Heat Transfer Enhancement and Entropy Generation of Nanofluids Laminar Convection in Microchannels with Flow Control Devices

Entropy

Gongnan Xie¹  Ping Li²  Di Zhang²  Yonghui Xie³ 

[1] Department of Mechanical and Power Engineering, School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China;Key Laboratory of Thermal Fluid Science and Engineering of Ministry of Education, Xi’an Jiaotong University, Xi’an 710049, China;School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China;

关键词: nanofluids;    microchannels;    heat transfer enhancement;    entropy generation;    flow control devices;   

DOI  :  10.3390/e18040134

来源: DOAJ

【 摘 要 】

The heat transfer enhancement and entropy generation of Al2O3-water nanofluids laminar convective flow in the microchannels with flow control devices (cylinder, rectangle, protrusion, and v-groove) were investigated in this research. The effects of the geometrical structure of the microchannel, nanofluids concentration φ(0%–3%), and Reynolds number Re (50–300) were comparatively studied by means of performance parameters, as well as the limiting streamlines and temperature contours on the modified heated surfaces. The results reveal that the relative Fanning frictional factor f/f0 of the microchannel with rectangle and protrusion devices are much larger and smaller than others, respectively. As the nanofluids concentration increases, f/f0 increases accordingly. For the microchannel with rectangle ribs, there is a transition Re for obtaining the largest heat transfer. The relative Nusselt number Nu/Nu0 of the cases with larger nanofluids concentration are greater. The microchannels with cylinder and v-groove profiles have better heat transfer performance, especially at larger Re cases, while, the microchannel with the protrusion devices is better from an entropy generation minimization perspective. Furthermore, the variation of the relative entropy generation S′/S′0 are influenced by not only the change of Nu/Nu0 and f/f0, but also the physical parameters of working substances.

【 授权许可】

Unknown