Abstract

The need of fast and uninterrupted online services and applications in our daily life leads to rapid expansion in both quantity and capacity of data centers to handle these huge amounts of digital information. However, the energy use associated with hundreds of information technology (IT) equipment running 24/7 in data centers creates a huge burden to the global economy and environment. Globally, electricity consumption of data centers accounts for about 238 billion kWh per year which is corresponding to about 1.3% of total global electricity consumption. In a typical data center, about 30-50% of its total energy is dedicated to remove the heat from running the IT equipment all year round. Conventional cooling energy saving strategy is to utilize outdoor air directly to cool the IT equipment when outdoor temperature is lower, which known as direct airside free cooling. However, the main concerns about this approach is the breakdown of IT equipment due to poor outdoor air quality. This could be a limiting factor in certain locations for using the direct free cooling system. Therefore, an indirect free cooling approach is more interested to be used under poor outdoor air environments.

In this thesis, an indirect airside free cooling based on thermosiphon loop is proposed and investigated to reduce energy consumption and improve the IT equipment reliability in a novel vertical data center (VDC) which is designed by Vert.com Inc. An energy model was established to evaluate the energy performance of this new proposed design in different selected cities across North America. The energy results show that approximately 41% to 59% of an annual overall HVAC energy are saved with the thermosiphon free cooling system depending on the local climate conditions in comparison to the data center without any free cooling implementations.

Analysis of indoor airflow distribution was also conducted in this VDC project because it can help to optimize different design options and enhance cooling efficiency. Unlike other typical data centers that are designed horizontally and occupied a large footprint like warehouses, the proposed data center in this study is designed vertically like a tower with a compact rectangular form. In this thesis, two proposed locations of the indoor thermosiphon heat exchangers were compared and analyzed through CFD simulation. The simulation results indicate that there are many turbulent flows developed inside the building, especially at 90° bends, which can affect the air distribution uniformity and cooling performance through the heat exchanger.