Abstract
The experimental study on the boiling heat transfer performance and visualization of Al2O3-H2O, SiO2-H2O and Al2O3-SiO2-H2O nanofluids with 0.01% mass concentration were carried out. Alumina and silica nanoparticles with average particle diameters of 30 nm and 50 nm were selected. Al2O3-SiO2-H2O was the mixed aqueous nanofluids with a mass ratio of Al2O3 to SiO2 of 1: 1. The results show that the effect of particle size on the boiling heat transfer performance is small. For nanofluids with a particle size of 30 nm, the boiling heat transfer performance of Al2O3-H2O nanofluids is better than that of Al2O3-SiO2-H2O and SiO2-H2O nanofluids under the working pressure of 101 kPa. The critical heat fluxes increased by 7.9% and 22.1% respectively, and the maximum heat transfer coefficients increased by 18.3% and 32.6% respectively. The critical heat flux and the maximum heat transfer coefficient are 162.1 W/cm2 and 7.01W/(m2·K). The working pressure has an important effect on the boiling heat transfer performance of nanofluids. Compared with the boiling heat transfer performance under high pressure conditions, the boiling heat transfer performance of nanofluids is better under low pressure.
Highlights
Boiling heat transfer is widely adopted in the power generation, metallurgy, refrigeration and other fields due to its distinct advantages such as small temperature difference and large heat flux density.[1]
SiO2-H2O nanofluids and Al2O3-SiO2-H2O nanofluids, the critical heat flux of Al2O3-H2O nanofluids increased by 41.3%, 21.7%, 6.7% respectively; As Figure 2(b) is shown that the critical heat flux of Al2O3-H2O nanofluids with the particle size 50nm reached 162.1W/cm[2], compared with pure water, SiO2-H2O nanofluids and Al2O3-SiO2-H2O nanofluids increased by 41.9%, 22.1%, 7.9% respectively
The comparative study and visualization of the nanofluids boiling heat transfer prepared by mixing the water-based Al2O3, SiO2 and the mixed aqueous nanofluids with a mass ratio of Al2O3 to SiO2 of 1: 1 were carried out, and the factors and mechanism of the boiling heat transfer of the nanofluids were further analyzed, the conclusions are draw as follows: (1) The boiling heat transfer coefficient and the critical heat flux of the nanofluids are related to the particle size of the added nanoparticles
Summary
Boiling heat transfer is widely adopted in the power generation, metallurgy, refrigeration and other fields due to its distinct advantages such as small temperature difference and large heat flux density.[1]. At the temperature of 30nm, the heat transfer coefficient of Al2O3 nanofluids is higher than that of TiO2 nanofluids. Saad Soltani[6] studied the boiling heat transfer characteristics of water-based SiO2 and Al2O3 nanofluids. The results show that the boiling heat transfer coefficient of silica nanofluids is smaller than that of alumina for the same concentration of two nanofluids. Hsieh et al.[7] took experiment study on the heat transfer enhancement of seven different types of nanofluids with low concentration. Sulaiman et al.[8] took experimental study on the boiling heat transfer characteristics of saturated water-based nanofluids, the effects of the parameters such as the kinds (TiO2, Al2O3, and SiO2), mass concentrations (0.04, 0.4 and 1kg/m3) and dispersion conditions of the nanoparticles on the boiling
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