Cold water supply system

1. A cold water supply system that cools water flowing through a water pipe, and supplies the cooled water to a cooling load, the cold water supply system comprising:

at least one independent refrigerant circuit unit including a first compressor and a first water heat exchanger configured to exchange heat between refrigerant flowing in the first water heat exchanger and the water flowing through the water pipe to cool the water;

at least one composite unit configured to cool the water flowing through the water pipe; and

a controller configured to control operation of the independent refrigerant circuit unit and operation of the composite unit, wherein

the composite unit includes

a free cooling unit including a pump and a second water heat exchanger configured to exchange heat between a heat medium and the water to cool the water, and

a coupled refrigerant circuit unit connected in series with the free cooling unit and including a second compressor and a third water heat exchanger configured to exchange heat between refrigerant flowing in the third water heat exchanger and the water to cool the water, and

the controller controls an operating frequency of the first compressor, an operating frequency of the second compressor, and an operating frequency of the pump based on a temperature of the water flowing out from the water pipe.

2. The cold water supply system of claim 1 , wherein

the free cooling unit is disposed upstream of the coupled refrigerant circuit unit along a flow direction of the water flowing through the water pipe.

3. The cold water supply system of claim 1 , further comprising

an outside air temperature sensor configured to detect an outside air temperature, wherein

the controller is configured to

store a target water temperature of the water flowing out from the water pipe,

set a threshold based on the target water temperature,

compare the outside air temperature with the threshold to determine, based on a comparison result, a unit to be operated from among the independent refrigerant circuit unit, the free cooling unit, and the coupled refrigerant circuit unit, and

calculate a number of the units determined to be operated.

4. The cold water supply system of claim 3 , wherein

the controller is configured to preferentially operate the free cooling unit in a case where the outside air temperature is lower than the threshold.

5. The cold water supply system of claim 4 , wherein

the controller determines a number of the operated free cooling units based on a total load of the free cooling unit in operation.

6. The cold water supply system of claim 4 , wherein

the controller determines a number of the operated free cooling units based on an operating frequency of the pump of the free cooling unit in operation.

7. The cold water supply system of claim 4 , wherein

the controller

operates the coupled refrigerant circuit unit in a case where all of the free cooling units are in operation, and a temperature of the water flowing out from the water pipe has not reached the target water temperature, and

operates the independent refrigerant circuit unit in a case where all of the free cooling units and all of the coupled refrigerant circuit units are in operation, and the temperature of the water flowing out from the water pipe has not reached the target water temperature.

8. The cold water supply system of claim 7 , wherein

the controller determines a number of the operated coupled refrigerant circuit units operated and a number of the independent refrigerant circuit units operated based on an operating frequency of the second compressor of the coupled refrigerant circuit unit in operation and an operating frequency of the first compressor of the independent refrigerant circuit unit in operation.

9. The cold water supply system of claim 8 , wherein

in increasing the number of the coupled refrigerant circuit units operated or the number of the independent refrigerant circuit units operated, the controller causes the coupled refrigerant circuit unit or the independent refrigerant circuit unit to be operated in an ascending order of cumulative operating time.

10. The cold water supply system of claim 3 , wherein

the controller determines to preferentially operate the independent refrigerant circuit unit in a case where the outside air temperature is equal to or more than the threshold.

11. The cold water supply system of claim 10 , wherein

the controller determines a number of the independent refrigerant circuit units operated based on an operating frequency of the first compressor of the independent refrigerant circuit unit in operation.

12. The cold water supply system of claim 10 , wherein

the controller operates the coupled refrigerant circuit unit in a case where all of the independent refrigerant circuit units are in operation, and a temperature of the water flowing out from the water pipe has not reached the target water temperature.

13. The cold water supply system of claim 10 , wherein

in increasing the number of the independent refrigerant circuit units operated or a number of the coupled refrigerant circuit units operated, the calculation unit causes the independent refrigerant circuit unit or the coupled refrigerant circuit unit to be operated in an ascending order of cumulative operating time.