MAXIMIZING USE OF AIR-SIDE ECONOMIZATION, DIRECT AND INDIRECT EVAPORATIVE COOLING FOR ENERGY EFFICIENT DATA CENTERS

Abstract

Data centers house information technology (IT) equipment such as servers and network switches which are vital for our networked modern society by providing digital data storage, data processing and connectivity. Data centers house few hundreds to tens of thousands of IT equipment that consume few kilowatt-hours to multi-megawatt-hours of electrical energy that gets dissipated as heat. IT equipment need to be properly cooled so that they operate reliably for their expected lifetime. For air cooled IT equipment, manufacturers provide heat sinks, cold plates, fans, et cetera to remove heat from the vicinity of heat dissipating components and data centers need to continuously supply cold air to the IT equipment and remove hot from the vicinity of the IT equipment. Type of cooling system used in a data center is an important factor in the overall efficiency and reliability of the data center. This dissertation focuses on use of air-side economization (ASE), direct evaporative cooling (DEC), indirect evaporative cooling (IEC), and indirect/direct evaporative cooling (I/DEC) as a way to reduce cooling cost of data centers. A test bed modular data center, which has a cooling unit that operates in ASE or two-stage I/DEC modes, and located in Dallas, TX, is primarily used for this study. Included in the study are analysis of weather data to determine what percentage of a year these cooling systems can be used, modeling of the test bed modular data center using computational fluid dynamics (CFD) tool, discussion on improvements that can be made to the cooling system and factors that limit use of ASE and I/DEC, method for improving the DEC control system, et cetera. In addition, CFD modeling of another modular data center is used to show importance of proper airflow management within cold aisle of data centers and impact of hot aisle pressurization on operating point of server fans.