Improved Gas Turbine Efficiency Through Alternative Regenerator Configuration

Abstract

An alternative configuration for a regenerative gas turbine engine cycle is presented that yields higher cycle efficiencies than either simple or conventional regenerative cycles operating under the same conditions. The essence of the scheme is to preheat compressor discharge air with high temperature combustion gases before the latter are fully expanded across the turbine. The efficiency is improved because air enters the combustor at a higher temperature, and hence heat addition in the combustor occurs at a higher average temperature. The heat exchanger operating conditions are more demanding than for a conventional regeneration configuration, but well within the capability of modern heat exchangers. Models of cycle performance exhibit several percentage points of improvement relative to either simple cycles or conventional regeneration schemes. The peak efficiencies of the alternative regeneration configuration occur at optimum pressure ratios that are significantly lower than those required for the simple cycle. For example, at a turbine inlet temperature of 1300°C (2370°F), the alternative regeneration scheme results in cycle efficiencies of 50% for overall pressure ratios of 22, whereas simple cycles operating at the same temperature would yield efficiencies of only 43.8% at optimum pressure ratios of 50, which are not feasible with current compressor designs. Model calculations for a wide range of parameters are presented, as are comparisons with simple and conventional regeneration cycles.

An insight into some innovative cycles for aircraft propulsion

“…This increase of fuel flow is compensated by an energy transfer from the exit of the LPT to the entrance of the combustor, the regenerative heat exchanger (RHE); the mechanical energy available at the exit of the LPT decreases smoothly producing an increase of thermal efficiency. It is a typical application in sea and terrestrial power generation [27][28][29][30][31], and in other special applications [32,33]. Some works can be found on the IRC application to aero-engines, especially in international symposia, including the development of heat exchangers for aero-engine applications [34,35].…”

Effect of Compression Ratio on the Performance of Different Strategies for the Gas Turbine

“…When the compression ratio increased from 3 to 30 in the strategies with regenerative, the exhaust temperature increased by approximately 120 to 300K, owing to more heat being recovered from the exhaust gases in the regenerative heat exchanger at a low compression ratio (Dellenback, 2002;Harvey & Kane, 1997). When the compression ratio increased from 3 to 30 for other strategies, the exhaust temperature decreased by approximately 210 to 390K.…”

“…In the regenerative strategy, thermal efficiency started to increase with the compression ratio after it had reached the value of 15. Thermal efficiency increased as there was a reduction in the losses due to the heat recovered from the flue gases (Dellenback, 2002). The regenerative model, when applied to reduce the exhaust temperature, proved to be inefficient after the compression ratio reached 15 (Elmegaard & Qvale, 2004;Ibrahim et al, 2011b;Rahman et al, 2010).…”

Optimum Performance Enhancing Strategies of the Gas Turbine Based on the Effective Temperatures

“…Utilization of ceramics material in blades manufacturing and difficult cooling ways in small GT plants are in practice. The huge power generation from the plants is only because of the high turbine inlet temperatures [15]. The thermodynamic model has been suggested by Kurt et al [16], the model measured the performance of the ideal open GT cycle.…”