The mixed convection of nanofluids in a vertical channel

Autor: Chien-Ta Lin, 林鍵達
Rok vydání: 2006
Druh dokumentu: 學位論文 ; thesis
Popis: 94
This research is to investigate mixed convection heat transfer phenomena of nanofluids in vertical channels by using numerical technique. The CFDRC software in conjunction with the self-developed adjustment subroutines for boundary conditions and for specified thermal properties is applied in this research. The mixed convection heat transfer phenomena of six different nanofluids, Water-Cu, Water-Al2O3, Water-SiO2, Water-TiO2, Engine oil-Cu, and Ethylene glycol-Cu, with various volume fractions, entrance velocities, and wall calefaction conditions are studied in this research. Moreover, the effects of the dispersion term on the heat transfer phenomena are also studied independently. It is observed that the heat transfer is enhanced the most by adding nanoparticle Cu. As Cu is the adding nanoparticle, the heat transfer of the Engine oil is enhanced the most for different basefluids. Increasing the nanoparticle volume fraction will enhance the heat transfer. Besides, it would also lengthen the hydrodynamic entry length, thin the hydrodynamic boundary layer thickness, shorten the thermal entry length, and thicken the thermal boundary layer thickness except for adding nanoparticle SiO2. The thermal entry length would be shorter and the thermal boundary would be thicker by simulating with the dispersion term than without it. The heat transfer is also more enhanced. Similar to common fluid, nanofluid’s heat transfer of mixed convection is better than that of forced convection. The effect of increasing particle volume fraction on the entrance length and Nusselt number would not be affected by temperature difference or convection type. Based on the research data and by curve fitting, the equations between Nu and Re and Pr based on various volume fractions are also obtained.
Databáze: Networked Digital Library of Theses & Dissertations
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