Thermal internal resistance minimisation in microchannel heat sink with perforated micro fins geometry

Abstract

This study presents a 3-D numerical analysis of complex heat exchanger systems featuring innovative fin geometries. These geometries are created by modeling and placing micro fins with perforated square, circular, and rectangular designs on the heat sink. The objective of the study is to minimise thermal resistance in a hybrid heat exchanger featuring various fin architectures. The hydraulic diameter ranges from 0.036 to 0.047 mm, with fin dimensions of 0.04 mm in height and length, and 0.02 mm in width. The fins are designed with square perforations of 0.01 mm, circular perforations with a diameter of 0.015 mm, and rectangular perforations measuring 0.04, 0.012, and 0.006 mm. A high-density heat flux q″ is applied to the bottom wall, and fluid with a Reynolds number ranging from 400 to 500 is used to dissipate the heat in the cooling channel. The finite volume method and computational fluid dynamics code are employed to discretise and solve for thermal and fluid flow solutions. The impact of Reynolds number on minimised temperature and thermal resistance is analysed for void fraction ratio (VFR) of 0.25, 0.44, and 0.18.The numerical analysis reveals that the hybrid microchannel, featuring double square, circular, and rectangular perforations, demonstrates a reduction in resistance by 15 %, 21 %, and 19 %, respectively, when the coolant Reynolds number is increased by 20 %. Notably, the heat sink with square perforations exhibits the most substantial decrease in resistance, followed by circular and rectangular perforations. The numerical code is validated with what is available in the existing literature.