Flow Boiling of Water on Nanocoated Surfaces in a Microchannel

Experiments were performed to study the effects of surface wettability on flow boiling of water at atmospheric pressure. The test channel is a single rectangular channel 0. 5 mm high, 5 mm wide and 180 mm long. The mass flux was set at 100 kg/m≤ s and the base heat flux varied from 30 to 80 kW/m≤. Water enters the test channel under subcooled condi tions. The samples are silicone oxide (SiOx), titanium (Ti), d iamond-like carbon (DLC) and carbon-doped silicon oxide (SiOC) surfaces with static contact angles of 26°, 49°, 63° and 103 °, respectively. The results show significant impacts of surface wettability on heat transfer coefficient. NOMENCLATURE Ah heat transfer area, m≤ Cp specific heat (J/kg K) Dh hydraulic diameter, m g gravity (m≤/s) G mass flux (kg/m≤ s) h heat transfer coefficient, W/m≤ K hlv latent heat of vaporisation, J/kg I current, A m& mass flow, kg/s q heat flux, W/m≤ qloss lost heat flux, W/m≤ N number of sections, T temperature, °C or K T average temperature, °C or K V voltage, V x vapour quality, ∆x variation of vapour quality, z z coordinate (m)