Objective: To perform the thermal analysis of a data center and predict the temperature distribution and air flow movement for minimizing computer room air conditioning units (CRAC’s). Using above-floor CFD modeling, we monitor and view the entire life cycle of the airflow through the data center. We track the air from the point at which it leaves the computer room air conditioning (CRAC) unit into the sub floor, as it travels from the sub floor through the perforated tiles into the ambient room, and as the air travels through the server racks and back to the CRAC unit.
Engineering Solution: The analyzed data center is rectangular with an area of 516 m sq. and height of 3.35m. Cooling is to be provided using raised flooring layout and demarcation is done for cold aisle and hot aisle. The source of heat from exterior wall according to thermal resistance of wall & heat source from 154 server racks are 1.26MW with each racks emitting 8kw of heat. Three fans of about 500CMH were assumed to transport air from cool aisle to hot aisle in each rack unit.
Figure: Image showing temperature profile (in oC ) inside data center
Conclusion:
- The Average temperature on the rack surface at the 0cold aisle side is 15oC.
- The temperature at cold aisle is varies from 12 to 17oC.
- The Average temperature on the rack surface at the 0hot aisle side is 27oC.
- The temperature in hot aisle is varying from 18oC to 32oC.
- The simulation shows that a good number of servers are experiencing temperatures well above and below the ASHRAE recommended temperature levels.
- Short circuiting of cold air is clearly visible in the simulation.
- Using Computational Fluid Dynamics the system was designed to reduce the capital cost of the data center design by 10% of the original design.
Simulation Experts 