Design Considerations in the use of Phase Change Materials in Data Center Cooling

ABSTRACT The demand for sustainable, energy efficient and cost effective heating and cooling solutions is exponentially increasing with the rapid advancement of computation and information technology. Use of latent heat storage materials also known as phase change materials (PCMs) for load leveling is an innovative solution to the data center cooling demands. These materials are commercially available in the form of micro-capsules. One product concept suspends these micro-capsules in a heat transfer fluid which creates a slurry of micro-encapsulated phase change material. The PCM latent heat aspect results in a higher heat capacity than the fluid alone for temperature ranges that include the phase change temperature. The composition and physical properties of phase change materials play significant role in energy efficiency of the cooling systems designed using PCM. The objective of this project is to study the effects of PCM physical properties on the development of energy efficient data center cooling schemes. In this study notional concepts are developed for the simulation of energy efficient data center cooling. Several important design characteristics have been identified. The phase change temperature of the material must be chosen to obtain optimum energy transfers within the system heat exchangers as the PCM interacts with the heat sources and heat sinks. State-of-charge of the phase change material is difficult to measure, therefore it should be tracked continuously. Performance is improved when flow through the PCM storage is reversed when switching from charging to discharging. Results of this project will aid in efficient design of data center cooling systems based on phase change materials.