Cold energy storage systems using heat pipe technology for cooling data centers

A novel type of heat pipe application for cold energy storage has been proposed and discussed in this paper. The cold storage system is aiming to save electricity for data center cooling. A typical wickless heat pipe - thermosiphon (thermal-diode heat pipe) will be employed in this application. The thermosiphon cold energy storage systems can be designed into several types that are ice storage, cold water storage and precool heat exchanger. Those systems can be used for co-operating with conventional chiller system for cooling data centers. The heat load used for discussing in this paper is 8800 kW which represents a large scale data center. The methodology addressed in this paper can be also converted into the middle and small sizes of the data centers. This type of storage system will help to downsize the chiller and decrease its running time that would be able to save significant electricity cost and decrease green house gas emissions from the electricity generation. The proposed systems can be easily connected into the existing conventional systems without major design changes. The analysis in this paper is using Air Freezing Index AFI >=400 °C-days/year for sizing the heat pipe modules. For the locations where AFI has different value the storage size will be varied accordingly. The paper also addressed a result that an optimum size of cold energy storage system that should be designed at a level to handle 60% of total yearly heat load of a data center.