Performance optimization and comparative analysis of a DME-fueled chemically recuperated gas turbine

Chemically recuperated gas turbines (CRGT) utilize exhaust waste heat to reform fuel into hydrogen-rich syngas, thereby increasing the fuel heating value and overall system efficiency. Dimethyl ether (DME), a liquid biofuel, offers advantages in storage, transportation, and low-carbon emissions. This study systematically compares the reforming characteristics and performance of DME and methane in CRGT using thermodynamic modeling, Gibbs free energy minimization, and exergy analysis. Results show that DME achieves substantially higher conversion at a lower temperature than methane. When integrated with a new generation high-pressure gas turbine, the DME-based system reaches a thermal efficiency of 63.7%, which is 2.4% higher than that of the methane system, although the methane system exhibits a 5.4% higher specific power output. At a steam-to-carbon molar ratio of 7, the mass ratio of hydrogen to carbon monoxide in DME reformate rises to 0.87, leading to a higher fuel calorific value than methane. Exergy analysis indicates that the DME system reduces exergy destruction in the combustion chamber, stack, and evaporator by 2.6%, 2.2%, and 0.6%, respectively, due to enriched hydrogen content; however, reformer loss increases by 3.1%. This study provides a quantitative basis for fuel selection and parameter optimization in CRGT systems.