Sealed rack server cooling unit

A server unit comprising a plurality of electronic components including at least one fan, memory and a central processing unit, the server unit comprising a first enclosure and a second enclosure, the at least one fan, the memory and the central processing unit, CPU, being provided within the first enclosure, the first enclosure being provided within the second enclosure, the second enclosure being sealed such that ambient air does not ingress or degress from the second enclosure, the first enclosure comprising air conduits to allow a passage of fan assisted air from the first enclosure to the second enclosure, and from the second enclosure to the first enclosure, and wherein:

• the second enclosure comprises at least one baffle to preferentially direct air egressing from a first end of the first enclosure to then enter into a second end of the first enclosure;
• an air liquid heat exchanger located in an air flow path between the first enclosure and the second enclosure such that heated air passing between the first enclosure and the second enclosure passes through the air liquid heat exchanger to effect an extraction of the heat from the heated air, the air liquid heat exchanger being in fluid communication with a liquid coolant conduit, the liquid coolant conduit being configured to effect a transfer of heat from the air liquid heat exchanger to a location externally of the second enclosure;
• and
• the first enclosure further comprises a liquid cooling unit configured to direct liquid onto the central processing unit, the liquid cooling unit being in fluid communication with the liquid coolant conduit, such that heat emitted from the central processing unit is also transferred into the liquid coolant conduit.