Effect of fin spacing on turbulent heat transfer in a channel with cascaded rectangular-triangular fins

Abstract EN

Through this work, we performed a two-dimensional analysis of a constant property fluid (air) flowing into a rectangular cross section channel with staggered cascaded rectangular-triangular shaped fins (CRTFs).

The governing flow equations, i.e., continuity, momentum, turbulence, and energy equations, employed to simulate the incompressible steady fluid and heat transfer in the whole domain investigated, were solved by the finite volumes approach, in two dimensions, employing the Computational Fluid Dynamics, Commercial Software FLUENT with the low-Reynolds-numberk-ε model to describe the turbulence phenomenon.

The simulations were conducted for the channel of aspect ratio, AR = 1.32 and aeraulic diameter, Dh = 0.167 m with five different finspacing, (S = Pi/2, 3Pi/4, Pi, 5Pi/4 and 3Pi/2) and five various Reynolds number values, (Re = 10,000, 15,000, 20,000, 25,000, and 30,000) while the CRTF height-to-channel height blockage ratio, BR is set to 0.55 and kept constant.

The velocity and pressure fields, skin friction loss, and local and average Nusselt numbers were obtained at constant surface temperature condition along the upper and lower surfaces of the channel.The analysis of the numerical results proved that both the Reynolds number and the CRTF separation distance had an effect on the dynamic and thermal behavior of air in the given computational domain.

The Nusselt numbers and skin friction coefficients increase with the rise in the Reynolds number but decrease with the increase in the fin spacing.

By comparing with those implemented in practice, our numerical results are very agreeable.

This analysis can be applied in improving the thermal efficiency of solar air collectors as well as heat exchangers.