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2013-04-17 - Colloque/Article dans les actes avec comité de lecture - Anglais - 11 page(s)

De Paepe Ward , Contino francesco, Delattin Frank, Bram Svend, De Ruyck Jacques, "A new route for water introduction in a micro gas turbine cycle" in The 3rd International Conference on Microgeneration and Related Technologies, MicroGen2013, Naples, Italy, 2013

  • Codes CREF : Thermodynamique appliquée (DI2210)
  • Unités de recherche UMONS : Thermique et Combustion (F704)
  • Instituts UMONS : Institut de Recherche en Energétique (Energie)
Texte intégral :

Abstract(s) :

(Anglais) Micro gas turbines (mGT) offer some advantages for small scale (up to 500 kWe) Combined Heat and Power (CHP) production compared to Internal Combustion Engines (ICE) due to their low vibration level, cleaner exhaust and lower maintenance cost. The major drawback is the lower electric efficiency, which makes mGTs less attractive for applications with a non-continuous demand for heat. Therefore, a reduction in heat demand will generally lead to a forced shut down of the unit, which makes the mGT less competitive compared to the ICE. Water injection in the compressor exhaust is considered as a possible route to improve the electrical efficiency of the mGT. To determine the optimal cycle settings for water injection, we have performed simulations using a two-step method. In a first step, the thermodynamic limit for the water injection is sought using a black box method. In a second step, the cycle layout is designed by means of composite curve theory. This paper summarizes the results of two case studies. In the first case, the black box is considered adiabatic and no fixed stack temperature is imposed (thus allowing condensation of the exhaust gasses). One of the major concerns when injecting water is the water consumption, which can be compensated in some cases through condensation and recycling of the condensate. Therefore, in the second case, the cycle is made self-sufficient with water. In this case, the black box is no longer considered adiabatic and heat exchange with the environment is allowed for condensation of the flue gasses. Simulations showed that lowering the stack temperature to 53°C results in an injection of 17 %wt of water and an increase in electric efficiency of 9% absolute. Results of simulations of the second case indicate that the stack temperature needs to be lowered under 30°C in order to make the cycle self-sufficient with water.