Comparison of performance for cogeneration systems using single- or twin-shaft gas turbine engines

摘要

Currently, gas turbine systems account for over 50% of the new capacity installed in the United States. Moreover, options chosen for further development seem to aim, very clearly, at the immediate higher efficiency mid-range aeroderivative market. Hence, twin-shaft engines are expected to be more widely used. Cogeneration with advanced aeroderivative engines has the prospect of attaining thermal efficiencies around 60% in the future. In this work, performance of cogeneration systems associated with twin-shaft engines is compared with those related to single-shaft engines over a wide range of loading conditions. A computer program was devised to perform the calculations. The results showed the superior performance of the twin-shaft cogeneration systems at part load. At a compressor pressure ratio rc of 8, the percentage of performance parameters relative to their values at design rc = 10 are as follows: recoverable HEAT = 13.8 and 77.4%; and overall EFFICIENCY = 45 and 93% for single- and twin-shaft cogeneration systems, respectively.