Air Conditioner Types
Commercially available close coupled solutions can be divided into two categories: Open-Loop and Closed-Loop.
Open-Loop Configuration
Open-Loop configurations are not totally independent from the room they are installed, and air flows interact with the ambient room environment.
In-Row Air Conditioners
Row-Based Air Conditioning units are installed inside the rack rows. Air flows generally follow short and linear paths, reducing, in this way, the necessary power needed to start up the fans and increasing the energy efficiency.
A Row-Based cooling solution offers one advantage with respect to the Room-Based solution, since the former one can be better adapted to the needs of cooling for specific rows; it is anyway appropriate not to locate the conditioning units at the beginning or at the end of the rows to maximise their performance.
Rear Door Heat Exchangers
This type of solution is based on the substitution of the rear door of an existing rack.
These heat exchangers leverage the front-to-back air dissipation of most of the IT equipments: the servers dissipate warm air, which passes the heat exchanger coil and is returned to the room at an agreeable temperature.
The cooling units of this category do not occupy additional space, so they are particularly indicated either to cool all the spaces originally designed as data centers, or to integrate an already existing cooling system.