Zhang Junqiang, Zou Zhengping, Fu Chao
School of Energy and Power Engineering, Beihang University, Beijing 100191, China.
National Key Laboratory of Science and Technology on Aero-Engine and Aero-Thermodynamics, Beihang University, Beijing 100191, China.
Micromachines (Basel). 2023 Jul 19;14(7):1451. doi: 10.3390/mi14071451.
Continuously improving heat transfer efficiency is one of the important goals in the field of energy. Compact heat exchangers characterized by microscale flow and heat transfer have successfully provided solutions for this purpose. However, as the characteristic scale of the channels decreases, the flow and heat transfer characteristics may differ from those at the conventional scale. When considering the influence of scale effects and changes in special fluid properties, the flow and heat transfer process becomes more complex. The conclusions of the relevant studies have not been unified, and there are even disagreements on some aspects. Therefore, further research is needed to obtain a sufficient understanding of flow structure and heat transfer mechanisms in microchannels. This article systematically reviews the research about microscale flow and heat transfer, focusing on the flow and heat transfer mechanisms in microchannels, which is elaborated in the following two perspectives: one is the microscale single-phase flow and heat transfer that only considers the influence of scale effects, the other is the special heat transfer phenomena brought about by the coupling of microscale flow with special fluids (fluid with phase change (pseudophase change)). The microscale flow and heat transfer mechanisms under the influence of multiple factors, including scale effects (such as rarefaction, surface roughness, axial heat conduction, and compressibility) and special fluids, are investigated, which can meet the specific needs for the design of various microscale heat exchangers.
持续提高传热效率是能源领域的重要目标之一。以微尺度流动和传热为特征的紧凑式换热器已成功地为此提供了解决方案。然而，随着通道特征尺度的减小，流动和传热特性可能与传统尺度下的有所不同。考虑到尺度效应和特殊流体性质变化的影响，流动和传热过程变得更加复杂。相关研究的结论尚未统一，甚至在某些方面存在分歧。因此，需要进一步研究以充分了解微通道内的流动结构和传热机理。本文系统地综述了关于微尺度流动和传热的研究，重点关注微通道内的流动和传热机理，从以下两个角度进行阐述：一是仅考虑尺度效应影响的微尺度单相流动和传热，二是微尺度流动与特殊流体（有相变（假相变）流体）耦合所带来的特殊传热现象。研究了包括尺度效应（如稀薄效应、表面粗糙度、轴向热传导和可压缩性）和特殊流体等多种因素影响下的微尺度流动和传热机理，这能够满足各种微尺度换热器设计的特定需求。
