Flameless combustion with liquid fuel: A review focusing on fundamentals and gas turbine application

- Technical and physical challenges in liquid flameless combustion are presented.
- The research status about the different liquid fuels used for flameless combustion are summarized.
- Flameless studies related with gas turbine engines are discussed in details.
- Several research areas needed to improve the flameless combustion's application are provided.

Flameless combustion has been developed to reduce emissions while retaining thermal efficiencies in combustion systems. It is characterized with its distinguished features, such as suppressed pollutant emission, homogeneous temperature distribution, reduced noise and thermal stress for burners and less restriction on fuels (since no flame stability is required). Recent research has shown the potential of flameless combustion in the power generation industry such as gas turbines. In spite of its potential, this technology needs further research and development to improve its versatility in using liquid fuels as a source of energy. In this review, progress toward the application of the flameless technique was presented with an emphasis on gas turbines. A systematic analysis of the state-of-the-art flameless combustion and the major technical and physical challenges in operating gas turbines with liquid fuels in a flameless combustion mode was presented. Combustion characteristics of flameless combustion were explained along with a thorough review of the modelling and simulation of the liquid fuel fed flameless combustion. A special focus was given to the relevant research on the applications of flameless combustion to the inner turbine burners. The paper was concluded by highlighting the recent findings and pointing out several further research directions to improve the flameless combustion in gas turbines, including in-depth flow and combustion mechanisms, advanced modelling, developed experimental technology and comprehensive design methods aiming at gas turbine flameless combustors.