Microturbine Performance Improvement Through the Implementation of Inlet Air Cooling

Microturbines have permeated the power generation infrastructure owing to their low cost, simple installation, and relatively low maintenance operation as compared to larger gas turbines. However, microturbines are susceptible to dramatic output power loss and efficiency degradation when the ambient temperature increases. To counteract the effect of increased inlet air temperatures, large scale turbines have utilized inlet air misting and fogging with water to reduce the temperature and increase density through evaporative cooling and ultimately increasing power output. Such a cooling scheme has not found wide spread utilization with microturbines possibly due to cost, complexity and/or implementation issues. This paper describes a simple, low cost system employed for cooling inlet air to a microturbine and the results of a testing program to characterize the improvements in performance. The system, integrated on a pair of Capstone C60 microturbines, has provided measured improvements in output power of approximately 25% as compared to the non-cooled operation. Specifically, at ambient temperatures between 32 C and 41 C, increases in output power from 9 kW to 12 kW have been observed. Improvements in efficiency have also been observed.Copyright © 2005 by ASME