Heat Transfer Enhancement of Crossflow Air-to-Water Fin-and-Tube Heat Exchanger by Using Delta-Winglet Type Vortex Generators

Josip Batista, Anica Trp and Kristian Lenic
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Josip Batista: Faculty of Engineering, University of Rijeka, Vukovarska 58, 51000 Rijeka, Croatia
Anica Trp: Faculty of Engineering, University of Rijeka, Vukovarska 58, 51000 Rijeka, Croatia
Kristian Lenic: Faculty of Engineering, University of Rijeka, Vukovarska 58, 51000 Rijeka, Croatia

Energies, 2022, vol. 15, issue 6, 1-25

Abstract: The aim of this work is to numerically analyse fluid flow and heat transfer characteristics in a crossflow air-to-water fin-and-tube heat exchanger (FTHEX) by implementing two configurations of delta-winglet type vortex generators at the air side: delta-winglet upstream (DWU) and delta-winglet downstream (DWD). The vortex generators are mounted on a fin surface and deployed in a “common flow up” orientation. The effects of attack angles of 15°, 30° and 45° on air-side heat transfer and pressure drop were examined. Since the implementation of the full-size model would involve large numerical resources, the computational domain is simplified by considering a small segment in the direction of water flow. The fully developed temperature and velocity boundary conditions were set at the water inlets. To validate the defined mathematical model and numerical procedure, measurements have been performed on a plain FTHEX. The air side Reynolds number, based on hydraulic diameter, was in the range of 176 ≤ Re Dh ≤ 400 and water side Reynolds number, based on inner tube diameter, was constant Re di = 17,065. The results have shown that the highest increase in the Colburn factor j (by 11–27%) and reduction in the air-side thermal resistance fraction (from 78.2–76.9% for Re Dh = 176 to 76–72.4% for Re Dh = 400) is achieved by using the DWD configuration with attack angle 45°. In addition, the overall heat transfer coefficient is improved by up to 15.7%. The DWD configuration with the attack angle 30° provides the greatest improvement in the heat transfer to pressure loss ratio, 5.2–15.4% over the range of Re Dh studied.

Keywords: crossflow air-to-water fin-and-tube heat exchanger; conjugated heat transfer; air side vortex generators; numerical analysis (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: 2022
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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