Numerical Study of the Effects of Structural and Functional Parameters on Unmixed Combustion of Natural Gas in Three Radiant Tubes with Different Geometries

Document Type : Original Article

Authors

• Mahdi Niknam-Azodi ¹
• Mohammad Moghiman ²

¹ Department of mechanical engineering, Ferdowsi University of Mashhad, Iran

² Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

10.22067/jacsm.2022.75343.1099

Abstract

In the present study, with the aid of computational fluid dynamics tools three different radiant tubes including straight, u-shape and w-shape were compared. After designing the geometry, the grids generated for geometries in Gambit software. Grid independence was also performed for the W-shaped geometry, which was the most complex geometry. Firstly, the results showed that the amount of nitrogen oxide emission in the U-shaped radiant tube is the highest compared to direct and W-shaped radiant tubes and the lowest was in the W-shaped type. W-shaped radiant tube had the highest efficiency (55.3%) among all radiant tubes. Besides, the ratio of radiant heat transfer from the tube wall surface to the total heat transfer from it in all three types of radiant tubes was high and more than 90%. By moving away from the wall of the radiant tube in all tubes, the amount of radiation per unit area decreases. Furthermore, the highest amount of radiation intensity was devoted to the W-shaped tube, then the U-shaped tube, and finally the lowest amount was related to the direct tube.

Keywords

• Combustion
• Radiant tube
• Pollutants
• Surface temperature

Main Subjects

• Combustion

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References

1. Wuenning, J., "Industrial Gases/Combustion-Self-Regenerative Burner for Single-Ended, P and Double-P Radiant Tubes-A New Type of Regenerative Burner Has Been Designed for Radiant-Tube Heating", This article, Industrial Heating, 74, No. 6, Pp. 47-50, (2007).
2. Wunning, J., "Retrofitting Radiant Tube-Heated Furnaces", Industrial Heating, 70, No. 6, Pp. 41-43, (2003).
3. Liu, X., Tian, Y., Yu, Y., Wen, Z., Zhang, D., Li, Z., and Feng, X. J. F., "Experimental Studies on the Heating Performance and Emission Characteristics of a W-Shaped Regenerative Radiant Tube Burner", Fuel, 135, Pp. 262-268, (2014).
4. Zhong, G., Wang, D., and Wu, D. J. E. P., "Application of Double-Regenerative Radiant Tube Technology on Roller Hearth Normalizing Furnace", Energy Procedia, 66, Pp. 201-204, (2015).
5. Wang, Y., Zhang, J. Li, L., Ling, H., and Li, Y. J. J., "Numerical Simulation of the Thermal Process in a W-Shape Radiant Tube Burner", The Minerals, Metals & Materials Society, Vol. 66, No. 7, Pp. 1253-1264, (2014).
6. Xu, Q., and Feng, J. J. A. T. E., "Analysis of Nozzle Designs on Zoned and Staged Double P-Type Gas-Fired Radiant Tube", Applied Thermal Engineering, 114, Pp. 44-50, (2017).
7. Scribano, G., Solero, G., Coghe, A. J. E. T., and Science, F., "Pollutant Emissions Reduction and Performance Optimization of an Industrial Radiant Tube Burner", Experimental Thermal and Fluid Science, 30, No. 7, Pp. 605-612, (2006).
8. Ahanj, M. D., Rahimi, M., Alsairafi, A. A., "CFD Modeling of a Radiant Tube Heater", 39, No. 3, Pp. 432-438, (2012).
9. Chuenchit, C., Jugjai, S. J. J. o. R., and Engineering, A. i. M., "Effect of Tube Length on Combustion Characteristics of a Self-Aspirating Radiant Tube Burner (SRTB)", Journal of Research and Applications in Mechanical Engineering, 1, No. 2, Pp. 19-23, (2012).
10. Niederer, M., Steinböck, A., Strommer, S., and Kugi, A., "Control of Radiant Tubes in an Indirect-Fired Strip Annealing Furnace for Improved Efficiency", Proceedings of European Control Conference ECC, IEEE, 4106-4111, 2013.
11. ANSYS Fluent Theory Guide 15.0, Inc, Canonsburg, PA, (2013).
12. Çengel, Y. A., and Boles, M. A., "Thermodynamics: An Engineering Approach",-PDF: McGraw-Hill, (2008).