Mechanically pumped system for direct control of two-phase isothermal evaporation

1. A thermal system comprising:

a reservoir;

a first fluid flowpath from the reservoir and returning to the reservoir comprising in a direction of fluid flow:

a first side of a sub-cooler;

a liquid pump;

a first side of a pre-heater; and

a first side of an evaporator

and

a second fluid flowpath from the reservoir and returning to the reservoir comprising in a direction of fluid flow:

a pressure regulator;

a vapor compressor;

a first side of a condenser; and

an expansion valve.

2. The thermal system of claim 1 , wherein said first fluid flowpath further comprises a pressure regulator after said first side of said evaporator.

3. The thermal system of claim 1 further comprising a sub-cooling fluid flowpath from the reservoir to a suction of the vapor compressor comprising in a direction of fluid flow:

a flow controller; and

a second side of the sub-cooler.

4. The thermal system of claim 3 further comprising a pre-heating fluid flowpath from a discharge of the vapor compressor to the reservoir comprising in a direction of fluid flow:

a flow controller; and

a second side of the pre-heater.

5. The thermal system of claim 3 further comprising a pre-heating fluid flowpath from the discharge of the vapor compressor to the reservoir comprising in a direction of fluid flow:

a second side of the pre-heater; and

a flow controller.

6. The thermal system of claim 1 further comprising a pre-heating fluid flowpath from a discharge of the vapor compressor to the reservoir comprising in a direction of fluid flow:

a flow controller; and

a second side of the pre-heater.

7. The thermal system of claim 1 further comprising a pre-heating fluid flowpath from a discharge of the vapor compressor to the reservoir comprising in a direction of fluid flow:

a second side of the pre-heater; and

a flow controller.

8. The thermal system of claim 1 comprising a fluid in said first and second fluid flowpaths, wherein said fluid is a sub-cooled liquid at a suction of the liquid pump by a first margin of sub-cooling and the fluid is a sub-cooled liquid at an inlet to the evaporator by a second margin of sub-cooling.

9. The thermal system of claim 8 wherein the fluid at an outlet of the evaporator has a vapor quality no more than 90%.

10. The thermal system of claim 9 wherein a temperature of the fluid at an inlet of an evaporator channel is the same as a temperature of the fluid at an outlet of the evaporator channel.

11. The thermal system of claim 8 wherein a temperature of the fluid at an inlet of an evaporator channel is the same as a temperature of the fluid at an outlet of the evaporator channel.

12. The thermal system of claim 1 further comprising a cooling fluid flowpath from the reservoir to a suction of the vapor compressor comprising in a direction of fluid flow:

a control valve; and

a heat exchanger.

13. The thermal system of claim 1 wherein a fluid at an outlet of the evaporator has a vapor quality no more than 90%.

14. A thermal system for maintaining the temperature of a primary heat load, said thermal system comprising:

a reservoir;

a cooling loop originating from the reservoir and returning to the reservoir, the cooling loop comprising:

a primary heat exchanger having a cooling fluid outlet in fluid communication with the reservoir;

a liquid pump having a suction in fluid communication with the reservoir and a discharge in fluid communication with a cooling fluid inlet to the primary heat exchanger;

a sub-cooler between the reservoir and the suction of the pump;

a pre-heater between the discharge of the pump and the cooling fluid inlet to the primary heat exchanger; and

a pressure regulator between the primary heat exchanger and the reservoir; and

a heat rejection loop originating from the reservoir and returning the reservoir, the heat rejection loop comprising;

a condenser having a hot fluid outlet in fluid communication with the reservoir;

a vapor compressor having a suction in fluid communication with the reservoir and a discharge in fluid communication with a hot fluid inlet of the condenser;

a pressure regulator between the reservoir and the suction of the vapor compressor; and

an expansion valve between a fluid outlet of the condenser and the reservoir.

15. The thermal system of claim 14 wherein a heat sink for the sub-cooler comprises fluid drawn from the reservoir.

16. The thermal system of claim 15 wherein a heat source for the pre-heater comprises fluid drawn from the discharge of the vapor compressor.

17. The thermal system of claim 14 further comprising a secondary cooling flowpath originating from the reservoir and discharging into the suction of the vapor compressor, the secondary cooling flowpath comprising a flow control valve and the cold side of a secondary heat exchanger.

18. A method of maintaining the temperature of a primary heat load comprising:

drawing a fluid from a reservoir;

sub-cooling the fluid drawn from the reservoir;

pumping the sub-cooled fluid to an inlet of an evaporator;

pre-heating the pumped fluid prior to the inlet of the evaporator to a predetermined margin of sub-cooling;

evaporating a portion of the fluid in the evaporator;

regulating the pressure of the fluid at the outlet of the evaporator to thereby maintain a substantially constant fluid temperature between the inlet and the outlet of the evaporator; and

returning the partially evaporated fluid to the reservoir;

while simultaneously:

drawing fluid from the reservoir;

regulating the pressure of the fluid drawn from the reservoir;

compressing the fluid drawn from the reservoir;

condensing the compressed fluid;

expanding the condensed fluid; and

returning the expanded fluid to the reservoir.

19. The method of claim 18 comprising sub-cooling the fluid drawn from the reservoir by transferring heat from the fluid to expanded fluid drawn from the reservoir.

20. The method of claim 19 comprising pre-heating the fluid prior to the inlet of the evaporator by transferring heat from fluid drawn from compressed fluid.

21. The method of claim 18 comprising pre-heating the fluid prior to the inlet of the evaporator by transferring heat from fluid drawn from compressed fluid.