锯齿型微通道流动与传热特性数值模拟

doi:10.16085/j.issn.1000-6613.2022-2321

摘要/Abstract

摘要：

设计了一种锯齿型微通道强化对流传热，利用COMSOL软件对该微通道的流动与传热特性进行了数值模拟，研究了正反流动方向上锯齿型结构对通道内流动和传热的影响，其中雷诺数为50~700。数值结果表明，锯齿型微通道极大地强化了流体在空间上的混合以及对热边界层产生了明显扰动，显著提升了微通道内的对流传热。相对常规矩形微通道，努塞尔数（Nu）提高了102.7%。另外，研究了不同流动方向下锯齿型微通道的流动与传热特性。在雷诺数Re=700时，反向流动的Nu相比正向流动增加了20%，但压降同时增加了110%。

关键词: 锯齿型微通道, 共轭传热强化, 流体混合, 努塞尔数

Abstract:

In this study, a saw-like microchannel was proposed to enhance convective heat transfer. The fluid flow and heat transfer characteristics of this proposed microchannel were numerically investigated using COMSOL software. The effect of saw-like microchannel on fluid flow and heat transfer performance were studied in both forward and backward direction. The Reynolds number (Re) ranged from 50 to 700. The numerical results indicated that the present microchannel configuration greatly strengthened the spatial mixing of fluid and significantly disturbs the thermal boundary layer, leading to dramatic enhancement of convective heat transfer. Compared to conventional microchannel, Nusselt number (Nu) was significantly enhanced by 102.7%. Additionally, fluid flow and heat transfer characteristics of this saw-like microchannel in both forward and backward directions were investigated. At Re=700, the Nu in the backward direction was increased by 20% compared to that in forward direction. However, the pressure drop was magnified about 110%.

Key words: saw-like microchannel, enhancement of conjugate heat transfer, fluid mixing, Nusselt number

中图分类号:

刘兆轩, 张程宾, 韩群, 姜海涛, 李文明. 锯齿型微通道流动与传热特性数值模拟[J]. 化工进展, 2023, 42(11): 5622-5636.

LIU Zhaoxuan, ZHANG Chengbin, HAN Qun, JIANG Haitao, LI Wenming. Numerical simulation of fluid flow and heat transfer characteristics in a saw-like microchannel[J]. Chemical Industry and Engineering Progress, 2023, 42(11): 5622-5636.

图/表 21

图1 锯齿型微通道结构示意图

表1 锯齿型微通道结构尺寸表

参数	物理意义	尺寸/mm
L	总长度	16.00
W	总宽度	0.6400
H	总高度	0.5000
L_m	单个锯齿长度	0.4000
W_m	锯齿最大宽度	0.5400
W_fs	正向流动入口壁厚	0.0875
W_rs	反向流动入口壁厚	0.2800
W_f_l	正向流动入口宽度	0.4650
W_r_l	反向流动入口宽度	0.0800
H_b	底部厚度	0.2000
H_m	微通道高度	0.3000
d	喉道处宽度	0.0800

表2 材料热物性表

物性参数	去离子水	硅
c_p /J·kg^-1·K^-1	4184.1	700
ρ/kg·m^-3	998.21	2329
k/W·m^-1·K^-1	0.598	130
μ/μPa·s^-1	1001.6	—

图2 边界条件设置

图3 网格划分示意图

表3 网格独立性验证

序号	网格数	T_out/K	参考基准误差 /%	Δp/Pa	参考基准误差 /%
Gird 1	2455459	332.3598	0.128	3661.7063	6.066
Gird 2	4510643	332.6778	0.032	3573.3352	3.506
Gird 3	6126720	332.7453	0.011	3452.8653	0.017
Gird 4	9074234	332.7834	—	3452.3023	—

图4 数值模拟结果与实验结果对比[31]

图5 理论和模拟施加热量对比

图6 锯齿型微通道内速度云图和矢量分布

图7 反向流动速度云图和矢量分布图

图8 锯齿型微通道与矩形微通道的流动特性对比

图9 不同流动方向流场发展

图10 近壁面处的局部流场分析

图11 压降和压降比随雷诺数的变化

图12 不同流动方向下温度分布

图13 锯齿型微通道与矩形微通道传热特性对比

图14 底面平均温度对比

图15 努塞尔数比αt随雷诺数的变化

图16 Nu随雷诺数变化情况

图17 不同形状微通道散热性能对比[19,27]

图18 PEC随雷诺数变化情况

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