High efficiency air delivery system for solid oxide fuel cell power generation

Abstract

Distributed power generation systems can be used in the electric grid to reduce peak loads, raise power quality, and reduce/eliminate transmission losses. One distributed energy system with distinct advantages is a Solid Oxide Fuel Cell (SOFC) integrated with an Internal Combustion Engine (ICE) which has the capability to operate at electric efficiencies as high as 70%. This research aimed to produce and test a high efficiency air delivery system that supports the SOFC-ICE to generate power on the scale of 80 kW. The air balance of plant (BOP) system utilized low speed scroll-type rotating compressors and brazed plate and frame heat exchangers for efficient preheating. The scroll compressors were modeled in GT-Suite and the remaining air BOP system was modeled with thermodynamic and heat transfer equations. Then testing was done on the compressors and heat exchangers to validate the model so that the air BOP system performance could be accurately predicted within a range of conditions. Both compressors were run from a range of 20 g/s to 60 g/s with the heat through the system being swept from 100°C to 600°C which yielded compressor efficiencies over 60% and heat exchanger effectiveness over 0.90. The validated model was then used to make predictions about system performance at on and off-design conditions.