Gas Turbine Power System Development for High Efficiency and Low Carbon Emission

A gas turbine is a major combustion engine for aerospace, aeronautical, and power engineering. The increasing environmental concerns require the researchers to work for improving thermal efficiency and reducing the carbon emission in gas turbine operations. In this talk, the liquefied natural gas (LNG) is firstly introduced for applying in the gas turbine power generation system. The cryogenic clean fuel removes the harmful emissions including nitrogen oxide, sulfur oxide, and particulate matters; and it is also convenient to transport and store. However, LNG should be regasified before the natural gas powers the gas turbine. We have proposed to reuse the cold energy from LNG regasification and the low-grade waste heat from the gas turbine exhaust gases to generate the power and improve the overall thermal efficiency of the combined system. The featured thermoacoustic Stirling engine is self-designed with a lower requirement for the sealing due to having no moving pistons. The patented system from the hot waste heat and cold energy can improve the overall efficiency above 10%.

Secondly, the talk shares the studies to use zero-carbon fuel, ammonia, to replace the hydrocarbon fuels in the gas turbine power systems for decarbonization. The relatively slow reaction kinetics and nitrogen oxide emission requires us to apply partial ammonia cracking for a solution to promote reactivity and ignition energy migration from the pure ammonia combustion. The applications of ammonia for power generation, the partial ammonia cracking process, and single-cycle and cogeneration gas turbine system are investigated. Parameter studies are performed to assess the gas turbine performance in the application scale with the various fuel types. It is found that the ammonia-fuelled gas turbine with a relatively narrow load operating range can be enlarged though the compression ratio increase, combustion stability enhancement, and ammonia fuel decomposing. By taking account of fuel interchangeability, components of cracker and turbine, and system safety, the feasible operating envelopes of the gas turbine, the partially cracking ammonia-fuelled gas turbine has the thermal efficiency at over 40% for single-cycle system, and reach 80% for the combined cycle system. Additionally, the kinetic modelling and emission characteristics of multi-staged partially cracked ammonia/ammonia-fuelled gas turbine combustors are also discussed. The multistage combustion configurations are discussed on both combustion stability and emission control on the parameters of ammonia substitution rate, local equivalence ratio, and ammonia cracking ratio. Most recent results uncover that the novel ammonia-based intake cooling can enable a more compact gas turbine configuration by integrating inlet-air cooling with fuel supply through the validated high-fidelity simulations for a high-subsonic compressor by achieves higher loss reduction, yielding 11.0% and 6.1% lower entropy generation in rotor and stator, to enhance gas turbine performance. Finally, the talk briefly overviews the related studies on jet engine development for propulsion, electronic cooling for aviation thermal management, and Marangoni flow testing potentials in the space exploration.

Prof. Fei Duan joined the School of Mechanical and Aerospace Engineering at Nanyang Technological University (NTU), Singapore, in 2008 and was granted tenure in early 2014. He received his Ph.D. from the University of Toronto, Canada, in 2005, and has also worked as a visiting scientist at the Institute of Fluid Mechanics at Friedrich-Alexander University Erlangen–Nuremberg, Germany. Prof. Duan’s research focuses on Marangoni flow, droplet wetting and evaporation dynamics, advanced thermal management, and efficient gas turbine power systems with decarbonization applications. His work bridges fundamental fluid mechanics with energy and thermal engineering innovations. At NTU, Prof. Duan has secured approximately SGD 30 million in research funding as a principal investigator from government agencies and industry partners. He has supervised and mentored a substantial number of researchers, including over 28 postdoctoral fellows and research associates, 20 Ph.D. students, and 14 Master’s students. Prof. Duan is a prolific scholar, having published over 210 peer-reviewed journal papers, 7 book chapters, and delivered more than 150 conference presentations, including 22 plenary and keynote lectures. He currently serves as Executive Editor and Subject Editor for Applied Thermal Engineering (Elsevier), is on the Editorial Board of Scientific Reports (Nature Portfolio) and Frontiers in Heat and Mass Transfer, and serves as Editor-at-Large for Droplet (Wiley).