Rack Level Server Power and Cooling by Solid Oxide Fuel Cell and Liquid Desiccant System in Humid Climate

In this study, the integration of highly efficient, near zero-emission, high-temperature solid oxide fuel cell with a liquid desiccant dehumidification system has been studied to meet the power and air conditioning demands of data centers. Serves can directly be powered by solid oxide fuel cell stack direct current produced and SOFC high-quality heat is used as the primary thermal energy source to supply cooling through a bottoming cycle. Data centers need cooling and humidity control to protect servers and electronic equipment. The system considered in this study integrates a solid oxide fuel cell with a liquid desiccant cycle that uses the heat generated in a solid oxide fuel cell for dehumidification. The high-quality solid oxide fuel cell exhaust heat is used to increase the concentration of lithium chloride solution (regenerator), then the concentrated liquid desiccant solution is stored. The high concentration solution is used to dehumidify the outside air (dehumidifier) when moisture must be removed.

The objectives of this study focus on theoretically evaluating the integrated system concept and to assess the achievable air conditioning from solid oxide fuel cell waste heat. To explore the feasibility of thermally integrating solid oxide fuel cell with liquid desiccant dehumidification, a spatially resolved physical model developed in Matlab is used to simulate the operating characteristics of the solid oxide fuel cell system. A corresponding physical model is developed to simulate the liquid desiccant air conditioner including regenerator, dehumidifier, and indirect evaporative cooler. The integrated physical models are validated by experimental data collected from a commercialized solid oxide fuel cell system and custom-built dehumidifier system. This study considers solid oxide fuel cell systems capable of powering a single server rack (~12kW) and the operation of liquid desiccant dehumidification for cooling and dehumidification of that same rack. The small-scale liquid desiccant dehumidification operation is based on the distributed waste heat from each individual solid oxide fuel cell at the rack level. The analysis will indicate whether waste-heat based cooling and dehumidification is capable of powering the servers and maintaining server operating temperatures and humidity in the safe range for different weather conditions. In this study, the regenerator and dehumidifier behavior throughout the entire year for humid weather conditions in four different locations are analyzed. Preliminary findings show that the solid oxide fuel cell exhaust retains sufficient quality heat for regenerating the liquid desiccant and providing sufficient cooling for keeping the server rack in a safe range of temperature and humidity by seasonal storage of strong desiccant.