Study on Flow and Heat Transfer Characteristics of 25 kW Flameless Combustion in a Cylindrical Heat Exchanger for a Reforming Processor

Ruiqi Zhu and Donghoon Shin ()
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Ruiqi Zhu: Department of Mechanical Engineering, Kookmin University, Seoul 02707, Republic of Korea
Donghoon Shin: School of Mechanical Engineering, Kookmin University, Seoul 02707, Republic of Korea

Energies, 2023, vol. 16, issue 20, 1-20

Abstract: Flameless combustion has advantages such as low pollution and uniform temperature in the combustion chamber, making it an excellent option for heat exchangers. Previous studies have focused solely on the flameless combustion phenomenon, without considering its interaction with the target being heated. In this study, we conducted experimental and computational fluid analyses on a cylindrical reformer for reverse air injection flameless combustion. Typically, small-scale reformers of 10 kW or less are coaxial triple-tube cylindrical reformers. In contrast, multitubular reformers are used for larger-scale applications, since the heat transfer rate in single-burner cylindrical reformers decreases sharply as the scale increases. Flameless combustion, with high heat transfer efficiency, helps overcome the limitation of premixed burner. Compared with conventional premixed burners, flameless burner decreases the combustion gas outlet temperature by 30% at 25 kW while reducing energy consumption by 24% (owing to the high heat transfer rate) for a given cooling fluid outlet temperature. Furthermore, it is shown that introducing a ring at the combustion chamber exit can enhance combustion gas recirculation. The experimental result was confirmed through computational fluid analysis. It is concluded that for reverse air injection flameless combustion, the combustion gas recirculation rate in the combustion chamber is strongly related to the heat transfer.

Keywords: flameless combustion; reverse air injection; cylindrical heat exchanger; heat transfer efficiency; computational fluid dynamics; hydrogen reformer (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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