(a) a refrigerant for absorbing heat from the one or more heat sources?under at least some operating conditions?at least in part by changing from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks at least in part by changing from a vapor back into a liquid, the refrigerant having?white the principal configuration is inactive and the enclosure of the airtight configuration is in thermal equilibrium with the environment of the airtight configuration?saturated-vapor pressures lower than the pressure of the ambient air of the airtight configuration, none of the one or more heat sources including an electrical apparatus having windings insulated at least in part by an inert gas inside the airtight configuration; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated, and also having one or more liquid-refrigerant injectors for increasing the velocity at which liquid refrigerant is supplied to the one or more evaporator refrigerant passages; a liquid-refrigerant injector of the one or more liquid-refrigerant injectors having an inlet through which liquid refrigerant enters the injector and one or more orifices through which liquid refrigerant exits the injector, the one or more orifices having a smaller total cross-sectional area than the cross-sectional area of the inlet of the injector. (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; and (d) one or more airtight refrigerant circuits containing refrigerant partly in the liquid phase and partly in the vapor phase under at least some operating conditions, the one or more refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the principal configuration is active; the refrigerant principal circuit including (i) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (ii) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages, and (iii) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages. 32. A heat-transfer system, in a gravitational field, for absorbing heal from one or more heat sources, and for transferring the absorbed heat to one or more heat sinks, the system having(1) a refrigerant principal configuration comprising: (a) a refrigerant for absorbing heat from the one or more heat sources?under at least some operating conditions?at least in part by changing from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks at least in part by changing from a vapor back into a liquid; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; and (d) one or more airtight refrigerant circuits containing refrigerant usually partly in the liquid phase and partly in the vapor phase under at least some operating conditions, the one or more refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the principal configuration is active; the refrigerant principal circuit including (i) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (ii) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages, and (iii) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; ?the one or more airtight refrigerant circuits also containing non-condensable gas generated inside the one or more airtight refrigerant circuits, the non-condensable gas being mixed with refrigerant vapor; and (2) means for removing, at least in part, the non-condensable gas generated inside the one or more airtight refrigerant circuits, the non-condensable-gas removing means comprising (a) an airtight space fluidly connected to the one or more airtight refrigerant circuits so that non-condensable gas, mixed with refrigerant vapor, enters the airtight space; (b) means for separating non-condensable gas and refrigerant vapor, entering the airtight space, primarily (i) by condensing a major portion of the refrigerant entering the airtight space, and (ii) by returning the thus generated refrigerant condensate to the one or more airtight refrigerant circuits; and (c) means for removing from the airtight space, and discharging into ambient air, non-condensable gas mixed with residual refrigerant vapor still present in the airtight space after non-condensable gas and refrigerant-vapor separation inside the airtight space. 33. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources and for transferring the absorbed heat to one or more heat sinks; the system having a refrigerant principal configuration comprising:(a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; (d) one or more airtight refrigerant circuits containing?under at least some operating conditions?refrigerant partly in the liquid phase and partly in the vapor phase while the refrigerant principal configuration is active and essentially no air while the refrigerant principal configuration is active and while the refrigerant principal configuration is inactive, the one or more airtight refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the refrigerant principal configuration is active; the refrigerant principal circuit including (1) the one or more evaporator refrigerant passage; and the one or more condenser refrigerant passages, (2) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages; and (3) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; (e) one or more refrigerant pumps having one or more refrigerant passages which are a part of the one or more airtight refrigerant circuits; (f) means, including controllable means not excluding a diverting valve, for by-passing around the one or more condenser refrigerant passages refrigerant flowing in the refrigerant-vapor transfer means, and for transferring the by-passed refrigerant to a point of the liquid-refrigerant principal transfer means; and (g) means for ensuring?for a preselected range of refrigerant evaporation rates which includes at least two refrigerant evaporation rates differing significantly from each other?that each of the one or more refrigerant pumps has, while the evacuated configuration is active, an available net positive suction head high enough to prevent, under steady-state conditions, each of the one or more refrigerant pumps cavitating. 34. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources and for transferring the absorbed heat to one or more heat sinks; the system including a refrigerant principal configuration comprising:(a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at feast a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; (d) one or more airtight refrigerant circuits containing?under at least some operating conditions?refrigerant partly in the liquid phase and partly in the vapor phase while the refrigerant principal configuration is active and essentially no air while the refrigerant principal configuration is active and while the refrigerant principal configuration is inactive, the one or more airtight refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the refrigerant principal configuration is active; the refrigerant principal circuit including (1) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (2) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages; and (3) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; (e) one or more refrigerant pumps having one or more refrigerant passages which are a part of the one or more airtight refrigerant circuits; (f) a subcooler having one or more refrigerant passages, the one or more subcooler refrigerant passages being a part of the liquid-refrigerant principal transfer means; (g) means, including controllable means not excluding a mixing valve, for by-passing around the one or more subcooler refrigerant passages refrigerant flowing in the liquid-refrigerant principal transfer means segment between the one or more condenser refrigerant passages and the one or more subcooler refrigerant passages, and for transferring the by-passed refrigerant to a point of the liquid-refrigerant principal transfer means between the one or more subcooler refrigerant passages and the one or more evaporator refrigerant passages; and (h) means for ensuring?for a preselected range of refrigerant evaporation rates which includes at least two refrigerant evaporation rates differing significantly from each other?that each of the one or more refrigerant pumps has, while the evacuated configuration is active, an available net positive suction head high enough to prevent, under steady-state conditions, each of the one or more refrigerant pumps cavitating. 35. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources and for transferring the absorbed heat to one or more heat sinks; the system including an evacuated configuration comprising:(a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator hiving one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; the evaporator also having one or more liquid-refrigerant injectors for increasing the velocity at which liquid refrigerant is supplied to the one or more evaporator refrigerant passages; a liquid-refrigerant injector of the one or more liquid-refrigerant injectors having an inlet through which liquid refrigerant enters the injector and one or more orifices through which liquid refrigerant enters the injector, the one or more orifices having a smaller total cross-sectional area than the cross-sectional area of the inlet of the injector; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; (d) one or more evacuated refrigerant circuits containing?under at least some operating conditions?refrigerant partly in the liquid phase and partly in the vapor phase while the evacuated configuration is active and essentially no air while the evacuated configuration is active and while the evacuated configuration is inactive, the one or more evacuated refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the evacuated configuration is active; the refrigerant principal circuit including (1) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (2) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages; and (3) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; (e) one or more refrigerant pumps having one or more refrigerant passages which are a part of the one or more evacuated refrigerant circuits; and (f) means for ensuring?for a preselected range of refrigerant evaporation rates which includes at least two refrigerant evaporation rates differing significantly from each other?that each of the one or more refrigerant pumps has, while the evacuated configuration is active, an available net positive suction head high enough to prevent, under steady-state conditions, each of the one or more refrigerant pumps cavitating. 36. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources and for transferring the absorbed heat to one or more heat sinks; the system including an evacuated configuration comprising:(a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; (d) one or more evacuated refrigerant circuits containing?under at least some operating conditions?refrigerant partly in the liquid phase and partly in the vapor phase while the evacuated configuration is active and essentially no air while the evacuated configuration is active and while the evacuated configuration is inactive, the one or more evacuated refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the evacuated configuration is active; the refrigerant principal circuit including (1) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (2) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages; and (3) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; (e) one or more refrigerant pumps having one or more refrigerant passages which are a part of the one or more evacuated refrigerant circuits; (f) means for removing, at least in part, non-condensable gas which may be generated inside the one or more evacuated refrigerant circuits, the non-condensable-gas removing means comprising (1) an evacuated space fluidly connected to the one or more evacuated refrigerant circuits so that non-condensable gas, mixed