A Novel Numerical Method for Simulating Boiling Heat Transfer of Nanofluids

In this paper,a new approach called the Eulerian species method was proposed for simulating the convective and/or boiling heat transfer of nanofluids.The movement of nanoparticles in nanofluids is tracked by the species transport equation,and the boiling process of nanofluids is computed by the Eulerian multiphase method coupled with the RPI boiling model.The validity of the species transport equation for simulating nanoparticles movement was verified by conducting a simulation of nanofluids convective heat transfer.Simulation results of boiling heat transfer of nanofluids were obtained by using the commercial CFD software ANSYS Fluent and compared with experimental data and results from another numerical method(Eulerian three-phase model).Good agreement with experimental data was achieved,and it was proved the Eulerian species method is better than the Eulerian three-phase model since it can give better simulation results with higher accuracy but needs fewer computation resources.

Experimental Study on the Bubble Dynamics of Magnetized Water Boiling

Boiling heat transfer,as an efficient heat transfer approach,that can absorb a large amount of latent heat during the vaporization,is especially suitable for heat transfer occasions with high heat flux demands.Experimental studies show that the surface tension coefficient of pure water can be reduced sharply(up to 25%)when it is magnetized by amagnetic field applied externally.In this paper,magnetized water(MW)was used as the work fluid to conduct boiling heat transfer experiments,to explore the influence of magnetization on the boiling characteristics of pure water.The electromagnetic device was used to magnetize water,and then the MW was used as the work-fluid of boiling heat transfer experiments,the bubble dynamic behavior of the MW boiling was captured by a video camera,and the characteristics andmechanism were analyzed.It was found that at the same conditions,the boiling of MW can produce more vapor bubbles of smaller size than the water without magnetization,which leads to a higher heat-transfer efficiency.This indicates that magnetization can enhance the boiling heat transfer of pure water.Furthermore,the thermal conditions required by magnetized water when the boiling is started are lower than the non-magnetized water boiling,whichmeans the earlier start of nucleate pool boiling when using the MW.