Systems and methods for cooling electrical equipment

1. A cooling system comprising:

a first refrigerant circuit in thermal communication with a heat load and in fluid communication with a main condenser;

a free cooling circuit in fluid communication with the main condenser and a free-cooled water source, the free cooling circuit being in thermal communication with the first refrigerant circuit via the main condenser;

a chilled water circuit in fluid communication with the main condenser and an evaporator, the chilled water circuit being in thermal communication with the first refrigerant circuit via the main condenser;

a second refrigerant circuit in fluid communication with the evaporator and a secondary condenser, the second refrigeration circuit being in thermal communication with the chilled water circuit and the free cooling circuit, wherein during a low wet-bulb temperature condition of ambient air, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled solely by the free cooling circuit;

a first control valve that, when in an open position, enables fluid flowing through the free cooling circuit to flow through the main condenser; and

a second control valve that, when in a closed position, inhibits fluid flowing through the free cooling circuit to flow through the secondary condenser, which causes a refrigerant of the first refrigerant circuit flowing through the main condenser to be condensed by a fluid flowing through the main condenser that is cooled solely by the free cooling circuit.

2. The cooling system of claim 1 , further comprising a third control valve,

wherein when the first and third control valves are placed in a closed position and the second control valve is placed in an open position, a refrigerant of the first refrigerant circuit is condensed by fluid flowing through the main condenser that is cooled by the chilled water circuit.

3. The cooling system of claim 2 , wherein when the first, second, and third control valves are placed in a partially open position, the refrigerant of the first refrigerant circuit is condensed by a fluid flowing through the main condenser that is cooled by the free cooling circuit and the chilled water circuit.

4. The cooling system of claim 1 , further comprising a water pump that pumps fluid through the chilled water circuit.

5. The cooling system of claim 4 , wherein the second refrigerant circuit includes a compressor.

6. The cooling system of claim 5 , wherein the chilled water circuit includes a one-way valve, wherein the one-way valve inhibits fluid from flowing from an inlet port of the evaporator and toward the water pump.

7. The cooling system of claim 1 , wherein during a high wet-bulb temperature condition of ambient air, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled by the chilled water circuit.

8. The cooling system of claim 7 , further comprising a third control valve that, when in an open position, inhibits fluid flowing through the free cooling circuit to flow through the main condenser and enables fluid flowing through the free cooling circuit to flow through the secondary condenser,

wherein when the first control valve is in a closed position, the second control valve is in an open position, and the third control valve is in an open position, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the chilled water circuit.

9. The cooling system of claim 1 , wherein during an intermediate wet-bulb temperature condition of ambient air, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled by a combination of the free cooling circuit and chilled water circuit.

10. The cooling system of claim 9 , wherein when a first, second, and third control valve are placed in a partially open position, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled by a combination of the free cooling circuit and chilled water circuit.

11. The cooling system of claim 1 , wherein the chilled water circuit includes a water pump that circulates fluid through the chilled water circuit,

wherein the second refrigerant circuit includes a compressor that circulates a refrigerant through the second refrigerant circuit, and

wherein the water pump and compressor are placed in an idle state during the low wet-bulb temperature condition.

12. A method of operating a cooling system, comprising:

providing a cooling system, including:

a first refrigerant circuit in thermal communication with a heat load and in fluid communication with a main condenser;

a free cooling circuit in fluid communication with the main condenser and a free-cooled water source, the free cooling circuit being in thermal communication with the first refrigerant circuit via the main condenser;

a chilled water circuit in fluid communication with the main condenser and an evaporator, the chilled water circuit being in thermal communication with the first refrigerant circuit via the main condenser; and

a second refrigerant circuit in fluid communication with the evaporator and a secondary condenser, the second refrigeration circuit being in thermal communication with the chilled water circuit and the free cooling circuit, wherein during a low wet-bulb temperature condition of ambient air, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled solely by the free cooling circuit;

placing a first control valve in an open position to enable fluid flowing through the free cooling circuit to flow through the main condenser; and

placing a second control valve in a closed position to inhibit fluid flowing through the free cooling circuit to flow through the secondary condenser, thereby causing a refrigerant of the first refrigerant circuit flowing through the main condenser to be condensed by a fluid flowing through the main condenser that is cooled solely by the free cooling circuit.

13. The method of claim 12 , wherein during a high wet-bulb temperature condition of ambient air, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled by the chilled water circuit.

14. The method of claim 13 , further including placing a first control valve in a closed position, a second control valve in an open position, and a third control valve in an open position to inhibit fluid flowing through the free cooling circuit to flow through the main condenser and to enable fluid flowing through the free cooling circuit to flow through the secondary condenser thereby causing a refrigerant of the first refrigerant circuit flowing through the main condenser to be condensed by a fluid flowing through the chilled water circuit.

15. The method of claim 12 , wherein during an intermediate wet-bulb temperature condition of ambient air, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled by a combination of the free cooling circuit and chilled water circuit.

16. The method of claim 15 , wherein when the first control valve, the second control valve, and a third control valve are placed in a partially open position, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled by a combination of the free cooling circuit and chilled water circuit.

17. The method of claim 12 , wherein the chilled water circuit further includes a water pump and the second refrigerant circuit includes a compressor, the water pump capable of circulating fluid through the chilled water circuit and the compressor capable of circulating a refrigerant through the second refrigerant circuit, and

wherein during a low wet-bulb temperature condition the water pump and compressor are placed in an idle state.

18. A cooling system comprising:

a first refrigerant circuit in thermal communication with a heat load and in fluid communication with a main condenser;

a free cooling circuit in fluid communication with the main condenser and a free-cooled water source, the free cooling circuit being in thermal communication with the first refrigerant circuit via the main condenser;

a chilled water circuit in fluid communication with the main condenser and an evaporator, the chilled water circuit being in thermal communication with the first refrigerant circuit via the main condenser; and

a second refrigerant circuit in fluid communication with the evaporator and a secondary condenser, the second refrigeration circuit being in thermal communication with the chilled water circuit and the free cooling circuit,

wherein during a low wet-bulb temperature condition of ambient air, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled solely by the free cooling circuit, and

wherein during an intermediate wet-bulb temperature condition of ambient air, a refrigerant of the first refrigerant circuit flowing through the main condenser is condensed by a fluid flowing through the main condenser that is cooled by a combination of the free cooling circuit and chilled water circuit.

19. The cooling system of claim 18 , further comprising:

a first control valve in fluid communication with the secondary condenser; and

a second control valve in fluid communication with the main condenser and the evaporator,

wherein when the first control valve is placed in an open position and the second control valve is placed in a closed position, a refrigerant of the first refrigerant circuit is condensed by a fluid flowing through the main condenser that is cooled solely by the free cooling circuit.