Abstract
Flat tubes heat exchangers are commonly used in many industrial applications as a consequence of the distinctive geometrical characteristics of the flat tube compared with round tube. This paper aims to investigate the flow and heat transfer characteristics of laminar cross-flow forced convection in compact fin-and-flat tube heat exchangers. The experiment was performed to explore the influence of the tube inclination angle on the thermal hydraulic performance of the flat tube heat exchanger. Four flat tubes arranged in two aligned rows having the same longitudinal and transverse pitches have been examined in the range of Reynolds number between 1768.27 and 2259.46. A constant heat flux of 4169.63 W/m2was applied at the inner surface of each flat tube. On the other hand, the numerical simulation is solved by ANSYS FLUENT for a two dimensional model with unstructured mesh and the results are compared against the experimental results. The numerical simulation results indicate that the average Nusselt number increased by 78.24 % for Reynolds number 1768.27. Besides that, for Reynolds number 1964.75 and 2259.46 the Nusselt numbers were increased by 75.89 % and 54.49%, respectively, compared to experimental results. Moreover, the pressure drop is increased 25 % and 83.38 % for both experimental and numerical simulation with respect to three Reynolds number. It was found that, the tube with 30° degree provides the higher heat transfer with Reynolds number 2259.46. This study could assist engineers in decisions regarding the application of compact fin-and-tube heat exchangers in the automotive field.
Highlights
Fin-and-tube heat exchangers are employed in a wide variety of engineering applications such as modern heat exchangers, automotive radiators, automotive air conditioning evaporators and condensers [1] .In automotive industries, there is a strong necessity of lighter heat exchangers due to the fact that there is direct relationship between fuel consumption and vehicle weight
Before the simulation model was performed to predict the Nusselt number and pressure drop inside the heat exchanger, the model was validated by comparing the results obtained with the experimental data
The maximum percentage errors between the simulation results and experimental data for Figs. 5 and 6 are 7.6%, and 9.6%, respectively. Both the experimental and simulation results indicate that the temperatures decrease as the Reynolds number increase. Both figures confirm that the temperature changes along the heat exchanger is moderate and definition of Raleigh number based on the average surface temperature will not make a considerable deviation
Summary
Fin-and-tube heat exchangers are employed in a wide variety of engineering applications such as modern heat exchangers, automotive radiators, automotive air conditioning evaporators and condensers [1] .In automotive industries, there is a strong necessity of lighter heat exchangers due to the fact that there is direct relationship between fuel consumption and vehicle weight. The aerodynamic and aesthetic design restrictions have led to a progressive reduction of the frontal area of the vehicle. The size and performance of compact heat exchangers have significant effect on the end product of automotive components [2, 3]. Compact heat exchangers involve in engine cooling and air conditions functions of automobiles. The design of heat exchangers affects the aerodynamics and performance of the automotive automobile. An optimized design of the heat exchangers is a key aspect to achieve these trends without losing engine cooling performance. Because of these reasons, an extensive study on the thermal and fluid dynamics of compact heat exchangers is essential
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