In the paper, a computational investigation of compact heat exchangers that are primarily used in dissipating heat generated by electronic components is performed for three-dimensional fluid flow and turbulent forced convective heat transfer from an array of elliptical pin fins. Aluminum was considered to be the material of pin fins. In order to assess the effect of major and minor axis of elliptical shape pin fins on the pressure drop and heat transfer capabilities, two different types of elliptical pin cross-sections of constant surface area, namely, ellipse-1.3 and ellipse- 1.4 were computationally investigated. Incompressible air as the working fluid is modeled using the Reynolds-Averaged Navier-Stokes equations. RNG k- turbulence model is used to account for the effect of turbulence. Temperature field inside the fins is obtained by solving Fourier’s conduction equation. The conjugate differential equations are solved simultaneously for both solid and gas phases by the finite volume method using the SIMPLE algorithm. Pressure, temperature and velocity profiles at different locations within the computational domain are considered for different Reynolds number. The heat transfer and pressure drop characteristics are assessed in the computational domain. It is seen that heat transfer and pressure drop characteristics change with changing shape of elliptical fins by varying the major and minor axis. The results show that the overall performance of ellipse 1.4 pin fins is better than that of ellipse 1.3 pin fins.

Fins are used to enhance convective heat transfer in a wide range of engineering applications. Staggered finned ducts are one of the widely used passive methods for the enhancement of heat transfer and are commonly encountered in the compact heat exchangers, resulting in a reduction in the size of heat exchanger. Generally, attached fins in a channel play the role of extension of the heat transfer area, while they also lead to a pressure loss. Many experimental, analytical and numerical procedures have been proposed in the literature for the enhancement of performance of pin fin heat exchanger. Kays (1955) performed an extensive study of compact heat exchanger and derived several correlations for the heat exchanger’s thermal performance and flow behavior. Dewan et al. (2010) presented the effect of fin spacing and material on the performance of a heat sink with circular pin fins. A numerical study was done by Rao et al. (2013) on elliptical pin fin heat sink; minor axis was taken as parameter and simulated at various wind speeds. They found that 2 mm minor axis elliptical pin fin performed better compared to 1.5 mm and 2.5 mm elliptical pin fin at all wind speeds. Sahiti et al. (2006) showed that the best fin geometry from the overall performance point of view is the straight elliptical pin fin under the fully developed laminar flow conditions. Li et al. (1998) observed heat transfer and pressure drop characteristics of elliptical pin fins in a rectangular channel. They measured higher heat transfer coefficients for elliptical fins than those measured by other workers for circular pin fins. Furthermore, they reported a lower pressure drop for elliptical pins in the range of 44-58%. Based on the literature survey, it can be concluded that a single comparative study dealing with different shapes of elliptical pin fin cross-section with a detailed investigation under turbulent flow conditions has not been reported in the literature. The heat transfer and pressure drop characteristics can change significantly with the change in ellipse’s axis.

Mechanical Engineering Journal, Major and minor axis, Elliptical, Performance, Pin fin, Pressure Drop Characteristics, Elliptical Shape Pin Fins, HeatTransfer.