Thermodynamic Analysis of Innovative Micro Gas Turbine Cycles

Abstract

The growing global energy demand has been faced with increasing concerns about climate change over recent decades. In order to cover the additional demand and to mitigate CO2 emissions, one option is to utilize renewable energies such as solar and wind power. These energy sources are, however, intermittent by nature. Therefore, it is inevitable that a quick balancing and back-up power should be available to maintain grid stability at a certain level. Gas turbine (GT) technology could certainly be one alternative for back-up/balancing power and could be utilized to complement renewable energy in the energy market. However, the GT industry needs to consider innovative cycle configurations to attain higher system performance and lower emissions and to cope with renewable powers. In this regard, the humid air turbine (HAT) cycle and the exhaust gas recirculation (EGR) cycle are amongst the promising GT cycles. In the current study a micro gas turbine (MGT), a Turbec T100, has been selected as the base case for further investigation. A thermodynamic model for the base case has been developed in IPSEpro software and validated using experimental data obtained from an existing test facility in Stavanger, Norway. Based on this validated model, system performance calculations for other alternative cycles, i.e. EGR and HAT cycles, have been carried out. Results confirm that the performance improvement potential is significant for the HAT cycle with only minor modifications to the baseline MGT cycle. The EGR cycle, with a maximum attainable recirculation ratio of 50%, shows a slightly lower level of performance compared to the base case. However, its potential for future CO2 capture is greater compared to the base case and the HAT cycle. The overall cycle efficiencies for the base case, the HAT, and the EGR cycles at full load operation, i.e. 100kW power, are 31.1%, 32.8%, and 30.4%, respectively.

Thermodynamic Analysis and Process System Comparison of the Exhaust Gas Recirculated, Steam Injected and Humidified Micro Gas Turbine

“…Most of the literature pertains to commercial combined cycle systems with an exhaust gas that already has a higher CO2 content than in the micro gas turbine. For MGT with EGR, the literature reports only 40% and 50% EGR ratios [17,18]. Further, they have compared the EGR and HAT cycle and studied the effect of ambient temperature on the system performance.…”

Optimisation of stress distribution in a highly loaded radial-axial gas microturbine using FEM

“…Therefore, during the development of the numerical model (and thus during the development of the optimisation algorithm), the hole was left intact. Very often, in radial-flow and axial-flow microturbines, the diameter of the shaft is quite small [33,34]. In fact, the turbine disc is mounted at the end of the assembly process.…”

Benchmarking of a micro gas turbine model integrated with post-combustion CO 2 capture

“…Due to the low CO 2 concentration, and thus partial pressure in the exhaust gas, its integration with a post-combustion carbon capture plant introduces a major efficiency penalty [12][13][14]. Various innovations have been proposed, with modifications to the configuration of the basic gas turbine cycle [15,16]; these include activities aimed at efficiency enhancements, such as steam injection and humid air turbine cycles (HAT) [17][18][19], and those increasing the CO 2 content of the exhaust gas, such as through adaptations like exhaust gas recirculation (EGR) [20]. This study is dedicated to the latter option as one of the best novel solutions under discussion.…”

“…With EGR in place, the efficiency of the capture process for large-scale GTs could be further improved [34][35][36][37]. The effect of the EGR ratio (varying from 40 to 55%) on the system performance and degree of CO 2 enhancement, as well as the effects of ambient conditions, are also reported in the literature, explored through the use of various process modelling tools [17,34,38,39].…”