Patent ID: 8274790

Claim:
A cooling apparatus for facilitating cooling of an electronics rack comprising at least one electronic subsystem, the cooling apparatus comprising: at least one cooling unit configured to provide, via a coolant loop, system coolant to the at least one electronic subsystem for facilitating cooling thereof, wherein each cooling unit comprises a liquid-to-liquid heat exchanger, a first coolant path and a second coolant path, the first coolant path of each cooling unit receiving, in normal operation, chilled coolant from a source and passing at least a portion thereof through the liquid-to-liquid heat exchanger, and the second coolant path being coupled in fluid communication with the coolant loop, and in normal operation, providing cooled system coolant to the at least one electronic subsystem, and expelling heat in the liquid-to-liquid heat exchanger from the system coolant to the chilled coolant in the first coolant path; an air-to-liquid heat exchanger associated with the electronics rack for cooling, in normal operation, at least a portion of air passing through the electronics rack, the air-to-liquid heat exchanger being coupled to the coolant loop to receive system coolant therefrom and exhaust system coolant thereto; multiple isolation valves coupled to the coolant loop to facilitate transitioning of the cooling apparatus between a normal-mode, parallel flow of system coolant through the at least one electronic subsystem and the air-to-liquid heat exchanger and a failure-mode, serial flow of system coolant from the at least one electronic subsystem to the air-to-liquid heat exchanger; and at least one controller coupled to the multiple isolation valves for automatically transitioning the cooling apparatus from the normal-mode, parallel flow of system coolant through the at least one electronic subsystem and the air-to-liquid heat exchanger to the failure-mode, serial flow of system coolant from the at least one electronic subsystem to the air-to-liquid heat exchanger responsive to a failure of the chilled coolant from the source, wherein in normal-mode, the at least one cooling unit provides cooled system coolant in parallel to the at least one electronic subsystem, for liquid-cooling thereof, and to the air-to-liquid heat exchanger for cooling at least a portion of air passing through the electronics rack, and responsive to detection of the failure, the at least one controller employs the multiple isolation valves to automatically transition the cooling apparatus to the failure-mode, serial flow of system coolant from the at least one electronic subsystem to the air-to-liquid heat exchanger for rejecting, via the system coolant, heat from the at least one electronic subsystem to air passing across the air-to-liquid heat exchanger.