with refrigerant vapor, enters the evacuated space; (2) means for separating non-condensable gas and refrigerant vapor, entering the evacuated space, primarily by (i) condensing a portion of the refrigerant vapor entering the evacuated space, and (ii) returning the thus generated refrigerant condensate to the one or more evacuated refrigerant circuits; and (3) means for removing from the evacuated space, and discharging into the evacuated configuration's surroundings, non-condensable gas mixed with residual refrigerant vapor still present in the evacuated space after non-condensable gas and refrigerant-vapor separation inside the evacuated space; and (g) means for ensuring?for a preselected range of refrigerant evaporation rates which includes at least two refrigerant evaporation rates differing significantly from each other?that each of the one or more refrigerant pumps has, while the evacuated configuration is active, an available net positive suction head high enough to prevent, under steady-state conditions, each of the one or more refrigerant pumps cavitating. 37. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources and for transferring the absorbed heat to one or more heat sinks; the system including an evacuated configuration comprising:(a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; (d) one or more evacuated refrigerant circuits containing?under at least some operating conditions?refrigerant partly in the liquid phase and partly in the vapor phase while the evacuated configuration is active and essentially no air while the evacuated configuration is active and while the evacuated configuration is inactive, the one or more evacuated refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the evacuated configuration is active; the refrigerant principal circuit including (1) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages; (2) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages; and (3) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; (e) one or more refrigerant pumps having one or more refrigerant passages which are a part of the one or more evacuated refrigerant circuits; (f) a variable-volume reservoir for storing liquid refrigerant, the reservoir being fluidly connected to the one or more evacuated refrigerant circuits; and (h) means for ensuring?for a preselected range of refrigerant evaporation rates which includes at least two refrigerant evaporation rates differing significantly from each other?that each of the one or more refrigerant pumps has, while the evacuated configuration is active, an available net positive suction head high enough to prevent, under steady-state conditions, each of the one or more refrigerant pumps cavitating. 38. A system, according to claim 37, wherein the evacuated configuration also comprises means for fluidly isolating, while the evacuated (configuration is inactive, a first part of the one or more evacuated refrigerant circuits from a second pail of the one or more evacuated refrigerant circuits; wherein said variable-volume reservoir is fluidly connected to said first part; wherein said first part is completely filled with liquid refrigerant immediately prior to the instant in time at which the evacuated configuration becomes inactive; and wherein said isolating means fluidly isolates said first part from said second part for at least some of the time during which the evacuated configuration is inactive, and fluidly connects said first part to said second part under at least some operating conditions.39. A system, according to claim 38, wherein the refrigerant has one or more saturated-vapor pressures at a given refrigerant temperature; and wherein the total pressure inside said first part is maintained, for at least some of the time during which the refrigerant principal configuration is inactive, at or above a preselected minimum pressure having a value higher than the lowest value of the refrigerant's one or more saturated-vapor pressures corresponding to the lowest temperature experienced by the refrigerant while the refrigerant principal configuration is inactive.40. A heat-transfer system, in a gravitational field, for absorbing heat from one or more heat sources and for transferring the absorbed heat to one or more heat sinks; the system including an airtight refrigerant configuration having(1) a refrigerant principal configuration comprising: (a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?under at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; and (d) one or more refrigerant circuits containing refrigerant partly in the liquid phase and partly in the vapor phase under at least some operating conditions, the one or more refrigerant circuits containing essentially no air while the principal configuration is active and while the principal configuration is inactive, said circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the principal configuration is active; the refrigerant principal circuit including (i) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (ii) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages, and (iii) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; ?the refrigerant principal configuration also comprising means for fluidly isolating, while the refrigerant principal configuration is inactive, a first part of the one or more refrigerant circuits of the refrigerant principal configuration from a second part of said one or more refrigerant circuits; and wherein said isolating means fluidly isolates said first part from said second part for at least some of the time during which the refrigerant principal configuration is inactive, and fluidly connects said first part to said second part under at least some operating conditions; the airtight refrigerant configuration also having (2) a refrigerant ancillary configuration comprising (a) a liquid-refrigerant variable-volume reservoir for storing liquid refrigerant outside the principal configuration's one or more refrigerant circuits; (b) liquid-refrigerant transfer means for allowing the transfer of liquid refrigerant from the variable-volume reservoir to the first of said one or more refrigerant circuits, and for allowing the transfer of liquid refrigerant from the first of said one or more refrigerant circuits to the variable-volume reservoir. 