The correlation based zonal method and its application to the back pass channel of oxy/air-fired CFB boiler

New analytical methodologies for radiative heat transfer in enclosures based on matrix formalism and network analogy

“…In [129] it is made a comparison by criterion of CPU computing cost and it is demonstrated that solutions can be obtained at least 10 times faster when computing the direct exchange areas (DEA) by using correlations. A description of the heat transfer mechanism in a CFB that uses correlations, hydrodynamic parameters and the thermal load of furnace is found in [130,131].…”

Improved banded method for spectral thermal radiation in participating media with spectrally dependent wall emittance

“…This assumption was validated by operational data of the back pass channel. In fact, in the back pass channel, the gas dominates the thermal radiation, and therefore the radiation modeling can be performed by considering the effect of the gas [1]. This makes the effect of non-gray gases more evident.…”

“…Numerical modeling of thermal spectral radiation in combustion gases is difficult, as the gas absorption coefficient varies rapidly with wavenumber. The shape and strength of the absorption lines in the spectrum are strongly affected by the thermodynamic state of the gas [1,2]. Consequently, non-gray gas radiative heat transfer modeling of combustion gases is challenging.…”

“…Gray gas models, in which the changes in the absorption coefficient with wavenumber are ignored and an average value is used for the absorption coefficient in the entire spectrum, have been widely used in engineering calculations of combustion systems [3,4], owing to their simplicity and low computational cost [2]. However, several studies have demonstrated that using gray gas models may often result in significant inaccuracy [1,5].…”

“…In CFB combustors, the combustion of fuel particles takes place in a fluidized suspension of ash and other particles. CFB combustion has been widely used for power generation and has several advantages, including fuel flexibility, high combustion performance, and low NOx emissions [1]. Owing to the increasing attention given to new carbon capture and storage (CCS) technologies, cleaner and more efficient techniques, such as oxygen-fired combustion, and chemical looping combustion, have been implemented in CFB boilers.…”