Coolant control unit and cooled electronics system employing the same

A cooled electronics system comprising:

• an electronics assembly including a support structure supporting at least one electronic device to be cooled;
• and
• a coolant control unit for facilitating liquid cooling of the at least one electronic device, the coolant control unit comprising:
• an external coolant inlet and external coolant outlet for respectively receiving external coolant from and returning external coolant to a coolant distribution unit, the coolant distribution unit controlling at least one of temperature, pressure or cleanliness of the external coolant;
• an internal coolant loop for circulating coolant to the at least one electronic device;
• a first control valve coupling the external coolant inlet to the internal coolant loop at a coolant supply location of the internal coolant loop and a second control valve coupling the external coolant outlet to the internal coolant loop at a coolant return location of the internal coolant loop;
• a liquid-to-air heat exchanger connected between the first control valve and the second control valve;
• and
• control logic for controlling operation of the coolant control unit in one of an external coolant mode and an internal coolant mode, wherein in the external coolant mode, the first control valve and the second control valve are controlled to allow passage of external coolant through the internal coolant loop to the at least one electronic device, and in the internal coolant mode, the first control valve and second control valve are controlled to isolate coolant within the internal coolant loop from the external coolant inlet and outlet, and pass the coolant therein through the liquid-to-air heat exchanger.