Numerical simulation of convective heat transfer performance of bifurcated microchannel heat sink

doi:10.7523/j.ucas.2024.071

Abstract

Abstract:

Inspired by the natural bifurcation structure such as leaf veins， this paper uses numerical simulation to study the convective heat transfer of the basic unit of the bifurcated microchannel heat sink. On the basis of fixing the parameters of the first-stage-channel， changing the width of the second-stage-channel of the bifurcated structure， and analyzing the temperature field and flow field in the channel in detail， the pressure drop， convective heat transfer coefficient and comprehensive heat transfer evaluation coefficient from the inlet to the second-stage were obtained. The results show that the bifurcation structure can enhance the fluid disturbance， interrupt and form a new fluid boundary layer， strengthen the heat transfer and make the temperature distribution more uniform. Within 1 mm of the inlet of the second-stage-channel diameter， the inlet effect of internal flow is more influential， and the comprehensive heat transfer evaluation coefficient reaches its maximum when the ratio of hydraulic diameter after bifurcation to that before bifurcation is 0.54. When the ratio of hydraulic diameter bifurcation is 0.80， the comprehensive heat transfer evaluation coefficient reaches its maximum outside the second-stage-channel above 1 mm. The research can be used as a reference and guidance for the optimal design of bifurcated microchannel heat sinks.

Key words: microchannel heat sink, enhanced heat transfer, bifurcated structure, fractal

CLC Number:

TK124

Weixuan KE, Jianchao MU, Hao WANG, Kemeng CAI, Jie LIU. Numerical simulation of convective heat transfer performance of bifurcated microchannel heat sink[J]. Journal of University of Chinese Academy of Sciences, 2026, 43(4): 478-487.

Figures/Tables 15

Fig.1 Bifurcated structures in nature

Fig.2 3D model of bifurcated microchannel heat sink unit

Table 1 Value of the second-stage-channel width and the corresponding aspect ratio and hydraulic diameter ratio

W₂/mm	0.10	0.11	0.12	0.13	0.15	0.17	0.20	0.22	0.24	0.30
$α 2$	6.00	5.50	5.00	4.50	4.00	3.50	3.00	2.75	2.50	2.00
β	0.43	0.46	0.50	0.54	0.60	0.67	0.75	0.80	0.86	1.00

Table 1 Value of the second-stage-channel width and the corresponding aspect ratio and hydraulic diameter ratio

W₂/mm	0.10	0.11	0.12	0.13	0.15	0.17	0.20	0.22	0.24	0.30
$α 2$	6.00	5.50	5.00	4.50	4.00	3.50	3.00	2.75	2.50	2.00
β	0.43	0.46	0.50	0.54	0.60	0.67	0.75	0.80	0.86	1.00

Table 2 Material property parameters

	$ρ$ /(kg·m^-3)	$C p$ /(J·(kg·K)^-1)	$μ$ /(mPa·s)	$k$ /(W·(m·K)^-1)
水	998.2	4 128	1.003	0.6
硅	2 328.0	700	—	148.0

Table 2 Material property parameters

	$ρ$ /(kg·m^-3)	$C p$ /(J·(kg·K)^-1)	$μ$ /(mPa·s)	$k$ /(W·(m·K)^-1)
水	998.2	4 128	1.003	0.6
硅	2 328.0	700	—	148.0

Fig.3 Comparison of the numerical simulation and experimental results

Fig.4 Grid division diagram

Table 3 Grid independence validation

网格量	最小网格尺寸/mm	$h ¯$ /(W·m^-2·K^-1)	$h ¯$ 相对偏差/%	$Δ P$ /Pa	$Δ P$ 相对偏差/%
12 100 774	0.002	30 142	0.0	6 005	0.0
9 499 880	0.003	29 961	-0.6	5 992	-0.2
8 599 340	0.004	30 054	-0.3	5 787	-3.6
7 713 785	0.005	29900	-0.8	5 998	-0.1

Table 3 Grid independence validation

网格量	最小网格尺寸/mm	$h ¯$ /(W·m^-2·K^-1)	$h ¯$ 相对偏差/%	$Δ P$ /Pa	$Δ P$ 相对偏差/%
12 100 774	0.002	30 142	0.0	6 005	0.0
9 499 880	0.003	29 961	-0.6	5 992	-0.2
8 599 340	0.004	30 054	-0.3	5 787	-3.6
7 713 785	0.005	29900	-0.8	5 998	-0.1

Fig.5 Isothermal contours section at y=0 mm and y=-0.5 mm of the α2=2.75 model

Fig.6 Isothermal contours section at y=0 mm and y=-0.5 mm of the α2=4.50 model

Fig.7 Isothermal and streamline contours of different regions of the α2=2.75 model

Fig.8 Isothermal and streamline contours of different regions of the α2=4.50 model

Fig.9 Heat transfer coefficients at different positions of the second-stage-channel when uin=3 m/s， Re =1 050

Fig.10 Total pressure at different positions from inlet to outlet when uin=3 m/s， Re=1 050

Fig.11 Temperature at different positions from the entrance to the exit of the channel boundary when uin=3 m/s，Re=1 050

Fig.12 Comprehensive heat transfer coefficient at different positions of the second-stage-channel

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