Reliability of Al2O3 nanofluid concentration on the heat transfer augmentation and resizing for single and double stack microchannels
Ibrahim Elbadawy, Mohamed Fayed
Abstract
The influence of using nanofluids on heat transfer augmentation and characteristics of fluid flow in rectangular cross sectional microchannel heat sink (MCHS) is numerically investigated for single and double stack microchannels at uniform heat flux, q̏ = 100 W/cm2 and Reynolds number ranging from 200 to 1500. In this study, alumina–water (Al2O3-H2O) nanofluid with different nanoparticle volume concentrations from 1% to 5% was used as a coolant for the MCHS. The three-dimensional steady, laminar flow and heat transfer governing equations are solved by finite volume method using ANSYS-Fluent 18.2. The MCHS performance is evaluated in terms of temperature profile, heat transfer coefficient, pressure drop, pumping power and volume reduction. The results reveal that increasing the nanoparticles concentration improves the cooling process. The maximum heat transfer augmentation in the current study was achieved at the highest concentration of 5%. For example, at this concentration the temperature was reduced by 7.3% using single stack microchannel. However, 33.5% temperature reduction was achieved using double stack microchannels. Also, it results in an increase in the heat transfer coefficient by 13.12% compare to that of the pure water. On the other hand, for a single stack at nanoparticle concentration of 5%, both pressure drop and power increased by 10% and 8%, respectively. Because of the significant influence of the nanofluid on the improvement of the cooling process, an estimation of the volume reduction was made. It was found that 62.6% volume reduction for single stake at concentration 5% can be achieved.