High ambient temperature effects on the performance of a gas turbine-based cogeneration system with supplementary fire in a tropical climate

Abstract

High ambient temperature negatively affects gas turbine performance, especially in a tropical climate. Cogeneration improves fuel utilization by taking advantage of the energy discharged as waste heat in the exhaust gases. This case study assesses the effects of high ambient temperature on the performance of a natural gas-based cogeneration plant in Barranquilla, Colombia, a location with a hot and humid tropical climate throughout the year with an annual average temperature of 27.4 °C. The cogeneration plant encompasses gas and vapor turbine generation, supplementary fire, waste heat recovery, and process heat exchange. Validated ASPENHYSYS® simulation allows comparing gas-turbine-alone indicators with those at ISO conditions, i.e., 15 °C and 101.3 kPa. Ambient temperature reduces gas turbine power output by up to 22% and decreases thermal efficiency by around 0.06% for every °C rise above ISO conditions. Cogeneration with and without supplementary fire increases power output by 17% and 5% compared to gas-turbine-alone operation. The energy utilization factor increases by 27–37% without supplementary fire and above 37% with supplementary fire. Results give insight into the challenges of cogeneration plants in a tropical climate. Further studies should include the effects of high humidity on power plant performance and the potential benefits of cooling inlet air.