41. A system, according to claim 40, wherein the first part of said one or more refrigerant circuits is completely filled with liquid refrigerant at the time at which the first part of said one or more refrigerant circuits is being isolated from the second part of said one or more refrigerant circuits.42. A system, according to claim 40, wherein the refrigerant has one or more saturated-vapor pressures at a given refrigerant temperature; and wherein the total pressure inside the first part of said one or more refrigerant circuits is maintained, for at least some of the time during which the refrigerant principal configuration is inactive, at or above a preselected minimum pressure having a value higher than the lowest value of the refrigerant's one or more saturated-vapor pressures corresponding to the lowest temperature experienced by the refrigerant while the refrigerant principal configuration is inactive.43. A heat-transfer system for absorbing heat from one or more heat sources, and for transferring the absorbed heat to one or more heat sinks, none of the one or more heat sources including an electrical apparatus having windings electrically insulated even in part by an inert gas inside the airtight configuration; the system including an airtight configuration having(1) a refrigerant principal configuration comprising: (a) a refrigerant for absorbing heat from the one or more heat sources by?under at least some operating conditions?changing at least in part from a liquid to a vapor, and for releasing the absorbed heat to the one or more heat sinks by?under at least some operating conditions?changing at least in part from a vapor back into a liquid, none of the one or more heat sources including an electrical apparatus having windings electrically insulated even in part by an inert gas inside the airtight configuration; (b) one or more hot heat exchangers for transmitting heat from the one or more heat sources to the refrigerant, the one or more hot heat exchangers including an evaporator for transmitting heat from a first heat source of the one or more heat sources to the refrigerant and for?under at least some operating conditions?evaporating liquid refrigerant; the evaporator having one or more refrigerant passages wherein?tinder at least some operating conditions?at least a portion of liquid refrigerant entering the one or more evaporator refrigerant passages is evaporated; (c) one or more cold heat exchangers for transmitting heat from the refrigerant to the one or more heat sinks, the one or more cold heat exchangers including a condenser for transmitting heat from the refrigerant to a first heat sink of the one or more heat sinks and for?under at least some operating conditions?condensing refrigerant vapor; the condenser having one or more condenser refrigerant passages wherein?under at least some operating conditions?refrigerant vapor is condensed, the highest pressure at which condensation occurs in the one or more condenser refrigerant passages, at an instant in time, not exceeding the lowest pressure at which evaporation occurs in the one or more evaporator refrigerant passages at the selfsame instant in time; (d) one or more refrigerant circuits containing refrigerant partly in the liquid phase and partly in the vapor phase under at least some operating conditions, the one or more refrigerant circuits comprising a refrigerant principal circuit around which the refrigerant circulates, not excluding intermittently, while the principal configuration is active; the refrigerant principal circuit including (i) the one or more evaporator refrigerant passages and the one or more condenser refrigerant passages, (ii) refrigerant-vapor transfer means for transferring refrigerant vapor from the one or more evaporator refrigerant passages to the one or more condenser refrigerant passages, and (iii) liquid-refrigerant principal transfer means for transferring liquid refrigerant from the one or more condenser refrigerant passages to the one or more evaporator refrigerant passages; and (e) means for fluidly isolating while the principal configuration is inactive, a first part of the one or more refrigerant circuits of the refrigerant principal configuration from a second part of said one or more refrigerant circuits; wherein said isolating means fluidly isolates said first pant from said second part for at least some of the time during which the refrigerant principal configuration is inactive, and fluidly connects said first part to said second part under at least some operating conditions; and (2) an inert-gas passive configuration comprising (a) an inert gas; (b) an inert-gas reservoir for storing inert gas outside the principal configuration; and (c) inert-gas passive transfer means for transferring the inert gas from the reservoir to said first part, and for transferring the inert gas from said first part to the reservoir. 44. A system, according to claim 43, wherein the refrigerant has one or more saturated-vapor pressures at a given refrigerant temperature; and wherein the total pressure inside said first part is maintained for at least some of the time during which the refrigerant principal configuration is inactive, at or above a preselected minimum pressure having a value higher than line lowest value of the refrigerant's one or more saturated-vapor pressures corresponding to the lowest temperature experienced by the refrigerant while the refrigerant principal configuration is inactive.