Numerical investigation on fluid flow and convective heat transfer in a microchannel heat sink with fan-shaped cavities and ribs

Abstract

In the present study, a detailed numerical simulations of liquid flow in microchannel heat sink with four different geometry of ribs: rectangular (RR), backward triangular (BTR), forward triangular (FTR) and diamond (DR) arranged symmetrically inside reentrant fan shaped cavities (FC) on side walls has been conducted and compared with smooth channel (SC) to acquire fluid flow and heat transfer characteristics between Reynolds numbers of 136−588. The local pressure, temperature and heat transfer coefficients were determined to understand the convective heat transfer regimes and to analyze local flow behavior. The three-dimensional conjugate heat transfer model, investigation is done extensively to identify the influence of geometrical parameters towards augmenting thermal performance with parametric optimization. Evolved governing equations are solved by using SIMPLEC algorithm. Attempt has been made to improve heat extraction ability with reasonable pressure drop by replacing the existing simple design of microsink. It is observed that Nusselt number and friction factor are in good agreement with previous experimental data. Based on detailed parametric study, it was found that FC-RR is good in achieving maximum Nusselt number, but due to higher pressure drop penalty giving lower performance. Out of four proposed, FC-DR is conferring upstanding balance between heat transfer, pressure drop and giving the best thermal performance of 1.97 at Re = 391.47.

Parametric study of heat transfer performance including entropy generation of microchannel heat sink with fan cavity and different rib structure

“…3(a)–(h). The geometrical parameters are selected based on the previous studies done in Subrahmanyam et al 18 The structural parameters considered are relative width of cavity α ( = W fc /W c ), relative length of cavity β ( = L fc /L ), relative width of rib γ (= W r /W c ), relative pitch λ ( = B/L ), variation with influence of k sf = 247.07, 395.65, and 669.44 on M and corresponding Nu are reported together. The parametric study reveals that out of three materials selected, silicon is most promising in axial conduction perspective in obeying M < 0.01.…”

“…In our previous work, 18 conjugate heat transfer analysis was conducted on a fan-shaped cavity (F) with four different model ribs placed symmetrically; firstly investigation is done numerically based on TP and parametric optimization. An optimal design is merely one that meets all the specifications.…”

“…TP of the heat sink is also represented with total thermal resistance and is defined as Bejan 12,13 proposed an equation for EG due to pressure and heat transfer. This method was discussed previously by many authors 14,15,18 for various configurations. The temperature gradient and pressure drop in terms of EG rate can be expressed as And Total EG can be represented as where m is the mass flow rate.…”

“…Bejan 12,13 proposed an equation for EG due to pressure and heat transfer. This method was discussed previously by many authors 14,15,18 for various configurations. The temperature gradient and pressure drop in terms of EG rate can be expressed as…”

“…Tiwari et al observed that two key factors that can influence axial conduction number (M) are wall to fluid thermal conductivity ratio ( k sf ) and Reynolds number. Bala Subrahmanyam et al 18 investigated numerically on fan-shaped cavities and ribs. Out of four different rib structures considered, diamond rib geometry manifested for lower pressure drop that leads to achieve maximum TP of 1.97.…”