Numerical simulation of turbulent heat transfer in boiler with supercritical fluid and asymmetric thermal conditions

Document Type : Original Article

Author

• saied moghaddam

Department of Food Technology, College of Aburaihan, University of Tehran, Tehran, Iran

10.22067/jacsm.2024.81867.1179

Abstract

Heat transfer in boiler with supercritical fluid is asymmetrical. Also, in this type of boilers, pipes are installed both horizontally and inclined. But usually in the previous works, heat transfer is considered symmetrically or the pipes are horizontal or vertical. Therefore, in the present paper, heat transfer in a boiler tube with supercritical fluid in which there are both horizontal and inclined parts is studied and analyzed. The heat flux of the pipe is considered asymmetric. Numerical simulation has been done using Fluent software. Also, the REFPROP database has been used to apply the supercritical fluid properties of water. In order to model the turbulence, the RNG k-ε model based on Reynolds-averaged Navier–Stokes has been used. The results show that the highest and lowest internal tube temperature reach near the pseudocritical temperature range (380 Celsius) at a height of 10 m and 15.5 m, respectively. The highest temperature of the tube wall changes from the beginning to the end of the tube between 603 oC and 666 oC.Also, the Nusselt number increases with the increase of the tube height and its value increases significantly near the pseudocritical temperature. In this range, the value of the Nusselt number reaches 6800, which is 3.6 times its value at the entrance of the tube.

Keywords

• Supercritical boiler
• Pseudocritical point
• numerical solution
• Asymmetric thermal flux
• Thermophysical properties

Main Subjects

• Heat transfer

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