Exergy analysis of a gas turbine trigeneration system using the Brayton refrigeration cycle for inlet air cooling

Abstract Trigeneration with gas turbines as prime mover can improve energy utilization efficiency significantly because of their potential of high economic and energy saving characteristic. In this article, a novel method for compressor inlet air cooling in gas turbine trigeneration is achieved by the Brayton refrigeration cycle driven by the gas turbine and air is used as a working fluid. Introducing the air refrigeration cycle for inlet air cooling provides the advantage of quite low temperatures close to 0 °C and even lower, and enhances the performance significantly. The performance was evaluated by both energy and exergy efficiencies, with the latter providing good guidance for system improvement. The influences of key parameters, which include extraction pressure ratio, extraction mass rate, turbine inlet temperature (TIT), process heat pressure, and ambient relative humidity on the cycle performance parameters, have been investigated. It is found that the inlet air-cooled gas turbine trigeneration cycle has a good thermal performance, with first and second law efficiencies of 91 per cent and 55 per cent, respectively, for the base case studied (having a maximum cycle temperature of 1327 °C). For a minimum process heat pressure of 4 bar, the energy and exergy efficiencies were obtained as 89 per cent and 51 per cent, respectively. Gas turbine trigeneration plants with and without inlet air cooled by the Brayton refrigeration cycle are compared with each other, and the effect of inlet air cooling on energy and exergy efficiencies is clarified. Inlet air cooling increases the energy and exergy efficiencies and decreases the electrical to thermal energy ratio significantly. Exergy analysis indicates that maximum exergy is destroyed during combustion and steam generation, which represents around 65 per cent of the total exergy destruction in the overall system. The exergy destruction in major components of trigeneration varies significantly with TIT and process heat pressure. The present analysis provides further information on the role of inlet air cooling through extracted mass rate influence on the performance of a gas turbine-based trigeneration system.

[1]  Mohand Tazerout,et al.  Thermodynamic analysis of tri-generation with absorption chilling machine , 2003 .

[2]  Gunnar Tamm,et al.  Theoretical and experimental investigation of an ammonia–water power and refrigeration thermodynamic cycle , 2004 .

[3]  G. M. Zaki,et al.  Brayton refrigeration cycle for gas turbine inlet air cooling , 2007 .

[4]  Graeme Maidment,et al.  Combined cooling heat and power in supermarkets , 2002 .

[5]  Ling Wang,et al.  Thermodynamic Study of an Indirect Fired Air Turbine Cogeneration System With Reheat , 1987 .

[6]  A. Bejan.  Fundamentals of exergy analysis, entropy generation minimization, and the generation of flow architecture , 2002 .

[7]  Abdul Khaliq,et al.  Thermodynamic Performance Assessment of Gas Turbine Trigeneration System for Combined Heat Cold and Power Production , 2008 .

[8]  T.-B. Chang.  Exergetic Efficiency Optimization for an Irreversible Carnot Heat Engine , 2007 .

[9]  Ziyang Sun,et al.  Energetic efficiency of a gas-engine-driven cooling and heating system , 2004 .

[10]  Antonio Piacentino,et al.  A VALIDATION METHODOLOGY FOR A COMBINED HEATING COOLING AND POWER (CHCP) PILOT PLANT , 2004 .

[11]  I Dincer,et al.  Energy and exergy analyses of compressor inlet air-cooled gas turbines using the Joule—Brayton refrigeration cycle , 2009 .

[12]  S. C. Kaushik,et al.  Thermodynamic performance evaluation of combustion gas turbine cogeneration system with reheat , 2004 .

[13]  Mohand Tazerout,et al.  Fuel savings and CO2 emissions for tri-generation systems , 2003 .

[14]  Yousef S.H. Najjar,et al.  Augmentation of gas turbine performance using air coolers , 2004 .

[15]  Y. H. Zurigat,et al.  Thermodynamic assessment of power requirements and impact of different gas-turbine inlet air cooling techniques at two different locations in Oman , 2005 .

[16]  R. Schneider,et al.  Trigeneration in the food industry , 2002 .

[17]  G. M. Zaki,et al.  Performance enhancement of gas turbines by inlet air‐cooling in hot and humid climates , 2006 .

[18]  Kim Choon Ng,et al.  Improved thermodynamic property fields of LiBr-H2O solution , 2000 .

[19]  David Gordon Wilson,et al.  Models for predicting the performance of Brayton-cycle engines , 1994 .

[20]  Cyrus B. Meher-Homji,et al.  Inlet Fogging of Gas Turbine Engines: Climatic Analysis of Gas Turbine Evaporative Cooling Potential of International Locations , 2006 .

[21]  Abdul Khaliq,et al.  Exergy analysis of gas turbine trigeneration system for combined production of power heat and refrigeration , 2009 .

[22]  S. C. Kaushik,et al.  Second-law based thermodynamic analysis of Brayton/Rankine combined power cycle with reheat , 2004 .

[23]  Yi Jiang,et al.  Energy utilization evaluation of CCHP systems , 2006 .

[24]  Antonio Piacentino,et al.  A methodology for sizing a trigeneration plant in mediterranean areas , 2003 .

[25]  Cha'o-Kuang Chen,et al.  Exergetic efficiency optimization for an irreversible Brayton refrigeration cycle , 2005 .

[26]  Ibrahim Dincer,et al.  Exergy Analysis of an Industrial Waste Heat Recovery Based Cogeneration Cycle for Combined Production of Power and Refrigeration , 2009 .