Optimum supply air temperature ranges of various air-side economizers in a modular data center

• Energy optimization process of air-side economizer for data centers is established.
• Supply air conditions, server thermal characteristics, and cooling systems are analyzed for energy simulation.
• Annual cooling energy simulation is conducted in 16 locations in South Korea by considering various parameters.
• Optimum supply air temperature ranges are suggested for various air-side economizers in each location.

In order to reduce data center cooling energy, ASHRAE Technical Committee 9.9 expanded thermal environmental ranges for data centers and recommended using the economizer, and it has reduced data center cooling energy successfully. The main purpose of this research is to establish an energy optimization process for the air-side economizer in a modular data center with respect to various parameters (supply air conditions, server thermal characteristics, cooling system configurations, and heat exchange effectiveness), and to determine optimum supply air ranges through simulation. The cooling energy simulation is conducted for three types of air-side economizers by changing the supply air temperature (SAT) and heat exchanger effectiveness at 16 locations in South Korea based on the three thermal environmental ranges. The simulation result shows that the lowest cooling energy consumption appears when the computer room air handler (CRAH) SAT is within 18–23 °C, and at higher SAT conditions, the cooling energy consumption increases, since chiller energy reduction is offset by the increase in CRAH fan energy.