Numerical investigation of heat transfer and pressure drop characteristics in an offset strip fin heat exchanger

Bahadır Doğan,L Berrin Erbay,M Mete Ozturk

doi:10.18186/thermal.990795

Bahadır Doğan, L Berrin Erbay + Show 1 more

Open Access

https://doi.org/10.18186/thermal.990795

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Abstract

This paper presents a numerical simulation to determine the air-side heat transfer and the pressure drop characteristics of a flat tube heat exchanger with offset strip fin. The effects of the fin bending ratio such as 29%, 36%, 44%, 50%, and the fin spacing such as 2.10 mm, 2.35 mm, 2.60 mm on the performance of the heat exchanger are studied by using a commercial CFD software. The air having constant viscosity, thermal conductivity, and density enters the heat exchanger at 298 K and the wall temperature of the strip fins is considered as constant at 314 K. Variations of the heat transfer coefficient and the pressure drop in the airside are presented with respect to the frontal air velocity while Colburn j-factor and the friction factor f are presented with respect to the airside Reynolds number ranging from 200 to 1200. Finally, the thermal-hydraulic performance of all investigated cases is compared by using the volume goodness factor, j/f 1/3. The results show that the air-side heat transfer coefficient and the pressure drop increase when the frontal air velocity ascends. The air-side heat transfer coefficient decreases with the increase of fin spacing. The fin bending ratio does not have a significant effect on the pressure drop in the considered fin spacing. Both the Colburn j-factor and friction factor reduce with the increment of Reynolds number and fin spacing.

Highlights

Looking at the historical development of the heat exchanger, surface density has been increased gradually by the time and the compact heat exchangers are emerged and gain importance among the heating and cooling systems
The results show that the air-side heat transfer coefficient and the pressure drop increase when the frontal air velocity ascends
*Corresponding author. *E-mail address: bdogan@ogu.edu.tr This paper was recommended for publication in revised form by Regional Editor Liu Yang perforated fin [1, 2]. These fin types increase the heat transfer performance of the compact heat exchangers by breaking the boundary layer formed on the air-side [3, 4]

Summary

INTRODUCTION

Looking at the historical development of the heat exchanger, surface density has been increased gradually by the time and the compact heat exchangers are emerged and gain importance among the heating and cooling systems. Rahul and Kumar [29] studied numerically by using a commercial code to analyze the velocity, pressure, and temperature fields of air-cooled strip fin heat exchanger, and the results were compared with the correlations. A commercial CFD program (Ansys-Fluent) is used to determine the heat transfer and pressure drop of the OSF for various fin bending ratio and fin spacing. In the present three dimensional numerical study, due data of the [22] which is the unique study in this particular to the thickness of the aluminum flat tube, which is very topic that considers the effect of fin bending distance either thin (0.4 mm), and the heat conduction coefficient is high, from numerical and experimental aspects, as shown in the thermal resistance of the flat tube is neglected and Figure 5. The second- order discretization technique was chosen under laminar h= Q (6)

RESULTS AND DISCUSSION

CONCLUSION

CONFLICT OF INTEREST