摘要
在考虑速度滑移的前提下,对于圆管形微通道内温度边界层充分发展的恒热流量对流传热,推导了速度和温度分布表达式,并进一步得到对流传热系数和Nusselt数计算式。此外,还针对超疏水表面不同结构参数下的滞留空气层,提出了超疏水表面的有效导热模型,推导出超疏水表面不同结构参数下的热阻。最后将传热系数与超疏水表面热阻进行耦合,得出超疏水表面有效传热系数及其与超疏水表面结构参数的关系。计算结果表明:超疏水表面上流体的滑移使得管内温度更加均匀,传热系数或Nusselt数有所增加,恒热流条件下最多可以增加1.8倍;超疏水表面热阻随肋间距和肋高的增加而增大;超疏水表面的表观传热系数随肋间距或孔宽的增加而显著降低,随肋高或孔深的增加,表观传热系数也降低,其幅度与肋间距以及肋高与肋间距之比有关;各种结构参数条件下均存在表面滞留空气层的临界厚度,在此厚度以下表面有效传热系数不低于普通表面无滑移时的数值。因此,需要综合考虑超疏水表面的结构参数,包括肋高、肋间隙等,才能使超疏水表面有利于传热。
The convective heat transfer with constant heat flux condition inside a circular microchannel was investigated.The velocity and temperature profiles with a slip velocity at the surface were derived,and then the heat transfer coefficient and Nusselt number were obtained.A model was proposed for effective conduction at the super-hydrophobic surface with different structural parameters and the thermal resistance of the surface with trapped air was calculated.The effective heat transfer coefficient of super-hydrophobic surface was related to the heat transfer coefficient and surface thermal resistance.The calculation gives the following results.The slip of fluid on a super-hydrophobic surface makes the temperature profile inside the channel more uniform,so that the heat transfer coefficient or Nusselt number is increased,which may reach 2.8 times that without slip under constant heat flux condition.The thermal resistance of super-hydrophobic surface increases with trapped air volume.The effective heat transfer coefficient on super-hydrophobic surface declines seriously as the trapped air volume increases,especially as the trapped air area at the surface increases.There exists a critical thickness for the trapped air on the super-hydrophobic surface with given surface structural parameters,under which the effective heat transfer coefficient is not less than that on general surfaces without slip.Therefore,it is necessary to adopt appropriate structure for the surface,such as rib height and distance between ribs,to avoid trapping air,so that the heat transfer on the super-hydrophobic surface is enhanced.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2010年第3期594-600,共7页
CIESC Journal
基金
国家自然科学基金项目(50876015)~~
关键词
超疏水表面
滑移速度
传热系数
热阻
结构参数
super-hydrophobic surfaces
slip velocity
heat transfer coefficient
thermal resistance
structural parameters
作者简介
范新欣（1985-），女，硕士研究生。
联系人：刘天庆
