Cooling system for high density heat load

1. A cooling system for transferring heat from a heat load, the cooling system comprising:

a two-phase working fluid;

a pump configured to increase the pressure of the working fluid without substantially increasing the enthalpy of the working fluid;

an air-to-fluid heat exchanger in fluid communication with the pump and in thermal communication with the heat load;

a fluid-to-fluid heat exchanger having a first fluid path in fluid communication with the air-to-fluid heat exchanger and the pump, and a second fluid path, the first and second fluid paths being in thermal communication with one another;

a second heat transfer system in fluid communication with the second fluid path and comprising:

a second portion of the fluid-to-fluid heat exchanger;

a working fluid; and

a compressor;

wherein air passing through the air-to-fluid heat exchanger causes at least a portion of the two-phase working fluid to change phase from a liquid to a gas within the air-to-fluid heat exchanger; and

a controller operatively coupled to at least the second fluid path and configured to prevent condensation on the air-to-fluid heat exchanger by controlling the amount of heat transferred to the second fluid path so that a temperature of the two-phase working fluid within the air-to-fluid heat exchanger is above a dew point temperature of the air passing through the air-to-fluid heat exchanger.

2. The cooling system of claim 1 , further comprising a flow regulator positioned between the pump and the air-to-fluid heat exchanger.

3. The cooling system of claim 1 , further comprising a working fluid receiver in fluid communication between the fluid-to-fluid heat exchanger and the pump.

4. The cooling system of claim 1 , further comprising a working fluid flow regulating valve in fluid communication between the pump and the air-to-fluid heat exchanger.

5. The cooling system of claim 1 , further comprising a working fluid flow regulating valve in fluid communication between the pump and the air-to-fluid heat exchanger and a working fluid receiver in fluid communication between the fluid-to-fluid heat exchanger and the pump.

6. A cooling system for transferring heat from a heat load to an environment, the cooling system comprising:

a first cooling cycle containing a two-phase working fluid; and

a second cooling cycle thermally connected to the first cooling cycle;

wherein the first cooling cycle comprises:

a pump configured to increase the pressure of the working fluid without substantially increasing the enthalpy of the working fluid;

an air-to-fluid heat exchanger in fluid communication with the pump and in thermal communication with the heat load;

a second heat exchanger having a first fluid path for the working fluid in fluid communication with the air-to-fluid heat exchanger and the pump, and a second fluid path comprising a portion of the second cooling cycle;

wherein the first and second fluid paths are in thermal communication with one another;

wherein the heat load causes at least a portion of the two-phase working fluid to change phase from a liquid to a gas within the air-to-fluid heat exchanger; and

wherein the second cooling cycle comprises a vapor compression refrigeration system in thermal communication with the environment and wherein the second cooling cycle is controlled to maintain a temperature of the two-phase working fluid entering the air-to-fluid heat exchanger above a dew point of air flowing through the air-to-fluid heat exchanger.

7. The cooling system of claim 6 , further comprising a working fluid receiver in the first cooling cycle between the second heat exchanger and the pump.

8. The cooling system of claim 6 , further comprising a working fluid flow regulating valve in fluid communication between the pump and the air-to-fluid heat exchanger.

9. The cooling system of claim 6 , further comprising a working fluid flow regulating valve in fluid communication between the pump and the air-to-fluid heat exchanger and a working fluid receiver in fluid communication between the second heat exchanger and the pump.

10. A cooling system for transferring heat from a heat load to an environment, the cooling system comprising:

a working fluid pump configured to increase the pressure of a two-phase working fluid without substantially increasing the enthalpy of the working fluid;

an air-to-fluid heat exchanger connected to the pump and having a fluid path in thermal communication with the heat load;

a second heat exchanger having first and second fluid paths in thermal communication with one another, wherein the first fluid path provides fluid communication from the air-to-fluid heat exchanger to the pump, and wherein the second fluid path is adapted to thermally connect the air-to-fluid heat exchanger in the first fluid path to a vapor compression refrigeration system that is in thermal communication with the environment;

wherein air passing through the air-to-fluid heat exchanger transfers heat from the heat load and causes at least a portion of the working fluid to change phase from a liquid to a gas; and

a controller operatively coupled to the vapor compression refrigeration system and configured to maintain a temperature of the working fluid between the second heat exchanger and the air-to-fluid heat exchanger above a dew point temperature of the air passing through the air-to-fluid heat exchanger so that the cooling system removes only sensible heat from the air and thereby prevents condensation on the air-to-fluid heat exchanger.

11. The cooling system of claim 10 , further comprising a working fluid receiver in fluid communication between the second heat exchanger and the pump.

12. The cooling system of claim 10 , further comprising a working fluid flow regulating valve in fluid communication between the pump and the air-to-fluid heat exchanger.

13. The cooling system of claim 10 , further comprising a working fluid flow regulating valve in fluid communication between the pump and the air-to-fluid heat exchanger and a working fluid receiver in fluid communication between the second heat exchanger and the pump.

