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Showing 2 results for Nanofluid Subcooled Boiling
Hasan Alimoradi, Mehrzad Shams, Ziba Valizadeh,
Volume 16, Issue 12 (2-2017)
Abstract
In this research, subcooled flow boiling of water and water-based nanofluid in the different channels cross sections with the same hydraulic diameter is simulated. The subcooled flow boiling of water in the channels is studied by Euler – Euler model. The results of this part was matched with the experimental data very well. To study the effects of nanoparticles in the subcooled boiling flow, copper oxide nanoparticles with 40 nm in diameter were injected at the inlet to the flow. The nanofluid subcooled boiling is simulated by considering three phases, liquid, vapor and nanoparticles. The water and vapor interaction is simulated by Euler-Euler approach; and the motion of nanoparticles in the continuous fluid is modeled by Euler – Lagrange model. Water, vapor and nanoparticles were considered continuous fluid, dispersed fluid and dispersed solid, respectively. After model validation, boiling of nanofluids was modeling in different channels. Volume fraction and temperature variations is obtained along the channels. The results showed that, at low concentrations of nanoparticles (0.001 kg/s) rectangular channels and at higher concentrations (0.005 kg/s) square channels have the greatest changes in vapor volume fraction compared to pure water boiling.
H. Alimoradi, M. Shams,
Volume 19, Issue 7 (7-2019)
Abstract
In this research, a numerical scheme for subcooled flow boiling with water based fluid in a channel with a hot spot was developed. The effect of nanoparticles was studied in the subcooled flow boiling. Alumina nanoparticles were used for the protection of nanofluid. The properties of nanofluid are assumed to be temperature independent. The mixture of nanofluid is studied by using Eluer–Eluer approach. In addition to considering the variable properties of temperature in this study, a model for the density of the nucleation site was used, which is the surface roughness and sedimentation rate of the nanoparticles. After verifying the model, the nanofluid boiling was modeled, using 4 roughnesses of 25, 50, 75, and 100 nm. Changes of bubble dynamics parameters were investigated in different heat fluxes and roughnesses. According to the results, it was found that with increasing surface roughness, the surface temperature drop and the density of the nucleation site density increased. Also, bubble departure diameter is increased and bubble detachment frequency is decreased by increasing surface roughness. Moreover, the results shows that bubble detachment diameter is increased by increasing the heat flux and bubble detachment waiting time.
