Numerical Investigation of Heat Transfer Enhancement in Fin-Tube Heat Exchangers by Vortex Generators in Common-Flow-Up and Common-Flow-Down Configurations
S. Jayavel1 and Shaligram Tiwari2
1Department of Mechanical Engineering, Indian Institute of Information Technology, Design and Manufacturing Kancheepuram, Chennai 600 036, India.
sjv@ iiitdm.ac.in
2Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India.
shaligt@iitm.ac.in
ABSTRACT
Fin-tube heat exchangers are compact and are characterized by high heat duties per unit volume and high heat transfer coefficients. In these heat exchangers, mostly there occurs low Reynolds number gas flow on the fin-side associated with much higher thermal resistance. In order to enhance the fin-side heat transfer coefficient without much increase in pressure drop, vortex generators (VGs) are employed. The enhancement of heat transfer in presence of VGs is mainly due to high degree of mixing produced over the region adjacent to the vortex generators, resulting in increased mixing of the slower fluid in the wake region behind the tubes and further downstream. The present work carries out a three-dimensional numerical study to compare heat transfer augmentation and associated pressure drop due to VGs in common flow up and common flow down configurations mounted on flat fin surfaces which are maintained at constant temperature.
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