UC Irvine

Electricity consumption projections place data centers at up to 13% of global electricity demand in 2030 due to the expected growth in the production and use of electronic devices, cloud services, and computer networks. Cooling infrastructure accounts for up to 40% of the total energy delivered to a data center. With businesses and society relying so much on data centers, there is a greater need for reliable and clean electric power for data centers. Solid Oxide Fuel Cell (SOFC) systems have the potential to provide more reliable and cleaner electrical load-following characteristics compared to other technologies while enabling dynamic operation and control. The high-temperature exhaust of SOFC can be used to run a bottoming cycle such as a cooling system which makes it an attractive integrated system for data center applications. However, cost and durability are major challenges associated with SOFC technology. On the other hand, the biggest challenge for using hydrogen as an energy carrier for SOFC is the very high pressure or very low temperature required for its storage, transmission, and distribution, which makes the need for a more dense liquid energy carrier like ammonia inevitable.This dissertation, first, focuses on evaluating the integrated system concept and assesses the achievable air conditioning from SOFC waste heat. To explore the feasibility of thermally integrating SOFC with liquid desiccant dehumidification (LDD), a spatially resolved physical model developed in MATLAB is used to simulate the operating characteristics of this SOFC system. A corresponding physical model is developed to simulate the liquid desiccant air conditioner for dehumidification. This research evaluated SOFC systems for powering the demand of a single server rack (~12kW) to powering a row of servers (~240kW). The LDD operation is based on the distributed waste heat from SOFC that powers the servers. This research indicates whether waste-heat-based cooling and dehumidification could power the servers and maintain server operating temperatures and humidity in the safe range for different weather conditions. It calculated the yearly storage capacity required for each location to meet the demand of the data center for the entire year. Next, the performance and degradation of a 1.5kW (AC) commercial system, that is proposed for the source of power and cooling of servers, is evaluated under steady-state and dynamic load cycling conditions for over 6000 hours. The degradation rate and performance characteristics of the SOFC system is analyzed to determine the long-term performance and durability of the SOFC system under dynamic condition. Finally, to analyze and compare the degradation of single-cell SOFC directly fed with ammonia (NH3), externally reformed ammonia (N2-H2), and pure hydrogen (H2), three durability tests are conducted on anode supported SOFC. Electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) are conducted to study the performance losses during operation and to observe the microstructure changes of the cell after testing.