14. A heat transfer system, comprising:

a first heat transfer subsystem adapted to circulate there through a first working fluid, wherein the first working fluid is selected from the group consisting of: chlorofluorocarbons, hydrofluorocarbons and hydrochlorofluorocarbons, comprising:

at least one air-to-fluid heat exchanger in thermal communication with a heat load;

a pump configured to increase the pressure of the first working fluid without substantially increasing the enthalpy of the first working fluid; and

at least a portion of a second heat exchanger;

a second heat transfer subsystem comprising:

at least a second portion of the second heat exchanger;

the second heat transfer subsystem adapted to circulate a second working fluid there through; and

wherein air passing through the air-to-fluid heat exchanger causes at least a portion of the first working fluid to undergo a phase change from a liquid to a gas in the first heat transfer subsystem; and

a system controller operatively coupled to the second subsystem and configured to prevent condensation on the air-to-fluid heat exchanger by maintaining the first working fluid leaving the second heat exchanger above a dew point temperature of the air passing through the air-to-fluid heat exchanger.

15. The system of claim 14 , wherein the heat load is a room.

16. The system of claim 14 , wherein the heat load is an electronics cabinet.

17. The system of claim 14 further comprising a flow regulator associated with at least one air-to-fluid heat exchanger and which is adapted to control an amount of first working fluid flowing through the associated air-to-fluid heat exchanger.

18. The system of claim 17 , wherein the flow regulator is adapted to control the amount of first working fluid flowing through the air-to-fluid heat exchanger independently of fluid pressure.

19. The system of claim 17 , wherein the flow regulator is adapted to maintain a substantially constant flow of first working fluid through the air-to-fluid heat exchanger.

20. The system of claim 14 , further comprising a receiver in fluid communication with the first heat transfer subsystem for accumulating a portion of the first working fluid.

21. The system of claim 20 , wherein the receiver is adapted to accumulate a portion of the first working fluid based upon temperature and/or heat load.

22. The system of claim 14 , further comprising a flow regulator associated with a plurality of air-to-fluid heat exchangers and which is adapted to limit an amount of first working fluid flowing through each of the associated air-to-fluid heat exchangers.

23. The system of claim 14 , wherein the second heat exchanger is selected from the group consisting of: a tube-in-tube heat exchanger, a shell and tube heat exchanger and a plate and frame heat exchanger.

24. The cooling system of claim 14 , further comprising a working fluid receiver in the first heat transfer subsystem between the second heat exchanger and the pump.

25. The cooling system of claim 14 , further comprising a working fluid flow regulating valve in fluid communication between the pump and the air-to-fluid heat exchanger and a working fluid receiver in fluid communication between the second heat exchanger and the pump.

26. A cooling system for removing heat from a high density heat load, comprising:

a first heat transfer system comprising:

a two-phase working fluid;

a plurality of air-to-fluid heat exchangers configured to transfer heat from the load to the working fluid so that at least a portion of the working fluid changes phase from a liquid to a gas within at least one of the air-to-fluid heat exchangers;

a working fluid flow regulator associated with at least one of the plurality of air-to-fluid heat exchangers and configured to limit the maximum working fluid flow to each associated air-to-fluid heat exchanger;

a working fluid receiver configured to hold working fluid based on working fluid temperature or cooling system load;

a pump configured to increase the pressure of the working fluid without substantially increasing the enthalpy of the working fluid; and

a first portion of a fluid-to-fluid heat exchanger;

wherein all of the first heat transfer system is arranged in fluid communication;

a second heat transfer system comprising:

a second portion of the fluid-to-fluid heat exchanger;

a working fluid;

a compressor; and

wherein all of the second heat transfer system is arranged in fluid communication;

wherein the first heat transfer system is thermally coupled to the second heat transfer system by the fluid-to-fluid heat exchanger; and

a cooling system controller monitoring the dew point temperature of air flowing through the air-to-fluid heat exchanger, and operatively connected to the second heat transfer system to prevent condensation on the air-to-fluid heat exchangers by maintaining the first heat transfer system working fluid entering the air-to-fluid heat exchangers at a temperature above the dew point temperature of the air flow.

27. The system of claim 26 , wherein the air-to-fluid heat exchangers are located within an enclosure and the high density heat load is created by electronics within the enclosure, the enclosure having a forced air flow path across the electronics and through the air-to-fluid heat exchangers.

28. The system of claim 27 , wherein first heat transfer system is configured so that the working fluid is cooled in the fluid-to-fluid heat exchanger and then flows to the receiver and pump, and then flows through the regulating valves and then into each air-to-fluid heat exchanger where at least a portion of the working fluid boils in each air-to-fluid heat exchanger, and then the heated working fluid returns to the fluid-to-fluid heat exchanger where it is once again cooled.

29. The system of claim 26 , further including a working fluid flow regulator associated with each air-to-fluid heat exchanger and each flow regulator configured to limit the maximum working fluid flow to each air-to-fluid heat exchanger.