Thermal Performance Enhancement of Cylindrical Heat Sinks, Numerical Simulation, and Predictive Model

Abstract

The present numerical study uses finite volume formulation to investigate the thermal performance of cylindrical heat sinks with different minichannel profiles and working fluids, including nanofluid and pure water. The numerical simulations are carried out in the laminar flow regime. The considered minichannel profiles include straight, converging-diverging, zigzag, and wavy. First, the straight design and the nonstraight ones with equal amplitudes were compared based on their thermal performance, and it was observed that the wavy minichannel has an edge over the other profiles in the studied range of Reynolds numbers. Then, the wavy design was chosen and further investigated by changing the amplitude of the walls’ waveform for both working fluids. It was found that larger wave amplitudes raise the pressure drop and the heat transfer coefficient; however, the thermal performance parameter, which compares the relative importance of these two parameters, still follows an increasing trend. For the wavy minichannel heat sink, the thermal performance factor can increase up to 17% when the waviness is increased from 0.25 to 0.75 mm. Finally, after fitting the obtained numerical data, novel predictive correlations are derived based on different thermal and hydrodynamic parameters of the wavy heat sinks. This is achieved by the optimization of independent variables using a genetic algorithm.