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It is known that dispersion of a small amount of nanometer-sized particles in liquid can cause substantial improvement of the critical heat flux in pool boiling. Nanofluids (colloidal suspensions of nanoparticles in a base fluid) may therefore be used as the coolant in industrial applications in which high-heat-flux removal is needed. If it is supposed that the deposition of nanoparticles onto the heated surface during nucleate boiling is the main cause of the CHF enhancement in nanofluids, a certain time period is considered to be necessary for the CHF to be improved. In view of this, preliminary experiments were performed in the present work to investigate the time scale of CHF improvement; here, distilled water was used as a base fluid, and TiO2 and copper were selected as the materials of nanoparticles and heated surface, respectively. Under a particular experimental conditions of nanoparticle concentration and nucleate boiling heat flux (40 mg/l and 500 kW/m2), an approximate time scale of CHF improvement was 10 min; this value might not be negligibly short in some nanofluid applications. The measured time-variations of the wall superheat during the nucleate boiling in nanofluid suggested that longer time periods are required for the CHF enhancement at lower heat fluxes and lower nanoparticle concentrations. In particular, 40 min was not sufficient for the wall superheat to reach a steady-state value at the lowest nanoparticle concentration of tested in this work (9 mg/l).

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［ ［ he nonequilibrium molecular dynamics simulations are conductedfor the liquid wetting phenomena on a solid surface with a nanometer scale slit pore using SPC ／ E potentiaL The results show thaUhe wetting phenomena of the slit pore depend Qn the liquid molecule − solid atoms interaction intensity and the width of the slit pore ， There was a critical value of the liquid − solid interaction intensity which deterrr 〕ines the wetting phenomena of the slit pore ， and the critical value was changeable depending on the slit pore width ． The calculation results didn ' t show pronounced differences qualitatively under the present simulation condition compared with the previous results obtained using Lennard − Jones( LJ) potential for liquid molecules ．