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Technical gazette, Vol. 26 No. 6, 2019.

Original scientific paper

https://doi.org/10.17559/TV-20170422140007

Effects of Fin Spacing and Gas Radiation on Heat Transfer in Utility Boiler Economizers

Azad Hamzehpour* orcid id orcid.org/0000-0001-9434-3239 ; Department of Mechanical Engineering, Science and Research Branch, Islamic Azad University, Daneshgah Blvd, Simon Bulivar Blvd, Tehran, Iran
Cyrus Aghanajafi ; Department of Mechanical Engineering, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, No. 7, Pardis St, Molla Sadra Ave, Vanak Sq, Tehran, Iran
Hossein Shokouhmand* ; School of Mechnical Engineering, College of Engineering, University of Tehran, Jalal-e-Al-e-Ahmad Hwy, North Kargar St, Tehran, Iran
Mohammad Najafi ; Department of Mechanical Engineering, Science and Research Branch, Islamic Azad University, Daneshgah Blvd, Simon Bulivar Blvd, Tehran, Iran

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Abstract

The aim of this paper is to estimate fin spacing and gas radiation effects on heat transfer in utility boiler economizers to achieve the highest feed water temperature, and the biggest amount of heat transferred from flue gases to economizer tubes. This study is carried out for five different cases including a bare tube economizer and four finned-tube economizers with different fin spacing values. A finite volume method is employed to discretize and solve the governing equations for all cases in 3D. As a result, for verification purpose, the present numerical result is compared to the experimental outputs and it shows that the average Nusselt number difference is 15%. The finned-tube economizer with fin spacing value of 21mm absorbs the biggest amount of heat, and it has the highest outlet feed water temperature; therefore, it has the best thermal performance among the other cases. It is also concluded that radiation heat transfer mechanism has a minor effect on heat exchange in utility boiler economizers.

Keywords

fin spacing; gas radiation; heat transfer; numerical investigation; utility boiler economizer

Hrčak ID:

228526

URI

https://hrcak.srce.hr/228526

Publication date:

27.11.2019.

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