Improving heat dissipation characteristics of concurrent flow through a novel mini- and micro-channel stacked double-layer heat sink

Abstract

In the practical applications, it is important to reduce the temperature gradient and pressure drop in mini- and micro-channel heat sinks. In the present investigation, the numerical study is conducted to provide a new design of the mini- and micro-channel stacked double-layer heat sink with the pure water as the coolant. The study discusses whether the mini- and micro-channel stacked double-layer heat sink can provide a higher heat dissipation effect than the single-layer micro-channel heat sink. The three-dimensional velocity field in the channel is calculated by the pseudo-vorticity-velocity method, and the finite volume method is used to discrete the mathematical formulas. The relevant parameters and their ranges in the numerical simulation are used as follows: the inlet temperature is$T_{\mathrm{in}}$ = 34 °C; the single-layer channel’s range of Reynolds number is 500 ∼ 2000 (equivalent to the total flow 12.19 ∼ 52.05 ${cm}^3$/min), the heat fluxes imposed to bottom of the heat sink are 25, 50 and 75 W/${cm}^2$, and the ratios of flow rate for the heat sink are 0.5, 1.0, 1.3, 2.0, 2.5, and 3.0. From the numerical simulation results, it is found that when mini- and micro-channel stacked double-layer heat sink uses pure water/pure water as the coolants, the pressure drop decreases by 87.74 % at the ratio of flow rate of 3.0, and when the ratio of flow rate is 0.5, and the total flow rate is 38.77 ${cm}^3$/min, the overall heat transfer coefficient increases by 16.56 % compared with the single-layer heat sink. The figure of merit index ratio has a maximum value of 2.0795 when the total flow rate is ${\dot{Q}}_{\mathrm{uc}}+{\dot{Q}}_{\mathrm{lc}}={\dot{Q}}_{\mathrm{sl}}=$ 52.05 cm³/min and the flow rate ratio is 3.0, and a minimum value of 1.4455 can be achieved when the total flow rate is ${\dot{Q}}_{\mathrm{uc}}+{\dot{Q}}_{\mathrm{lc}}={\dot{Q}}_{\mathrm{sl}}=$ 12.19 cm³/min and the flow rate ratio is 0.5.