Simulation of forced convective heat transfer in Kelvin cells with optimized skeletons

Abstract

The optimization of pore structure for metal foam is a feasible method for reducing the pressure drop and improving the overall heat transfer performance, especially at high velocity. In this regard, the optimized Kelvin cell with elliptical skeletons with a cross-section ratio of the long axis to the short axis (b/a) of 1.0, 1.4, and 2.0 are considered to evaluate the effects of b/a on the pressure drop and the heat transfer coefficient (HTC). The results indicate that both the pressure drop and HTC decrease with an increase in b/a. However, the pressure drop reduces more significantly. For instance, as b/a increases from 1.0 to 2.0, the pressure drop and the volumetric HTC at 90 m/s decrease by 98.5% and 6.3%, respectively. Therefore, the value of the volumetric area goodness factor (which considers both the effect of heat transfer coefficient and pressure drop on the overall heat transfer performance) jv/fof the sample with b/a = 2.0 is 86.7% higher than the sample with b/a = 1.0 at 90 m/s. As the velocity increases, the effect of b/a on the overall heat transfer performance increases. Compared with the cylindrical skeleton velocity distribution and pressure drop, the elliptical skeletons lead to a more uniform velocity distribution and reduce pressure drop significantly; nevertheless, the temperature distributions barely change. Moreover, the elliptical skeleton increases the specific surface area. Therefore, the jv/fof the elliptical skeleton significantly improves. This study provides a new direction for the design of novel metal foams with excellent overall heat transfer performance for heat transfer devices.