What mainly affects the cooling capacity of a raised floor tile?

The cooling capacity of a raised floor tile is a measure of the volume of conditioned air it can deliver from the underfloor plenum into the cold aisle. This airflow is primarily governed by four factors:
1. Percentage of the surface opening: A tile's fundamental design characteristic determining its maximum potential airflow.
2. Pressure under the raised floor: The static pressure differential across the tile is the driving force that pushes air through the openings.
3. Obstruction of the supporting construction: Pedestals, stringers, and underfloor cabling can block the tile from underneath, reducing effective airflow.
4. Damper construction: Dampers are used to regulate or throttle airflow, directly impacting the delivered volume. These factors directly influence the tile's performance characteristics.

A. These factors relate to the overall cooling system design and demand, not the intrinsic airflow capacity of an individual tile.
B. While air temperature and humidity affect air density, their impact on airflow volume is minor compared to pressure and physical obstructions. The tile's material is irrelevant to airflow.
D. ICT equipment airflow direction and temperature difference (Delta T) define the demand for cooling, not the perforated tile's supply capacity.

1. EPI-USA, Certified Data Centre Specialist (CDCS) Courseware, v3.2, Module 5 - Cooling. The course material explains that the raised floor acts as a supply air plenum and the airflow through perforated tiles is a function of the underfloor static pressure and the tile's open percentage. It explicitly discusses the negative impact of underfloor obstructions and the use of dampers to balance airflow to match IT load requirements.

2. ASHRAE TC 9.9, "Thermal Guidelines for Data Processing Environments," 4th Edition, 2015, Chapter 4, Section 4.5.2 Airflow Management. This chapter details that the airflow delivered by a perforated tile is a function of the pressure differential across the tile and the tile's flow coefficient, which is determined by its open area percentage and the geometry of the perforations. It notes that obstructions beneath the tile can significantly degrade its performance.

3. Geng, H., "Data Center Handbook," John Wiley & Sons, 2014, Chapter 12, Section 12.3.1 Raised Floor Plenum. This academic handbook states, "The airflow rate (CFM) through a perforated tile is a function of the tile’s free area and the static pressure in the plenum." It provides formulas (e.g., CFM = C × A × √P) where 'A' is the open area and 'P' is the static pressure, confirming the direct relationship.